Valve Body Pressure Testing Procedures

Introduction

Pressure testing of valve bodies verifies structural integrity and leak-tightness before installation in service. Tests are performed at the manufacturing facility per applicable standards including API 598, ASME B16.34, and customer specifications.

Shell Test (Body Test)

Applied at 1.5 times the maximum allowable working pressure (MAWP)Tests body, bonnet, and all pressure-containing partsHydrostatic test preferred using clean water with corrosion inhibitorDuration typically 3 minutes minimum per API 598No visible leakage permitted through pressure boundary

Seat Leakage Test

Seat leakage tests verify the sealing capability of the valve's obturator against its seat. Test pressure is typically 1.1 times MAWP. Allowable leakage rates are defined by leakage class (API 598 Class I through VI, or ASME FCI 70-2).

Test Medium Considerations

Water is standard for most valves; air or nitrogen for special applicationsOxygen service valves require degreased water or dry nitrogen testingCryogenic valves tested at ambient then at cold temperatureValves with soft seats (PTFE, PEEK) may require low-pressure air testTest water chloride content controlled for austenitic stainless valves

Documentation Requirements

All pressure tests must be documented with test reports showing valve tag number, date, test pressure, duration, test medium, temperature, and results. Witness tests require third-party inspector signature. Documentation is retained as part of the valve's material traceability records.

High-Pressure Test Equipment

Test pumps, pressure gauges (calibrated), and test fixtures must be rated above the test pressure. Pressure gauges should have full-scale reading of 1.5 to 4 times the test pressure for accuracy. Test stands must be anchored and safety relief valves installed per local safety regulations.