Hydrostatic test pressures for ASME B16.5 flanges attached to nozzles are listed in the COMPRESS nozzle report. How are the hydro test pressures for ASME B16.5 flanges determined?

Knowledgebase Article 1244

Question:

For example, from the nozzle report:

Example from Nozzle Report

Answer:

ASME B16.5 flanges are not governed under Section VIII Division 1 rules for hydrostatic test because they are accepted as standard pressure components by paragraph UG-44. However, the B16.5 standard does have rules for testing of flanges and flanged fittings.

B16.5, paragraph 8, "PRESSURE TESTING" gives rules for testing flanges (paragraph 8.1) and flanged fittings (paragraph 8.2). Per paragraph 8.1, flanges are not required to be tested. Paragraph 8.2.2 specifies the test pressure for flanged fittings. For reference, COMPRESS reports the test pressure determined per Paragraph 8.2.2.

The test pressure per Paragraph 8.2.2 is specified as:

Test Pressure = 1.5 x (flange pressure rating at 100° F), rounded to next increment of 25° F

For example, in the nozzle report extract shown above the flange rating at the test temperature is 740 psi. The test pressure is found as:

1.5 x (740) = 1110 psi; round to next increment of 25 psi => 1125 psi

If the pressure vessel's test pressure plus hydrostatic pressure due to test static head exceeds the test pressure from B16.5 Paragraph 8.2.2, COMPRESS returns a Warning message.

Also see http://www.codeware.com/support/faq/1033.html for a discussion of how ASME B16.5 flanges are treated under the hydrostatic test rules of UG-99.