Field Fitter

Every table in the book, one tap away. If you already know what you're doing and just need the number, start here and skip the reading.

A table in this book gives you a number fast. Knowing what kind of number it is — and what beats it — is what keeps it from costing you a joint.

Working the table itself

• Find your size down the left. The first column is frozen on the wide tables, so it stays put while the rest scrolls.
• Wide tables scroll sideways. If a table looks like it stops at the edge of your screen, drag it left — there are more columns.
• Copper numbers are the ones worth noticing. Anywhere a figure is printed in copper it is either the one people use most or the one that breaks the pattern.
• Every dimension in this book is in inches unless the column head says otherwise. Millimetres are in 17.4.

What kind of number you are looking at

Between two rows

Most of these tables step in whole sizes, half degrees or hundredths. When your number falls between two rows, take the difference between them and split it by how far along you are.

Interpolating works on anything that changes smoothly — trig, ordinates, conversions. It does not work on fitting dimensions. A 5" take-out is not halfway between the 4" and the 6", and pipe schedules do not interpolate at all.

Weld pipe is the simplest material in this book to figure and the least forgiving to get wrong. There is no thread to back off and no socket to slide in — the pipe stops at the face of the fitting and the welder closes the gap. Get the number right and it fits. Get it wrong and you cut a new piece.

Everything in this section follows one joint from the print to the finished weld, in the order you actually do it. This page is the vocabulary you need before any of the rest of it makes sense.

Centre to centre: the most common dimension on prints

The most common measurement in the pipe world is centre to centre (C-TO-C or CTC), and it is the centreline of one fitting to the centreline of the next. Not the outside of one fitting to the outside of the next. Not face to face. The centre of one fitting to the centre of the next.

It is measured that way because the centreline is the only thing that does not change. Faces move when you swap a long radius elbow for a short one; the point where the two centrelines cross does not care what fitting you hang there. That crossing point is the working point, and it sits out in mid-air where there is no metal at all — which is exactly why you cannot hook a tape on it and why take-outs exist.

Take-out, in detail

Take-out is not the size of the fitting. It is how much of your dimension the fitting eats. Every elbow and tee has one, it is published in a standard, and it is a fixed nominal figure for a given size and pattern — which is what makes the math reliable. (The fitting in your hand can still be off by its tolerance; 1.11h.)

You will also hear it called centre to face or centre to end. Same number, three names. Where it comes from geometrically is the bend radius times the tangent of half the turn — worked through in 18.16 if you want it — but on the job you read it off 1.11 or, on a long radius 90, you do 1.5 times the size in your head.

The words, and what each one points at

C-to-C

Centre to centre. Working point to working point. How prints dimension.

Working point

Where two centrelines cross. A point in mid-air with no metal at it.

Take-out

Working point to the face of the fitting. What you subtract.

Face of fitting

The flat, prepped end of an elbow, tee or reducer, where your pipe stops.

Face of pipe

The cut and bevelled end of the pipe itself. On a butt weld joint the two faces sit a gap apart — they never touch.

Face of flange

The gasket surface. Flange dimensions and valve face-to-face figures run to it, and it is what lands against the mating flange.

TOP / BOP

Top of pipe and bottom of pipe — the outside, not the bore. BOP is what sits on the steel, so it is what racks get set to.

Invert

The inside bottom. Drainage grade is set to invert, and it differs from BOP by one wall thickness.

TOS

Top of steel. The beam, not the pipe.

Cut length

The raw piece of pipe, end to end, before it is bevelled. What you write on the cut list.

Root gap

The space between the two faces that the welder needs to get the root in. Usually 1/16" to 1/8".

Bevel

The angle ground or cut on the end of the pipe or fitting so the weld can reach the full wall. Standard is 37-1/2° off square (± 2-1/2°, ASME B16.25), so two bevelled ends make a 75° groove.

Land / root face

The flat strip left at the bore when you bevel — about 1/16".

Spool

Pipe with fittings already welded on, built at the bench and set as one piece.

Field weld

A joint deliberately left open so the spool can be adjusted in place. Marked FW on the iso.

The full trade glossary is 12.9, and the parts of a fitting are drawn and labelled in 19.1.

Why weld pipe has no add-back

What you measure and mark with

• 25 ft tapeOne tape for the whole job, and do not lend it. Two tapes can disagree a sixteenth over ten feet and both be in tolerance. Reading one properly is 19.2.
• Wrap-aroundThe single most useful thing in your bags on weld pipe. Squares a line all the way round a pipe, which nothing else will do. Full page at 1.4.
• Soapstone and a holderMarks on hot, oily, scaled steel where a marker will not. Keep it sharpened flat, not pointed.
• Silver streak or paint penFor marks that have to survive handling. Keep paint off anything about to be welded.
• Framing square and a combination squareChecking a face, marking square across, and finding the centre of a pipe end (19.7).
• Torpedo level and a 2 ft levelThe torpedo lives in your bags; the 2 ft is the one you trust on a run. Reverse-check both (19.3).
• Centre punchA soapstone line disappears the first time somebody handles the pipe. A punch mark does not.
• Hi-lo gaugeCheap, small, and the only way to know what the bores are doing once the outsides are lined up.
• Contour markerA washer with a soapstone through it. Scribes a fishmouth around anything round, faster than any layout.

The full weld-pipe kit — cutting, bevelling, fit-up and rigging — is 1.10.

The math is the easy part. Getting a good measurement to run it on is what gets people, because there’s usually nothing at the working point to hook a tape to.

Where the tape actually goes

Measuring off a square end

A square end is the most useful thing on a piece of pipe, because it is the only end you can hook a tape to and trust. Every layout in this section starts from one.

1. Check it is actually square before you measure anything off it. A wrap-around laid round the end will show you in five seconds — if the edges of the wrap line up with each other but not with the pipe end, that end is out. Full check in 1.6a.
2. If it is not square, make it square first. Cutting a piece to a perfect dimension off a crooked end gives you a perfectly wrong piece.
3. Hook the tape on the end and pull your dimension. The hook slides by its own thickness so it reads true both pushing and pulling — that slop is not wear (19.2).
4. Mark with a wrap line, not a tick. A tick tells you where. A wrap line tells you where and square, and it is the line you are going to cut to.

Taking a field weld measurement

The common job: two spools are hung, there is a gap between them, and you have to make the piece that closes it.

1. Get both ends supported and where they will finally sit. A spool resting on a come-along is not where it will be tomorrow.
2. Measure face to face — the actual gap between the two prepped ends, not centre to centre. This is the one place in weld pipe where face-to-face is the number you want.
3. Take off the two root gaps the welder is going to hold. Your piece has to be shorter than the opening by two gaps.
4. Take it in two places, 90° apart around the pipe, and take the same measurement twice. If the two readings differ, something is out of square or out of line — find out which before you cut.
5. Write it on the pipe along with the line number and which end is which.

Habits that keep field measurements honest

• Pull everything from one benchmark, not from the last thing you set. Chained measurements stack their errors, and on a long rack that is how the far end ends up two inches out with every individual measurement correct. String lines and how to use them: 19.5.
• Measure it twice, and the second time act like you have not seen the first number. Reading what you expect to read is the commonest error in the trade.
• Both people say the number out loud. "Forty-one and an eighth" beats a thumbs-up across a bay every time.
• Photograph anything you are about to cover up, with a tape in the shot.
• Check the print against the field before you cut, not after. When they disagree, that is a foreman question — 12.7.

One subtraction per end, and then whatever else sits in the joint. Most of the math on a weld spool starts here, and when a spool comes out long or short, this is usually where it went wrong.

What comes off, in order

The gap question — ask on day one

Welder preference — gap and land

The gap and the land are not yours to pick alone. They belong to the welder and to the procedure he is running, and they change the math and the fit-up both.

Check the answer before you cut it

• Is the cut shorter than the C-to-C? It has to be. On weld pipe, always.
• Is what came off roughly right? Two LR 90s on 6" take off 18". If your math took off 9" or 36", you used one take-out or doubled one.
• Did you convert once, at the end? Do the whole thing in decimal inches and go to a fraction on the final number only.
• Is it a negative number? Then the fittings are longer than the dimension and no pipe goes between them. That is a real answer — see the shortest-offset tables in 18.18 — and it means the print needs a different fitting or a different route.

A wrap-around is a flat strip of stiff, bendable material — usually roofing felt, heavy paper or a bought canvas or plastic wrap — that you wrap around the outside of the pipe until it overlaps itself. You run soapstone along its edge to mark a line all the way round. It is the cheapest tool in your bags and the only one that will put a truly square line around a pipe — which is the line you cut to, bevel to and measure from.

Why it works

A pipe end is almost never square, and a pipe is almost never perfectly round. Neither matters. A wrap-around references the pipe against itself, so as long as the two edges of the strip line up with each other, the line you scribe is square to the axis. That is not true of a square laid on the side, a tick mark by eye, or a line snapped along the top.

Marking a square line

1. Pull your dimension and mark it with a tick, anywhere on the pipe.
2. Lay the wrap on the pipe with its edge at the tick and roll it round until it laps itself.
3. Slide the lap until the two edges are dead on top of each other. Look down the lap, not across it. This is the step that decides whether the cut is square.
4. Hold it tight to the pipe — a wrap standing off the surface on scale or a weld seam walks the line sideways.
5. Scribe all the way round in one pass, keeping the soapstone flat against the wrap edge and tipped the same way the whole time.
6. Check it closes. Come back to where you started. If the line does not meet itself, your edges were not lined up — slide and do it again.

Everything else it does

What to use

Bought wrap-around

Heavy rubberised canvas or plastic, straight edges, a few feet longer than your biggest pipe's circumference. The right answer if you run big bore.

Roofing felt

The shop standard for generations. Stiff enough to hold an edge, cheap enough to cut up for templates.

Heavy paper or banner

Fine for small bore and for one-off templates you are going to mark on.

Ratchet strap

Works in a pinch on big pipe. Watch that it does not stretch unevenly — check the line closes.

Every method below cuts the same line. The line is the job — get it square and marked, then pick the tool that suits the size, the material and where you're standing.

Marking the line first

1. Pull your length and put one mark on the pipe. One mark, on the keep side. Don't ring the pipe by eye.
2. Lay the wrap on so its edge splits your mark. Roll it around until the two edges of the wrap lap over each other and line up dead even — that overlap is what makes the line square.
3. Look at the overlap before you scribe. If the edges step or spiral, the wrap is crooked and so is your line. Reset it.
4. Mark the full way around with soapstone, a paint marker or a scribe, holding the tip tight to the wrap edge the whole trip.
5. X the waste side so the kerf goes there and not into your piece.
6. Take the wrap off and check. Measure from the square end to the line at four places around the pipe. All four the same means you're square.

Picking the method

Pick one:

• 1.5aOxy-fuel — the torch and the gasesHow burning steel works, the outfit, the bottles and handling them›
• 1.5bOxy-fuel — setting up, lighting, shutting downOrder of operations, pressures, flame types, bleeding down›
• 1.5cOxy-fuel — making the cut, reading the facePierce, travel speed, drag lines, and what a bad face tells you›
• 1.5dPlasma cuttingAmperage by thickness, air, consumables, stainless and aluminum›
• 1.5eBandsaws — portable and horizontalBlade TPI, speed, clamping, and why it's the best cut you can make›
• 1.5fAbrasive chop saw and cold sawFast and dirty versus slow and square›
• 1.5gGrinder and cut-off wheelScoring the line, wheel types, and the ways they hurt people›
• 1.5hTrack burners, clamshells and bevelersBig bore, in-service and code work where the face has to be machined›

A cutting torch does not melt steel. It heats one spot until the steel is hot enough to burn, then blows a jet of pure oxygen at it — and the steel catches and burns, fast, giving off its own heat as it goes. The stream blows the molten oxide out the bottom and the torch walks the fire along your line.

That is the whole trick, and it is why the torch only works on carbon steel. It is also why a torch will cut 6" plate its flame alone could never melt through — that much steel soaks the heat away faster than the flame puts it in. Once the steel lights, the steel is doing the burning and the flame is only keeping up.

The rig

Oxygen

Green bottle, tall and thin, and under very high pressure when it is full — a couple of thousand psi. It does the cutting.

Fuel gas

Acetylene is the common one — red bottle, shorter and fatter, packed with a porous filler soaked in acetone. Propane and propylene also cut, but they need their own tips.

Regulators

One per bottle. The high gauge reads what is left in the bottle; the low gauge reads what you are sending down the hose.

Arrestors

A flashback arrestor and a reverse-flow check valve on each line, at the regulator. This is the part people leave off, and it is the part that saves the bottle.

Torch

Handle, plus a cutting attachment with two preheat knobs and the oxygen lever. The lever is a separate circuit — it is the cut.

Handling the bottles

• Cap on whenever a bottle is not hooked up, and never lift a bottle by the cap.
• Stand them up and secure them — chained, strapped or in a cart. A cylinder that goes over and snaps its valve off becomes a rocket.
• Never use a bottle as a roller, a support or a ground. An arc strike on a cylinder wall condemns it.
• Acetylene stands up, in use and in storage. It is full of acetone and lying it down lets the acetone find the valve. If a bottle has been down, stand it up for at least an hour before you use it.
• In storage, oxygen and fuel get separated — 20 ft apart, or a noncombustible barrier at least 5 ft high with a half-hour fire rating between them (OSHA 1910.253).
• A bottle that has been in a fire, or has a hot or frosted valve, gets left alone and reported. Clear the area.

Same order, every time, cold outfit to cutting. It takes about three minutes and every step in it is there because somebody skipped it once.

Setting it up

1. Stand the bottles up and secure them before the caps come off. Chained, strapped or in a cart — something that will not tip.
2. Crack each cylinder valve for an instant, pointed away from you and from anything that could ignite, to blow dirt out of the seat before the regulator goes on.
3. Back the adjusting screw all the way out on both regulators so they are closed, then fit them.
4. Open the oxygen valve slowly, all the way up until it seats at the top. Slowly — a fast open slams the regulator, and that has started fires.
5. Open the fuel valve about three-quarters of a turn, no more than one and a half, and leave the wrench on the stem so anyone can shut it in one motion.
6. Set the working pressures with the gas flowing — open the torch valve, set the regulator, close it. A pressure set on a dead line reads high and drops the moment you cut.
7. Purge each hose separately, then leak test every joint with soapy water. Never with a flame.

Typical starting pressures and tip sizes

Typical published figures for one common one-piece acetylene tip series, read at the regulator. The chart that came with your torch governs — tip series differ, propane and propylene tips differ more, and hose length and diameter move the numbers. Start in the middle of the range and trim by what the flame and the cut are doing. The kerf column is the one you need for a cut sheet: see 1.5c.

The flame

1. Open the fuel valve on the torch about a quarter turn and light it with a striker — never a lighter, never a cigarette, never somebody else's cut.
2. Open the fuel until the smoke stops and the flame just stops jumping away from the tip.
3. Open the preheat oxygen until the white feather pulls right back into a sharp cone. That is neutral, and it is what you cut with.
4. Press the cutting lever and look again. The lever pulls oxygen and will usually push the flame carburizing. Re-trim with the lever held down, so it is neutral while it is actually cutting.

Shutting down

1. Cutting oxygen off, then preheat oxygen, then fuel — oxygen first at the torch, so you never leave a fuel-rich flame crawling back.
2. Done for the day: close both cylinder valves, bleed each line at the torch until both gauges read zero, then back both adjusting screws out.
3. Coil the hose off the floor and put the caps back on the bottles.

Leaving a regulator loaded overnight is how a diaphragm creeps and how a hose is found soft in the morning. Thirty seconds now.

Everything about a good burn comes down to two things: how far the cone is off the steel, and how fast you walk. Get those right and the torch does the rest. Get them wrong and you spend twice as long grinding as you spent cutting.

Starting at an edge

1. Hold the inner cone about 1/16" off the steel — close, but not touching. Touching pops the tip and loads it with slag.
2. Preheat the corner until it is a bright cherry red, and be patient. Nearly every bad cut starts with a lever pressed too early.
3. Press the lever smoothly — all the way, in one motion. Feather it and the cut starts wandering.
4. When the sparks blow out the underside, you are through. Now start moving.
5. Walk at the speed the sparks tell you. A clean cut throws its spark stream nearly straight down out the bottom. If the sparks come back up at you, you are going too fast and it has not gone through.

Piercing a hole in the middle of a plate

1. Preheat one spot to bright cherry, then lift the tip another 1/4" or so.
2. Crack the lever slowly while you tip the torch off vertical, so the first blast throws slag sideways and away instead of straight back up into the tip.
3. Once it blows through, bring the torch upright, come back down to height, and go where you are going.

Piercing is where tips get ruined and where people get burned. Slow lever, tilted torch, and nothing of yours directly above the hole.

What the face is telling you

• Near-vertical drag lines, square top edge, slag knocks off with a tap. That is a good cut. Do exactly that again.
• Lines rake hard backward and the bottom edge is still hanging on. Too fast — the cut never got all the way through. Slow down.
• Top edge rounded and melted, kerf wide. Too slow, or the cone is too close. Pick up the pace and lift about 1/16".
• Hard slag welded to the underside that will not knock off. Too slow, or the cutting oxygen is low. Speed up, and re-check the pressure with the gas flowing.
• The cut wanders off the line. Freehand with nothing to rest on. Brace both hands, or use a guide or a track.
• Top edge blown wide and ragged. Oxygen pressure too high for the tip. Back it off, or go up a tip size.
• The cut keeps going out. Plugged tip, or the steel is not hot enough. Clean the tip with a tip cleaner, never a drill bit, and preheat longer.
• Popping and spitting at the tip. Tip overheated, held too close, or slag in the orifice. Shut down, cool it, clean it.

Cutting pipe

• Wrap it and mark it. A freehand line around a pipe is never square and you will chase it all the way round. Wrap template, soapstone, then cut. Layout is 15.1 onward.
• Aim at the centreline of the pipe, not straight down — you want the stream pointing at the middle so the cut stays square through the wall as you roll around.
• Roll the pipe if you can. Cutting at 12 o'clock with the pipe turning under you beats crawling around it, and the slag falls away instead of onto the cut.
• Burn inside the line and grind out to it on anything that has to be welded. The torch gets you close; the grinder gets you the fit.
• Over about 4", use a track or a pipe cutting machine for anything that has to be square and bevelled. See 1.5h.

Bevelling with the torch

• Tip the torch to the bevel angle — 37½° from the pipe end for a standard V — and hold it there the whole way round. A guide or a bevelling attachment is worth its weight.
• A torch bevel is a rough bevel. It always needs the grinder afterwards to true the angle, clean the oxide off the face, and leave the root face (land), which the torch cannot produce.
• Grind the oxide scale off before anybody welds on it. A weld laid over torch scale is a weld with slag rolled into the root.

An arc squeezed through a small hole and blown by gas. It melts the metal and the jet blows it out the back. It doesn't care whether the steel will oxidize, so it cuts everything a torch can't: stainless, nickel alloy, aluminum, copper, cast.

Amperage against wall

"Clean cut" is the number that matters. Sever capacity means the machine will part the metal and leave you a face you'd be ashamed of. Size the machine to your heaviest wall at the clean-cut rating, not the sever rating.

Air is half the machine

• Dry. Water in the line eats electrodes and wanders the arc. A desiccant dryer or a coalescing filter at the machine, not just at the compressor.
• Clean. No compressor oil. Oil carbons the nozzle and, on stainless, contaminates the weld prep.
• Enough of it. Check the machine's CFM at pressure. A small compressor that keeps up with an impact gun will starve a 65 A torch, and a starved torch double-arcs and burns consumables in minutes.
• Bottled gas — nitrogen or argon/hydrogen — gives a better face on stainless and aluminum if the work is worth it.

Consumables, and how they fail

Change the electrode and nozzle as a set. A new nozzle on a dished electrode will be a dished nozzle by lunch.

Cutting

1. Ground clamp on clean bare metal, close to the cut. Paint and rust make the arc hunt.
2. Drag tip or standoff. A drag tip rides the pipe — steadier, easier around a line you're following. A standoff tip sits about 1/8" off and gives a squarer face.
3. Pierce at an angle. Start the arc tipped 30–45° away from you so the blow-back goes past the nozzle, then roll upright once you're through. Piercing straight down blows molten metal back into the tip.
4. Start off the pipe where you can — edge starts are easier on consumables than pierces.
5. Follow the line, don't chase it. One steady walk around, rolling the pipe or walking yourself around it. Stopping mid-cut leaves a notch you'll be grinding out.
6. Cut to the waste side. Plasma kerf is about 1/16" to 1/8" depending on amperage.

Reading the cut

• Dross stuck along the bottom, soft and rolled — too slow, or too much amperage. Speed up.
• Hard dross welded to the bottom edge — too fast, or the arc isn't getting through. Slow down or turn it up.
• Cut face bevelled the same way all the way round — worn swirl ring, or the torch isn't perpendicular.
• Wandering, sputtering, won't pierce — electrode, air pressure, or a bad ground, in that order.

The best cut you can make on a jobsite. Cold, square, no slag, no heat-affected zone worth arguing about, and on stainless and alloy it's often the only cut the spec will let you make.

Blade teeth

Three teeth in the wall at all times. That's the whole rule. Fewer and a tooth straddles the wall and snaps off; more and the gullets pack up and the blade rubs instead of cutting.

Bi-metal, not carbon. A bi-metal blade costs twice as much and lasts five times as long, and it's the only thing that will stay sharp in stainless.

Blade speed

On a variable-speed portaband that's the dial: top speed for aluminum, mid for carbon, slow for stainless. Running stainless fast work-hardens it under the tooth and the blade stops cutting and starts polishing.

Making the cut

1. Break a new blade in. First two cuts at half your normal feed pressure. It knocks the burr off the fresh teeth and doubles blade life.
2. Clamp the pipe so it cannot roll. A vee block, a chain vise, a pipe stand with a dog, or a portaband jig. A pipe that rotates mid-cut ruins the blade and the cut together.
3. Let the weight of the saw feed it. Steady pressure, no leaning. If it isn't cutting, the blade or the speed is wrong, not the pressure.
4. Watch the chip. Tight curls of solid swarf means you're right. Powder means too fast or too much speed. Thick blue chips mean you're forcing it.
5. Support the drop. The last 1/4" is where the offcut hangs and binds the blade. Have a hand or a stand on it.
6. Don't back up in the kerf with the blade running. Stop it, then pull out.

Horizontal saw at the bench

• Square the vise once at the start of the day against a known square and re-check after any angle cut. Every out-of-square piece for the rest of the day comes from here.
• Stop block for repeat lengths, and measure the first one out of the box before you run twenty.
• Coolant on for stainless and alloy. Dry-cutting stainless on a big saw is how blades die.
• Dedicate a blade to stainless so you're not dragging carbon particles into a stainless prep.

Going wrong

• Cut comes out out-of-square across the wall — blade guides worn or loose, or blade tension low.
• Blade wanders out the back of the pipe — dull blade, or too much feed pressure.
• Teeth stripped in a row — too coarse for the wall, or the pipe moved.
• Blade breaking at the weld — wheel diameter too small for that blade, or over-tensioned.

Two machines that look alike and are nothing alike. One is fast and rough, one is slow and dead accurate.

Abrasive chop saw

A spinning abrasive wheel that grinds its way through. Fast on small bore, cheap, and it will get you through a day — but it burns the end, throws a heavy burr inside and out, and drifts out of square the thicker the wall gets.

• Check the wheel RPM rating against the saw before it goes on. Over-speeding a wheel is how it comes apart.
• Look the wheel over every time. Chips, cracks, a soaked wheel that's been left in the rain — all of them go in the bin.
• Clamp both sides of the cut. A chop saw grabs, and an unclamped pipe becomes a projectile.
• Let it cut, don't lean on it. Pressure glazes the wheel and bows the cut.
• Fire watch. The spark stream carries 20 feet and lands where you're not looking. Screens, an extinguisher, and somebody watching for at least 60 minutes after you stop, per NFPA 51B (full hot-work rules in 12.4).
• Never a carbon-steel wheel on stainless. Separate wheels, marked, kept apart.
• Expect to dress the end. Plan on grinding the face back to square and deburring both sides before it's fit to prep.

Cold saw

A toothed carbide or HSS blade turning slowly with coolant on it. Shop machine, bench-mounted, and the cut comes off square, bright and nearly burr-free — ready to prep with almost no dressing.

• Slow RPM, heavy feed. It should make chips you can pick up, not sparks.
• Coolant every cut. Dry cutting kills a blade that costs more than the saw's day rate.
• Match the blade to the material — carbon-steel blade, stainless blade, aluminum blade. They are not interchangeable and the tooth geometry is the reason.
• Clamp tight and short. Vibration chips teeth, and one chipped tooth starts a chain.
• Worth it when you're cutting a list of repeat lengths, working in stainless or alloy, or the spec won't take a heat-affected edge.

The tool that's always on your belt. It'll cut anything up to about 3" cleanly if you work the line instead of attacking it, and it's the fastest way to trim a quarter inch off a piece that's long.

Working the line

1. Score the whole way around first, about a third of the way through the wall, keeping the wheel on the waste side of the line. One trip around, light.
2. Second trip around, deeper. The groove you already cut steers the wheel and keeps it square.
3. Third trip through. Roll the pipe toward you so you're always cutting at a comfortable angle instead of reaching over the top.
4. Support the drop before the last bit of wall goes. A falling offcut pinches the wheel and the wheel goes wherever it wants.
5. Wheel square to the pipe, not to you. Watch the wheel against the pipe wall, not the sparks.

Going all the way through in one place first is what puts a cut out of square. The wheel starts leaning the moment it's buried, and by the time you're round the far side you're an eighth off.

Wheels

• Wheel RPM rating must be equal to or higher than the grinder's max RPM. Every time, before it goes on.
• Guard stays on. A guard is what stands between you and a wheel that lets go at 11,000 rpm.
• Dedicated stainless wheels, contaminant-free (marked "Fe/S/Cl free"), and never used on carbon steel. Iron embedded in a stainless prep rusts and cracks.
• Store wheels flat and dry. A wheel that's been rattling loose in the bottom of a gang box is a wheel you throw away.

When the pipe is too big, the tolerance too tight, or the job won't allow a spark, the cut stops being handwork and becomes a machine setup. These cost time to rig and pay it back in a face you don't have to fix.

What's out there

Why cold cutting gets specified

• No heat-affected zone. Duplex, nickel alloy and some stainless grades change properties when you heat them. Machining doesn't.
• No ignition source. In a live unit, a spark is the whole argument.
• No cross-contamination. Tool bits and a clean setup instead of grinding dust and slag in the bore.
• The face comes off machined. Square, the right bevel angle, the right land, every joint the same — which is what the CWI is going to ask for.
• Repeatability. Forty joints on a tie-in and every one identical beats forty joints ground by five different hands.

Setting one up

1. Mark and check the line first exactly as you would by hand. The machine cuts where you clamp it, square or not.
2. Clamp off a good reference. Out-of-round pipe, a dented OD or scale under the jaws throws the whole cut.
3. Dial it in. Most machines let you sweep an indicator around before you commit. Do it — it's five minutes against re-prepping a 24" joint.
4. Support both sides before you break through. The drop on big bore is a rigging job, not a catch.
5. Check the prep against the WPS when it comes off — angle, land, and square — before the fitter behind you starts pulling to it.

The cut got you close. The prep is what the welder actually welds. Four things have to be true before the joint is fit to tack: square, clean, the right bevel, and the right land.

• 1.6aChecking the end is squareWrap, square, four-point measure — and what to do when it isn't›
• 1.6bBevel geometry — angle, land, gap, hi-loThe cross-section, with a step-through walkthrough›
• 1.6cCutting the bevel — tools and techniqueGrinder, flap disc, beveling machine, torch bevel, file›
• 1.6dCleaning and deburringBack off the OD and ID, get the burr out of the bore, what “clean” means›
• 1.6eGap and land — what your welder wantsBy process and by hand. Ask before you prep twenty joints›

An end that isn't square gives you a root gap that's wide at 12 and shut at 6, and the welder will be fighting it for the whole joint. Check it before you bevel, not after.

Three ways, quickest first

1. Wrap-around. Wrap it round the pipe right at the end, lap the edges even, and slide it until the edge just touches the longest point of the cut. Now look down the wrap edge. Daylight between the edge and the pipe end means it's out. The daylight is on the short side, and the widest gap is the whole error.
2. Framing square or a combination square. Sit the blade along the pipe and the head across the face. Check it at 12, 3, 6 and 9. Good on small bore; a big square on a big pipe reads the crown, not the face.
3. Four-point measure. Measure from a known-square reference (the far end, or a scribed ring) to the cut end at 12, 3, 6 and 9. Four readings the same is the only proof that works on any size.

How much is too much

The spec beats the table. Most codes and shop WPSs call out squareness and root-gap tolerance directly. Where one exists, that's the number.

When it's out

• A little out — take it off with a flap disc or a grinder, working the long side and checking as you go. Re-check all four points.
• Badly out — re-cut. Take a new square line 1/4" back and start over. Chasing a bad face with a grinder wastes more pipe than a clean recut.
• Out because the saw is out — stop and square the vise. Every piece behind it is wrong too, and they're all still in the rack.
• Out and there's no length left — tell the foreman now. A short piece found at fit-up is a problem; a short piece found at the weld-out is an incident report.

The fitter owns the joint before the welder strikes an arc. A perfect weld on a bad fit-up is still a bad joint.

Bevel angle

37-1/2° ± 2-1/2° per side — 75° included on a standard V-groove

Root face

1/16" ± 1/32", flat and even the whole way around

Root gap

3/32" to 1/8" for a stick root — match the rod they're rooting with. TIG runs tighter (1.6e)

Hi-lo

1/16" max internal misalignment is the usual limit — B31.1 sets it (127.3), B31.3 leaves it to the WPS. Gauge it, don't thumb it.

Squareness

About 1/32" across the end on small bore, up to about 1/16" on 8" and up — table in 1.6a

Getting the bevel

• Bevelling machine or a torch on a track for anything over 4" (the torch: 1.5a to 1.5c). Freehand torch work on big bore costs more in grinding than the machine costs to set up.
• Grind the bevel before you fit, never after you tack.
• Dress the inside — knock the burr and any slag off the ID. It ends up in the root otherwise.
• Wire-wheel the prep clean for an inch back on both faces. Mill scale, paint and oil all end up as porosity.
• Stainless gets its own wheels and brushes. A carbon-contaminated stainless weld rusts from the inside. Keep the tools separate and marked.

Clean means clean

Most porosity is not the welder. It is something that was on the steel when he struck the arc, and it came from the fitter.

• Back an inch, inside and out, both pieces. Bright metal — not "mostly bright", not "clean enough".
• What has to come off: mill scale, rust, paint, primer, galvanize, cutting oil, marker, grease, moisture, and the soapstone you laid the line out with.
• Torch-cut ends carry oxide scale. The torch leaves a hard glassy layer on the face that a wire wheel will not touch — it has to be ground off (1.5c).
• Grind, then wipe. Grinding drives contamination around as much as it removes it. A rag and solvent afterwards on anything critical, and let it flash off before you strike.
• Galvanize gets ground back a couple of inches, not just to the edge. Zinc vaporises ahead of the arc and gets into the weld anyway — and into the welder (12.4).
• Moisture counts. A cold pipe brought into a warm shop sweats. Condensation in a bevel is hydrogen in the weld, and on heavy wall that is how you get cracking a day later.
• Cap the ends between prep and fit. An open bevel in a shop collects grinding dust, and an open bevel outdoors collects rain.

The target is a 37.5° face and a land of about 1/16" unless the WPS says different. How you get there depends on what's in the truck.

The tools

Bevelling with a grinder

1. Set your angle once and hold it. Rest the guard on the pipe so the wheel sits at the angle, and let the pipe roll under it rather than swinging the grinder around the pipe.
2. Work in trips, not in one spot. Go all the way round light, then all the way round again. Digging one section deep is how you get a bevel that's 30° at 12 and 45° at 6.
3. Leave the land alone until the end. Bevel down to about 1/8" of land, then take the last bit off deliberately with the edge of the wheel or a file.
4. Check with a gauge, not a thumb. A bevel gauge or a Hi-Lo welding gauge every quarter turn.
5. Look at the land in the light. It should be an even bright ring the whole way round. A land that's 1/8" at 12 and a knife edge at 6 will burn through at 6.

Clean means bright metal, inside and out, at least an inch back from the bevel. Everything else — scale, rust, paint, oil, cutting fluid, marker — ends up in the weld as porosity or a crack.

The inside burr

Cutting rolls a lip of metal into the bore. Leave it and it does three things: it stands proud into the root so the welder can't see the joint, it breaks off later and travels down the line into a pump or a valve seat, and on a flow-critical line it throws off the hydraulics.

1. Feel it with a finger (carefully — it's sharp) or run a rag round the bore and see what catches.
2. Take it off with a half-round file, a deburring tool or a flap wheel, working from inside out so the swarf falls out of the pipe, not into it.
3. Chamfer the bore edge lightly — a slight break, not a second bevel. You're removing the lip, not machining the ID.
4. Blow it out or swab it. Every filing you left in the bore is a filing in the root of the weld.
5. Cap or tape the end if the piece is going to sit. Debris and rain in an open bore costs you the prep you just did.

What "clean" means

Brushes and wheels

• Stainless-bristle brushes for stainless, carbon for carbon, and never the same brush on both. A carbon brush leaves iron in a stainless prep and it will rust in service.
• Mark your brushes and keep them in separate bags. This is the single most common contamination failure on a stainless job.
• Solvent before abrasive, every time, when there's oil involved.
• Don't burnish. A wire wheel that polishes instead of cutting is smearing contamination flat, not removing it.

The gap and the land are the two numbers that decide whether the root pass goes in easy or turns into a fight. They belong to the welder, not to you — ask before you prep the second joint.

Starting points by process

The questions to ask, once, at the start of the job

• What gap do you want?And is that the same on the 2" as it is on the 8"?
• How much land?Knife edge, 1/16", or heavier?
• Bevel angle — standard 37.5°, or do you want it opened up?Some hands want 40°+ on heavy wall to get a rod in.
• Do you want it bridged or open?Some welders want tacks only; some want bridge tacks they'll grind off.
• Do you want the tacks feathered, or will you grind them?Settle it once instead of arguing per joint.
• Purging — who does it, and do you need a dam?If it's stainless or alloy, this changes your fit sequence.
• How clean, how far back?An inch is the default; some want two.

Why the numbers are what they are

• Too tight a gap and the root doesn't fuse through — lack of penetration, and it's a repair that means grinding the whole root out.
• Too wide a gap and the root falls through or burns back — excess penetration, icicles, and a bore full of suck-back.
• Too heavy a land and the arc can't melt all the way through it — incomplete penetration, the unmelted land left as a line straight down the middle of the root.
• Knife-edge land and it melts away before the puddle establishes — blow-through and a hole to fix.
• Uneven gap round the joint — the welder changes technique four times in one pass. This is the one that's your fault, and it comes from an end that wasn't square.

Fit-up is where the cut list becomes a spool. Everything here is about holding two prepped ends in the right relationship long enough to tack them, and then proving you still have the dimension you started with.

Setting the root gap

1. Bring the faces together dry first and look at the gap the whole way round. If it opens and closes, one end isn't square — go back to 1.6a before you tack anything.
2. Set the gap with something you can measure. A piece of filler wire of the right diameter, a cut nail, a spacer wedge, or a Hi-Lo gauge. Never by eye.
3. Check hi-lo all the way round. The two IDs have to line up, not the two ODs — wall thickness varies. A Hi-Lo gauge reads it directly; a straightedge across the OD lies to you.
4. Pull it in with alignment tools if it fights: a cage clamp, a chain clamp, a spider, or a lug-and-wedge on big bore. Don't force a joint closed with a tack — it'll crack.
5. Get the spacers out before the last tack goes in. A cut nail welded into the root is a hard inclusion and a repair.

Tacking

• Three tacks on 2" and under, four at 12, 3, 6 and 9 up to 6", and more above that — sizes and lengths in 1.8a. On a fixed joint, ask the welder where he wants them: many want them off 6 o'clock, where the root starts (1.8m).
• Tack opposite, never in sequence. 12, then 6, then 3, then 9. Going around the circle pulls the joint closed on one side.
• Tacks about 1/2" to 3/4" long on most pipe (1.8a has them by size), full penetration, and feather both ends so the root pass ties in and runs over them.
• A tack is a weld. Same rod, same preheat, same procedure, same welder qualification. Cracked tacks get ground out, not welded over.
• Bridge tacks on light wall if the joint wants to close — but grind them off before the root, don't weld through them.
• Purge before you tack on stainless and alloy. Once four tacks are in, getting a dam past them is a different job.

Keeping it straight

• Sight down every spool. Hold one end up, close an eye, look through it. A dogleg you can see is 1/4" or more.
• Set the level on plain pipe, clear of the long seam and the weld caps. Either one will rock the level and lie to you.
• Two fittings on one nipple: set them in plane with a straightedge or a framing square across both faces before you tack the second. Out of plane is the hardest error to find and the most expensive to fix.
• Check alignment after tacking and again after the root. Welds pull.

Seam orientation

• Roll the longitudinal seam up where you can see and inspect it.
• Keep it out of the bottom third of a horizontal line.
• Stagger seams joint to joint so they don't line up across a weld.
• Never put a seam where a branch or an olet is landing.

Rechecking before it goes to the welder

• Centre to centre against the cut listTape on it, not memory. Both directions if it's a two-fitting piece.
• Gap even all the way roundSame feeler, same wire, four places.
• Hi-lo inside toleranceGauge it, don't eyeball the OD.
• Flange bolt holes two-holedStraddling the centreline unless told otherwise.
• Fittings in planeSquare or straightedge across both faces.
• Sighted through for doglegBoth ends, both ways.
• Spacers and clamps removedNothing left in the root.
• Prep still cleanIt's been handled since you cleaned it. Wipe it again.

The joint is fit and tacked. What follows is the welder's work — but you're the one holding the pipe, checking the dimension and answering to the inspector, so it pays to know what's happening in there and why the hand in the hood keeps asking you for things.

• 1.8aTacking and tack prepA tack is a weld. Size, spacing, feathering, and when to grind them out›
• 1.8bThe root — quartering out and root prepPositions, quarters, keyhole, starts and stops, purging›
• 1.8cFill passes — clean and tied inInterpass cleaning and temperature, bead placement, tie-in›
• 1.8dThe cap and cap prepLeaving room for it, width, reinforcement limits, toes›
• 1.8eWeld defects, inspection and testingWhat gets rejected, what a CWI looks at, VT / PT / MT / RT / UT›
• 1.8fSMAW — stickPolarity, amperage by rod size and type, rod storage›
• 1.8gGTAW — TIGTungsten, gas, polarity, amperage, purging›
• 1.8hGMAW — MIGTransfer modes, wire and gas by material, starting numbers›
• 1.8iFCAW — flux coreSelf-shielded versus gas-shielded, polarity, starting numbers›
• 1.8jMachine setup — starting numbersAll four processes on one page›
• 1.8kReading a filler metalDecode E7018, ER70S-6, E71T-1, 308L — step-through walkthrough›
• 1.8lThe four processes at a glanceWhich one gets used where, and why›
• 1.8mWhat the welder needs from youThe fitter's side of the deal›
• 1.17Weld symbols — reading the calloutWhat the print is telling you to prep, weld and inspect›

A tack is a weld. Same filler, same preheat, same procedure, same qualified welder — and it stays in the joint forever, because the root pass runs straight over it.

Before the first tack

• Prep clean and brightAn inch back, OD and ID. Re-wipe it — it's been handled.
• Gap and hi-lo checkedEven all the way round, IDs lined up.
• Purge in and flowingStainless, duplex, nickel, chrome-moly. After the tacks it's much harder.
• Preheat to the WPSHeavy wall, chrome-moly and cold weather. Check with a temp stick, not a hand.
• Ground clamped close and cleanNot through a chain fall, not through a bearing.
• Rod out of the oven, wire cleanLow-hydrogen out of the oven is good for 4 hours on E7018 (AWS D1.1), less on higher-strength rods — not a shift. See 1.8f.

Size and spacing

Tack opposite, never around. 12, then 6, then 3, then 9. Working around the circle walks the gap closed on one side and open on the other, and once it's tacked you own it.

On a fixed joint, ask first. The root starts at 6, and a lot of welders don't want to start on a tack. They'll ask for 10, 2, 4 and 8 instead — same rule, still opposite pairs.

Tack prep

1. Full penetration. A tack that only sits on the bevel faces is a cold lap waiting to be found by RT.
2. Feather both ends with a grinder or a file — taper them down to nothing so the root pass can run up onto the tack and fuse it instead of bridging over it.
3. Take the crown off. If the tack stands proud into the groove the root pass will ride over it and leave lack of fusion underneath.
4. Clean each tack — chip the slag, wire brush it, and look at it before you go to the next one.
5. Any crack, any porosity — grind it out completely and tack again. Welding over a cracked tack propagates the crack into the root.

Bridge tacks and spacers

• Bridge tacks sit across the top of the groove on light wall to stop the gap closing. They are temporary — grind them off before the root, and dress the base metal where they sat.
• Spacers (wire, cut nails, wedges) come out before the last tack. Nothing gets welded into the root that isn't filler metal.
• Never tack a clamp, lug or dog to a code line without checking — the removal and dressing of those attachments is usually specified, and on some materials it needs NDE afterwards.
• Arc strikes outside the joint are rejectable. Strike in the groove, not on the pipe.

The root is the pass that gets x-rayed, the pass that leaks, and the pass everything else sits on. On a fixed joint you can't turn, it gets run in quarters.

Quartering out

On a fixed horizontal pipe (5G) the welder can't reach all the way round in one go, and the position changes from overhead at the bottom, to vertical up the sides, to flat at the top. So the joint is broken into quarters and each quarter is run as its own weld:

• Uphill (6 to 12) is the usual direction for a code root — more penetration, more control, slower.
• Downhill (12 to 6) is used on pipeline work and thin wall with 6010 — fast and shallow. The WPS has to call for it and the welder has to be qualified downhill; an uphill ticket doesn't cover it.
• Balance the halves. Running one whole side before the other pulls the joint out of round and out of line. Alternate sides.
• 2G (pipe vertical, weld horizontal) is run all the way round in one direction; 6G (45° fixed) is the test position because it hits every one of these at once.

Starts, stops and tie-ins

1. Grind every stop to a taper before you restart on it. A square crater is a lack-of-fusion notch and a crack starter.
2. Restart back on the good weld, not in the crater, and walk forward into it.
3. Feather the tacks as you come to them — the root has to fuse through the tack, not ride over it.
4. Break the keyhole cleanly. Fill the crater, don't just snap the arc off — a crater crack in the root is the most common RT reject there is.
5. Clean each quarter before the next — slag on a tie-in is an inclusion on the film.

The keyhole is the little hole out ahead of the puddle that tells an open-root welder they've got full penetration. Too big and the root falls through; gone and the root isn't tying in. Even, consistent keyhole = even, consistent root — and that only happens if your gap was even to start with.

Root prep and purging

• Carbon steel open root — no purge; the root oxidizes and that's accepted.
• Stainless, duplex, nickel alloys and titanium — purge or it sugars. A sugared root is scale on the inside of the bore and it is a reject, not a cosmetic issue. Higher chrome-moly (P91, and P22 on many specs) gets a purge on a TIG root too — check the WPS.
• Purge gas is argon (or nitrogen on some austenitics). Dam both sides, fill from the bottom, vent at the top, and get the oxygen down — typically below 0.1% (1000 ppm), tighter for titanium.
• Leave the purge running through the root and the hot pass at minimum.
• Water-soluble dams dissolve on hydrotest; tape and cardboard dams have to come out. Know which you used and write it down.

Hot pass

The second pass, run hot and fast right on top of the root. It burns out any small slag or porosity in the root, ties the root into the sidewalls, and gives the fill passes something solid to sit on. On a 6010 root it's not optional — grind the root first, then hot-pass it before it cools if the procedure allows.

Fill is where a good joint is quietly won or lost. Two things decide it: everything is clean before the next bead goes on, and every bead ties into the one beside it and the sidewall behind it.

Keeping it clean

• Chip and brush every pass, every time. Not the good passes — every pass. Slag left in a corner becomes an inclusion on the film that nobody can see from the outside.
• Get into the toes. Slag hides where the bead meets the sidewall, which is exactly where the next bead has to fuse.
• Grind out anything that looks wrong as soon as you see it. Ten seconds now against gouging out four passes later.
• Wire brush the right brush. Stainless brush on stainless, carbon on carbon, and never swap.
• Watch for a slag trap — a bead that leaves a deep notch beside it. Flatten it or grind the notch out before you weld beside it.

Interpass temperature

These are typical field numbers — the WPS governs. Check with a temp stick or a contact pyrometer an inch from the groove, and check before each pass, not once at the start.

Bead placement

• Stringers over weave on most pipe work, and on nearly all stainless and alloy. Weaving puts too much heat in and widens the heat-affected zone.
• Stack them against the sidewall first, then work across. Each bead should overlap the one before by roughly a third to a half.
• Watch the toe angle. A bead that piles up steep against the sidewall leaves a notch the next pass can't reach — that's where lack of fusion comes from.
• Undercut along the sidewall gets fixed now, not at the cap. Once it's buried it's a rejectable notch nobody can see.
• Keep the groove flat as it fills. A humped fill leaves the cap nowhere to go and the welder ends up with excess reinforcement.

Roughly how many passes

The cap is the only pass the world ever sees, and it's the one the inspector measures. It also can't fix anything underneath it.

Prepping for the cap

1. Stop the fill about 1/16" below flush with the pipe surface. Fill flush and the cap has to sit entirely proud — that's how you end up over the reinforcement limit.
2. Flatten the fill. Grind out any hump, any deep valley between beads, any slag trap.
3. Clean the toes back onto base metal so the cap has bright steel to fuse to at both edges, about 1/8" past where the cap will land.
4. Check the groove is even the whole way round — a groove that's deep at 6 and shallow at 12 gives a cap that's high at 6 and thin at 12.
5. Check interpass temperature one more time before you strike.

Running it

• Stringers, overlapping by about half, working the same direction in each quarter as the rest of the joint.
• Cap width = groove width plus about 1/16" each side. Wide enough to tie in past the toes, no wider — extra width is heat you didn't need to put in.
• Pause at the toes just long enough to fill them. Undercut at the cap toe is the single most common visual reject.
• Keep the crown low and even. A cap you can run a gloved hand over and feel as a smooth ridge is right; a stack of separate ropes is not.
• Fill every crater. Craters crack.
• Clean it and look at it in good light before you call it done — wire brush, then walk the whole circumference with a light held low across the weld so it throws shadows.

Reinforcement limits

Check the code that applies to your job. B31.1, B31.3, B31.9, API 1104 (pipelines under B31.4 and B31.8) and AWS D1.1 all set these differently, and a client spec can be tighter than any of them. B31.1 also changes the limit with design temperature.

A discontinuity is anything that interrupts the weld. It becomes a defect when it's outside what the code allows — and then the joint gets repaired or cut out.

What gets found, and where it came from

Cracks are rejectable in any amount under B31.1, B31.3 and AWS D1.1. Pipeline work under API 1104 tolerates only tiny crater cracks. Treat every crack as a reject. Everything else has a limit written somewhere.

What a CWI looks at

Most inspection is visual, and a lot of it happens before anybody strikes an arc:

• Before weldingMaterial and heat numbers, prep angle and land, cleanliness, gap, hi-lo, alignment, preheat, welder qualification, filler metal and its storage.
• During weldingProcess and parameters against the WPS, interpass cleaning and temperature, purge, bead sequence.
• After weldingReinforcement height and width with a fillet/weld gauge, undercut depth, toes, craters, arc strikes, spatter, root condition where visible, weld ID.

Test methods

A coated rod carrying the current and making its own shielding gas and slag as it burns. Portable, wind-tolerant, works on dirty steel, and still the backbone of field pipe work.

Amperage by rod

Start in the middle of the range and adjust to the puddle. Overhead and vertical-up run 10–15% under flat. Open root runs lower than fill. The box lid has the manufacturer's numbers and they beat this table.

What each rod is for

• E6010 — the open-root rod. Deep digging arc, fast-freezing, cuts through mill scale and light rust. DC only. Cellulose coating, runs with a whip.
• E6011 — the AC version of a 6010. For buzz boxes and engine drives without DC.
• E7018 — low-hydrogen fill and cap. Smooth, strong, low crack risk, but it wants clean metal and it must stay dry.
• E7024 — flat and horizontal only, high deposition. Not a pipe rod.
• E308L / E316L — austenitic stainless. Run cool, keep the arc short, chip the heavy slag.

Low-hydrogen storage

• 7018 comes out of a sealed can or a hot oven at 250–300°F and goes into a portable rod caddy.
• Exposure limit under AWS D1.1 is 4 hours for E7018, 2 hours for E8018 (8018-B2), 1 hour for E9018 (9018-B3), 1/2 hour for E100 and E110 rods. Your spec can be tighter. Past that they get re-baked the way the maker says, or binned.
• A rod that's been in a puddle, a pocket or the bottom of a gang box overnight is scrap. Moisture in the flux is hydrogen in the weld, and hydrogen cracks show up days later.
• Never re-bake cellulose rods (6010/6011) — they need their moisture. Different rod, opposite rule.

Running it

• Arc length roughly the diameter of the core wire. Long arc = porosity and spatter; too short = sticking and a rod that freezes in.
• Drag angle 5–15° for 7018, pushed slightly for 6010 uphill.
• Whip and pause for a 6010 root; steady drag for 7018 fill.
• Chip and brush every pass. 7018 slag peels if the bead is right — slag that fights you is telling you the bead is wrong.
• Machine set to DC+ for both 6010 and 7018 on almost every pipe job. Check the lead polarity if the arc is harsh and won't stabilize.

A non-consumable tungsten electrode, an inert gas shield and filler added by hand. The cleanest root you can put in a pipe, and the only practical answer on thin-wall stainless and alloy.

Polarity by material

Tungsten

• 2% lanthanated (blue) or 2% ceriated (grey — orange on older stock) for everything, AC and DC. This is the modern default.
• 2% thoriated (red) still common on DC steel work — it's mildly radioactive, so grind it with extraction and don't breathe the dust.
• Pure (green) / zirconiated (brown) older AC aluminum choices — they ball rather than point.
• Grind lengthwise, never across. Grinding marks running around the tip make the arc wander. Point length about 2–2.5× the diameter, with a small flat on the tip.
• Dedicated tungsten grinder or wheel. Grinding tungsten on a carbon-steel wheel contaminates both.
• Stick-out about the diameter of the cup — more for an inside corner, less in a groove.

Gas

Setting up and running

• Rule of thumb: about 1 amp per 0.001" of thickness on steel and stainless, less on stainless if it's running hot. That's a ceiling for sheet and fillets, not a root setting: the rule says 154 A for a 0.154" wall (2" Sch 40), but an open root there runs more like 90–120 A. Adjust to the puddle.
• Gas lens if you can get one — better coverage, more stick-out, fewer sugared roots.
• Pre-flow 0.2–0.5 s, post-flow about 1 second per 10 amps. Pulling the torch away while the metal is still bright is how you get a black tip and a contaminated end.
• Keep the filler inside the gas. Dipping in and out of the shield oxidizes the wire and drags it into the puddle.
• Touch the tungsten to the puddle and stop. Regrind it — a contaminated tungsten will never run right and will drop inclusions into the weld.
• Walking the cup is the standard pipe technique where it's allowed — rock the cup on the bevel faces for a rhythm you can hold all the way round. Some specs ban it on thin wall.
• Amperage control — foot pedal in the shop, thumb wheel or fingertip control on pipe in a rack.

Solid wire fed continuously through a gun with a gas shield. Fast, easy to learn, and fussy about wind and cleanliness — which is why it's a shop process more than a field one.

Transfer modes

Gas by material

Polarity is DCEP for all solid-wire GMAW. Flow 25–35 CFH, more in a draft, and get a screen up — a 5 mph breeze strips the shield.

Starting numbers — carbon steel, short circuit, C25 (last row: spray on 90/10)

Running it

• Stick-out 3/8" to 1/2" and hold it. Stick-out changes amperage more than the dial does.
• Push on carbon steel for a flatter, wider bead with less penetration; drag for deeper penetration and a narrower bead. Always push on stainless and aluminum.
• Listen for bacon frying. A steady sizzle is right. Popping means volts too low or feed too fast; a hissing crackle with a long arc means volts too high.
• Clean base metal. MIG has no flux — whatever's on the steel ends up in the weld.
• Common wires: ER70S-6 (carbon steel, most tolerant), ER70S-2 (TIG root wire), ER308LSi / ER316LSi (stainless), ER4043 / ER5356 (aluminum).

Tubular wire with flux inside it. Deposits fast, runs out of position, and tolerates the field — which is why it owns structural work and heavy fabrication.

The two families

Get the polarity right. Running a self-shielded wire on DCEP or a dual-shield on DCEN gives a filthy arc, huge spatter and a bad weld — and it's the first thing to check when a flux-core machine "won't run".

Starting numbers — E71T-1, CO₂ or 75/25

Gas flow 35–45 CFH on gas-shielded. Stick-out is longer than MIG — 3/4" to 1" — and it matters just as much.

Reading the designation

• E71T-1 — E electrode, 7 = 70 ksi tensile, 1 = all positions (0 would be flat and horizontal only), T = tubular, -1 = the usage/shielding class.
• -1, -9, -12 gas-shielded, the common shop wires. All-position when the digit after the 7 is a 1 (E71T-1), flat and horizontal when it's a 0 (E70T-1).
• -5 gas-shielded, better toughness, flat and horizontal.
• -8, -11, -GS self-shielded. -GS is single-pass only — not for pipe.
• Metal-cored (E70C-6M) looks like flux core but behaves like high-deposition MIG, with almost no slag.

Running it

• Drag angle, 10–20°, always. Pushing flux core traps slag ahead of the puddle.
• Vertical up on all-position wire. Down only if the wire and the procedure both say so.
• Chip and brush every pass. The slag is heavier than stick slag and it hides in the toes.
• Keep the wire dry. Flux core absorbs moisture the same as a low-hydrogen rod — opened spools go in a heated cabinet or a sealed bag with desiccant.
• Fume. Self-shielded especially. Ventilation or a fume gun, and a respirator in a confined space.
• Check the drive rolls — knurled rolls for tubular wire, not the smooth V-rolls you use for solid wire, and don't over-tension or you crush the wire flat.

Starting points, not gospel. Every one of these gets tuned by ear and by the puddle — but you have to start somewhere, and starting 60 amps off wastes a rod and a coupon.

Stick — amperage by rod and size

TIG

Steel & stainless

DCEN. Sharp point on the tungsten, 2½ times the electrode diameter long.

Aluminum

AC. Balled or lightly truncated tip. Set AC balance to about 70% electrode-negative (penetration), 30% electrode-positive (cleaning) to start, and add cleaning only if the oxide won't break up.

Argon flow

15–20 cfh on a standard cup. More is not better — too much flow turns turbulent and pulls air in.

Purge

Stainless and alloy roots need argon inside the pipe. Low, steady flow until the air is displaced, then just enough to hold it.

Tungsten

3/32" 2% lanthanated covers most of what you will touch.

Band colors follow AWS A5.12, which moved ceriated from orange to grey in 2009, and suppliers still vary. Read the class printed on the electrode, not just the colour on the end.

Wire

MIG on carbon, short circuit

DCEP, 75/25 argon-CO₂ at 25–35 cfh. .035" wire, roughly 18–22 volts to start.

MIG spray transfer

Needs an argon-rich mix (90/10 or richer) and more voltage. Will not spray on straight CO₂.

Flux core, gas shielded

DCEP. Straight CO₂ or 75/25.

Flux core, self-shielded

DCEN, no gas. The outdoor answer.

Stickout

Short for short circuit, longer for flux core. Wrong stickout ruins a bead faster than wrong amperage.

Every number on a rod or a spool means something specific. Once you can read it you can walk into any gang box and know what you are holding.

Stick — E XX Y Z

Wire and TIG rod

ER70S-6

ER electrode or rod · 70 70,000 psi · S solid · 6 the chemistry. The 6 carries extra manganese and silicon, so it handles mill scale better. The most common carbon steel TIG and MIG wire there is.

ER70S-2

Triple deoxidized. What you reach for on a root that is not as clean as it should be.

E71T-1

7 70 ksi · 1 all position · T tubular (flux cored) · -1 gas shielded, rutile, DCEP. A 0 in the position slot means flat and horizontal only. Current labels add the gas on the end: E71T-1C is classified on CO₂, E71T-1M on 75–80% argon. Run it on the gas it's classified for.

E71T-8

Self-shielded, all position, DCEN. No gas bottle, works in wind.

ER308L

Stainless for 304 base. L is low carbon — it resists the carbide precipitation that wrecks corrosion resistance at the weld. ER308LSi adds silicon so the puddle wets out better on MIG.

E308L-16

The stick version (AWS A5.4). E electrode · 308 the stainless grade · L low carbon, 0.04% max · -16 the coating: -15 is DCEP only, -16 and -17 run AC or DCEP.

ER309L

The transition rod. Carbon steel to stainless, and the first (buttering) layer on carbon steel before you put 308L over it.

ER316L

For 316 base. Molybdenum for chloride service.

You are not the welder. But the man who knows what is about to happen to his joint fits it better, and the day somebody asks you to run a bead you will not be starting from zero.

Polarity, once, properly

DCEP

Electrode positive, "reverse polarity". On stick and wire it gives the deepest penetration and the steadiest arc — that's why they live here. On TIG it would put most of the heat into the tungsten and melt it.

DCEN

Electrode negative, "straight polarity". On TIG most of the heat goes into the work — TIG on steel lives here. So does self-shielded flux core. On stick, DCEN melts the rod faster with shallower penetration.

AC

Alternates. TIG on aluminum needs it — the electrode-positive half of the cycle blasts the oxide skin off. On stick it also cuts down arc blow.

You don't have to weld it, but knowing what happens after you hand it off will make you a better fitter.

SMAW (stick)

6010 for the root, 7018 for fill and cap. The workhorse on carbon steel pipe.

GTAW (TIG)

Root pass on stainless, alloy, thin wall and anything critical. Slow, clean, unforgiving of bad fit-up.

Combo

TIG root, stick or wire fill. Very common on process work.

FCAW / GMAW

Wire. Fast fill on big bore in the shop.

What a bad fit-up costs the welder

• Uneven gap — burn-through on the wide side, incomplete penetration on the tight side.
• Hi-lo — the root can't tie both sides, and it shows on the X-ray.
• Dirty prep — porosity all the way through the root.
• Wrong root face — too thick and it won't penetrate, too thin and it melts away.

Purging

Stainless and most alloys need argon inside the pipe for the root pass or the back of the weld sugars and is worthless. That means purge dams, and somebody has to fit them, vent them, and remember to pull out the ones that don't dissolve. If you're setting a purge, tell the welder where the vent is.

Preheat and interpass

Heavy wall and alloy pipe gets preheated before the first pass and held between passes. If there's a preheat on the WPS, the spool doesn't get welded cold because it's faster — that's how you crack a joint.

The part nobody writes down — giving him a joint he can actually weld

A fit-up can be geometrically perfect and still be a miserable joint, because of where you put it. This is the difference between a fitter people ask for and one they work around.

• Leave him room to swing. He needs a hand, a rod or a torch, a hood, and enough clearance to get all the way round. A joint 4" off a wall means the back of it gets welded blind, by feel, badly.
• Never put a weld in a corner, against steel, or behind something else. If you can move it a foot along the run and it is still within tolerance, move it. That foot costs you nothing and saves him an hour.
• Roll it if you possibly can. A joint that turns on rollers is welded flat, fast and sound. The same joint fixed in position is a 5G or a 6G — slower, harder, and a lot more likely to be repaired. Ask before you tack whether it is going out rolled or fixed.
• Get it off the ground. Flat on the deck means he welds the bottom lying in it. Horses, dunnage, anything.
• Tack where it helps. Feathered, ground at both ends, and not sitting at 6 o'clock where he has to start his root.
• Point the seam away from him and away from the bottom of the joint.
• Support the spool so it cannot move. A joint that shifts under him as he welds it is a cracked root.
• Tell him what you know. Which end is fixed, where the purge vent is, what the spool has to pull to, and whether the far end is already tied in. He cannot see any of that from the joint.

There are seven places a weld pipe dimension can go wrong and only one place anybody finds out. Check at every one of them and the last check is a formality.

The checkpoints

Weld shrinkage is real

• A butt joint pulls roughly 1/16" as it cools on common sizes — more on heavy wall, more with a wide gap, more with high heat input.
• It's cumulative. Six joints on a spool is 3/8". Nobody notices until the last flange won't reach.
• It pulls angular too. A joint that welds hotter on one side cocks the pipe out of line — that's what balanced quartering is for.
• Where it matters, hold one end long and trim the closing piece after the rest of the spool is welded out.

Measuring discipline

• One datum. Measure everything on a spool from the same reference point. Chaining measurement to measurement stacks every small error into one big one.
• One tape per crew where you can. Two tapes with different hooks on the same spool will disagree by a sixteenth and you'll never find out which one was right.
• Check your hook. The sliding hook on a tape is supposed to float by exactly its own thickness. Bent, loose or worn, and every reading off the hook is wrong — hooked over an edge or pushed against a face. Check it both ways against a steel rule: hooked on, then butted against a stop. Both should read the same.
• Write it down. Cut list on paper or on the pipe. A number carried in your head across a lunch break is a number you'll get wrong.
• Mark the pipe, not just the list. Piece number, cut length, which end is prepped.
• Read the tape square on. Reading a tape at an angle on big bore will cost you an eighth all by itself.

When it's wrong

1. Stop and measure it again from the datum before you touch anything. Half of "wrong" is a misread.
2. Find out where it went wrong, not just by how much. If the saw is out of square, everything behind it is wrong too.
3. Long is fixable, short is not. If it's long, trim. If it's short, you're adding a piece or remaking the spool — say so now.
4. Tell somebody before it goes in the rack. A mistake found at the bench is a rework; the same mistake found at the tie-in is a crane, a permit and a crew standing around.

What actually comes out of the gang box on a weld pipe job. Tick what you've got before you walk to the rack, not after.

• 25' tapeAnd know your hook is true — see 1.9.
• Wrap-aroundOne sized for your pipe range. See 1.4.
• Framing square and combination squareChecking square and setting fittings in plane.
• Torpedo level and a magnetic levelPlus a protractor or digital angle finder for rolled work.
• Soapstone, paint markers, scribeSeparate stainless-safe set, kept in its own bag.
• Centre punch and a small hammer
• Chalk lineLong runs, layout on big bore.
• Take-out card and a calculatorOr this book — see the charts at the top of the home screen.

• Torch outfitTips to suit, striker, tip cleaners, spare flints, flashback arrestors.
• Portable bandsaw and spare bladesTwo TPI ranges. Bi-metal.
• Cut-off wheelsMore than you think. Separate stainless wheels.
• Pipe stands and vee blocksTwo minimum, three if the piece is long.
• Chain vise or a portaband jig

• 4-1/2" grinderTwo if you can — one set up for cutting, one for grinding.
• Grinding wheels and flap discsType 27, 40/60/80 grit flaps.
• Half-round file and a deburring toolThe land and the bore burr.
• Wire brushes — carbon and stainless, marked
• Bevel gauge / Hi-Lo welding gaugeAngle, land, gap and hi-lo in one tool.
• Solvent and ragsBefore the abrasive, not after.

• Cage clamp or chain clampSized for the pipe you're on.
• Spacer wire / cut nails / gap wedgesWhatever the welder's gap calls for.
• Two-hole pins and a flange spreaderPins line up the bolt holes; the spreader opens a flange joint to get a gasket in or out.
• Come-along, chain fall, ratchet strapsPulling a spool in without forcing a tack.
• Wedges, dogs and lugsCheck first whether you're allowed to tack them on.
• StraightedgeFittings in plane.

• Ground clamp and leadClean jaws. Not through a bearing or a chain fall.
• Rod caddy / heated quiverIf you're running low-hydrogen.
• Purge kitDams, tape, hose, flow meter, oxygen analyzer if the spec wants one.
• Temp sticks or a contact pyrometerPreheat and interpass.
• Chipping hammer and slag brush
• Welding blankets and a fire extinguisherPlus a fire watch who stays at least an hour after the last spark (NFPA 51B) — see 12.4.

• Safety glasses and a full face shieldShield over glasses, never instead of.
• Cutting goggles, shade 5And a hood if you're near an arc.
• Leathers, gloves, sleevesCutting gloves and welding gloves are different gloves.
• Hearing protection
• Respirator rated for the fumeGalvanized, stainless or a confined space changes this.
• Hard hat, boots, fall protection as required

• Iso or spool drawingThe current revision, not the one in your truck since Tuesday.
• Cut listWritten, with piece marks.
• WPSGap, land, angle, preheat, interpass, filler, acceptance.
• Hot work permitSigned, current, and in your pocket.
• Weld map / weld logJoint numbers and who welded them.
• Material heat numbersTransfer them before you cut the stencil off the pipe.

A take-out is how much of your centre-to-centre dimension the fitting eats. Every elbow and tee has one — reducers, caps and stub ends are measured end to end instead — and this is where they all live — with how to measure for each, and how to get the number off a fitting nobody gave you a number for.

Three kinds of number, and they are not interchangeable

The five you will use every day

Centre of fitting to face, in inches, nominal per ASME B16.9 (short radius used to be B16.28; it moved into B16.9 in 2001). Each column is its own fitting: the 90 columns are for a 90, the 45 column is for a 45, and the Tee number is the same to all three ends. The Cap column is face to back, not a take-out — see 1.11e.

Tap a size to open it in the cut length calculator.

Every fitting, one page each

• 1.11aElbows90 long and short radius, 3R, 45s, odd angles, reducing ells, cut elbows›
• 1.11bReturns and long bends180° returns, and 3D, 5D and 10D induction bends›
• 1.11cTees, crosses and lateralsStraight and reducing tees, crosses, 45° laterals and wyes›
• 1.11dReducers and swagesConcentric, eccentric, and the offset an eccentric puts in your line›
• 1.11eCaps, stub ends and lap jointsWhere the dimension stops on a fitting with only one weld on it›
• 1.11fFlanges in the dimensionWeld neck, slip-on, socket and lap joint — and the two that add back›
• 1.11gBranch outlet fittingsOlets of every type, and the run-centreline number nobody prints›
• 1.11hMeasuring a fitting you have no number forFour methods, from a framing square to a sheet of paper›

Every elbow take-out in the trade comes out of one piece of geometry: the centreline radius of the bend and half the angle it turns. Learn that and you can work out an elbow nobody has a table for.

Work out R first from line 2 or line 3, then put it into line 1. ANGLE is how far the elbow turns — 90 for a 90, 45 for a 45.

The table

Centre of fitting to face, in inches, nominal per ASME B16.9 — long radius, short radius (formerly B16.28) and 3R. The 45 SR column is not a standard fitting; see the note under the table.

Tap a size to open it in the cut length calculator.

3R means the bend radius is 3 × the size, so a 3R 90 takes out 3 × the size — a long sweeping turn used where flow or pigging matters. 45 SR is not a B16.9 fitting; the column is the formula (size × tan 22½°) for a 45 cut from an SR 90, so check it against the fitting before you cut to it.

Elbows that turn some other angle

Stock butt weld elbows come as 90s and 45s. When the job needs a 60°, 30°, 22½° or 11¼°, you cut that piece out of a 90 (15.18) — and its take-out is not the 90's number or the 45's number. It is smaller, because the piece turns less. You do not need the formula to get it. Use this table:

1. Find how far your elbow turns in the left column.
2. Take the number beside it — long radius or short radius column, whichever elbow you cut it from.
3. Multiply that number by the pipe size. The answer is the take-out at each end of that elbow.

Where the numbers come from: each one is the formula above with R already put in — 1.5 × tan(half the turn) for long radius, 1 × tan(half the turn) for short. *A stock 6" LR 45 is 3.75", not 3.73: B16.9 rounds its stock 45s, so for a bought 90 or 45 use the table above. These multipliers are for the pieces you cut yourself.

Reducing elbows

Measuring an elbow you are holding

1. Framing square. Lay the elbow flat on the bench with one face tight against a blade of the square. Measure square off that blade to the centre of the other opening — that is the take-out. Flip it and do the other face; on an equal elbow the two readings must match.
2. Stand it on the bench. Stand the elbow on one face on a flat bench, so the other opening faces sideways. Hold the tape plumb and measure from the bench up to the centre of that opening. That is the take-out.
3. For a 45 or any odd angle, trace it. Lay it on paper or on the bench, mark both faces, draw a line square off the centre of each face, and where those two lines cross is your working point. Measure from there. That method works on anything — full detail in 1.11h.
4. Sanity check against the rule. A 6" LR 90 should read 9". If your tape says 6", somebody sent you short radius.

A 180° return turns the line back on itself; a long bend sweeps it round without a fitting at all. Neither one has a take-out you can subtract the usual way, which is exactly why they catch people.

180° returns

Inches, nominal per ASME B16.9. A return is two 90° bends back to back, so O is simply twice the bend radius. The K formula lands within 1/16" of the table; the table is the standard's number.

Long bends — 3D, 5D, 10D

An induction or pulled bend has no fitting and no weld in the turn. It is specified by radius in pipe diameters, so a 5D bend on 8" pipe has a 40" centreline radius. That is how most shops mean it; some pipeline specs take D as the actual OD (5 × 8.625 = 43.1"), so check the PO. Take-out works exactly like an elbow, because a bend is an elbow with a big radius.

R is on the centreline, in inches: R = n × nominal size. The arc is how much pipe the turn itself eats — you need it to work out material, not cut length.

Measuring a return or a bend

1. A return: lay it flat and measure face to face across the two legs — that is O plus nothing, because the faces are at the tangent points. Then measure from the face plane to the outside of the U for K. Put a straightedge across both faces to get the plane honest.
2. A bend, tangent to tangent: find where the straight stops and the curve starts by running a straightedge along the tangent — the point it lifts off is the start of the bend. Mark both, and the straight length from each mark to the end is your tangent.
3. A bend's radius, from a chord: lay a straightedge across the inside of the curve (the throat) so both ends touch the pipe. Measure between the two touching points for c and the biggest gap in the middle for h. Then R = (c² ÷ 8h) + (h ÷ 2) is the throat radius — add half the OD to get to the centreline.
4. Working point: extend both tangents with a string or a chalk line until they cross. That crossing is the working point on a bend exactly as it is on an elbow, and the distance from it to the end of the pipe is what you subtract.

A tee has two take-outs from one working point — one out the run, one down the branch — and on a straight tee they are the same number. On a reducing tee and on a lateral they are not, and that is where the cuts go wrong.

Straight tees and crosses

Centre to end, inches, nominal per ASME B16.9. On a straight tee the run number C and the branch number M are equal, and a cross uses the same number on all four ends.

Tap a size to open it in the cut length calculator.

Reducing tees

Laterals and wyes

A 45° lateral is a tee with the branch swung round so it points the way the flow is already going — less turbulence, less pressure drop, which is why they turn up on pump headers, flare lines and big drainage.

• Three different take-outs. A is short (the branch leans away from that end); C and M are long. They change with size, combination and maker, and there is no clean multiplier — never guess a lateral.
• The working point is not on the fitting. On a lateral the centrelines cross inside the body, and on a reducing lateral they cross somewhere you cannot put a tape at all. You get to it by extending lines, not by measuring to it.
• There is no B16.9 lateral. The standard leaves laterals out as pipe fabrication, so every butt-weld lateral is built to its maker's drawing. Get that drawing, or measure the one you were sent.
• Fabricating one instead of buying it — the layout, the ordinates and the cut — is 15.10, and a true Y is 15.6.

Measuring a tee, cross or lateral

1. The run, both ends: measure face to face straight across the run and halve it. On a straight or reducing tee that gives you C, and both ends are the same.
2. The branch: measure from the branch face to the far outside of the run, then subtract half the run's OD. That gives you M without having to find the centreline.
3. A lateral: lay it on the bench, chalk or scribe the run centreline on the bench using the two run faces, then scribe the branch centreline square off the branch face. Where the two scribes cross is the working point — now measure to all three faces.
4. Write it on the fitting. Soapstone the three numbers on the body before it leaves the bench. Nobody wants to do that layout twice.

A reducer is the odd one out. It has no working point and no take-out — it is a length in the middle of the run, and it comes off your dimension once, whole.

End-to-end, concentric and eccentric

Inches, nominal per ASME B16.9. Listed by the large end — a 6"×4" and a 6"×3" are both 5.50" long. Concentric and eccentric are the same length.

The eccentric — and the offset it puts in your line

Swage nipples

• A swage does the same job in small bore — a solid forged piece, concentric or eccentric, to MSS SP-95.
• Ends come BE (bevelled, for butt weld), PE (plain, for socket weld or slip-on) or TE (threaded), and you can have one of each on the same piece.
• MSS SP-95 sets the length by the large end — a 1" is 3-1/2", a 2" is 6-1/2", a 4" is 9". It is a length, like a reducer — measure the one you have and subtract it whole.
• A bushing or a reducing insert is not a butt weld fitting and does not belong in a welded line unless the spec calls for it. Reducing inserts in particular are banned on plenty of jobs.

Measuring a reducer

1. Length: face to face, straight down the side. That is the whole number — there is nothing to halve and nothing to add.
2. Is it eccentric? Stand it on its large end and hold a square up the side. An eccentric has one side that runs dead straight up — the flat. A concentric slopes in all the way round.
3. Offset: lay it flat side down on the bench and measure from the bench to the top of each end. Subtract, then halve it — the difference is the whole change in OD, and the centreline only moves half of that.
4. Check the wall at both ends. Each end has to match the schedule of the pipe it welds to. Compare each bore to your pipe's ID, or read the stamp, before you tack it in — a mismatch is hi-lo on the inside of the root.

Fittings with a weld on one end only. The dimension does not pass through them — it stops at them, and that changes what you subtract.

Caps

A cap closes the end of a line. Its number E is face to back: from the weld face to the outside of the dome.

Inches, nominal per ASME B16.9. E is for walls up to extra strong (XS). Heavier than XS and the cap is longer — that is E1.

Tap a size to open it in the cut length calculator.

Stub ends and lap joint flanges

F, inches, per ASME B16.9, which lists two lengths: long pattern and short pattern (the short one is also the MSS SP-43 length, common on stainless). The PO has to say which. Type A, B and C describe the shape of the lap, not the length.

Measuring these

1. Cap: stand it on a flat bench on its weld face and measure straight up to the top of the dome. That is E. Mind the little flat some caps have — measure to the highest point.
2. Stub end: lay a straightedge across the lap face and measure back to the bevelled weld end. That is F. Do not measure to the back of the lap — the lap has thickness, and the face is what seals.
3. Lap diameter: measure across the lap. It has to be bigger than the flange bore (that is what the flange pulls on), clear the bolts, and cover the gasket on whatever you are bolting to.
4. Test fit the flange over the shaft before anything gets welded. A stub end from one maker and a flange from another will occasionally not pass.

A flange is a take-out like anything else, and the number you subtract depends entirely on which kind of flange it is. Two of them even give length back.

Weld neck — length through hub Y

Inches, nominal per ASME B16.5, raised face included. Full flange data — OD, bolt circle, hole count, stud lengths — is 10.1 and 10.2.

Tap a size to open it in the cut length calculator.

Every flange type — and the two that give length back

Gaskets between two flange faces

When your dimension runs face to face across a bolted joint, the gasket is in that dimension and the pipe has to give up its thickness.

• 1/16" — compressed sheet, the usual on raised face 150 and 300.
• 1/8" — heavier sheet, full face on flat face flanges.
• Spiral wound — nominally 0.175" uncompressed, seating down to about 0.130". Where it matters, ask which number the spec holds you to.
• Ring joint — the ring seats in the groove and the faces close up; that is its own math and the flange data governs. See 10.3.

Measuring a flange

1. Weld neck: stand it face down on a flat bench and measure to the bevelled weld end. That is Y — raised face and all.
2. Socket weld: stand it face down and measure to the top of the hub. Then drop a rule into the socket until it stops on the shoulder — that is the socket depth. The first minus the second is how far the socket bottom sits back from the face. Slip-on: nothing to measure but the setback you hold.
3. Which class: the class is stamped on the outside edge along with the size, material and maker. If it is illegible, count the bolt holes and measure the bolt circle against 10.1 and 10.2.
4. Which face: run your thumb across it. Raised face has a step and a serrated finish; flat face is flat to the edge; ring joint has a groove you cannot miss. They do not bolt to each other.

An outlet fitting sits on the run instead of in it, so its catalogue number is measured from the outside of the run pipe — and the number the print wants is measured from the centreline. Nobody prints the second one. You work it out.

The family

Heights and hole sizes by size and run are in 16.3. Weldolet, Sockolet, Thredolet, Elbolet, Latrolet and Nipolet are registered trade marks of Bonney Forge — used here because that is what people say on the job (see 20.9). The generic term is branch outlet fitting.

Measuring and setting one

1. Height: sit the olet on the actual run pipe — not on the bench, because the base is curved. Lay a straightedge across the branch face and measure down to the run's outside surface at the centre of the olet.
2. Take-out: add half the run OD. Pipe ODs are in 1.12.
3. The hole: the olet has its own bore and the hole in the run has to match it — not the branch's nominal size. Get it off 16.3 or off the fitting, mark it with a wrap and a template, and cut inside the line so you can dress out to it.
4. Square to the run: set it with a square off the run's centreline in two directions before tacking, and check it again after the root. An olet that leans 1° puts the branch about 1-1/4" out of place six feet away; 2° is 2-1/2".
5. Clock it off the print. Top dead centre, 45° up, horizontal — a vent has to be at the top and a drain at the bottom, and there is no fixing it afterwards.

Sooner or later you get handed something with no stamp, no box and no catalogue — a used fitting out of a laydown yard, an import, a shop-made elbow, an odd angle somebody cut last year. Every one of them will tell you its take-out if you ask it properly.

Four methods, fastest first

1. Framing square — 90° elbows only. Lay the elbow on the bench with one face tight against a blade. Measure square off that blade to the centre of the other opening. Flip it and do the other face. Ten seconds, and on an equal elbow the two readings must match.
2. Stand it on the bench — elbows and tees. Stand the fitting on one face on a flat bench. Hold the tape plumb (a torpedo against it helps) and measure from the bench up to the centre of the opening that faces sideways. On a tee, measure the run face to face and halve it for C; stand it on the branch face and measure up to the run centre for M.
3. Trace it — any angle, any fitting. The method in the figure. Lay it on paper, cardboard or a clean bench, mark both faces, draw a line square off the centre of each, and measure from where they cross. Slower, and it is the only one that never lies.
4. Far side minus half the OD — tees, branches and olets. When you cannot get to the centreline, measure to the far outside of the run and subtract half the run's outside diameter. Pipe ODs are in 1.12.

The check that catches the rest

What to do with the number

• Write it on the fitting in soapstone or paint pen, the moment you have it. Nobody wants to do that layout twice, and the next hand will not know you did it.
• Write it on the cut sheet too, next to the number it replaced, so the paperwork says what you actually built.
• Tell the foreman if it is off. One fitting out of tolerance is a fitting. A whole pallet out of tolerance is a purchasing problem and somebody needs to hear about it before the spools are welded.

How far off is too far off

OD never changes with schedule. Only the wall thickens and the ID shrinks — which is why a 2" socket-weld or slip-on fitting fits 2" pipe of any schedule (threads and cut grooves still need enough wall to cut into). A butt-weld fitting has to match the wall as well, or you get hi-lo inside the joint.

Dimensions nominal per ASME B36.10M. The standard governs; this is the working subset.

Schedule 40 — the standard

Sch 40 and STD (standard weight) are the same wall through 10". At 12" they split: 12" STD is .375, Sch 40 is .406. Sch 80 and XS match through 8"; 10" and 12" XS are .500. Fittings are often ordered STD or XS, so check which one the spec means.

lb/ft is empty pipe. +water is what the water adds. Add them for the hanging weight of a running line.

Schedule 80 — heavy wall

Schedule 10 — light wall

Common on grooved systems and stainless. Sprinkler Sch 10 (ASTM A135/A795) is heavier from 8" up — .188". Too thin to thread.

Weld neck

Butt-welded like any fitting, tapered hub matches the pipe bore. The one for pressure, cycling and anything critical.

Slip-on

Slides over the pipe, welded inside and out. Same class rating as a weld neck but a fraction of its fatigue life — cheaper and easier to fit, not for cyclic or severe service.

Socket weld

Small bore. Pipe bottoms in the socket, then gets pulled back.

Lap joint

Over a stub end. Rotates freely — the answer when bolt holes have to line up with something fixed.

Blind

Caps the end. Rated the same as the flange class.

Weld neck take-out

It's the length through hub (Y) — flange face to weld end, with the 1/16" raised face already in it on Class 150 and 300 — and it changes with class. Check the catalog for the class you're running, or measure the first one — face of flange to the weld end.

Length through hub, raised face included. Nominal — confirm against the flange in your hand.

Butt weld outlet

Butt weld branch. For anything the branch has to be full strength. Weldolet®

Socket weld outlet

Socket weld branch, small bore. Sockolet®

Threaded outlet

Threaded branch — gauges, vents, drains. Thredolet®

Elbow outlet

Off the back of an elbow. Thermowells and vents. Elbolet®

45° outlet

Angled branch. Latrolet®

Everybody on the job says "olet", and the names in the right-hand column are what you will hear. Those are registered trademarks of Bonney Forge Corporation — other makers sell the same fittings under their own names. Order by what the fitting does and any supply house will get you the right thing.

• Olets save a tee and a lot of layout — but cut the hole to the olet's bore, dress it, and make sure the olet sits down with full contact. Don't bridge a bad hole with weld.
• Lay the hole out with a wrap template, not by eye. Cut inside your line and grind out to it.
• Hole for a full-size branch is roughly the branch ID plus room for the root. Get the contour right — a saddle that rocks will never weld sound.
• 45° laterals flow better and are required on some drainage and process lines. They eat a lot more room than a tee — check the space before you order.
• Branch direction on a horizontal main: vapor and steam off the top, liquid drains off the bottom, general water branches top or side so they don't collect debris.
• Keep the olet off the seam and off any other weld. Minimum weld-to-weld spacing is usually in the spec.

Everything past take-outs and fittings out of a box. When the angle, the size or the schedule doesn't come off the shelf, you make the fitting out of pipe: miters, cut elbows, branches, laterals, Ys and orange peels.

Weld pipe advanced fab

• 1.15aMitered elbowsTwo-piece and multi-piece turns: the cut angle, the ordinates and how long each piece is›
• 1.15bCutting elbows to odd anglesTurning a 90 into a 60, a 75 or two 45s, and the take-out that goes with it›
• 1.15cBranches: set-on, set-in and padsFishmouthing a branch onto a header, sizing the hole, and when a pad goes on›
• 1.15dLaterals at any angleA branch coming in at 30, 45 or 60, full size or reduced, with the one formula for all of them›
• 1.15eYs and wyesTrue Ys, Ys at other angles, and when a Y is really two laterals›
• 1.15fOrange peelsClosing a pipe end into a dome, and pulling one down into a reducer›
• 1.15gBuilding it: sequence and distortionTack order, weld order and keeping a fabricated fitting from walking off its angle›

The full layout pages

Section 15 has the ordinate tables and the geometry behind all of this, for every material. These are the ones weld pipe uses most.

• 15.2Dividing the circumferenceStations round the pipe, every size›
• 15.790° saddles on standard weightOrdinates for every branch-to-header ratio›
• 15.9Eccentric branchesA branch off to one side of the header centreline›
• 15.11Concentric reducers from plateCones laid out flat›
• 15.14Orange peel heads from plateBig domes built from rolled gores›
• 15.17Dummy legs on elbowsThe fishmouth onto the back of an elbow›
• 15.20Pipe bendsRadius, arc length and take-out on a bent pipe›

When there's no fitting, or the bore's too big to buy one, you make it out of pipe. The cut line around a pipe is a curve, and you lay it out with ordinates.

1. Cut angle = total turn ÷ number of mitred ends. Count every cut end. A two-piece 90 has two, so each is 45°. A three-piece 90 has four — one on each end piece, two on the middle piece — so each is 22-1/2° and the middle piece is a 45° wedge.
2. D = OD × tan(cut angle) — the difference between the long side and the short side.
3. Step 16 stations around with circumference ÷ 16 — the outside circumference, OD × 3.1416.
4. Square a line round the pipe through the long point. Mark each cut-back back from that line using the table below.
5. Connect the marks with a flexible batten or a wrap, then cut and dress.