Maximum pressure allowed in piping by the ASME code…2 For this material, the ASME code recommends that an allowable stress (S) of 16,000 psi be used for a temperature range of -20 F to +100 F.
The purpose of a pilot valve is to control the opening and closing of the main valve by trapping or releasing water from the main valve's "operating chamber" ("K" - the chamber above the main valve piston).