Natural Gas Processing

3.14. Valves

For economy and interchange ability, types of standard valves to be selected should be kept at a minimum.

All valves for steam services in piping designation PN100 (classes 600) and higher should be of the butt weld end type, except for instrument isolation valves and blow-down valves.

3.14.1. Low-temperature services

1. The following types of valve may be used for services down to –20 °C:

a. Gate, globe, and check valves, with metal seats or with soft insert

b. Ball valves and floating and trunnion mounted ball with soft and metal seats

c. Butterfly valves, offset type, soft and metal seated

2. Gate and ball valves may have cavities where cryogenic liquid could be trapped and cause excessive pressure buildup during warmup of the valve body. ...