Achieving Excellence in PRD Integrity Management-

By Grady Hatton at Versa Integrity Group, and Melissa Guerra at Chevron Products Company. This article appears in the July/August 2016 issue of Inspectioneering Journal.

Introduction

Most inspection programs do an adequate job of managing Pressure Relieving Devices (PRDs), without giving much consideration to the potential consequences of PRD failure to open or leak. Many plants inspect PRDs on preset intervals as recommended by inspection code API 510, and implement inspection practices such as API RP 576. But with the introduction of PRD risk-based inspection (RBI), these delicate instruments (yes, PRD’s are delicate & they are instruments) should be receiving much more dedicated attention. Are we really giving those PRD’s the appropriate amount of care they need?

Just seeking PRD compliance with codes and standards usually results in mediocre mechanical integrity and process safety. Companies must go further to climb the ladder to “excellence.”

1. Don’t wait until a fire or explosion or injury to implement an effective PRD program.
2. PRD “Excellence” does not mean “overdone or excessive.”
3. PRD excellence consists of QA/QC, procedures, training, discipline, effective implementation, and constant re-evaluation.
4. PRD excellence means your pressure-relieving system is adequate for the protected equipment.
5. PRD excellence means you have an excellent relationship, communications, and QA process in place with testing and refurbishment shops, that conforms to your company standards.

Assessing Your PRD System

Rarely does our industry experience a failure, explosion or fire because of something that was caused by some new unknown phenomena. Failure incidents are obvious once you see them. We have a tendency to assume what we think, or what we want to believe, rather than what is actually there. We have the tendency to see what our minds want us to see rather than what’s really there. It's the same problem all of us run up against when we try to proof-read our own text. We see what we know the text means, rather than what is actually printed on the page. We become so familiar with what we are looking at, that we no longer see the problem.

People can look at PRD opportunities again and again without being able to see what can be improved. The real reason that Third Party Reviews (TPR's) and Cold Eyes Reviews (CER's) can detect issues that have been missed by on-site staff for years is that they don't know the routine. TPR’s provide a fresh set of eyes that have not been influenced by that attitude of, “we have always done it that way”.

In trying to avoid incidents, we have to struggle constantly to be alert to what is actually before our eyes, as well as what we are tempted to believe. We have to be aware of the pressure to join the club. Like minds think alike. Break out, and get that third party to identify your opportunities for improvement.  Too many compliance "audits" are focused on "Gotcha’s" instead of offering useful, actionable suggestions and recommendations that actually improve Mechanical Integrity (MI) programs. When conducting incident investigations, it is often found that data in the site records was pointing to the possibility of an incident, but the site was so busy collecting and recording data that they didn't have time to review and analyze the data to see what it was telling them.

Before your PRD system can be optimized, an assessment of your PRD reliability program and practices can serve as a powerful tool for improvement. Start your road to excellence with the assessment.

PRD Procedures

Well-written procedures help improve the quality of work within the organization, help reduce the number of errors and omissions, and help inexperienced people perform complex tasks quickly, consistently and effectively. Procedures should describe Who, What, Where, When, and Why. Effective PRD procedures will point to the use of governing codes and standards, such as API 510, API RP 576 (Inspection of Pressure Relieving Devices), API RP 581 (API RBI methodology), API RP 520 & 521. Governing codes and recommended practices provide instructions to the industry on when, where, why, what, and how often they need to inspect? These codes and practices can also allow for increases in inspection intervals based on reliable historical performance of the PRD. 

Training

Training on your PRD procedures should cover all aspects, including process steps, guidelines, and resources. Training ensures that individuals have a complete understanding of the procedures and the expected outcome. But who do you train? Do you train every person that handles relief valves, or do you have a designated PRD lead? How much training does each person need? Role-based training is essential to an excellent PRD program.

Regular inspection, testing, and overhaul of pressure relieving devices is needed to ensure proper PRD function and reliability when they are called upon to protect equipment and people. The governing API-510 code allows for adjustment of the inspection interval based on the historical performance of the PRD. But who does the paperwork to document the history of the relief valve in the as-found condition, as well as all the other relevant information? It’s the “who” that we want to train and develop, as this individual must carefully document consistent and reliable information that can be used in the evaluation process to determine inspection frequency. Checklists can help make sure the necessary steps are followed, that captured data and the work process is consistent. This can be done by using paper or mobile devices. One advantage of mobile devices is that you can see when actions are completed and coordinate work happening in the plant and in the shop.

There are many different types of PRDs for different processes and equipment that need to be considered. Each one of these safety devices has their own characteristics related to desired functionality, the type of service in which they are placed, their individual design, and the demands of the system or equipment they protect.

• Pressure-Relief Valve
• Safety Valve
• Relief Valve
• Safety-Relief Valve
• Conventional Safety-Relief Valve
• Balanced Safety-Relief Valve
• Pilot-Operated Pressure-Relief Valve
• Pressure and/or Vacuum Vent Valve
• Rupture Disk Device

There are many details that must be considered when inspecting PRDs. This means training to specifics is key to effective PRD integrity management.

PRD Handling

Improper handling is one of the common reasons PRDs to fail to perform correctly in service. PRDs should be handled as follows:

• Normally, PRDs must be inspected in the “as-received” condition. This means that no cleaning of residue or by-products is done prior to visual inspection, and perhaps prior to pressure (pre-pop) testing, to get the most accurate assessment of how it would have behaved in-service.
• PRDs should be shipped in an upright position. When large low pressure valves are laid down on their side, the springs may not exert the same force all around the seating surface and therefore the setting may change.
• Rough handling during maintenance could degrade tolerances and destroy the basic valve alignment, rendering them unfit for service. 
• During installation, PRDs should be handled carefully with caution being exercised to prevent bumping or dropping. Either event could cause poor valve performance.
• The inlet and outlet of the valves should be covered when the valves are not in-service.
• After the PRD has been removed from service and is on its way back to the shop for repair, it is critical that the valve be carefully handled. Part of the inspection process is to do a pre-pop test. The pre-pop test is important because it tells the inspector whether the PRD would have accurately lifted in the event of an over pressure. This is valuable information for the RBI evaluation.

Discipline

It's clear that people who maintain focus on long-term goals can achieve much bigger things than those who jump from idea to idea, or those who give up after the slightest setback. If you do not see someone or something frequently, you will forget about it. Are your PRD’s “out of sight – out of mind”? Just because we don’t deal with them on a daily basis, are they any less important? We have to have the discipline to stay focused on and attentive to these safety instruments. 

Is PRD RBI for you?

Industry is implementing PRD RBI, but are you ready for it? PRD RBI has the potential to significantly reduce maintenance costs without jeopardizing safety, and for this reason, it looks very attractive. The RBI methodology and calculations rely on a lot of good quality historical data for input and calculation. This input will have a large bearing on the overall effectiveness of the RBI calculation, revealing the stability of the process, reality of corrosion/damage rates, and clarifying perceptions.

But the programs are only as good as the input data. Has your data been consistency collected? Have your procedures been in place to ensure consistency in data? Have you trained and audited your people and methods to ensure you are documenting reliable data? Why not take advantage of RBI and let it evaluate the criticality of PRDs to set inspection and testing frequencies accordingly.

PRD Excellence Summary

Just seeking PRD compliance usually results in mediocre mechanical integrity and process safety programs. Climb the ladder of excellence! A review from a qualified Third Party can help you start your journey to PRD excellence. This assessment from fresh set of eyes should be focused on offering useful suggestions to actually improve your PRD system. You don’t need an “audit” focused on “Gotchas.” Commit to that audit and prepare yourself with excellent data. It will come in handy should you need to look back, analyze, and trend. It will also be extremely useful should you progress to implementing PRD RBI. 

Don’t let your PRD’s be “out of sight – out of mind!”