What course of action should managers pursue when a clause in an industry standard no longer reflects best available technology or practices? The answer is: Go with best available technology and, if appropriate, place relevant illustrations, documentation and thought processes in the company’s files.
Although relatively infrequent, there are instances where technical clauses are outdated and best practices should prevail. The sealing of firewater pumps is a case in point but other examples exist. This article discusses an incident in 2015 when a large overseas oil refinery suffered great losses by having a firewater pump out of service on the day of a major fire.
By the early to mid-1950s, some knowledgeable multinational corporations with refineries and chemical plants around the world developed supplements to industry standards. These corporations then superimposed and attached their applicable “best practices addenda” to almost every industry standard they invoked or referenced when purchasing equipment. At least one corporation realized that among the items and details that needed to be amended were then-existing stipulations relating to firewater pumps. While these stipulations were well intended when first issued, they were outdated by 1965. One of the old clauses in the industry standard required braided packing in firewater pump stuffing boxes. However, in the mid-1960s, corporations with best practices addenda fitted these pumps with mechanical seals because braided packing risked more frequent failures and unanticipated outages.
There is a trail of documents about the topic of upgrading firewater pump sealing, among them articles advising that modern mechanical seals required less maintenance labor, were leaking orders of less magnitude, and reduced frictional power losses by 50% compared to braided packing. In total, modern mechanical seals are more reliable than packing in firewater service. Starting around 1965, single-spring mechanical seals had become the best available technology for firewater pumps. In some instances, these mechanical seals were to be backed up by a floating throttle bushing and a deflector guard. Because reliability professionals must advocate “designing out” maintenance, they are also encouraged to read about the feasibility and desirability of securely installing an advanced rotating labyrinth-style bearing housing protector seal. Such protector seals should take the place of the deflector guards used decades ago. Moreover, these protector seals should incorporate axially or diagonally moving O-rings. Radially moving O-rings near sharp-edged components were disallowed by knowledgeable users.
Three Layers of Defense
If a facility still uses packing, maintenance and reliability managers would do well to reconsider. Leaking packing jeopardizes pump bearings. Because good managers strive to instill the habit of learning from the mistakes of others and demand fact-based solutions, they may insist on follow-up by their staff. In their quest to make informed decisions, managers might ask reliability groups to research what happened at the above-mentioned refinery in 2015. Requesting to be briefed on the calamity-experiencing major refinery’s total economic losses would be a good start. The primary firewater pump at that refinery was out of service because a packing leak had compromised its bearings. On the day when water was desperately needed to fight a major fire, the pump was unavailable. It is a sobering fact that upgrades implemented elsewhere 50 years earlier had not been pursued by the overseas facility prior to mid-2015.
Of interest is the thinking that led many leading oil refineries to opt for single-spring mechanical seals instead of braided packing in firewater pumps as early as 1965. In the 1960s, accurate statistics were kept (for insurance purposes) by a major multinational oil company well known to the author. The statistics for firewater pumps showed that leaking packing tended to ruin bearings. Well-designed mechanical seals were selected by the reliability-focused multinational because these seals generally leaked far less than packing. It was reasoned that mechanical seals were less likely to allow water spray to enter an adjacent bearing housing. Old-style, brittle mechanical seal faces might shatter when abused, but intelligent seal face material combinations have been available for some time. Today, seals that are properly designed, selected and installed are highly unlikely to fail unexpectedly. Moreover, floating throttle bushings represent a “second line of defense” and advanced bearing protector seals clearly represent a “third line of defense” in firewater pumps.
Testing & Operation
The use of packing in modern firewater pumps is not recommended. The finding that packing no longer represents best practice is amplified by the frequent lack of training of maintenance personnel observed at some plants. Included in best practices is periodic testing of all standby equipment. A frequently asked question relates to the testing and alternate operation of standby equipment. Operators ask if switching the “A” and “B” pumps and running each for one month, or if turning on the standby pump once a month and then running it for four to six hours, is the preferred choice. When people argued—many decades ago—that plants might get away by testing only twice a year, responsible reliability professionals took the position that testing only twice a year would not be acceptable and monthly testing was needed. Depending on lubricant selection and lube application method, switching “A” and “B” every two or three months is considered best practice. This keeps the bearings lubricated and prevents seal faces from sticking.
The well-publicized reliability-focused practice of implementing mechanical seals for firewater pumps had not been accepted by the overseas refinery that experienced the fire in 2015. After this event, the refinery investigated why its major firewater pump was unavailable at a critical time. The feedback is not all there, but it can be assumed they closed the case after establishing that “a 50-year-old specification clause was adhered to and so the incident is nobody’s fault.” Nevertheless, the claim that packing is safer was disproved by the corporation that had collected worldwide statistics for insurance purposes. It determined that consistently using modern cartridge seals would be the first step toward ensuring that future outcomes will be more favorable for pump availability and asset protection.
Any industry standard should explain the intent of its clauses. If there are better ways than following an outdated clause, follow the path of reason and use what is safest for the plant and the community. Of course, when informed users deviate from an old industry standard, they carefully and authoritatively document why they deliberately moved on to less risky methods. Corporate lawyers at the author’s petrochemical company agreed that in case of litigation, statistically proven best practices will prevail over an occasional but demonstrably outdated clause found in old industry standards.