Does your PSM/RMP utilize “check valves” as a safe guard to PRVENT “reverse flow”? (NRC and API 570)

Check valves are a common piece of equipment within chemical processes; however, often times these specialized valves go years without any inspection or verification they are performing as designed. In some processes, these valves play a pivotal role in PREVENTING the initiation of an incident and can even be the sole layer of protection for the process deviation. And yet, most check valves sit in the pipe circuits and go un-noticed and un-inspected! This Temporary Instruction (TI) procedure developed by the U.S. Nuclear Regulatory Commission (NRC) for nuclear power plants may be an excellent start for those wishing to establish some means to INSPECT and VALIDATE their “check valves”…

On August 29, 1988, the NRC staff issued Information Notice 88-70, “Check Valve Inservice Testing Program Deficiencies,” as a result of inspections of check valve activities at several nuclear power plants. A common finding from those inspections was that not all safety-related check valves had been included in the Inservice Testing (IST) programs. Another finding was that some of the check valves within the IST programs were not being tested in a manner that verified their ability to perform their safety-related functions. This program may be useful for our check valves.

INSPECTION REQUIREMENTS

Verify a program in place to ensure the operability of check valves in safety-related systems.

1. Select a sample of safety-related check valves and verify they are addressed in the check valve program. The inspector should review the Technical Specifications, the IST Program and the Final Safety Analysis Report (FSAR) to select valves that should be addressed for this inspection verification.
2. Review the scope of the check valve program, the tests performed on check valves, preventative maintenance activities, the instrumentation used for the tests and verify that vendor supplied skid-mounted check valves are included in the program.

From the sample selected:

1. Verify that the check valves in the sample are included in a testing program.
2. Review maintenance activities, including maintenance history records for the sampled check valves, to determine whether a trend performance process exists to identify degradation before failure and whether appropriate corrective actions are taken based on the maintenance results. 
3. If a sampled check valve has a history of failure during service or demonstrated inability to meet test acceptance criteria, verify that, in each instance of failure or inability to meet acceptance criteria, the licensee or permit holder:  
   1. initiated a deficiency report, 
   2. follows NRC regulatory and technical specification requirements for system operability and reporting, and  
   3. initiated and implemented work requests to conduct troubleshooting, repairs, and corrective actions, or redesign, as appropriate.
4. Review any third party or vendor reports regarding notification of cautions to observe as the result of any failures that have occurred at other sites, and evaluate the licensee’s action upon receipt of this industry information.
5. Conduct a walk down to inspect the sampled check valves to assess the application of processes, material condition (including internals, when accessible through in-progress maintenance), and installed configuration to the extent possible. 
6. Perform a review of the design documentation for each sampled check valve to determine whether the key attributes (valve type, installed location, orientation, sizing, and materials) were properly considered in the selection of the valve for its application.
7. Evaluate the types and extent of use of non-intrusive testing methods employed.  
8. Evaluate the extent to which important check valves are reverse flow closure tested. 
9. Evaluate the extent of design application review, and implementation of its results. 
10. Evaluate implementation of a preventative maintenance program. 
11. Record the overall check valve failure rate (failure(s) per year).

CLICK HERE for more from this NRC report

As a side note for those who use API 570 as their MI RAGAGEP for process piping, the following is stated:

Critical check valves should be visually and internally inspected to ensure that they will stop flow reversals. An example of a critical check valve may be the check valve located on the outlet of a multistage, high head hydroprocessing charge pump. Failure of such a check valve to operate correctly could result in overpressuring the piping during a flow reversal.

The normal visual inspection method should include the following items.

1. Checking to ensure that the flapper is free to move, as required, without looseness beyond tolerance due to wear.
2. The flapper stop should not have wear beyond tolerance. This will minimize the likelihood that the flapper will move past the top dead central position and remain in an open position when the check valve is mounted in a vertical position.
3. The flapper nut should be secured to the flapper bolt to avoid backing off in service.

Leak checks of critical check valves are normally not required, but may be considered for special circumstances.