A piping fabrication QC checklist covers seven checkpoints: material receipt, fit-up, in-process welding, visual inspection, NDT, repairs, and final release. At each one, the inspector verifies a short list of items (for example heat numbers against MTRs at receipt, root gap and alignment at fit-up, preheat and welder qualification during welding) and records the result against the weld or spool number. The checklist below is ready to adapt into your inspection and test plan (ITP).

Use it as a starting point. Your client's specification and the applicable code (ASME B31.3, EN 13480 or others) set the final acceptance criteria.

What is an ITP, and how does a piping fabrication QC checklist fit in?

An inspection and test plan lists every inspection activity, who performs it, the acceptance criteria, the record produced, and the involvement of each party:

Code	Meaning	Effect on work
H – Hold point	Work stops until the inspection is done and released	Cannot proceed without sign-off
W – Witness point	Client or third party is invited to attend	Work may proceed if they don't attend after notice
R – Review	Records are reviewed, no attendance	Paperwork check
S / M – Surveillance / monitor	Random checks by the inspector	No notice needed

The checklist is the inspector's working list for each stage. The ITP is the agreement on who signs what.

Seven QC checkpoints from material receipt to release, shown as a flow

Stage 1: What should you check at material receipt?

Material grade, size, schedule/thickness and rating match the purchase order and line spec
Heat numbers on the material match the material test reports (MTRs)
MTR values meet the material specification (chemistry, mechanicals)
Fittings and flanges marked per their standard (manufacturer, grade, size, rating)
Visual condition: no damage, corrosion, damaged bevels or faces
Stainless and alloy stored separately from carbon steel
PMI done where required (alloy materials)

Record: material receiving report and material log by heat number.

Stage 2: What should you check at fit-up?

Correct components per the iso, at the current revision
Heat numbers transferred and recorded for both sides of the joint
Bevel angle and root face per WPS
Root gap per WPS
Internal misalignment (hi-lo) within the WPS or code limit
Joint clean and free of paint, oil, scale and moisture
Tack welds made by a qualified welder, sound and correctly prepared
Dimensions and orientation of branches and flanges (bolt holes straddling centrelines unless specified)

Record: fit-up acceptance against the weld number.

Stage 3: What should you monitor during welding?

Welder is qualified for the process, position, thickness and material, and continuity is current
Approved WPS is available at the workplace and followed
Correct filler metal; consumables stored and handled per requirements (low-hydrogen electrodes in ovens)
Preheat temperature measured and recorded when required
Interpass temperature controlled
Purge gas used where required (stainless, alloy roots)
Weather protection for site welding

Record: welder ID and date against the weld; preheat/interpass records if required.

Stage 4: What does visual inspection of a pipe weld include?

Weld profile and reinforcement within limits
No cracks, lack of fusion visible at the surface, or undercut beyond limits
No arc strikes, spatter left on pressure parts
Root profile acceptable where accessible
Welder identification marked or recorded
Spool dimensions checked against the iso

Record: visual inspection report by weld number.

Stage 5: How do you control NDT?

NDT extent per line class and spec (for example 5% random RT for normal fluid service under B31.3)
Random selection made by the inspector and covering each welder's work
NDT procedures and technician qualifications approved
Reports received, reviewed and entered against weld numbers
Rejects trigger repair and progressive sampling

Details in NDT Tracking for Pipe Fabrication.

Stage 6: How should repairs be handled?

Defect removed and excavation checked (often MT or PT) before re-welding
Repair welded to an approved WPS by a qualified welder
Re-examined by the same method as the original
Extra samples examined if the reject came from random sampling
Repair number recorded against the original weld (W07-R1)
Repair limits respected (number of repairs at one location)

See weld repair traceability for the record structure.

Stage 7: What is checked at final release?

All welds on the spool accepted (visual, NDT, repairs closed)
PWHT and hardness tests done where required
Pressure test done if performed in the shop (for B31.3 hydrotest, typically 1.5 times design pressure, adjusted for temperature)
Internal cleanliness, no debris or loose material
Coating or painting inspected if in scope
Flange faces protected, ends capped
Spool marked and records complete for the dossier

Record: spool release note.

A finished spool with orange flange protectors strapped on a flatbed truck while an inspector wires an ID tag to the flange

What are the most common QC checklist failures?

Checking at the end instead of at each stage. Fit-up problems are cheap at fit-up and expensive after RT.
Records kept on paper at the bench and typed later (or never).
Welder continuity not checked until the client audit.
NDT reports filed but not entered against welds.
Release done "from memory" without a completeness check.

Paper checklists or digital?

Printed checklists work at the bench. The risk is the step after: transferring results into the register. Spreadsheets need disciplined entry. Enterprise QA systems handle ITPs and sign-offs with workflows. Lightweight tools capture results directly against the weld on the drawing. Pick based on how many times each result is written down. Once is the target.

MapWeld covers part of this list: welds on the iso, fit-up, welding, visual and NDT data per weld, and an Issues list for incomplete records. Material receipt, ITP sign-offs and testing stay in your own procedures.

FAQ

What is the difference between QA and QC in piping fabrication? QA is the system: procedures, plans, audits. QC is the inspection work that checks the product against requirements.

Who writes the ITP? Usually the fabricator, approved by the client. It references the code, the specs and the checklists.

What is a hold point? A step in the ITP where work cannot continue until the specified inspection is done and released.

How much hi-lo is allowed at fit-up? It depends on the WPS, the code and the service. Check your spec; do not use a generic number.

Is pressure testing part of fabrication QC? Sometimes. Spools can be tested in the shop, or the system is tested on site after installation. The ITP defines which.

MapWeld does this on the PDF isometric, offline: QC data per weld, gaps flagged before release.