Valve Inspection During Construction: Hold Points and Witness Points

Construction quality control for valve installation requires planned inspection points. Hold points stop work until an inspector approves; witness points invite inspection but allow work to proceed if the inspector does not attend.

Defining Hold Points and Witness Points

Inspection and Test Plans (ITPs) identify which activities require holding or witnessing. The level of oversight depends on valve criticality, regulatory requirements, and client specification.

• Hold point (H): Work cannot proceed without inspector sign-off; used for critical activities

• Witness point (W): Inspector notified; work can proceed if inspector does not appear within specified time

• Review point (R): Document review only; no physical presence required

• Monitor point (M): Contractor performs and records; owner may audit records

Typical Hold Points for Valve Installation

Factory acceptance testing, material receiving inspection, and pre-commissioning hydrostatic testing are commonly designated hold points for critical valves.

• Factory acceptance test (FAT): Witness valve testing at manufacturer's facility before shipment

• Material receiving inspection: Verify materials received match order and are undamaged

• Pressure test: Witness hydrostatic or pneumatic test of installed valve and adjacent piping

• First-of-type installation: Inspector present for first installation of each new valve type

Documentation Requirements at Inspection Points

Every hold and witness point requires completion documentation. Inspection records become part of the permanent plant record and support future maintenance decisions.

• Inspection test record (ITR): Standard form with date, inspector name, result, and signature

• Non-conformance report (NCR): Issued when acceptance criteria not met; tracks resolution

• Punch list item: Minor deficiency recorded and tracked to closure before mechanical completion

• Photographic record: Digital photos with timestamp at key inspection stages

Third-Party Inspection Requirements

Projects with third-party inspection (TPI) agencies add an additional layer of oversight. TPI representatives witness hold points and issue inspection release notes authorizing work to continue.

• TPI notification: Written or system-based notice sent with minimum 48-hour lead time

• Inspection release note (IRN): TPI sign-off required before next activity begins

• Punch list closure: All TPI-raised punch items must be closed before mechanical completion

• Final certificate: TPI issues final inspection certificate at end of construction phase