Naylor

Chemical Coupling Installation Instructions

Our Chemical Coupling installation instructions ensure the correct size coupling is used to suit pipe or fitting size. Consult the Naylor Hathernware Technical Department on 01226 794074 for advice.

Pipes and Fittings

  • All ends in the area of the coupling to be clean and free from grit or dirt.
  • All cutting to be a single clean cut by a suitable disc cutter ensuring cut end has all burrs or snags ground off flat.
  • All ends, whether site cut or not, to have sharp edges or corners removed and chamfered on the outer edge a minimum of 5mm x 45°. This is most important to avoid damage to the chemical resistant FEP liner.

Procedure

  • For couplings/adaptors with site fitted heat shrink sleeves:
  • Place FEP sleeve and coupling onto 1st pipe.
  • Align second pipe leaving appropriate gap.
  • Slide sleeve into position centrally over joint and mark sleeve ends onto pipe.
  • Slide sleeve back onto 1st pipe.
  • Place PTFE tape around pipe so self adhesive backing adheres to the pipe in such a position that the outer edge of the tape aligns with marks for outer edge of FEP sleeve. At the top of the pipe overlap the tape 5mm.
  • Reposition sleeve over joint covering sealing tape.
  • Apply hot air to shrink sleeve onto pipe face and PTFE tapes. (The hot air gun should be kept in motion at all times to avoid scorching the FEP liner). Work all around FEP liner to ensure whole area is tight down onto pipe face and PTFE tape either side of pipe gap.
  • Position coupling/adaptor centrally over sleeve.
  • Tighten all clamps equally working from the centre outwards in equal stages using 4″ lever ratchet and socket or socket style screwdriver to specified torque.

For couplings fitted with pre-shrunk FEP liners incorporating expanded PTFE secondary seals.

Slide coupling over 1st pipe taking care not to dislodge the PTFE seal.

Align second pipe leaving a 5mm gap.

Position coupling centrally across joint.

Tighten all clamps equally working from the centre outwards in equal stages using 4″ lever ratchet and socket or socket style screwdriver to specified torque.

Additional Protection

In ground where contaminants may degrade stainless steel or the elastomer, the following additional procedure shall apply.

  • Two layers of Denso tape or similar shall be wound around the coupling to completely encase same and adjacent pipe area to avoid salts penetration to the coupling.
  • In more severe conditions the coupling and adjacent pipe area shall be encased in a heat shrunk polyethylene sleeve or tape with hot melt glue adhesive backing as manufactured by Raychem.

These protective materials shall be installed in accordance with their manufacturers instructions and shall entirely encase the coupling and 50mm minimum of adjacent pipe.

It is advantageous to place a small block of resilient material over the worm drives and threaded clip ends to avoid these projections from penetrating the protective layer.