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101 Essential Elements in a Pressure Equipment Integrity Management Program for the Hydrocarbon Process Industry - Part 5

By John Reynolds at Intertek. This article appears in the January/February 2001 issue of Inspectioneering Journal
This article is part 5 of a 5-part series.
Part 1 | Part 2 | Part 3
Part 4 | Part 5

 

Part 5 of this article continues to outline the 101 essential elements that need to be in place, and functioning well, to effectively and efficiently, preserve and protect the reliability and integrity of pressure equipment (vessels, exchangers, furnaces, boilers, piping, tanks, relief systems) in the refining, gas processing and petrochemical industry. This article is not just about minimum compliance with rules, regulations or standards; rather it is about what needs to be done to build and maintain a program of excellence in pressure equipment integrity management (PEIM) that will permit owner-users to make maximum use of their physical assets to generate income. Compliance is not the key to success in PEIM; excellence is.

In parts 1-4 of the article, which appeared in the four previous issues of the IJ, I introduced the full paper and provided some background on why and how these issues were being covered. It is against that background that I continue the series of articles with 8 more of the 101 essential elements in a pressure equipment integrity management (PEIM) program for the hydrocarbon process industry.

There are at least 101 essential elements to any program aimed at preserving the mechanical integrity of stationary pressure equipment, in-service, in the hydrocarbon industry. Each of these 101 elements may need to be prioritized by site management, basis risk or current status of each element, in order to assign resources and schedule improvements in the PEIM work processes. However, the user must keep in mind that each and every one of these 101 elements, regardless of work priority and resource limitations, needs to be implemented effectively, continuously, in order to avoid the potential for pressure equipment incidents.

In other words, it is not a matter of choosing between the 101 elements and deciding that some are important and others are not, over the long haul. If any one of these 101 elements is neglected long enough, there will be a potential for incidents involving the breech of containment, and the subsequent consequences, i.e. fires, explosions, toxic releases, environmental damage, personnel exposure to hazardous substances, and business interruption.

There is no real secret to achieving success in maintaining pressure equipment integrity at a high level. It’s simply doing all the things (101 of them), that need to be done, and doing them well, day after day, without let up, regardless of what the “hot program” of the month is, or regardless of what other work priorities may get in the way. We must not let other distractions get in the way of effectively executing our PEIM programs, every day.

One more thing before I continue. You may have already noticed that I have and will use the term “effective” on numerous occasions throughout this series of articles. Webster defines it as “producing a decided, decisive, or desired result”. And that’s exactly how I use it. I’ve seen a lot of time, money, and motion wasted on “supposedly” doing all the things described in this series of articles, without really being effective. It does no good to write procedures and best practices that are not effectively implemented or adhered to. It does no good if the necessary information to do the job is known but is not transferred effectively to those who need the information. It does little good if the following issues get attention as a “flash in the pan”, and then take a back seat to the next “hot rock” of the day. Watch for the word “effective” through the remainder of this article and think about what it really takes to get the desired results for each essential element.

So now let’s continue with 8 more essential elements of an effective PEIM program.

Cast Iron

There have been numerous recorded incidents with unexpected fracture of inherently brittle materials, cast iron (CI) being one of the most common. I remember well, early in my career when a cast iron steam strainer fitting broke while a fitter was working on it. He died from his burns. About ten years ago, a refinery discovered they had a cast iron pump transferring crude oil from ships to the refinery, when a football sized piece of the pump casting fell out, dumping thousands of gallons of crude oil into an ecologically sensitive bay area. Last year, we had a large cast iron block valve installed with a hot tap on a water system. Unfortunately, the bronze seats in the CI valve, were scored with hot tap shavings causing the valve to leak after the hot tap machine was disconnected. Repeated attempts to seal the gate valve eventually resulted in cracking the body of the CI valve 180 degrees. Lesson learned: Don’t ever use a cast iron valve in a hot tapping situation, even if it is acceptable in the service being hot tapped. I’m sure every plant has had their near misses or incidents caused by brittle castings breaking. We need to make sure that CI is not used in anything but the lowest risk services, if we use it at all.

Do you know where all your cast iron components are in your plant, and do your specifications allow CI to be used in anything but low risk service?

Heat Tracing in Safety Systems

It is not uncommon for safety systems (relief devices, nozzles under relief devices, vent lines, dump lines, etc.) to be heat traced when there is a potential for product solidification and plugging that could render the safety system ineffective. Heat tracing is often installed to keep solid materials from forming. But periodically we find these heat tracing systems not functioning properly (shut off), and if we are lucky, we didn’t find it because a relief device failed to open. This is another of those issues that easily “falls through the cracks”, if we don’t have the procedures, training, discipline and audits, to assure ourselves that the heat tracing is still functioning as intended, and turned back on after some maintenance activities.

Do you audit your heat tracing systems that are associated with maintaining process safety, at frequent enough intervals to be reasonably assured that you do not have a significant risk of safety system plugging from lack of heat?

Soil-to-Air Interfaces of Buried Piping

Back in the late 80’s, I remember the news story on the gulf coast about a sudden, large fire caused when a welder bumped up against a pipe that was emerging from an underground section of the line. The pipe broke in two segments, and the light hydrocarbon immediately ignited, from the welding operation. I can’t remember what happened to the welder, and I don’t think I want to. After that, we embarked on a program to inspect these soil-to-air interfaces on our buried piping systems and found a number of lines with significant corrosion and severe thinning at this interface. This area on a pipe (6-12 inches above and below the soil line) is usually not benefited by cathodic protection (if it is present), and is exposed to some of the most aggressive soil and atmospheric corrosion. The accelerated corrosion at the interface is due to oxygen concentration cells and alternate wet-dry conditions, and coatings and wrappings that are often damaged and/or deteriorated at the interface. API 570 provides good guidance on inspecting these soil-to- air interfaces.

Are your soil-to-air interfaces on buried piping routinely scheduled for inspections, especially in higher risk services like API 570 Class 1 piping; and do you maintain your coatings and wrappings at the interface?

Exchanger Bundle Classification

Leaks from heat exchanger bundles are not infrequently the cause of reliability problems during scheduled process unit runs. If we are lucky, the leak has only economic consequences and some of our assets have to be shut down to fix the unexpected leak. If we are unlucky, the leak causes an environmental problem in our effluent or a safety problem when hazardous substances leak into the adjacent fluids.

One way to get a handle on this problem is to classify all your bundles into a simple system of A-B- C, where A bundles must have maximum assurance against on line leakage due to safety, environmental, or large economic consequences; B class bundles are those that have varying degrees of economic consequences, should an unexpected leak occur; and C class bundles are those that have minimal or no consequences. With this simple system in place, we can better schedule our inspections and preventive maintenance on bundles, to provide better assurance that higher risk exchanger bundles will receive more attention than lower risk bundles. Tube renewal thicknesses should be established that will provide for greater margin for error on higher risk bundles.

Do you have exchanger bundles that leak while the process unit is on-stream, causing unexpected safety or reliability consequences?

Wire Wrapping/Boxing of Flange Leaks

Boxing and/or wire wrapping of flange leaks has long been a safe and successful practice in our industry for stopping leaks, while maintaining equipment in-service until permanent repairs could be completed. However, this should not be done without the oversight of knowledgeable, pressure equipment or materials/corrosion engineers.

One significant incident occurred at a west coast refinery in the mid-80’s when a channel head blew off of a steam generator because of bolt failure. It seems the channel head flange, which was leaking, was sealed by wire wrapping. In so doing, the caustic in the steam condensate concentrated, on the now enclosed bolting, causing caustic stress corrosion cracking of the higher tensile bolts. After a number of them failed, the remaining bolts could not carry the pressure load, and failed simultaneously, resulting in a vapor cloud that ignited.

Sometimes a contributing factor to such a situation occurs when sealant that is injected in the boxing assembly, puts so much hydraulic pressure on the flange bolts that they overload. There are several other compounds that can cause bolt failure by stress corrosion cracking, including wet H2S containing streams.

Are you always cautious about what might happen to bolts when leak sealing devices cause them to be exposed to fluids normally contained within the pressure equipment?

Relief Valve Prepopping

One of the most important aspects of relief valve (RV) servicing is the need to prepop (before the valve is completely cleaned or dismantled) all RV’s when they get to the shop for servicing. The results of this test are vital to any inspector who will be rescheduling the valve for it’s next servicing. Regardless of whether you use short time- based inspection intervals, condition-based inspection intervals, or the more modern, risk-based inspection intervals, the inspector needs to know the results of this prepopping test in order to do an effective job of setting the next inspection interval. This is especially true of valves that are stuck or pop at pressures significantly different from their documented set pressure; but is also true of valves that repeatedly pop right on target, since those valves may be good candidates for longer intervals between servicing.

Do you have a documented practice of always prepopping RV’s before they are serviced and effectively recording the results so that they will mean something to the person whom is responsible for scheduling the next inspection?

Hydrotesting Safety

Hydrotesting is a common activity in our industry, and for good reason, but it should never get so common place that the routine hydrotesting work causes the people involved to let down their guard. Pressure testing is not risk free, and can be quite hazardous if all the right precautions and procedures are not followed, every time. I’m aware of inspectors being severely bruised when a hydraulic hose flew off the pump and started whipping around, uncontrollably. I’m also aware of an incident where an inspector was cut on the neck, when a high pressure flange started to leak at 2500 psig. In another case, an inspector was injured when a flange gasket blew out and a piece of the gasket struck him in the head. We now make it a practice of backing off the highest pressure of the test, and making sure that the system is stabilized before letting anyone into the roped off area. We usually take great care in applying pneumatic and hydro- pneumatic tests, but these incidents also underline that there is sufficient energy involved with hydrotesting to injure people.

Do all your employees know and appreciate the hazards involved in hydrotesting, and do your standard operating practices for hydrotesting reflect these hazards?

On-Stream Inspection (OSI)

An effective overall inspection program would include an appropriate amount of on-stream inspection (OSI) of vessels and piping, in order to enhance both the effectiveness and efficiency of a total PEIM program. Recent significant advances in OSI technology and commercialization of that technology have made OSI much more useful and promising than in the recent past. Not only is OSI often more cost effective than the costs of decontamination and entry of a vessel, but it is often safer, because of the hazards associated with confined space entry. It seems like every year or so, someone in our industry loses their life in a confined space entry mishap. Two other good reasons for doing OSI, are the advance planning knowledge it supplies for turnaround planning; and when we do OSI in lieu of turnaround vessel entry, we reduce turnaround work load. Since turnarounds are one of the most expensive activities in our industry (second only to rebuilding a unit after a fire), anything we can do to improve and eliminate turnaround work with OSI, will help the cause. On-stream inspection is now specifically mentioned in each of the API Codes that deal with pressurized and storage equipment (510/570/ 653), so it is no longer even necessary, for Code compliance, to enter every piece of equipment. Of course there are pitfalls associated with using OSI, and many of those can be avoided by accessing the knowledge of a qualified NDE specialist.

Are you still entering all your pressure vessels and storage tanks for internal inspection instead of making adequate use of on-stream inspection techniques to enhance the effectiveness and efficiency of your inspection program?

Conclusion

In parts 1-5 of this series of articles, I have covered the first 43 of the 101 essential elements of a pressure equipment integrity management (PEIM) program for the hydrocarbon process industry. In the next few articles, I will continue to enumerate what I believe are the other 58 essential elements, including such topics as: carbon - 1/2 moly equipment; localized corrosion phenomena; “gray zone” equipment; tank bottom inspections; welding on equipment in-service, specialized NDE; PRV auditing, and much more. If you have some thoughts on what you have just read or suggestions for inclusion in the remaining 58 elements, let me hear from you through the IJ at inquiries@inspectioneering.com. Stay tuned.


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