These little safety devices cause such big troubles because of pure ignorance. I continue to have silly debates with very smart people about meeting the absolute bare minimums from so many different recognized and generally accepted good engineering practices (RAGAGEPs). As of today, I have written about Hydrostatic Relief Valves 84 times.
This week, I am back in my process safety saddle, helping a client with a release and a flash fire that seriously injured three (3) workers. Had it not been for their FRC PPE program we implemented several years ago, this could have easily been a triple fatality. Needless to say, I was confused when my old boss told me OSHA and EPA were asking a lot of questions and taking issues with the fact that the piping that failed did not have an HRV in place; however, the PSI RV data stated one was there, and the P&ID stated one was there AND the PHA listed the HRV for the “blocked in scenario.” If you have ever wanted to see how OSHA issues Willful Citations, here is a perfect example.
The engineer made a conscious decision to leave out some of the HRV, and she did so without utilizing the Management of Change program. The PSSR team also missed this critical inspection, as the line item was initialed off as having been inspected. Had this incident happened nine months and one week later, the facility may have had a chance to fix this… as my PM Work-Order for that HRV would have spit out of the CMMS, and that would have gotten some folks scratching their heads!
Sadly, the actual HHC/EHS in the covered process does NOT have its own chemical-specific RAGAGEP, as we have with LPG and NFPA 58. But as I always do, I use NFPA 58 as a baseline for all my flammable gas process designs. But this engineer would not go along with me without a legal battle about what she had to do to make OSHA/EPA happy… “not me happy.” So, I pulled out old-faithful ASME B31.3 as my RAGAGEP; however, she thought B31.3 was unnecessary.
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322.6.3 Pressure-Relieving Devices (a) Pressure-relieving devices required by para. 301.2.2(a) shall be in accordance with the BPV Code, Section VIII, Division 1, UG-125(c), UG-126, UG-127, and UG-132 through UG-136, excluding UG-135(e) and UG-136(c). The terms design pressure and piping system shall be substituted for maximum allowable working pressure and vessel, respectively, in these paragraphs. The required relieving capacity of any pressure-relieving device shall include consideration of all piping systems that it protects. (b) Relief set pressure shall be in accordance with Section VIII, Division 1, with the exceptions stated in alternatives (1) and (2), below. (1) With the owner’s approval the set pressure may exceed the limits in Section VIII, Division 1, provided that the limit on maximum relieving pressure stated in (c) below will not be exceeded. (2) For a liquid thermal expansion relief device that protects only a blocked-in portion of a piping system, the set pressure shall not exceed the lesser of the system test pressure or 120% of design pressure. (c) The maximum relieving pressure shall be in accordance with Section VIII, Division 1, with the exception that the allowances in para. 302.2.4(f) are permitted, provided that all other requirements of para. 302.2.4 are also met. |
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301.2.2 Required Pressure Containment or Relief (a) Provision shall be made to safely contain or relieve (see para. 322.6.3) any expected pressure to which the piping may be subjected. Piping not protected by a pressure-relieving device, or that can be isolated from a pressure-relieving device, shall be designed for at least the highest expected pressure. (b) Sources of pressure to be considered include ambient influences, pressure oscillations and surges, improper operation, decomposition of unstable fluids, static head, and failure of control devices. (c) The allowances of para. 302.2.4(f) are permitted, provided that the other requirements of para. 302.2.4 are also met. |