Mechanical vs. Fused Fittings on Plastic Pipe

Question:  Can you explain the advantages and disadvantages of mechanical fittings on plastic pipe versus fused fittings?
Answer: Here are some facts that show advantages and disadvantages of each type:
  • Heat fusion, electrofusion, and mechanical fitting installations have been proven safe in the industry, as long as proper procedures are performed.
  • For each mechanical fitting connection (coupling), two connections must be made. For butt fusion, only one connection is made.
  • Compared with mechanical fitting joints, butt fusion has by far the fewest failures, as documented by the U.S. Department of Transportation.
  • Minor scratches on PE pipe/tubing can be detrimental and are prohibited by the manufacturer when installing compression and stab-type mechanical fittings.
  • Fusion joints, when performed correctly, become stronger than the pipe itself.
  • For butt fusion, no materials other than polyethylene are in the connection; thus, there’s no possibility of corrosion.
  • Qualified fusion personnel must ensure that required fusion pressure is calculated correctly with hydraulic fusion units.
  • Butt heat fusion is the most widely used method for joining individual lengths of PE pipe and pipe to PE fitting. (This method produces a permanent, economical, and flow-efficient connection.)
  • Mechanical or electrofusion couplings are frequently used for convenient replacement of damaged PE pipe segments.
  • Butt fusion joints are used in manufacturing some mechanical fittings.
Tip: It’s important to understand that any approved method of PE pipe joining will be successful if every facet of the procedure/process is followed correctly. I cannot stress enough the vital importance of pipe/fitting preparation (cleanliness) and ensuring that all completed joints are inspected thoroughly!

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