What course of action should managers take when a clause in an industry standard no longer reflects the best available technologies or practices? The answer is: Go for the best technology available and, where appropriate, place relevant artwork, documentation, and thought processes in company records.
Although relatively rare, there are instances where technical clauses are outdated and best practices should prevail. The sealing of fire water pumps is one example, but other examples exist. This article discusses an incident in 2015 when a major overseas oil refinery suffered heavy losses due to a fire water pump shutting down on the day of a major fire.
In the early to mid-1950s, some knowledgeable multinational corporations with refineries and chemical plants around the world developed industry-standard supplements. These companies then overlaid and appended their “best practice addenda” applicable to nearly every industry standard they invoked or referenced when purchasing equipment. At least one company realized that among the items and details that needed to be changed were then-existing stipulations relating to fire water pumps. Although these stipulations were well-intentioned when first published, they were obsolete in 1965. One of the old clauses of the industry standard required braided packing in fire water pump glands. However, by the mid-1960s, companies with best practice addenda fitted these pumps with mechanical seals because the braided packing was at risk of more frequent breakdowns and unplanned failures.
There is a series of papers on the topic of fire water pump sealing upgrades, including articles stating that modern mechanical seals required less maintenance labor, leaked lesser controls and reduced frictional power losses by 50% compared to braided packing. All in all, modern mechanical seals are more reliable than seals in fire water service. By about 1965, single spring mechanical seals had become the best available technology for fire water pumps. In some cases, these mechanical seals had to be reinforced with a floating throttle ring and baffle. Since reliability professionals must advocate for “design” maintenance, they are also encouraged to inquire about the feasibility and desirability of safely installing a labyrinth-type advanced rotary bearing housing guard seal. Such protective seals should replace the deflectors used decades ago. In addition, these protective seals must incorporate axially or diagonally movable O-rings. Radial displacement O-rings near sharp-edged components have been prohibited by knowledgeable users.
Three layers of defense
If a facility still uses trim, maintenance and reliability managers would do well to reconsider. A leaky packing compromises the pump bearings. Because good managers strive to inculcate the habit of learning from others’ mistakes and demanding fact-based solutions, they may insist that their staff follow up. In their quest to make informed decisions, officials could ask reliability groups to research what happened at the aforementioned refinery in 2015. Asking to be informed of the total economic losses of the major refinery that suffered the calamity would be a good start. The main fire water pump at this 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 not available. It is a sobering fact that upgrades implemented elsewhere 50 years earlier had not been continued by overseas installation until mid-2015.
Interestingly, the thinking that led many leading oil refineries to switch to single spring mechanical seals instead of braided packing in fire water 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. Fire water pump statistics have shown that leaking packings tend to damage bearings. Well-designed mechanical seals were selected by the reliability-focused multinational because these seals typically leaked much less than the packing. Mechanical seals were found to be less likely to allow water spray to enter an adjacent bearing housing. Flimsy, old-fashioned mechanical seal faces can break with abuse, but clever material combinations for seal faces have been available for some time. Today, properly designed, selected and installed seals are highly unlikely to fail unexpectedly. Additionally, floating throttle rings represent a “second line of defense” and advanced bearing protection seals clearly represent a “third line of defense” in fire water pumps.
Testing and operation
The use of packings in modern fire water pumps is not recommended. The observation that packaging no longer represents best practice is amplified by the frequent lack of training of maintenance personnel observed in some factories. Best practices include periodic testing of all backup equipment. A frequently asked question concerns the testing and alternative operation of emergency equipment. Operators ask if switching pumps ‘A’ and ‘B’ and running them for a month, or starting the standby pump once a month and then running them for four to six hours, is the choice. prefer. When people said decades ago that factories could get away with testing only twice a year, reliability professionals took the position that testing only twice a year would not be acceptable. and that a monthly test was necessary. Depending on lubricant choice and lubricant application method, changing “A” and “B” every two or three months is considered best practice. This keeps the bearings lubricated and prevents the seal faces from sticking.
The much publicized reliability-focused practice of implementing mechanical seals for fire water pumps had not been accepted by the foreign refinery that experienced the fire in 2015. After this event, the refinery investigated why its main fire water pump was unavailable at a critical time. The comments aren’t all there, but presumably they closed the case after establishing that “a 50-year-old specification clause was met and therefore the incident is no one’s fault. “. Nevertheless, the claim that the packaging is safer was refuted by the company which had collected worldwide statistics for insurance purposes. He determined that the consistent use of modern cartridge seals would be the first step in ensuring that future results will be more favorable to pump availability and asset protection.
Any industry standard should explain the intent of its clauses. If there are better ways than following an obsolete clause, follow the path of reason and use what is safest for the factory and the community. Of course, when informed users deviate from an old industry standard, they carefully and authoritatively document why they deliberately switched to less risky methods. Corporate attorneys for the author’s petrochemical company agreed that in the event of a dispute, statistically proven best practices would prevail over an occasional but demonstrably outdated clause found in older industry standards.
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