API 598 pdf download.Valve Inspection and Testing 1 General 1.1 SCOPE 1.1.1 This standard covers inspection, examination, supple- mentary 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 solid and semi-solid grease type (e.g., lubricated...