API 598 – Valve Inspection and Testing
This standard covers inspection, examination, supplemetary examinations, and pressure test requirements for resilient-seated, nonmetallic-seated (e.g. ceramic), and metal-to-metal-seated valves of the gate, globe, plug, ball, check, and butterfly types, Resilient seats are considered to be:
a) soft seats, both silid and semi-solid grease type(e.g. lubricated plug)
b) cmbination soft and metal seats;
c) any other type valve designed to meet resilient seat leakage rates as specified in Table 6 of this standard.
The following tests and examination 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 by the manufacturer,
g) high-pressure pneumatic shell test.