Fixed Equipment: Pressure Vessels, Heat Exchangers, Piping, Valves, and Fittings
Vessels
Know the parts and the rules that govern them: shell courses, 2:1 ellipsoidal and torispherical heads, nozzles and reinforcement, flanges, manways, supports, and the nameplate. Confirm the minimum design metal temperature and its impact-test exemption (UCS-66 curves), the joint efficiency implied by the radiography category, and the accuracy of the data report. Verify nozzle projection and orientation, head-to-shell alignment, and heat treatment of the completed seams.
Heat exchangers
Identify the configuration: fixed tubesheet, U-tube, or floating head, to TEMA and API 660. The critical joints are tube-to-tubesheet, shell-to-tubesheet, and channel-to-shell. Test sequencing matters. Many specifications require the shell side to be tested with a test ring or with the channel removed to prove the tube-to-tubesheet joints, then the tube side tested separately, often at a different pressure.
Piping, valves, and fittings
Piping follows ASME B31.3. Check spool dimensions, support locations, flange facing and rating, gasket and bolting, and weld records for each joint. Valves are shell- and seat-tested to API 598, with pressure, duration, and allowable leakage tied to size and class. Check the nameplate, trim material, and any fire-test certification such as API 607 or 6FA.
Traps
Confusing shell-side and tube-side test pressures; accepting a seat test at the wrong differential; ignoring flange-facing damage found after the test.
Worked example
A Class 150 carbon steel valve: shell test at 1.5 x 285 psi = 428 psi; seat test at 1.1 x 285 = 314 psi. Hold each for the duration API 598 gives for that size and class, and look it up rather than guessing.
Rule of thumb
Test the joint you are trying to prove, not just the cavity behind it.