Intermittent Weld Symbol Explained: Length, Pitch, Chain vs Staggered (Complete Guide)

What an Intermittent Weld Symbol Actually Tells You

Picture the scene: a 20-foot stiffener on a skid, a 2-8 fillet callout on the drawing, and a crew member who reads the “8” as the weld size. He lays down two inches of 8 mm bead — and the inspector red-tags the entire run. That hyphen between the two numbers is the single most misread detail on a welding print, and it is exactly what the intermittent weld symbol exists to communicate.

An intermittent weld is simply a fillet weld made in segments along a joint instead of as one continuous bead. You weld a short length, skip ahead, weld another length, and repeat — chain-style or staggered, depending on what the designer wants. The symbol has to say four things at once: what kind of weld, what size, how long each segment should be, and how far apart those segments sit. Get any one wrong and the joint is either under-strength or over-built.

The Anatomy of a Complete Welding Symbol

Per AWS A2.4, the Standard Symbols for Joining and Nondestructive Examination, every complete welding symbol is assembled from the same handful of parts. The arrow points to the joint. The reference line carries the welding information. The tail holds the process or specification reference — or stays empty when none is needed. Supplementary symbols like the all-around circle or the field-weld flag add extra instruction.

• What kind of weld it is — fillet, in almost every intermittent case
• The weld size, measured as leg length
• The length of each individual weld segment
• The pitch: the center-to-center distance from one segment to the next

Symbols exist precisely because words are slow and ambiguous on a shop floor. A welder flipping through a 60-page drawing package needs to understand a joint in two seconds. A standard symbol does that — as long as everyone reads the standard the same way.

Designers specify intermittent welds to save time, filler metal, and heat input on long joints where the full strength of a continuous fillet isn’t needed. On a 20-foot stiffener, that math adds up fast. If you’re feeding wire for hours of short segments, tips and drive rolls matter as much as the print does — our guide to contact tip selection and maintenance is worth a read before those long runs begin.

The intermittent information rides on the reference line as two dimensions separated by a hyphen: the length of each weld segment and the pitch, or center-to-center spacing between them. Everything below the reference line applies to the arrow side — the face the arrow touches. Everything above applies to the other side. That convention makes chain and staggered symbols readable, and if you miss it you will misplace half the welds on a two-sided joint.

One limitation worth stating up front: intermittent welds belong to fillet and similar partial-joint-penetration welds. A groove weld fuses through the joint thickness, so it is specified as continuous — you cannot make it intermittent in the same way.

A misread here is expensive in both directions. Too much weld means extra filler, extra heat, and slower production. Too little means a joint that fails inspection — or worse, fails in service. Either way, the drawing was never the problem; the reading was.

In the sections ahead, we will decode length and pitch, compare chain versus staggered callouts, weigh the benefits against the trade-offs, dig into what AWS D1.1 and related standards require, walk through the mistakes that trigger red tags, and close with a symbol-reading checklist you can keep in the shop. The reading habits that prevent rework — steady travel speed, consistent starts and stops — are the same ones covered in our guide to building real welding skills.

Reading the Numbers: Length, Pitch, and the Hyphen Rule

Here’s where that red tag was born. On an AWS drawing, a lone number sitting to the left of a fillet weld symbol is the leg size — the actual weld dimension. A 1/4 fillet means a continuous 1/4 in. fillet running the full length of the joint. One number, one meaning: size.

The second a hyphen shows up, the symbol changes jobs. Now those numbers describe a pattern, not a size. The convention in AWS A2.4 is fixed and worth memorizing: the length of each weld increment goes to the left of the fillet symbol, the pitch goes to the right, and a hyphen separates them.

So 2-8 reads “two-inch welds on eight-inch centers” — it never means an eight-inch weld size. Meanwhile a single 1/4 on its own is just the leg size of a continuous fillet. Same neighborhood on the symbol, completely different instruction on the shop floor.

Four Symbols, Four Meanings

That metric row matters more than it used to. Plenty of imported fabrications and ISO-flavored drawings now land in North American shops, and 6-150 is read exactly the same way: 6 mm weld increments, 150 mm centers, gap of 144 mm. No decimal inches anywhere near it.

The parenthetical count appears when the drawing can’t leave the number of increments to chance — short brackets, gussets, or a pattern that doesn’t divide evenly into the member length. Treat it as precise, not “close enough.”

What “Pitch” Precisely Means

AWS A3.0, the companion standard that defines welding terminology, treats pitch as the center-to-center distance between successive weld increments — which is simply weld length plus the unwelded gap. Do the arithmetic once and the pattern becomes self-checking: a 2-8 has a 6 in. gap; 3-8 leaves 5 in.; 4-8 leaves 4 in. Pitch stays 8 either way.

Knowing the gap tells you how much start-and-stop you’re signing up for — and how much distortion control you gain by balancing those stops around the joint.

Worked Example: Covering a 240 in. Member

Say a stiffener runs 240 in. and the symbol calls for 2-8. Pitch is the spacing, so divide: 240 ÷ 8 = 30 increments. That’s 30 welds, each 2 in. long — 60 in. of deposited weld and 180 in. of open gap spread across the run.

Now check the tail. Twenty-nine full pitches plus the last 2 in. weld gives 234 in., which is why the shop often ends with a longer final gap rather than a weld hanging off the end of the member. Same math in metric: a 6,000 mm member on 150 mm centers yields 40 increments.

That last increment is exactly where misreads get expensive. Read 2-8 as an 8 in. weld and you’d try to lay 8 in. beads on 8 in. centers — touching, effectively continuous, and far over the deposited length the engineer paid for. Excess weld like that drives heat input, distortion, and cost, and it’s a pattern an inspector spots in seconds. Clean restarts on each increment matter just as much; if your starts are cratered or cold-lapped, the technique in our how to use a wire welder guide covers the fix.

The hyphen rule, then, is short: number left of the symbol, hyphen, pitch right. Size on its own, pattern when paired. Get those two habits straight and reading a print becomes the easy part — deliberate practice turns it into muscle memory.

Chain vs Staggered Intermittent Welds: Same Numbers, Different Symbol

Two drawings can both read “3-12 fillet” and still call for completely different layouts. That’s because the numbers describe length and pitch — not how the increments sit relative to each other. The configuration lives entirely in where the symbols sit above and below the reference line. Miss that placement, and you’ll weld the right size in the wrong pattern.

Chain Intermittent: Welds Directly Opposite Each Other

In a chain intermittent weld, the fillet symbols appear on both sides of the reference line, sitting directly opposite one another. The increments line up across the joint: a weld on the near side has a matching weld on the far side, then both pause, then both restart. Run your eye along the toe and it looks like a chain of links. Chain is the default on many structural prints because it’s simple to lay out, easy to inspect, and delivers the same total weld length with a cleaner, repeatable pattern. That repeatability is exactly why high-deposition automated setups such as robotic submerged arc welding often run chain patterns down long stiffeners. Both chain and staggered are permitted under AWS D1.1; the drawing’s symbol placement is what governs which one you build.

Staggered Intermittent: Welds That Interlock Like a Zipper

Staggered intermittent welds still put symbols on both sides of the reference line — but offset. One side welds while the other is in its gap, and vice versa. Because the two sides never share a gap at the same station, the increments alternate along the joint and interlock like a zipper’s teeth. The total deposited metal is identical to chain for the same length and pitch; only the timing and location change.

Same “3-12” Numbers, Two Layouts

Take that familiar callout: 3-inch welds on 12-inch centers. Chain gives you 3 inches of weld on both sides at 0–3, then a 9-inch gap on both sides. Staggered gives you 3 inches on the near side at 0–3 while the far side stays open, then the near side gaps while the far side welds at 9–12. Same numbers, same total length, very different stress path and heat map.

Which One, and When

Chain is the stronger, stiffer arrangement. It builds a more continuous load path and is common on a plate girder web-to-flange joint, where you want both sides working together and the crew wants a clean, repeatable layout.

Staggered is the distortion fighter. By alternating heat input, it spreads thermal contraction along the member instead of stacking it at matching stations, which is why it shows up on stiffeners, thin plate, and long slender members where warping and bowing are the real enemy. It also suits welding practice on thin material where heat control matters more than raw section strength. Staggered also buys a little time: with only one side welding at any station, the previously welded increment can cool while you work the other side.

The Most Dangerous Misread

Here’s the trap that red-tags jobs: a staggered symbol means the far-side weld is not opposite the near-side weld. Weld one side as chain when the drawing called for staggered — or read a staggered callout as chain — and you’ll drop a weld opposite a gap that should have stayed open, or leave a gap opposite a weld. The result is a nonconforming pattern that inspectors catch on the floor and that often has to be gouged and redone.

Short Note: When symbols sit on both sides of the line, don’t just count them. Check their alignment — opposite means chain, offset means staggered.

Read the Placement First

Before you strike an arc, trace the reference line with a finger: are the increments mirror-imaged, or shifted? Same numbers, different symbol, different weld. Getting that one detail right is the difference between a passing joint and a rework order.

Why Specify Intermittent Welds? Benefits, and the Trade-Offs

On large fabrications, an intermittent weld is not a shortcut. It is an intentional design decision that trades a portion of a joint’s continuous strength for savings in time, material and heat. When a drawing calls for gaps between weld segments, there is a calculated reason for them. When it does not, filling those gaps can create problems that far outweigh the few minutes they appear to save. For that reason, the choice must remain with the designer, not the welder at the torch.

The Economic Gains

The most immediate appeal of intermittent welds is cost and efficiency. By welding only a set length at a set pitch, shops reduce filler metal consumption and arc-on time compared with a full-length continuous weld. For a long stiffener or a built-up member, cutting those segments can free up hours across a project and relieve strain on a rushed job. These gains are not automatic, however. They rely on consistency and precision, which can only be achieved through disciplined welding practice to prevent uneven segments from undermining the savings.

With less arc-on time also comes a practical side benefit: a reduction in total fume generation. This does not eliminate the need for proper ventilation or respiratory protection, but it can help lower a welder’s cumulative exposure over long production runs. As noted by NIOSH, controlling welding fumes remains a top priority for worker safety, so any verifiable reduction is a worthwhile byproduct of an efficient layout.

Less Heat, Less Distortion

Beyond time and cost, the strongest technical argument for intermittent welds is thermal control. Spacing the heat input allows the base metal to cool between segments, which lowers the overall heat input, reduces residual stress and minimizes distortion. This can mean the difference between a straight, square frame leaving the floor, or one that requires hours of cold working before it will bolt up to its mating parts. For large I-beams, built-up columns or heavy skid bases, that distortion can build gradually, so controlling where heat goes is just as critical as controlling how much is applied.

This advantage is especially valuable in shops with tight tolerances and mixed workloads. A well-planned sequence that takes advantage of intermittent welds must also account for the layout of your welding facilities, from fixturing to travel paths. Without that coordination, even a correctly specified spacing can concentrate heat in the wrong area and negate much of its benefit.

The Trade-Offs to Respect

These benefits cannot come at the cost of performance, and the trade-offs for intermittent welds are well defined. First and foremost, an intermittent weld cannot match the overall strength and stiffness of a full-length continuous weld. The gaps carry no load, so every remaining segment must be sized and placed to satisfy the design load without relying on the missing material. Second, those gaps can create crevices that trap moisture, dirt or process fluids. In exposed, marine or liquid-containing service, that trapped moisture can accelerate pitting and corrosion far more quickly than the weld size alone would suggest.

Due to these limitations, many structural and service-specific codes place strict restrictions on their use. For example, the AWS D1.1 Structural Welding Code limits intermittent welds for dynamically loaded joints, and they are rarely permitted for pressure-retaining, watertight or fatigue-critical seams. These restrictions exist for sound engineering reasons, not preference. In addition, OSHA reinforces that all welding must follow the applicable, approved specification for the job, so deviating from a print that prohibits them is not only unsafe, but also noncompliant.

A Final Rule for the Shop

Intermittent welding is a design decision, not a field adjustment. If the print does not call for gaps, do not leave them. If it does, mark the length and pitch with soapstone, tape or a fixture to keep them consistent across a long run. That simple habit protects the required performance, ensures code compliance and secures the very savings that justified the specification in the first place.

Code Requirements: What AWS D1.1 and Related Standards Demand

The symbol tells the welder what to build. The code tells everyone whether that shape is legal in the first place. You can read a 2-8 chain fillet perfectly, match the WPS, and still get red-tagged—because the governing standard controls minimum increment length, maximum pitch, and where intermittent welds are allowed at all. That second layer is where careful fabricators separate themselves from people who just copy the print.

The Four-Times Rule: Minimum Increment Length

For structural steel, the authority is AWS D1.1, Structural Welding Code—Steel. It sets the floor for how short an increment may be. The widely applied requirement is that the minimum length of an intermittent fillet weld increment equals four times the nominal weld size.

Take a 6 mm fillet. Four times six gives a minimum increment of 24 mm. Any callout asking for a shorter bead—say a 15 mm increment—does not comply, however neat it looks. Short beads cool fast, raise restraint, and plant start-stop stress risers in the joint, which is exactly why the code refuses them.

D1.1 sets minimum fillet sizes based on material thickness, too. A symbol asking for a 3 mm fillet on thick plate is non-compliant regardless of how the length and pitch read—the code simply won’t let you specify a bead that small on heavy steel.

Corners, Pitch Limits, and Where Increments May Not Land

AWS D1.1 prohibits intermittent fillet weld increments from terminating at the corner of a part. A corner already concentrates stress; ending a bead there stacks a weld crater and a stress riser in the same spot. The usual fix is to wrap the corner, or to weld continuously for a specified distance around it—check the applicable figure in the code before deciding how much.

Pitch has limits too. D1.1 caps pitch in many applications, tightening allowable spacing where fatigue, corrosion, or buckling governs. Wide gaps between increments mean less stiffness and more places for moisture and contaminants to collect.

Structural Steel vs. Pressure Work: Different Codes, Different Rules

Structure and pressure work live under different rulebooks. AWS D1.1 covers structural steel; AWS D1.2 handles aluminum. Where tubes, pipe, and pressure-retaining components are involved, ASME’s Boiler and Pressure Vessel Code—Section IX for welding qualifications—and the B31 piping codes take over. There, continuous welds are the norm, and intermittent symbols rarely belong on a joint at all. If your scope touches process piping or a pressure boundary, read our guide to weld tube fittings and fit-up before you accept the drawing’s callouts. Building the underlying technique first pays off in every code environment—our welding practice guide covers those fundamentals.

When the Symbol and the Code Collide: A Compliance Scenario

A contractor bid a pipe-rack and equipment-support package. A drafter copied an intermittent fillet symbol from an earlier structural job onto a connection tied to a pressure-retaining line. The shop built exactly what the print showed. At inspection, the CWI flagged it: the governing code for that portion of the work required a continuous weld. The crew cut out the increments, ground the toes, re-fit, and welded continuously—then paid for re-inspection and ate the schedule slip. Nobody welded badly. The detail was non-compliant, and the bid carried no contingency for it.

The symbol and the WPS must agree, and both must satisfy the governing code. An AWS Certified Welding Inspector reviews the built weld against the drawings and the qualified welding procedure—increment length, pitch, corner treatment, size, and profile. Bring the inspector in early when anything is ambiguous; a five-minute clarification beats a five-day cut-out.

Common Mistakes Welders and Drafters Make

Most intermittent-weld problems start before anyone pulls a trigger—with a symbol misread on the floor or misdrawn in the office. None of these seven mistakes are exotic; all of them are preventable.

1. Reading the Pitch as the Weld Size

On a “2-8” callout beside a 3/16 fillet, newcomers spot the big number and assume 8 is the bead. It isn’t. The 2 is each weld increment’s length; the 8 is pitch, measured center-to-center. The leg size sits separately on the symbol. Fix: add “circle the leg size” to your pre-weld checklist, then mark it on the joint in soapstone. Chasing the wrong size also means chasing the wrong heat—wide, shallow beads that roll over the toe are the classic overlap defect, and they fail visual inspection every time.

2. Wrong Side of the Symbol or a Missing Hyphen

Length and pitch both belong to the right of the fillet symbol, separated by that famous hyphen. Drop the hyphen and “2-8” reads as “28”; put the numbers on the wrong side and you’ve written a different weld entirely. Fix: redraw the symbol before fabrication and have a second person verify it. It takes thirty seconds and saves a 20-foot rework.

3. Measuring Pitch Edge-to-Edge Instead of Center-to-Center

Pitch is always center-to-center. Measuring from the end of one increment to the start of the next inflates your spacing, produces the wrong increment count, and fails inspection. Fix: make a simple pitch guide—wrap tape at each center point, or set a marker jig—and count increments against the drawing before you weld. That count is exactly what the inspector checks.

4. Drawing Chain When Staggered Was Intended

Chain and staggered share numbers but not layouts, and the symbols differ by the offset reference lines. Drafters flip them; welders then weld the wrong side. On a 20-foot stiffener, that’s a full run welded on the wrong line. Fix: if the intent isn’t obvious from the drawing, don’t guess—raise a written Request for Information (RFI) and get a redraw before fabrication.

5. Leaving the Tail Blank

The tail carries the process, WPS, and reference information. Leave it empty and the shop improvises, picking a process and settings from memory. Fix: every intermittent callout that matters gets a filled tail—process, WPS number, and standard, such as AWS D1.1.

6. Forgetting the Leg Size Still Applies

Intermittent is not code for “light duty.” The fillet leg size and technique are unchanged—only the length and spacing differ. Welders skip the settings check and burn too hot chasing the pattern. Fix: verify amperage and polarity for the actual size; a dial check and two-minute test coupon beat a rejected run. Our 3/16 E7018 amperage guide is a good starting reference.

7. Cold, Ugly Starts and Stops

Every increment creates two start/stop points, and those points are common locations for crater cracks and lack of fusion. Cold starts, unfilled craters, and abrupt tie-ins concentrate stress at each one. Fix: fill every crater, backstep where geometry allows, and feather tie-ins. The results should look like the passes in our good vs. bad MIG welds comparison—consistent, tied-in, and free of pinholes.

Fix-It Checklist Before You Weld

• Circle the leg size, then confirm the length-pitch pair sits right of the symbol with its hyphen intact.
• Mark pitch centers on the joint—never measure edge-to-edge.
• Confirm chain or staggered against the drawing; if unclear, stop and write an RFI.
• Check the tail for process and WPS; blank tails get clarified, not guessed.
• Match amperage and polarity to the actual leg size, not the pattern.
• Fill craters, tie in cleanly, and keep a consistent rhythm—build the habit with deliberate welding practice.

ISO vs AWS Symbol Conventions: Where Reading Gets Trickier

If you’ve spent your career welding to AWS drawings, the first ISO sheet you pick up can feel like someone shuffled the deck. The weld is the same; the language isn’t. ISO 2553 is the international standard for welding symbols, and it is a genuinely separate system from AWS A2.4, which governs how symbols are drawn in the United States. Shops that build for both domestic and overseas clients — or that weld imported fabrications — have to read both, and intermittent welds are exactly where the gap trips people up.

The n × l (e) Format

Where AWS writes a length-pitch pair like 2-8, ISO 2553 often expresses the same idea as n × l (e). Here n is the number of weld increments, l is the length of each increment, and e is the pitch — the center-to-center distance. So a note reading 4 × 3 (12) means four separate 3-inch weld segments on a 12-inch pitch.

ISO also uses a plain length-and-pitch convention, just like AWS, but it stacks the two numbers in a fraction: the increment length sits above the line and the pitch sits below. An AWS-trained eye reads left to right; an ISO stack reads top to bottom. Transpose those two numbers and a 2-inch weld on an 8-inch pitch becomes an 8-inch weld on a 2-inch pitch — a far heavier, far more expensive joint.

Same Weld, Two Notations

Take a drawing calling for 3-inch fillet increments on a 10-inch pitch, staggered on both sides. In AWS notation that’s a fillet symbol carrying 3-10, with the stagger symbol added. In ISO the same weld may appear as n × l (e) — 5 × 3 (10) for five increments — or as the 3/10 stack, with the dashed system line handling the far side. Identical weld, different grammar.

The Dashed Line Rule and Supplementary Symbols

In AWS, the side of the joint a weld lands on is shown by whether the symbol sits above or below the reference line. ISO 2553 keeps the solid reference line but adds a dashed system line: a symbol on the solid line means the near (arrow) side, while a symbol on the dashed line means the far side. Miss that dashed line and you may weld the wrong face — or weld both when only one was specified. ISO also carries its own supplementary symbol set, so a few marks you know from AWS won’t appear at all.

Here’s the side-by-side breakdown:

Fabrication shops that routinely handle both must train on both — not just the symbols, but the reading habits behind them. Building that skill is like any other weld: structured, deliberate practice. Our guide to welding practice covers how to drill fundamentals into habit, and if you’re setting up a print-reading station or training bay, see our piece on welding facilities. Tag the governing standard on the traveler and make symbol interpretation a checked step rather than an assumption.

From Symbol to WPS: Inspection, Verification, and QA

The symbol on the print is only the start. Before anyone strikes an arc, that 2-8 callout gets translated into a Welding Procedure Specification (WPS) — often a prequalified WPS under the AWS D1.1 Structural Welding Code — Steel, which treats weld size, increment length, and spacing as essential variables. The WPS has to match the drawing exactly. If the print reads 3-12 chain, the WPS cannot quietly call for staggered, and a welder who assumes otherwise is building the wrong joint.

What the WPS Records

A competent intermittent-weld WPS spells out:

• Weld size and the length of each increment
• Pitch — center-to-center spacing
• Configuration: chain or staggered
• Process, filler, polarity, amperage range, travel speed
• Position, and any preheat or interpass limits

The welder follows the WPS, not the print alone. The print says where; the WPS says how. Pitch is the variable that drifts most in the field, because a welder watching arc length can lose count of gaps without noticing. When the two documents disagree, work stops until the engineer or drafter resolves it — welding to the wrong reading means cutting metal back out.

How a CWI Verifies Length and Pitch

The AWS Certified Welding Inspector (CWI) is the recognized credential for verifying weld quality against codes and drawings. Intermittent-weld inspection is low-tech but disciplined:

• Visual check of size, profile, and increment count
• Tape measure: increment length first, then center-to-center pitch
• Chalk or paint marking each increment on long runs, where miscounts happen

Measure increment length first, then center-to-center pitch, and record both values against the symbol. On long stiffeners, inspectors often mark each increment in one color and any defect in another, then count. A run that should show twelve 2-inch increments over a 96-inch length at 8-inch pitch is easy to verify — and just as easy to fail.

Visual inspection is the first-line NDT method for fillet welds. Magnetic particle testing suits ferritic steel and finds surface and near-surface discontinuities at stops and restarts; dye penetrant works on austenitic stainless and other non-magnetic alloys. Neither is routine on every intermittent weld — they’re applied where the drawing, code, or engineer calls for them. Starts and stops are the highest-risk zones, because craters, porosity, and lack of fusion concentrate there. Restart technique matters as much as the bead body; our guide to telling good and bad MIG welds apart covers those visual cues. Non-conformances are written up, tagged, and dispositioned as repair, rework, or engineering accept-as-is.

Documentation That Protects Everyone

Weld maps locate every increment on the structure; symbol-interpretation notes capture the answers to RFIs; as-built records show what was installed versus what was specified. Keep the interpretation notes with the weld map, not in a separate file, so the reasoning travels with the record. A good weld map carries the drawing symbol number, the WPS number, the welder ID, and the date — so if a symbol is later revised, you know exactly which increments were affected. Photograph the marked increments before welding and after inspection. Note: an unanswered question about chain versus staggered can hold an entire girder while the crew waits.

Shop Scenario: Pre-Marking Pitch

On a bridge girder, a fabricator builds a simple jig — a spacer bar cut to the pitch — and pre-marks every increment along the flange before welding. The welder follows the marks, finishes the run faster, misses fewer increments, and the inspector measures instead of hunting for starts. The jig also standardizes the look: every increment the same length, every gap the same, so the pitch is obvious at arm’s length.

Building Symbol Fluency

The CWI credential path is one of the best ways to build symbol fluency, but you can start long before certification: read the print, write the pitch down, and weld to the WPS. Our complete guide to welding practice has drills that sharpen the fundamentals behind every symbol.

Practical Tips, Shop Setups, and Drill-First Practice

Reading the symbol right is half the job; the other half happens at the bench, where good habits turn a drawing’s numbers into consistent, inspectable welds.

Lay It Out Before You Strike an Arc

On long members, never eyeball the pattern. Measure the first length with a tape, mark it in soapstone or silver pencil, then transfer the pitch with a pitch jig or a spacer cut to the exact center-to-center distance. Marking a strip of tape at every pitch interval lets you peel and stamp fast down a 20-foot stiffener without re-measuring. A laser guide or chalk line keeps increments running straight when the member is too long to trust your eye.

Number each increment as you go — 1, 2, 3 — with a small soapstone tick. On long skids and rails, numbering gives the inspector a quick way to spot a skipped or doubled weld, and it lets two welders split a member without losing their place in the pattern.

If your bench or bay doesn’t support this kind of repeat work, it’s worth fixing. Good lighting, a solid table at the right height, and accessible power and ventilation all affect how consistent your increments stay over a long shift — our guide to planning and setting up a safe shop walks through the layout decisions that matter.

Keep Every Increment the Same Size

A consistent leg size across every increment means consistent settings at every start. Lock in your amperage, travel speed, and electrode angle, then repeat them each time you pull the trigger or strike up. Comfort is the enemy here — the temptation is to speed up as you settle in, which is how the last increment ends up thinner than the first. Treat each increment as a fresh start, never an extension of the last, and glance at your machine settings between passes so nothing drifts.

Start and Stop Without Craters

A crater at the end of each increment is a stress riser and a likely starting point for a crack. Don’t simply cut the arc — pause, add a touch of fill, then feather or backstep the end so the crater fills out. On restart, strike up slightly ahead of the previous crater, wash back into it, and move forward. That keeps the tie-in full-size instead of leaving a low, cold lap.

Safety on Long Runs

A long joint keeps you in one position far longer than a short one, so plan for the strain. Rotate or reposition the work when you can, take short breaks to reset your shoulders and posture, and swap hands if the joint allows. Route the stinger lead over your shoulder or along the member so it can’t loop your leg or drag through the puddle as you travel.

Fume control matters more on long runs because you’re generating smoke in one place for minutes at a time — and welding fume is a recognised health hazard. In small or enclosed spaces, OSHA 1910.252 calls for mechanical ventilation at a minimum of 2,000 cubic feet per minute per welder. The CDC/NIOSH fume guidance is worth a read before you work in a tight bay. Pair that airflow with proper eye and face protection, since arc flash and spatter are constant on long passes.

Build Symbol-to-Hands Fluency

The fastest cure for misread prints is deliberate practice: draw the symbols yourself, weld them on scrap, then measure the pitch and length of what you actually laid down. Compare the tape-measured result to the drawing. After a few sessions, your eyes translate 2-8 into hands that know exactly where to stop and restart. Our welding practice guide breaks this loop into drills you can run in an afternoon.

For high-volume shops chasing repeatability on long members, automation picks up where manual pacing slows down. Robotic submerged arc welding can reproduce intermittent patterns precisely, run after run, without the fatigue that creeps into hand welding. Build the manual skill first; automate it when volume justifies the investment.

Putting It All Together: A Quick Symbol-Reading Checklist

Think back to that twenty-foot stiffener, and the welder who saw “2-8” and laid down two inches of 8 mm bead. The steel was fine, the machine was dialed in, and his hands were steady. The failure happened before the arc ever struck — in the two seconds spent looking at a symbol without truly reading it. That little hyphen carries more consequence than almost anything else on the print, and decoding it is a skill you build deliberately, not a formality you wave through.

Every intermittent weld symbol follows the same quiet hierarchy. Identify the weld type first — fillet, groove, plug. Read the size of the leg or the groove depth. Then read the length-and-pitch pair, remembering the hyphen separates “how long” from “how far apart.” Confirm chain or staggered by which side of the reference line the symbols occupy. Finally, check the governing standard and the code limits that override the drawing. Get that order scrambled and the numbers start lying to you.

The Screenshot Checklist

1. Weld type: Fillet, groove, or plug/slot?
2. Size: Leg length or groove depth — read it before the hyphen.
3. Length and pitch: 2-8 means 2-inch welds on 8-inch centers, never an 8 mm leg.
4. Chain vs staggered: Symbols stacked on one side = chain; offset across both sides = staggered.
5. Standard: ISO or AWS? The same figures can sit in different places. Cross-check against the AWS A2.4 and A3.0 standards, which are meant to be used together.
6. Code floor: Minimum weld length and maximum pitch per AWS D1.1.
7. Flags and tails: All-around, field weld, or reference to a specific WPS.

Run the story again with the checklist in hand. Thirty seconds: fillet, 2-inch length, 8-inch pitch, chain, AWS D1.1, no field flag. The red tag never happens. Grinding out a full run and re-welding it costs a day of labor, a plate of consumables, and quite possibly a delivery milestone — all traded away for half a minute of careful reading. That trade is never, ever worth it.

Build the habit the same way you build arc time. Ask the engineer or inspector when a symbol is ambiguous rather than guessing quietly. Photograph the drawing detail. Keep a laminated card of common symbols in your hood bag. Deliberate practice on real prints pays off faster than most people expect, and it belongs alongside the fundamentals covered in our guide to building real welding skills.

Looking ahead, drawings themselves are changing. CAD packages and 3D models now annotate weld symbols directly onto digital geometry, and automated cells — like those in robotic submerged arc welding — read that data directly. The notation underneath hasn’t changed at all. A programmer who misreads pitch sends a robot down the same wrong path a human would, only faster and more repeatably. Symbol literacy is becoming more valuable, not less.

So treat print reading as a core welding skill, up there with travel angle and heat input. When your bead passes, inspect it the way you would any other: good and bad MIG welds look obvious once you know what to check. Then bookmark this reference, keep the checklist handy, and read the hyphen every single time.

Frequently Asked Questions

What does a 2-8 intermittent weld symbol mean?

It means each fillet weld increment is 2 inches long, and the pitch — the center-to-center distance between successive increments — is 8 inches. The first number is always the increment length and the second is the pitch, separated by a hyphen.

What is the difference between a chain and a staggered intermittent weld?

A chain intermittent weld has increments directly opposite each other on both sides of the joint, so they line up. A staggered intermittent weld offsets the increments so they alternate along the joint, which spreads heat input and can reduce distortion.

Is pitch the same as the gap between welds?

No. Pitch is measured center-to-center from one weld increment to the next, so it includes the weld length plus the unwelded gap. Measuring edge-to-edge gives the wrong number and produces too few increments.

Where do the length and pitch go on an AWS welding symbol?

Per AWS A2.4, the increment length is placed to the left of the fillet weld symbol and the pitch to the right, separated by a hyphen. If only one dimension is shown on a fillet weld, that dimension is the leg size, not the length.

Are intermittent welds allowed by AWS D1.1?

Yes, in many applications, but AWS D1.1 sets limits such as a minimum increment length and restrictions on terminating increments at the corner of a part. Some applications, including seismic and certain dynamic or exposed conditions, restrict or prohibit them.

How is ISO 2553 different from AWS A2.4 for intermittent welds?

ISO 2553 uses a stacked length-and-pitch convention (often written as n × l (e)) and a dashed reference line to indicate the far side of the joint, while AWS uses above/below the reference line and a hyphenated length-pitch format. The governing standard is usually stated in the drawing notes.

Can I make an intermittent groove weld?

Generally no — intermittent welds are used with fillet and similar partial-joint-penetration welds. A groove weld is normally continuous because an intermittent groove weld would leave an unsealed root and unpredictable strength.

What should I do if an intermittent weld symbol is unclear on a drawing?

Stop and issue a written Request for Information rather than guessing. Ambiguity in symbol placement, missing process information in the tail, or conflict with the code should be resolved before fabrication to avoid rework.

Why do intermittent welds sometimes fail inspection?

The most common reasons are incorrect pitch or increment length, wrong configuration (chain drawn but staggered built), undersized leg length, and defects at the many start and stop points. Taping or jigging pitch before welding greatly reduces these failures.

Authoritative Sources & Further Reading

• https://www.aws.org/standards-and-publications/codes-and-standards/a30m/
• https://www.aws.org/standards-and-publications/codes-and-standards/d1-1/
• https://www.aws.org/standards-and-publications/codes-and-standards/
• https://pubs.aws.org/
• https://www.aws.org/certification-and-education/professional-certification/certified-welding-inspector/
• https://www.osha.gov/welding-cutting-brazing
• https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.252
• https://www.cdc.gov/niosh/welding/about/index.html
• https://www.cdc.gov/niosh/docs/88-110/default.html
• https://www.asme.org/codes-standards
• https://www.nfpa.org/codes-and-standards