Electrofusion welding for PE is common place however the fittings are more
expensive than a butt welding procedure. The only problems that I have struck
were in Malaysia where the contractor failed to clean the surface of the pipe
and this resulted in failed joints. The automatic welding machine is generally
idiot proof. Its the same as welding steel, if the joint is contaminated you'll
end up with inclusions. Watch out if the trench has a high water table as there
is an occupational health and safety risk with having a machine down hole. EF
fittings are great in plant for elevated welds where it is impractical to get a
butt fusion welding machine. The EF fitting provides increased thickness that
overcomes the reduced weld strength of a BF weld.
I have not heard of using bladders to get over the internal weld bead. British Gas use a cutter called a "Daisy GorseLine" to remove the bead. Myself I like to leave the weld bead there. For a start the weld is considered to have no more than 80% of the strength of the original polymer. The increased thickness at the weld gives some comfort. I am not a believer in the European standards that promote a design factor of 1.25 for PE . Generally I use a factor of 1.6 for general work and 2 for critical applications. I think the gas industry uses 4.
One problem that is common with butt fusion welding is moving the pipe before the weld has cooled. When you evaluate the cost of welding PE to the manufacturers procedures it proves to be more expensive than ABS solvent welded.
The RF welding machines are promoted by George Fisher. This Swiss company developed the technique. It hasnt caught on in SE Asia because the machine is far more expensive than butt fusion machine.
You hit on the right person. I have been associated with thermoplastic piping for over 30 years and serve as a consultant in the industry. Also I am on several Australian standard plastic materials committees.
"SARE, RALPH H." <SARERH@YANPET.SABIC.com> on 30/05/2001 18:59:59
Please respond to <a href="/group/PipingDesign/post?postID=oJ7PSd2pdaA9I7qQaNn9fLRo1_ucvxOu7A_1S__3EfIBf4lz0-3qWr_jWJccvTSqwmXWxzsQF1yoP5eRMvlr9ERedU8">PipingDesign@yahoogroups.com</a>
To: "'PipingDesign@yahoogroups.com'" <PipingDesign@yahoogroups.com> cc:
Subject: RE: [PipingDesign] HDPE Piping
this is good geoff. we'll check it out. on related subject have you heard about electrofusion welding for plastic pipe. we've got a couple of HDPE here and im interested in buying a welding machine. Ive heard another guy suggested modified butt fusion using inflattable bladder for BCF (bead-and-creavice free) joints or some high-tech IR fusion butt fusion machine. Any expereince on these machines. Appreciate your reply on this.
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=sikNs0xIGWwbQujxtDXtPRoORrY0cS3tg_tbBQBN9on0KTUf50Wpvqwh4ifkSSA5G1rfNM3euRpP953YlXNMBI5XMZi18g">geoff.stone@lendlease.com.au</a> [mailto:<a href="/group/PipingDesign/post?postID=sikNs0xIGWwbQujxtDXtPRoORrY0cS3tg_tbBQBN9on0KTUf50Wpvqwh4ifkSSA5G1rfNM3euRpP953YlXNMBI5XMZi18g">geoff.stone@lendlease.com.au</a>]
In Australia & SE Asia lines for sea water are in Acrylonitrile Butadiene
Styrene (ABS). Tyco (Eurapipe) manufature to DN 750 in rubber ring jointed
or
chemicallly (solvent) welded. The ABS is not the same product as listed in
ANSI
B 31.3. Its much tougher. Of course you would need to have a few lines to
cater
for your flow.
The beauty of this material is that you dont get corrosion on the inside or
the
outside. Its great for sea water , septic sewerage, slurries, acid sulfate
soils, puire water (electronics & pharmaceuticals) etc. W ehave just
commissioned a 100 million dollar sewage treatment plant up grade where
there is
no ductile iron. All ABS or spiral wound stainless steel. I forget to
mention it
is cost effective too!
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Received on Wed May 30 19:50:00 2001
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