HDPE butt-welding and equipment

About Rendifield HDPE buttwelding machines

Buttwelding machines supplied by RENDIFIELD MINING AND INDUSTRIAL PIPING SOLUTIONS become reliable workhorse partners to any suburbian or urban challenge with regards to HDPE installation and pipe maintenance.  Rendifield’s commitment to Excellence in Service will ensure that your project stays on target.

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What is buttwelding?

Butt-fusion jointing is a thermo-fusion process that involves the simultaneous heating of the ends of two components which are to be joined until a melt state is attained on each contact surface. Two surfaces are then brought together under controlled pressure for a specific cooling time and homogeneous fusion if formed upon cooling. The resultant joint is resistant to end thrust and has comparable performance under pressure to the pipe.

This method of jointing required an electrically heated plate to raise the temperature of the pipe end to the required fusion temperature and is used for PE63, PE80, and PE100 grades of material for a pipe of size 32mm and above of the same Standard Dimension Ratio (SDR).

 

Applications most suitable for the butt-welding procedure?

Butt welding pipe fittings are commonly used for pipe joints which are not changed and assembled. Underground piping systems and long-distance pipelines are the best examples.

Advantages of butt-welding procedure?

Comparing to other types of steel pipe fittings,butt welding pipe fittings has advantages:

  • Butt welding joint is permanently leakproof and strong.
  • Continuous steel structure of the joints between the pipes and fittings have a good strength in the piping system.
  • The butt welding pipe fittings commonly have a smooth surface and gradual directional changes,it will decrease the pressure losses and turblence of the system,and protect from the corrosion and erosion.
  • The butt welding pipe fittings have a lower cost in bugdet.
  • The butt welding joints have a smaller space in the system. 
Equipment requirements for Buttwelding

All welding is done as per SABS 4427.

  • Approved Butt-Welding Machine (inclusive of trimmer), Heated Plate and Hydraulic Pump.
  • Generator
  • Welding Tent
  • Pipe Support Rollers
  • Clean Water or Clear Spirits Lint free cloths
  • External/Internal De-beading tool
  • Bead Gauge
  • Pipe end-covers
  • Marker Pens
  • Pipe Cutting Tools
  • Digital Thermometer (Calibrated)
Buttwelding procedure

 All welding is done as per SABS 4427.

  • Set up the equipment. If necessary, erect a welding tent to protect against wind and dust.
  • Mount the facing planer (trimmer).
  • Align the pipe ends or parts to be welded with the aid of roller mountings or other supports. (Never attempt to weld together pipes with different SDR ratings).
  • Clamp the pipe or parts and seal the ends. Trim/plane the joint faces.
  • Remove the planer and excess shavings. Take care not to touch joints face by hand.
  • Check for pipe alignment radially; by bringing the joint faces together. (Max Gap = 0.5mm).
  • Check for pipe alignment axially in line with wall thickness. (Max = 0.1/s-s {wall thickness} ).
  • Clean the area of the heating plate with lint free cloth and water/clear spirits.
  • Check the welding temperature. (195°C +/-10°C)
  • Insert the heated plate.
  • Exert the heating pressure by the hydraulic unit until a bead is formed along the circumference of the joint faces.
  • Reduce pressure to allow for heat dissipation into wall of pipe axially. (Soaking period).
  • Remove heating plate over the allocated time and immediately join the molten joint faces together, ensuring that the change-over time is not exceeded.
  • Steadily increase the welding pressure to its allocated value.
  • Keep at this pressure for the allocated time.
  • Allow for cooling down at the welding pressure over the allocated time.
  • (Never remove a weld from the machine before the cooling time has elapsed).
  • When this cooling time has elapsed, reduce pressure to 0 and remove welded joint from clamps.

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