Jointing of large bore pipes. Electrofusion Couplers and Branch Saddles


9a

In the AMI seminar, FRIATEC (www.friatec.com) introduced a new generation of electrofusion fittings Frialen –XL for PE pipe joining large diameter up to 1200mm which solves the Ovality problem and outer diameter Tolerances, that are important in these dimensions, through flexible electrofusion couplers.

These couplers operating principle is based on using conical rings (adapters) that by moving towards the coupler body inside, reduce the inner diameter, until adapting to the pipe outside diameter. The conical rings are inserted into the coupler body be screws equidistantly distributed allowing tolerances saving up to 20mm and 6% Ovality. The conical rings are welded by electrofusion to the pipe coupler body.

9b

Advantages:

  • Components inner large diameter. Easy assembly, particularly when sliding in the coupler body.
  • Scraping just enough to remove the oxide layer. There is no need for any kind of adjustment on the pipes diameter.
  • Pipes integrated rounding when introducing the conical rings. The conical rings are flexible for easy oval pipe assembly.
  • Snugly between the conical ring and the pipe. Tolerance compensation through mechanical adjustment.
  • Short process time. Quick and easy connection. Short fusion and cooling times. No preheating requirement

Other electrofusion fittings which we found interesting are the saddle type for large PE diameters.

Polyethylene pipes should not be battered and the existing good practice codes have to be followed. One of the defects which often result in the working place during handling and assembling, are bumps and scratches which are produces when dragging the pipes along the floor, without using rollers, or by the action of a mechanical element, such as a shovel, excavator, etc. In these cases and for water pipeline it is assumed that these bumps depth or scratches do not exceed 10% of the pipe thickness. For gas pipeline the maximum limit is 5% of the pipe thickness.

9c

Well, if for any reason we have these pipe damages, it is possible to fix them by using blind saddle fittings, like a tile, as shown in the photos. These fittings adaptation or simple sockets to the pipe by electrofusion, is made by vacuum.

NOTE by Rodolfo Vegas:

It is very important to scrape the pipe and remove the small outer layer which is rusted due to be in contact with the air oxygen. Since electrofusion fittings were introduced many years ago, most of the problems they have had is not scraping the pipe outer layer to be joined. AS SIMPLE AND UNWISE AS THAT!!  Currently, it is already being demanded that scrapers are mechanical rotating.

REFERENCES:

Introducing FRIATEC in the PIPES AND INFRASTRUCTURE 2013 Seminar organized by AMI at Dusseldorf in April 2013.

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