Description

ASME PTC 6 Report – PTC 6 Report – Guidance for Evaluation of Measurement Uncertainty in Performance Tests of Steam Turbines

1.1 The object of this Report is to provide guidance for the parties to the test to establish the degree of uncertainty of the test results when there are deviations from requirements of PTC 6, related to any of the following quantities or characteristics: (a) simmer-warn pressure (b) opening pressure (c) reseating pressure (d) blowdown (e) reproducibility of valve performance (f) mechanical characteristics of the valve as determined by seeing, feeling, or hearing such as: (1) ability to reseat satisfactorily; (2) tightness before and after relieving (see Note); (3) absence or presence of chatter, flutter, sticking, and/or harmful vibration; (4) the ability of the valve to withstand pressure temperature, and other service conditions to which it may be subjected; (5) physical measurements as necessary. (g) relieving pressure (h) relieving capacity at test pressure

Note: Under certain back-pressure testing conditions, it will not be possible to check tightness.

1.2 This Code is limited so far as flowing fluid is concerned to steam, gases, and liquids in such states that flashing will not take place. Separate procedures cover each flowing fluid.

1.3 This Code specifically applies to valves (see para. 0.1). It is not intended to exclude testing of other types of pressure-relief devices provided all parties to the test involved agree to accept the provisions of this Code.

1.4 This Code is applicable to but not limited to the following types of safety and safety relief valves: spring-loaded; weight-loaded; and pilot- operated.

1.5 This Code is applicable to tests in which the pressure at the valve discharge is either at, or above, atmospheric before the valve opens, or while the valve is relieving.

1.6 This Code only applies to the testing of valves where the pressure and flow capacity of the facility is adequate to conduct test.