In the Summer BULLETIN
First Steady Stream: How to Determine Set Pressure for Liquid Service Valves
The summer 2020 BULLETIN cover story explores one of the most common questions received by the National Board Pressure Relief Device Test Laboratory. Senior Staff Engineer Bob Viers writes about set pressure definition for liquid service valves.
Following is an excerpt:
The American Society of Mechanical Engineers PTC-25 defines “set pressure” as the “value of increasing inlet static pressure at which a pressure relief device displays an operational characteristic, where the applicable operating characteristic for a specific device is specified by the device manufacturer.” For many liquid service valves, this operational characteristic – or set pressure definition — is the “first steady stream.”
First steady stream is by far the most common set pressure definition for liquid service valve types, applying to about 80% of National Board/ASME certified design types for liquid service valves. While some set pressure definitions are almost unmistakable, first steady stream can be confusing without a good description of what to look for.
Other articles in this issue include ASME Section IX: Revised QG-106 Boosts Organizational Responsibility Requirements by Luis Ponce, Manager of Technical Services, and Walter Sperko, of Sperko Engineering; Implementation of New Filler Metal Specification by Jim Worman, Senior Staff Engineer; Access Granted: How Designing for Maintainability Can Prevent Disaster by columnist James R. Chiles; National Board Advisory Committee member Patricia Becker answers five questions in the Q&A Interview; updates on NB-18, the National Board Synopsis, and more.
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