scope:

SCOPE & LIMITATIONS

Selection of a leakage class is not restricted as to valve design, but acceptable values for various commercially available designs are suggested for each class under Section 4.

This standard applies to control valve seat leak production testing and cannot be used as a basis for predicting leakage at conditions other than those specified in Section 5.

These seat leakage provisions do not apply to control valves with a rated flow coefficient less than C_v=0.1 (K_V=0.086).

This standard is similar to IEC 60534-4, except that no provision is made for Class IV-S1.

This standard applies to control valve seat leakage testing. If line isolation or shut-off beyond Class VI is a normal expectation of the valve application, it is recommended the user consider specifying another standard such as API 598 Valve Inspection and Testing or ISO 5208 Industrial Valves - Pressure Testing of Metallic Valves. Test conditions stated in this standard are intended to accommodate production testing and it is recognized that these ambient conditions can affect test results. If a user requires tighter control of ambient test conditions, it should be stated on the purchase order.

This standard may be applied for bi-directional seat leakage testing by applying the pressurized test fluid to the traditional outlet of the test valve and measuring leakage flow rate from the traditional inlet in addition to the typical forward-direction leakage testing described below.

PURPOSE

This standard establishes a series of seat leakage classes for control valves and defines production test procedures.