A common finding in my past inspections under both Part 192 and Part 195 is missing relief device capacity checks for full flow pressure relief devices. Both gas and hazardous liquids code requires a check at the same time inspection and testing is done to see if conditions have changed and an engineering review to determine whether the relief device still has sufficient capacity for the flow volume in the pipeline is required. This does not mean that an engineering study is needed every year or 6 months depending on the code but rather a check every 6 months or year depending on code to determine if flow volume has changed (increased). If a changed occurred, then an engineering review is required. This applies only to full flow relief devices, not partial relief devices like thermal reliefs.
I § 195.428 Overpressure safety devices and overfill protection systems.
(a) Except as provided in paragraph (b) of this section, each operator shall, at intervals not exceeding 15 months, but at least once each calendar year, or in the case of pipelines used to carry highly volatile liquids, at intervals not to exceed 71⁄2 months, but at least twice each calendar year, inspect and test each pressure limiting device, relief valve, pressure regulator, or other item of pressure control equipment to determine that it is functioning properly, is in good mechanical condition, and is adequate from the standpoint of capacity and reliability of operation for the service in which it is used.
§ 192.739 Pressure limiting and regulating stations: Inspection and testing.
(a) Each pressure limiting station, relief device (except rupture discs), and pressure regulating station and its equipment must be subjected at intervals not exceeding 15 months, but at least once each calendar year, to inspections and tests to determine that it is—
(1) In good mechanical condition;
(2) Adequate from the standpoint of capacity and reliability of operation for the service in which it is employed;
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