A number of years ago a former client decided that process safety was not worth the effort and wanted to get their process below the 10,000 pounds TQ for their LPG. They hired a local architect/engineering firm that had no experience with the storage, handling, and processing of LPGs. This “architect/engineering firm” advised the facility that no MOC would be necessary; later admitting they really did not understand the role of the MOC process and the PSM/RMP requirements. A couple of years later I get a phone call from a friend at a regulatory agency asking me about my PHA(s) and Audits I had done for the facility. Seems the facility completed their change and had gotten the process done to less than 10,000 pounds, but the manner in which they (and their architect/engineering firm) did it may have led to a significant LOPC event. The case got settled last year and so now I can write about it without revealing who and where it happened. There are some excellent process safety learnings from this incident, most notably how a MOC procedure may prevent such an event and how even a reduction in inventory may not be as simple as flipping a switch to make PSM/RMP go away.
The process was a fairly small and simple process that involved an LPG. Years before the incident the business was using a lot of LPG for several of its products, but over time the demand was reduced such that the price of doing PSM/RMP was more than the cost of the products. So the business decided that it would do away with several products and focus on just two (2) which would allow for a substantial reduction in the volume of LPG – such that they could get below 10,000 pounds.
NOTE: my only involvement in this reduction project was to advise the facility that they needed to use the MOC tool and do a hazard review to ensure this change (removal from PSM/RMP) was done properly, as EPA still could hold them accountable under the CAA GDC.
The facility’s architect/engineering firm had never worked on a process before, much less one that stored flammable gas. The business was located in a more city-like setting and had operated with little involvement from the local government. They did not like my RMP HAZ Assessment and asked their environmental consultants to redo them to a more favorable (albeit wrong) result. The original process used an 18,000-gallon storage tank with 2″ inlets and outlets, including 2″ excess flow valves. For reasons unknown at the time, the process piping was placed underground. It remained there, uninspected and unprotected for nearly 30-years. As part of the “change”, the plan was to use all new and 0.75″ diameter piping above ground.
The change was made and a couple of years later a delivery truck backing up struck one of the above-ground 0.75″ LPG pipes. The tank had been filled the day prior and was just under 9,500 pounds of LPG. Every last bit of it was released causing major disruptions: roadways shut down, evacuations of office buildings, very angry responders, etc. As it turned out, my audit findings (repeats) that the environmental consulting company never submitted their RMP or their Tier II’s were accurate findings. The ability to fly below the city’s radar was simple – the city had no idea this business was using LPG in these quantities.
But the moral to this story goes back to my original PHA for the business and their SOLE DEPENDENCE on the tank’s excess-flow-valves. I had written two findings (identical) in both PHA’s that the facility needed to utilize more engineering controls to PREVENT and PROTECT the LPG containment system; that excess-flow-valves were a MITIGATION device and not a very good one at that. I referenced the OSHA/EPA guidance on giving too much credit to these valves and the CSB Report on the Herrig Brothers LPG BLEVE. Still, with all that supporting documentation, the business closed the PHA recommendations after deciding, on the advice of their supplier, that the excess flow valves were adequately sized for the process.
During my two audits at the facility, I advised the facility about the amount of traffic around the storage tank, vaporizers, and pipe runs. I advised them to comply with their state’s Fire Code which required vehicle protection in the form of Bollards or some equally effective protection. Once again they went to their supplier and the supplier said my finding(s) were “over the top” and there was no such requirement in the state.
And once they got below the 10,000 pounds TQ, all the former PHA and Audit recommendations went into the trash (literally) and no actions were taken.
Then one day a delivery truck hits the piping and because there were no emergency isolation valves as listed in the PHA recommendations (only the 2″ excess flow valves) there was no way to stop the flow of the LPG from this 0.75″ liquid line operating at about 200 psi. It was pure luck that the LPG did not explode as there were ample ignition sources in the area (no defined HAZ LOCs – other items covered in the PHA and audits).
The business is no more. They blame me for running up their cost of doing business and they blame the regulatory agencies who investigated them after the event of overreaching their authority. And they blamed the businesses that sued them for the nearly two days they were evacuated out of their businesses. Never once did the owner(s) or management consider their lack of concern for their LPG and all the warning signs of a poor design. The company seeked advice from two organizations:
1. A local architect/engineering firm that had no experience with the storage, handling, and processing of LPGs, and
2. Their LPG supplier(s)
In court, both organizations admitted they were not familiar with OSHA standards or the NFPA codes and standards. Both of the LPG suppliers claimed they had warned the company about the location of the tank, but this contradicted some of the company’s internal communications regarding my PHA and Audit reports. Apparently there were some e-mails between the owner and the plant manager discussing my findings and the response from the supplier – indicating that the supplier had informed the company that the tank (and piping) was “OK” and nothing more needed to be done.
I know I have harped on taking credit of excess flow valves several times, but it is a SERIOUS FLAW in our risk assumptions. In almost all my inspections I find process changes that basically bring into question the validity of the excess flow valves. The CSB said it best in their Herrig Brothers report… (emphasis by me)
The liquid line that ran from the tank to the vaporizers was equipped with an EXCESS FLOW VALVE, which was designed to automatically close when the flow through the valve exceeded a predetermined rate – the closing rating. This particular valve had a closing rating of approximately 200 GALLONS PER MINUTE. In the event of a complete break in the outlet pipe downstream from the excess flow valve, the valve should have closed and greatly reduced the flow of propane from the broken pipe. When the ATV severed the liquid line, however, the excess flow valve failed to close because the FLOW CAPACITY OF THE OUTLET PIPING SYSTEM WAS LESS THAN THE CLOSING RATING OF THE EXCESS FLOW VALVE. At this installation, the outlet PIPING DOWNSTREAM FROM THE VALVE WAS TOO NARROW for the valve installed in the tank.
If the pipe downstream from an excess flow valve is too narrow in diameter, flow through a severed line can be restricted so that it will not exceed the closing rating required for the valve to activate. Thus, an excess flow valve will generally not close if the PIPE DOWNSTREAM IS SMALLER IN DIAMETER THAN THE VALVE, even if a complete break of the line occurs.
For this reason, NFPA 58 requires:
5.9.8 Container Appurtenance Installation
…
(H) The connection or line that leads to or from any individual opening shall have a flow capacity greater than the rated flow of the excess-flow valve protecting the opening.
SAFTENG NOTE: The 1998 CSB report made reference to a much older edition of NFPA 58, so for the SAFTENG members I have updated the requirement with the NFPA 58, 2017 edition wording.
At this installation, however, the piping downstream of the excess flow valve did not conform to this NFPA requirement. Specifically, shut-off valve A20, which was downstream from excess flow valve FV3, was fitted with two bushings that reduced the flow of propane by decreasing the diameter of piping in the line to approximately ¾ of an inch. In this incident, the break in the line occurred at the point where the second bushing connected to the ¾-inch outlet pipe to the vaporizers (see Figure 6). Following the break, the excess flow valve did not close because the flow of propane through the line was restricted by the reducer bushings to a rate below the closing rating of the valve. A NASA laboratory, the Kennedy Space Center Materials Science Division, conducted tests on the excess flow valve which demonstrated that the valve closed properly when it was installed in accordance with the manufacturer’s recommendations and that it did not close when attached to a ¾-inch inside-diameter pipe.
I should also point out that NFPA 58 also requires the following (which could have made a lot of difference on that faithful day):
(E) Shutoff valves shall be located as close to the container as practical.
(F) Shutoff valves shall be readily accessible for operation and maintenance under normal and emergency conditions.
(G) Shutoff valves either shall be located in a readily accessible position less than 6 ft (1.8 m) above ground level; shall have extension handles, stairs, ladders, or platforms for access; or shall be equipped for remote operation.
So when the business kept their original 18,000-gallon tank with its 2″ excess flow valves and installed all-new 0.75″ piping ABOVEGROUND and without any vehicle protection, they were actually aligning the planets and were just waiting for the day they learned that excess flow valves are not all they had hoped they would be. Both the company and their engineering firm were sued in court and it was settled last year. I was not involved in the lawsuit due to a Non-Disclosure Agreement with the company, but the lawyers did not need me as they had all my PHAs and Audits and that was all they needed.