What Do Welder Interviews Actually Test?

Who's in the room

For a shop job, it's usually the shop foreman or welding supervisor, sometimes with the QA/QC manager sitting in if the work is coded (AWS D1.1 structural, ASME Section IX pressure vessel, or API pipeline work). On union jobs the first contact is often the hall dispatcher, and the actual test is administered by the contractor you're dispatched to, not the union itself. On pressure vessel or pipeline work, don't be surprised if a client's inspector or a CWI (Certified Welding Inspector) watches the weld test directly, because they're the one who has to sign off on your qualification record afterwards.

What this means practically: the person asking you questions has usually welded themselves, or inspects welds for a living. Answers that would satisfy an HR generalist — "I'm a hard worker, I pay attention to detail" — don't land, because that's not what they're listening for.

The weld test: what it actually checks

If there's a practical component — and for most welding jobs there is — you'll be given a coupon: a piece of plate or pipe, a specified process (SMAW, GMAW, FCAW, or GTAW), and a position (2G, 3G, 4G, or 6G if it's pipe). You may be handed a WPS (Welding Procedure Specification) and expected to follow it without being walked through it line by line — reading a WPS correctly, including joint prep, preheat, and interpass temperature limits, is part of what's being tested, not a formality before the real test starts.

You'll often set your own machine parameters: amperage, wire feed speed, travel speed. Nobody tells you the numbers. That's deliberate — a shop wants to see whether you can look at the joint, the material thickness, and the position, and arrive at the right settings yourself, then adjust mid-weld if the puddle tells you something's off.

The coupon then goes one of two ways. Destructive testing — a guided bend test, checked against AWS D1.1 or ASME IX acceptance criteria for cracks and lack of fusion. Or non-destructive testing — visual inspection (VT) first, and depending on the code and the job, radiographic (RT) or ultrasonic (UT) testing after. A 6G pipe test with an open root, done under RT, is a different order of difficulty from a 3G plate test that only needs to pass a bend — if you're told which one you're sitting, ask, because how you weld the root changes.

A test that only checks visual appearance and skips destructive or NDT testing tells you something about how the shop verifies its own welds day to day — worth noting either way.

Questions that are actually checking competence

The ones worth taking seriously are the ones with a specific, technical answer, because a vague reply exposes itself immediately to someone who's done the work.

"Walk me through how you'd run the root on an open-root 6G pipe joint." They want electrode or wire choice, root gap and land dimensions, current range, and how you're managing penetration without a backing ring — not "carefully."

"How do you deal with undercut on a vertical-up pass?" A real answer talks about dwell time at the toes, travel speed, and current — maybe dropping amperage slightly or adjusting the weave. "I just go slower" is halfway there but incomplete; it doesn't show you understand why undercut happens.

"Tell me about a weld that failed inspection and why." This is the question that separates people. A shallow answer is "I made a mistake and fixed it." A real answer names the actual failure mode — porosity from wind exposure or dirty base metal, cold lap from insufficient heat input, incomplete fusion from a bad travel angle — and what changed afterwards. Nobody who's welded structural steel or pipe for any length of time has a clean record. Claiming otherwise reads as either inexperience or dishonesty.

"How do you read this WPS / this drawing?" Sometimes they'll hand you an actual print with AWS welding symbols on it and ask you to explain the joint. This checks blueprint literacy directly, not welding skill in the abstract.

"What's your process for checking interpass temperature?" or "When do you preheat, and how do you check it?" These come up on structural and pipe work with thicker material or certain alloys. A contact pyrometer or temp stick, and knowing the actual preheat and interpass limits from the WPS rather than a guess, is the expected answer.

None of these are trick questions. They're the questions a foreman asks because the answer tells them whether you'll produce rework.

What a shallow answer sounds like

To someone who welds for a living, these give it away fast:

• "I just weld it till it looks good." Appearance and code compliance aren't the same thing, and everyone in the trade knows a weld can look clean and still fail a bend test.
• "I follow the manual" with no follow-up detail when asked what the manual actually says for that joint.
• Claiming a position or process on a resume — 6G, TIG on stainless, whatever — and then being unable to name the specific technique differences (like walking the cup, or backpurging) when asked.
• "I never get porosity" or "I always pass first time." Every experienced welder has had a bad day, wind exposure on a site job, or a dirty joint. Denying it signals either dishonesty or that the person hasn't done enough field work to have hit the common problems yet.
• Talking about safety only in generic terms — "I'm always careful" — instead of naming specifics relevant to the job: fume extraction and confined space entry procedures, fire watch requirements, or fall protection if it's structural steel at height.

Paperwork that gets checked, and why it matters

Expect questions about your journeyman card if it's a union or apprenticeship-trained role, and about which welding certifications you currently hold — AWS D1.1 structural, ASME Section IX, API 1104 for pipeline, or a specific employer-administered test. Certifications tied to a code often lapse if you haven't welded that process and position within six months, so "I'm certified" sometimes needs the follow-up "as of when, and have you kept it current." OSHA 10 or 30, confined space entry, and fall protection cards come up on industrial and structural sites specifically, not universally, so don't assume every interviewer cares about the same list — a structural steel erector and a fabrication shop floor are checking for different things.

What to do next

Before any interview, know exactly which processes, positions, and codes you can weld to right now, not what you learned in your apprenticeship five years ago. If a job advert mentions a specific code or position — 6G, D1.1, ASME IX — be ready to talk through the actual technique, not just claim the qualification. If your certifications have lapsed, say so plainly rather than letting it surface at the weld test.

If you're sending out applications and hearing nothing back, it's often not the welding — it's the resume not naming the specific processes and codes the advert asked for. jobmarket.pro reads each advert in full and prepares an application from your actual welding history, matched to what that specific job is asking for.