The dimensional family: a weld that is the wrong size or shape for the joint — reinforcement too high, too low, a throat that falls short, or members out of alignment. Every one of these is a shape problem, and every one of them is measured, not guessed.
Weld profile is the external geometry of the finished weld: reinforcement height, face contour, fillet leg and throat dimensions, and the alignment of the joint members. Incomplete or excessive profile is the family of discontinuities where those dimensions fall outside the envelope the governing code allows.
Profile decides how load flows through the weld. Excessive convex reinforcement concentrates stress at the sharp toes and cuts fatigue life; a flat or underfilled weld means the load-carrying throat is short; a misaligned butt joint turns the weld into a built-in stress riser. These rarely fail overnight — they fail in service under repeated load, which is why codes measure them so closely.
Excessive reinforcement, excessive convexity, excessive concavity, insufficient throat, undersized fillet, oversized fillet, misalignment, poor weld profile.
Profile defects are read with a gauge before they are read with an eye — but you see the pattern first.
Profile is a balance problem: heat input versus filler deposited, against the joint geometry you actually fit up. Three variables — fill, speed, and fit-up — account for nearly every profile defect.
Profile is the visible output of the heat-to-fill balance. The puddle is shaped by surface tension, gravity, and how much molten metal is present per inch of joint. Feed too much filler relative to travel — slow travel, high wire feed, low voltage — and the pool crowns: the weld comes out high and convex with sharp toes. Feed too little — fast travel, low current — and the pool starves: the weld comes out flat and underfilled, with a throat below requirement.
Fit-up sets the baseline. If the joint members are misaligned or the gap is wrong, no parameter will produce a code-conforming profile — the geometry is wrong before the first arc. And weld size feeds the system: an oversized weld carries extra heat, so it shrinks more and distorts the part. Profile, fit-up, and distortion are one system, not three separate problems.
Profile is the most preventable family in the library — it comes from the WPS, the fit-up, and the gauge in your pocket.
Verify fit-up and alignment against the drawing — root gap, edge prep, member alignment. Measure the joint, not just the drawing. Have the right gauges on the bench before you need them.
Run on the WPS parameters, not feel. Take a test bead on scrap or a run-off tab and gauge it before you start the joint — catch an oversize or underfilled setting cheap.
Gauge the bead as you go. Use stringer beads instead of wide weaves where the code allows — stringers give you a profile you can measure and correct pass by pass.
Grinding reinforcement down is a fix only if you stop at the code limits. Grinding below minimum reinforcement is itself a defect — you've traded oversize for undersize, and toes ground into the plate become undercut.
Profile defects are the most repairable family in the library — but the repair has to be measured too.
| Step | Action | Why |
|---|---|---|
| 1 | Identify which dimension is out — reinforcement, throat, leg, or alignment — with the right gauge. | You repair different things; a gauge, not a guess, says which. |
| 2 | Excessive reinforcement: grind smoothly to the code profile, blending the toes without cutting base metal. | Sharp toes concentrate stress; grinding into the plate makes undercut. |
| 3 | Underfill or undersized fillet: clean and build up with additional passes to the required throat. | Extra fill is the only fix for a short throat — grinding can't add metal. |
| 4 | Misalignment: remove the weld, realign the members, re-weld. | You cannot weld your way out of bad geometry. |
| 5 | Re-measure with gauges and verify by VT. | Acceptance is dimensional — prove it with numbers. |
Grinding is the trap. Removing excess reinforcement below the code minimum makes an undersized weld, and grinding into the base metal at the toes creates undercut. Grind to the envelope, verify with the gauge, and re-weld only where the throat needs building.
Every process has its own dial that writes the profile. Know which one is yours.
The voltage/WFS balance writes the profile. WFS too high for the voltage gives a ropey, convex bead; voltage too high for the WFS gives a flat, washed-out one. Watch the bead shape as the balance drifts.
Filler feed rate. Feed too little and the bead starves; feed unevenly and the bead swells and thins along its length. Add filler in consistent, deliberate increments.
Amperage. Too high burns the bead wide and flat; too low leaves it humped with poor wash-in at the toes. Match the electrode size to the pass you're running.
Deposition rate. The wire lays down metal fast — one extra pass or a slow run overshoots the size envelope quickly. Keep the gauge close.
The gauges answer "what" — these numbers answer "why". Check them in this order.
| Parameter | Check | Typical Fix |
|---|---|---|
| Wire feed / current | Against the WPS window, and that the feeder delivers what the dial says | Re-dial to the WPS; sort out feeder and liner problems that drift the size |
| Travel speed | Bead shape along the run | Slow = humping; fast = underfill; settle where the bead is uniform |
| Voltage | Bead flatness | Low = convex; high = flat/washed; balance against wire feed |
| Weld size vs. required throat | Fillet gauge, bridge cam gauge, weld size gauge | Add or remove fill to meet the measured requirement |
| Joint fit-up | Gap, edge prep, member alignment | Correct fit-up before welding — no parameter fixes geometry |
Use the Welding Calculator to size passes and check deposition, and the Material Thickness guide to confirm edge prep and joint geometry against plate thickness.
Two things write the profile from the hardware side: arc stability and per-pass fill rate.
Power source stability shows up directly in bead shape — an arc that wanders produces a puddle that wanders and a profile that follows it. On the consumables side, wire and electrode size set how much fill each pass deposits: the wrong size means either too many small passes or one oversized pass.
Profile is found with the eye first, then proven with a gauge — and where the code requires, NDT checks the internal consequences.
Acceptance depends on the code and project: AWS D1.1, ISO 5817, API 1104 and project specifications each set their own limits for this discontinuity. Check the governing document before judging a weld acceptable — there is no universal pass/fail rule.
The questions welders actually ask about weld profile — answered straight.
No. Oversized reinforcement concentrates stress at the sharp toes and hurts fatigue life, carries extra heat and distortion, and can exceed code limits. A weld that meets the minimum required throat is stronger under cyclic load than one that is over-built.
It is code-dependent. As a rule of thumb, structural codes like AWS D1.1 cap reinforcement at about 1/8 inch above flush for groove welds — but the exact limit lives in the governing code and the project spec. Measure the weld and check the document that applies.
Yes — smooth grinding that blends the toes is the standard fix for excess reinforcement. But grind only down to the code minimum: grinding below it makes an undersized weld, and grinding into the plate at the toes creates undercut.
The leg is the distance from the joint root along each member face — the two legs define the fillet size. The throat is the shortest distance from the root to the face of the triangle, and it is the throat that carries the load. Concavity shrinks the throat; convexity adds no strength beyond it.
Underfill is weld metal falling short of flush in a groove weld — a fill shortage. Undercut is a groove melted into the base metal at the toe — a base-metal loss. They can look similar at a glance, but the causes and the repairs are different.