Just by sheer luck (bad) I, unfortunately, came across a perfect example of how IMPROPER torquing can create a VERY SERIOUS HAZARD in a chemical process. I was helping a client with a process that has a runaway reaction potential. Our study took us to the reactor so we could examine the pressure relief system, where we noticed the rupture disc holder flange was off center and the two flange faces were not parallel with each other. Upon closer inspection, we discovered that there were 5 nuts and bolts in a row that were not even hand tight. The engineer could spin then with ease. The opposite side of the flange the bolts were much tighter. This led to the uneven flange and off-center RD.
If this was not bad enough, as it compromised the relief system, the real hazard would have been a potential fatality. With the improper torquing, the 200ºF plus material would have exited this gap rather than exit the system at the end of the vent line. The material that comes out is traveling very fast and has an oily viscosity which means the 200°F material will stick to a worker and safety showers are ineffective in the removal. The gap in the vent line was just below my waist in height, which means it could have covered me from head to toe if an over pressure event occurs. TORQUING MATTERS and in a process that contains serious hazards it is even CRITICAL!
This week I received an odd e-mail asking me if OSHA required “torque” values when installing PSM covered equipment and if they did to please provide the evidence of such a requirement. To protect the innocent I will not mention the industry this EHS professional currently works in. He openly admitted that in previous roles at other businesses in a different industry torque was a function of the Mechanical Integrity Program; however, his current employer is balking at this requirement…which lead him to seek consultation from others.
To answer the question directly…YES, torque is required in the vast majority of installs and PM’s. With that said, you will not find a specific requirement for using a torque wrench anywhere in 1910.119; just like you will find VERY LITTLE specifics in .119 and even less in the mechanical integrity element. What you will find in writing from OSHA regarding torque is in their Appendix C – Compliance Guidelines. In this appendix (non-mandatory) OSHA specifically mentions torque values when installing critical equipment. The argument some like to make is that Appendix C is “non-mandatory” and that OSHA cannot cite a facility for not following Appendix C. My response is you are correct; OSHA will never reference Appendix C in their citations, as there is no need to reference it, but keep in mind OSHA would not have written it if they did not believe it is necessary. Here’s why…
PSM is what we call a “performance-oriented standard”. This means that OSHA leaves the details up to the employer, as long as their management systems and practices follow Recognized and Generally Accepted Good Engineering Practice (RAGAGEP). In my previous post about “What is a RAGAGEP…” I mentioned that the FIRST PLACE to go for direction regarding a specific piece of equipment is the MANUFACTURER of the equipment. As for torque, if the MANUFACTURER REQUIRES a specific torque valve be applied during the installation of their equipment then OSHA has every right to cite (and will do so) under the MI Quality Assurance element that the facility is not following the MANUFACTURERS RECOMMENDATION (the FIRST STEP in establishing a RAGAGEP).
It was pointed out to me that some personnel in certain industries feel that torque is “being picky” or that OSHA is just trying to pay off the national debt by citing torque requirements. Appendix C was published in 1992 and OSHA was talking about torque way back then. For anyone to infer this is a new requirement or that it is not necessary on a process that contains a Highly Hazardous Chemical (HHC) is just nonsense. Recently I was referred to in a negative light by some in a forum when I questioned some historical practices in a particular industry. Some in the group were quick to post the “manufacturers manual” in an attempt to settle a debate regarding valve installation; now in these same manuals, the manufacturer requires their valve(s) be installed using some very specific torque specifications. But this same group claims that torque is not required and it is just ridiculous to even discuss.
Bottom Line…if you have a piece of equipment, you have to have the Process Safety Information on that piece of equipment. More times than not the PSI will be the “owner’s manual” and/or “specification sheet” for the equipment. If this manual/sheet has torque values listed and the employer does not follow them, the facility could be cited for not following the “manufacturer’s recommendations” (e.g. RAGAGEP). OSHA is NOT going to reference any type of external safety code from a trade group when citing an issue with a specific piece of equipment. They could use an external safety code/practice when citing a class of equipment, such as relief valve testing, but more often than not they will cite the “manufacturer’s recommendation” when the issue is with a specific piece of equipment.
Is torque an important part of a MI program? Most certainly it is. It is more important on items like rupture disc holders and critical instrumentation, but even on just everyday ordinary flanges, it plays a critical MI role. We have seen a lot of chemical releases and leaks caused by improper torque. We have seen problems with original installs, but most likely, what happens is that a SMALL LEAK begins and the solution is to just tighten down the flange nuts and bolts to stop the leak. A couple of days/weeks go by, it begins to leak again, and we go out and tighten them down even further to stop the leak. With each turn of the wrench, we flatten out and begin to spread the gasket and apply undo strain to the flanges. Eventually, the gasket completely fails due to this improper torque and we now have a MAJOR RELEASE. Although rarer, we have seen leaks occur during start-ups due to the installation not being done properly. Just like too much torque, not enough torque can be just as bad. So torque requirements play a vital role in our MI efforts to keep “the animal in its cage”. Not following such fundamental practices will eventually lead to a leak on your flanges and if it involves a HHC, you are now open to an OSHA inspection/investigation, which could lead to a PSM citation.