Plexco Service Tee Celcon®  Polyacetal Caps

On September 6, 2007 the Department of Transportation Pipeline and Hazardous Materials Safety Administration (DOT PHMSA) issued an updated notification on the susceptibility to premature brittle-like cracking of older plastic pipe.  Portions of this report regarding Plexco service tee Celcon® polyacetal may be misconstrued and as such we offer the following clarification. 
 
Plexco did use Celcon® polyacetal plastic material in tapping tee cap production.  Celcon® caps were designed to be hand tightened only, not tightened with a wrench. Celcon polyacetal is a thermoset material and as such is less forgiving of overstress in applications than is polyethylene.  Those caps over tightened with a wrench could fail (notice wrench marks in photo #1).   The over tightening of caps was identified as a problem in the 1995-96 time frame. There have only been problems associated with caps that were not properly installed.  The material itself has not been found to be a problem.
  
Identifying Celcon® Caps
All caps used on tapping tees at Plexco before 1996 were made of a material called Celcon® polyacetal.
 
Plexco Orange Tapping Tees
All Plexco tapping tees that are orange used Celcon® in producing caps (see photo #2). The original cap had an o-ring seal.  Most of the time, the labels on the tapping tee were made of foil.  Replacement caps in polyethylene are available for purchase where original cap has been over tightened.
 
Plexco Yellow Tapping Tees
Plexco tapping tees produced in yellow before 1996 used Celcon® in caps (see photo #3 below).  After 1996 Plexco started manufacturing polyethylene tapping tee caps.  We continued to manufacture some of the Celcon® polyacetal caps through March of 2000, because several customers specifically requested the Celcon® polyacetal caps over the polyethylene caps.  No Celcon® polyacetal caps were produced after March 2000.  Often the labels were made of paper. Replacement caps in polyethylene are available for purchase where original cap has been over tightened.
 
Other Identifiers
All Plexco labeled standard size tapping tee Celcon® caps used an o-ring seal inside the cap instead of a flat gasket (see photo # 3). 
 
Questions to ask to help determine if you have a Celcon Cap:
  • Who produced the tapping tee?  (Only Plexco tap tees are of concern)
  • Is the tapping tee a rectangle base? (Only rectangle base tap tees are of concern)
  • What color is the tapping tee? (Only yellow or orange tap tees are of concern)
  • Does the cap have an o-ring seal? (Standard tap tees with o-ring are of concern)
  • When was tapping tee produced? (Before 1996 is likely; before 2000 of concern)
  • Is the label on the tapping tee foil or paper? (Before 1996 is likely a concern)
  • Does the tapping tee have a shoulder just below the threads?  (Two pictures immediately above DO NOT have on stop shoulder after threads – this is a sign the fitting is older and of concern)
Other Info
Plexco did not use Delrin in tap tees (the grey tap tee in photo #4 was made by DuPont.) 
 
This document provides accurate and reliable information to the best of Performance Pipe’s knowledge.  Other distinct satisfactory methods, guidelines or specifications may be available for the fitting identification.  Performance Pipe makes no warranty, express or implied with the information supplied.  Replacement caps are available for purchase.