The Office of Pipeline Safety has issued the following Advisory Bulletin to operators of hazardous liquid pipelines with pilot-operated pressure relief valves:
Advisory Bulletin (ADB-05-05)
OPS shares NTSB’s concern that pipeline operators could be conducting in-service tests that do not identify unreliable pilot-operated pressure relief valves. Therefore, we are issuing the following advisory bulletin:
To: Operators of hazardous liquid pipelines regulated by 49 CFR part 195.
Subject: Inspecting and testing pilot-operated pressure relief valves.
Purpose: To assure that pilot-operated pressure relief valves function properly.
Advisory: Operators should review their in-service inspection and test procedures used on new, replaced, or relocated pilot-operated pressure relief valves and during the periodic inspection and testing of these valves. Operators can use the guidance stated below to ensure the procedures approximate actual operations and are adequate to determine if the valves functions properly.
Guidance: The procedures should provide for the following:
- During installation, review the valve purchase order (or comparable documentation) valve name-plate, and manufacturer’s specifications. Verify that the valve is:
- Compatible with the material and maximum operating pressure of the pipeline;
- Compatible with or protected from environmental attack or damage;
- Compatible with the liquid transported at all anticipated operating temperatures and pressures;
- In conformity with the manufacturer’s specifications for the valve model and type of service, and with the purchase order (or comparable documentation);
- Configured according to the manufacturer’s specifications for the pilot and in-line valves; and
- Operable at the set pressure (i.e., activation of the pilot valve opens the in-line valve).
- If the pilot assembly of a previously installed valve is reconfigured or repaired
- Do the work according to the manufacturer’s specifications;
- Test the valve to ensure it is operable at the set pressure (i.e., activation of the pilot valve opens the in-line valve) or, if testing the in-line valve would be unsafe or environmentally hazardous, tests the pilot valve according to paragraph (d) below; and
- Document the work.
- Verify that the valve set pressure is consistent with
- The design or configuration of the pilot valve and in-line valve; and
- Use of the valve as a primary overpressure protection device or as a backup safety relief device.
- Test the pilot valve at least twice and verify that it activates consistently at the intended set pressure.
- During periodic inspections and tests, review the valve installation to determine if it has been modified since the last inspection. If so, verify that the pilot sensor and valve inlet and discharge piping are properly sized and placed and that the installation is consistent with the intended design.
- Document all verifications, and sign, date, and keep for the operating life of the valve all documentation.
The full text of the Advisory Bulletin, with background information, is available on OPS’s website.