Tolerance & Fit-Up Reference

A practical hold-point guide for checking fit-up before work becomes difficult to correct. It identifies what to measure and where the acceptance value must come from.

Rule 01

The project document wins

Codes set frameworks, but drawings, specifications, ITPs and qualified procedures often set the actual project tolerance.

Rule 02

Record the measured value

“Accepted” is not a measurement. Keep the actual reading, location, instrument and drawing or procedure revision used.

Structural steel erection & fit-up

Member position & levelSurvey against setting-out points and approved drawings.Acceptance source:
Approved drawings, survey plan, project erection tolerance schedule
Column plumbnessMeasure in both principal directions; record elevation and survey method.Acceptance source:
Project specification and the adopted structural steel code
Base plate bearingCheck line, level, grout space, packers and full bearing condition.Acceptance source:
Approved detail, method statement and grout specification
Bolt holes & connectionsDo not flame-cut, enlarge or force alignment without an approved disposition.Acceptance source:
Connection detail, bolting procedure and NCR / concession process
Weld joint preparationConfirm bevel, root opening, alignment, cleanliness and tack condition before welding.Acceptance source:
Approved WPS and applicable welding code

Piping fit-up

Root opening & bevelMeasure before tacking; confirm surface preparation and joint type.Acceptance source:
Approved WPS and weld map
Internal misalignmentCheck hi-lo at several positions around the bore before welding.Acceptance source:
Approved WPS, project piping specification and governing code
Flange alignmentCheck parallelism, bolt-hole orientation and gap without using bolt force to pull the joint in.Acceptance source:
Piping specification, vendor requirement and approved isometric
Slope & supportSurvey the installed run before final tightening and before insulation.Acceptance source:
Approved isometric, line list and support drawings
Branch orientationConfirm clock position, reinforcement, projection and clearance.Acceptance source:
Approved isometric, piping class and branch detail
Field-use note: This page deliberately does not invent one universal millimetre limit. Acceptance values vary by code edition, joint type, material, service and contract. Confirm the current approved revision before accepting or rejecting work.

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