Pipefitter Interview Questions
& Model Answers, 2026

Identify the line number, size, schedule and material spec in the title block, then work each dimension centre-to-centre and subtract the take-out for every fitting and flange face at each end, allowing for gasket thickness and the weld gap. Call the spool breaks where the piece can still be handled and shipped. A strong candidate says out loud that dimensions on an iso are centre-to-centre unless noted, and checks the north arrow before assuming an orientation.

Typically a bevel around 37.5 degrees per side for a standard V-groove, a land of roughly a sixteenth, and a root gap set to the welder's process and preference — tighter for a TIG root, wider for open-root stick. The point of the answer is that you ask the welder rather than assuming, keep the prep clean and free of mill scale and moisture, and check hi-lo alignment on both sides before tacking. Poor fit-up is the single biggest cause of rejected radiography.

Process piping in a plant is normally built to ASME B31.3, while power piping is B31.1 and building services fall under the mechanical code. It changes material traceability, examination percentages, the qualified welding procedure you may use, and the test pressure and hold time. Candidates who cannot name the code they built to are telling you they never handled a test package.

Define the test boundary and blind it, remove or isolate instruments, relief valves and anything that cannot see test pressure, confirm supports are adequate for the weight of water, fill and vent from the high point, raise pressure in stages with a calibrated gauge, hold for the required duration, walk every joint, then depressurise slowly and drain. Sign the test sheet with the gauge serial and calibration date. Mentioning that the gauge must be calibrated is what separates a fitter who has closed packages from one who has not.

You let it move where you intend and stop it where you do not: anchors set the fixed point, guides keep the movement axial, and spring or constant-effort hangers carry the weight through the movement. Expansion loops or bellows absorb the growth. A strong answer mentions calculating expected growth from the temperature difference and the coefficient, and warns that a rigid hanger where a spring belongs will pull a nozzle off a vessel.

Clean and inspect both faces, check flange alignment and parallelism rather than pulling the gap closed with the bolts, use the correct gasket for the service, lubricate the studs, then torque in the standard crossing pattern in several passes to the specified value, followed by a final round pass. Retorque after thermal cycling where the spec calls for it. Bolting a misaligned flange together is a leak and a cracked nozzle waiting to happen.

The useful version names the actual defect — a hi-lo out of tolerance, a bad root from a gap that closed while tacking, a spool a quarter inch short because a take-out was missed — and what you changed in your process: checking the iso against the cut list before cutting, tacking in four places, measuring twice against a datum. Fitters who claim nothing has ever come back are not credible.

Fit-up and welding are one handoff, and the pair either works or the job stalls. Strong answers describe asking the welder what gap and prep they want, giving them clean and accessible joints, and raising a genuine quality concern through the QC or foreman rather than in front of the crew. Answers that treat the welder as someone to be argued with signal a fitter who will slow down a spool shop.

Turnaround examples carry weight: a line that was not verified drained and de-energised before a break, a permit that did not match the actual work, a confined-space entry with no atmospheric monitoring, a lift over live equipment. Say what you stopped, who you notified, and that you got the permit or isolation corrected rather than just walking away from the task.

Turnarounds run twelve-hour shifts for weeks, and the honest answer covers the mechanics: sleep discipline, hydration and food on nights, double-checking measurements late in the shift when errors spike, and a solid handover to the opposite shift so work is not repeated or half-finished. Bragging about working through exhaustion is a red flag to any safety-conscious contractor.

Anchor to the published series and then adjust for the work type. The BLS OEWS May 2025 median for plumbers, pipefitters and steamfitters is $63,800 a year ($30.67/hr), with the top 10% above $108,420 — a blended series covering residential plumbers as well as industrial fitters, so refinery and power turnaround fitters commonly sit in the upper part of the band. Base your number on your fit-up quality, code experience and willingness to travel.

Substantially, and they are negotiable. Ask the daily per-diem rate, whether it is paid on days off during the outage, whether mileage or a travel day is paid at each end, whether lodging is provided or reimbursed, and whether the per diem is taxable in that arrangement. Also ask the guaranteed hours per week, because a fifty-hour guarantee at a lower rate can beat an unguaranteed higher rate.

Counter with verifiable specifics: the codes you have worked to, your weld-reject rate as a fitter, alloy and stainless experience, rigging and confined-space tickets, and your record of finishing an outage without a recordable. Then negotiate the levers a contractor can move faster than base rate — guaranteed hours, per diem, a completion bonus tied to the outage end date, and a lead-fitter designation.