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Technical Articles

Threaded Connections


  1. APPLY A SUITABLE THREAD SEALANT, SUCH AS COMPATIBLE TAPE to male tapered threads to assure a “leak-tight” seal. Note that sealing tape will “string” as pipe threads are joined. Loose “strings” could lie across the seating surface and prevent the valve from completely closing. To avoid this problem, clean out old tape, and do not apply tape to the first thread.
  2. ASSEMBLE “HAND TIGHT” followed by a quarter (1/4) turn with a strap wrench. Do not over tighten.
  3. DO NOT USE PIPE WRENCHES, vise grips, channel locking pliers, etc. on plastic pipe and components.
  4. CONNECT TO PLASTIC PIPE AND FITTINGS ONLY; when using metal pipe, install an intervening plastic fitting. Metal pipe and straight threaded pipe tends to cut, stretch, and distort the plastic bodies, resulting in cracking or leaking over time.
  5. THERMOPLASTIC COMPONENTS CAN BE DAMAGED by contact with chemicals found in some thread sealing compounds — Pastes, Caulks, Tape, Dope, Lubricants, “Thread Lock,” etc. Reasonable care needs to be taken to ensure that products coming into contact with thermoplastic systems are compatible. Plast-O-Matic recommends confirming chemical compatibility with the manufacturer of the thread sealing product.
  6. FOLLOW THE INSTRUCTIONS provided with the thread sealant.
  7. DO NOT USE a valve damaged by incompatible thread sealants.