Q. I am interested in learning more about your May 2011 EH&S Clinic answer. I’ve contacted several plumbing suppliers and none of them were able to assist me in finding the glue you recommended for CPVC pipe or the pipe tape. We are seeing exactly what you were talking about on a leaky pipe containing caustic or alkaline solutions and would love to put them to rest. We use primarily CPVC schedule 80 pipe in our plating facility and have always opted for EPDM seals in our valves and unions. If you could get me the names of these products I would greatly appreciate it. T.R.
A. I can’t provide specific brand name products, so search the Internet using either “cpvc glue caustic” or “cpvc glue hypochlorite,” and the results bring a well known brand of glue for CPVC pipe. If your plumbing suppliers do not have the specific product, they will know how to obtain it, or you could order it on the Internet.
As a reminder to those who may have missed the article, normal PVC and CPVC glues contain fumed silica as a thickening agent; this is attacked by caustics over time causing leakage through the joint. There are glue formulations without fumed silica that are designed for caustic and hypochlorite usage.
Regarding the tape for threaded pipe, if you can’t find one for the military specification T 27730A, I recommend you purchase a high quality Teflon or PTFE tape.
Comment: I would like to offer a comment on ongoing pipe cement discussion. Users concerned about caustic service could look for what one manufacturer calls “industrial PVC cement” which is made without the fumed silica thickener. For small jobs, I have found that some cements available at retail home improvement stores do not list colloidal or fumed silica so, consumer protection being what it is, I think it’s a fair bet that those products don’t contain any silica. D.L.