Reference

Specifying a pressure test: the points to pin down

Most disputes about a pressure test are traceable to something that was never specified. These are the points worth pinning down before award, in the words a scope can use.

A caution before the list

What follows is technical specification language, not legal drafting. It describes what to require, not how to word a contract. Model contract clauses, with the qualifications a lawyer would want, are Appendix G of the field book, and any scope should be reviewed by whoever normally reviews your contracts.

1. The segment and its limits

Require the segment defined by its physical limits, with pipe grades, wall thicknesses, and every fitting and component that will see test pressure, each with a documented rating.

The thinnest wall and the lowest-rated component govern. Require that governing case to be stated explicitly rather than left to be inferred.

2. The pressures and the sequence

Require the pressure ladder in full: spike where applicable, strength, leak, each with its target pressure, hold duration and the point in the segment at which the pressure is defined.

Require the sequence explicitly. A spike applied after a long hold is not the same test as one applied first.

3. Instrumentation and resolution

• Pressure instrument type and resolution, stated as a number
• Number of temperature measurement points, their locations, and how they will be weighted
• A deadweight tester as the site pressure standard, with current certification
• Redundancy — what happens when an instrument fails mid-hold
• Calibration certificates whose serial numbers match the equipment delivered to site

Resolution is the point most often left out, and without it the residual you are trying to detect may be smaller than the instrument can see.

4. The analysis method, stated in advance

Require the predicted pressure-temperature response to be calculated before pressurisation, from measured fill volume and measured temperatures, and submitted as part of the procedure.

Require the pressure-volume plot to be compiled live during the climb.

A prediction made beforehand is evidence. The same number produced afterwards to explain a decay is an argument.

5. Acceptance criteria

Require, in writing and before mobilisation: the residual pressure change that will be treated as acceptable, over what window, on what temperature basis, and who signs acceptance against what document.

This single clause prevents more disputes than the rest of the scope combined.

6. Temporary works

Require ratings and proof-test records for test heads, manifolds and hoses specifically. These see full test pressure, are the components most often taken on trust, and are where the serious injuries in this work come from.

7. Records

Require the deliverable by contents, format and date: segment definition, ladder as executed, continuous pressure and temperature traces in an open format, instrument records and certificates, fill and medium data, the analysis and balance statement, the acceptance argument, and all deviations with their resolution.

Tie delivery to something meaningful — typically before final payment. Records requested six months later arrive incomplete.

Test records must be retained for the life of the pipeline under 49 CFR 192.517 and 195.310, so a one-page summary certificate does not meet the obligation you are under.

8. Deviations

Require deviations to be recorded as they occur, with the resolution and who authorised it. A test with no recorded deviations on a real jobsite is usually a test where deviations were not recorded.