Standard Practice for Installation, Inspection, and Maintenance of Valve-body Pressure-relief Methods for Geothermal and Other High-Temperature Liquid Applications

This practice covers installation, inspection, and maintenance of valve body cavity pressure relief methods for valves used in geothermal and other high-temperature liquid service. The valve type covered by this practice is a design with an isolated body cavity such that when the valve is in either the open or closed position pressure is trapped in the isolated cavity, and there is no provision to relieve the excess pressure internally. The installation shall be such that direct access to the body cavity is maintained and that the pressure relief device may be periodically removed, cleaned, inspected, and reinstalled without endangering the operating personnel or removing the valve from its functional application. The relief device may be mounted with an automatic shutoff, such as a check valve held in the open position by the relief device. The shutoff device will not be rendered inoperative. The recommended procedures for winterizing valves shall be as follows: the valve must be fully closed or fully opened and the body cavity should be purged with a nonreactive gas (for example, nitrogen) or filled with a fluid to produce a solution with a low freezing point.