API 598: Valve Inspection and Testing

API 598 covers the inspection, examination, and testing requirements for resilient-seated, nonmetallic-seated (e.g. ceramic), and metal-to-metal-seated gate valves, globe valves, plug valves, ball valves, check valves, and butterfly valves. Resilient seats are considered to be:

a) Soft seats, both solid and semisolid grease type (e.g. lubricated plug);

b) Combination soft and metal seats (e.g. laminated seat rings)

c) Any other type of seat material designed to meet resilient seat leakage rates as specified in Table 5.


API Standard 598 supplements the API standards that reference it, but it may also be applied to other types of valves by agreement between the purchaser and the valve manufacturer. Reference Annex A for information to be specified by purchaser.

The inspection requirements pertain to examinations and testing by the valve manufacturer and any supplementary examinations taht the purchaser may require at the valve manufacturer’s plant. The test requirements cover both required and optional pressure test at the valve manufacturer’s plant or at a facility mutually agreeable to bothe the manufacturer and the purchaser.


The following tests and examinations are specified in this standard:

a) Shell test;

b) Backseat test

c) Low-pressure closure test,

d) High-pressure closure test,

e) Double block and bleed high-pressure closure test,

f) Visual examination of castings,

g) High-pressure pneumatic shell test.

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