NAC455C.298. Hydrostatic tests for pressure; use of other testing media.

     1. A hydrostatic pressure test, when applied to pressure vessels, must not exceed 1 1/2 times the maximum allowable working pressure. The pressure must be under proper control so that the required test pressure will not be exceeded by more than 2 percent.

     2. During a hydrostatic test, the safety valve must be removed or each valve disc must be held to its seat by means of a testing clamp or plugging device and not by screwing down the compression screw upon the spring.

     3. The temperature of the water used to apply a hydrostatic test must be not less than 70 degrees Fahrenheit or more than 120 degrees Fahrenheit.

     4. When a hydrostatic test is applied, the pressure must be equal to:

     (a) The normal operating pressure of the pressure vessel but need not exceed the release pressure of the safety valve having the lowest release setting if tightness is in question.

     (b) One and one-half times the maximum allowable working pressure if safety is in question.

     5. If the contents of the vessel prohibit contamination by any other medium or if a hydrostatic test is not possible, other testing media may be used if the requirements of the applicable sections of the code are satisfied.

     (Added to NAC by Div. of Industrial Relations by R101-02, eff. 12-15-2004)