I'm the technical director for a small mutual water system. Most maintenance and repair is accomplished by volunteers of which I am one.
We have recently been replacing the 50 year old piping on our pumping plant. We have constructed a new pump platform for our two 10HP Berkeley pressure pumps and replaced the 50 year old galvanized piping with 2" Sched. 80 PVC. All valves (Check, On-Off, Selector) are new 2" brass with female threaded connections. The PVC universally uses male adapters that thread into the female metal parts. All pipe lines are glued PVC with EZ-Heat frost protection and insulation.
We recently had a failure where the threaded male PVC part simply came out of the female brass valve. Unbelievable, but close examination shows absolutely no obvious damage to either threaded part!
This joint was originally bench assembled using pipe joint compound, overlaid with a couple of wraps of teflon tape. In spite of my reservations, this combination was used on the advice of a local plumbing 'expert.'
My career experience includes lots of plumbing design and manufacturing, but mostly for precision gas handling. Largest fittings are typically 1/2", and Teflon tape is the preferred thread sealant. I had never heard of putting both pipe compound AND teflon tape in a joint.
Looking at websites for the manufacturers of PVC fittings produces even more confusion. One says to use either thread compound or tape. Another says to put the joints together with NO sealant, but then gives detailed instructions for using teflon tape.
BTW, the joint that failed is on a suction line, and has (operating) EZ-Heat frost protection.
We are only able to use one pump until I get this line repaired, so would really appreciate any suggestions on putting this joint back together so it won't fail.
We have recently been replacing the 50 year old piping on our pumping plant. We have constructed a new pump platform for our two 10HP Berkeley pressure pumps and replaced the 50 year old galvanized piping with 2" Sched. 80 PVC. All valves (Check, On-Off, Selector) are new 2" brass with female threaded connections. The PVC universally uses male adapters that thread into the female metal parts. All pipe lines are glued PVC with EZ-Heat frost protection and insulation.
We recently had a failure where the threaded male PVC part simply came out of the female brass valve. Unbelievable, but close examination shows absolutely no obvious damage to either threaded part!
This joint was originally bench assembled using pipe joint compound, overlaid with a couple of wraps of teflon tape. In spite of my reservations, this combination was used on the advice of a local plumbing 'expert.'
My career experience includes lots of plumbing design and manufacturing, but mostly for precision gas handling. Largest fittings are typically 1/2", and Teflon tape is the preferred thread sealant. I had never heard of putting both pipe compound AND teflon tape in a joint.
Looking at websites for the manufacturers of PVC fittings produces even more confusion. One says to use either thread compound or tape. Another says to put the joints together with NO sealant, but then gives detailed instructions for using teflon tape.
BTW, the joint that failed is on a suction line, and has (operating) EZ-Heat frost protection.
We are only able to use one pump until I get this line repaired, so would really appreciate any suggestions on putting this joint back together so it won't fail.
