Trapped at Berkeley

I wrapped up an FAT (Factory Acceptance Test) yesterday and learned something new during the inspection: the use of PTFE ‘Teflon’ tape on instrumentation joints is generally banned in oil refineries because the tape can tear off inside a pipe and accumulate at a valve, increasing the chances for equipment failure.

For those who haven’t done much plumbing, PTFE tape is an inexpensive, white, plastic tape that is commonly wound around pipe threads to enhance the sealing of a joint. It also acts as a lubricant of sorts, which can be a big help when disassembling a pipe joint at a later date. Teflon tape has become a staple of the plumbing industry and can be found at any respectable home improvement store. Heck, as a general rule of thumb, I always put Teflon tape on a metal pipe joint just because there wasn’t really harm in doing so in the household — it didn’t harm the pipe, and it ensured a more secure seal.

Unfortunately, Teflon tape has a tendency to break off in little particles. As a pipe joint is tightened, the threads ‘bite’ into the Teflon tape and sometimes cut off entire portions of the tape. These liberated pieces are generally found on the internal edge of the threads and get carried away by the fluid that flows through the pipe. For household plumbing, joints are disassembled and reassembled often enough that Teflon tape doesn’t get a chance to accumulate (ex., a garden hose), but, in a refinery, where entire process lines may operate continuously for years, the accumulation of particles in a pipeline is a very real danger. These particles can build up over time and block the operation of critical shutoff valves.

So, what do refineries use instead of Teflon tape? A growing list of manufacturers now produce a liquid pipe joint sealant that acts just like Teflon tape. You just brush it onto the pipe threads and screw the pieces together. The compound can get a bit messy, but it won’t clog valves. These liquid equivalents of Teflon tape are becoming popular, and I’ve seen them at some home improvement stores.

Personally, I still like Teflon tape. It’s not messy, it’s cheap, and it’s been tested for a much longer time. Nevertheless, for a refinery, where every little detail can save a life, Teflon tape has gone the way of the dodo bird.