Butt Fusion vs Electro Fusion 2

[phllp581]

Can someone briefly descibe the differences between butt fusion and electro fusion. My understanding is butt fusion uses heat to connect the butt ends of pipe while electro fusion runs electrcity through a fitting connecting two pieces of pipe to connect the pipes with the fitting. Is it possible to butt fuse fittings (90's, reducres, tee's, etc) or must they always be electro fused?

 

[LittleInch]

You don't say it but I assume you're talking about Poly Ethylene (PE)??

It is possible to use butt fusion for fittings, but normally this is only feasible in a factory setting as you need a lot of jigs and things to hold the bits in the right place whilst you heat them up and then hold them steady whilst they cool. Out in the field it is far easier and higher quality to use fusion couplings.

Have a look at this - download the technical guidelines document - it's excellent

http://www.gpsuk.com/literature-downloads/

The difference - butt fusion melts the PE directly (often a hot plate) and whilst still "molten" fuse it ot another also heated PE thing under force which extrudes seom PE and tis then allowed to cool with the materials fusing to each other in a homogeneous manner

electrofusion has a fitting which is in close contact with another piece of PE. within that fitting there are small electric wires which heat up, causes both surfaces to melt and then once the electricity is turned off, again it fuses. Because the metal wires are left in the fitting and to make it in the first place is a bit more, fusion is more expensive, but much easier to accomplish in the field.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bimr]

Various manufacturers of plastic piping use different materials of construction. Each different manufacturer has developed proprietary techniques (butt fusion, electro fusion, etc.).

For example, for polyethylene pipe:

There are three types of conventional heat fusion joints currently used in the industry; Butt, Saddle, and Socket Fusion. Additionally, electrofusion (EF) joining is available with special EF couplings and saddle fittings.

http://plasticpipe.org/pdf/chapter09.pdf

http://plasticpipe.org/publications/index.html

 

[phllp581]

Yes I was talking about PE pipe. I am typically dealing with 2" to 8" MDPE pipe and I am trying to determine which type of fittings (e.g. elbows, tees, reducers) would be best to specify for a natural gas distribution main (either butt fusion or electro fusion).

 

[bimr]

You might talk to your favorite Contractor as the Contractor may be set up to do the project with his particular skill set, techniques, and tools.

 

[LittleInch]

Depends on whether you know where these fittings are going. Tees and branches and other fittings for butt fusion need longer straight ends to get the fusion machine on but are usually cheaper. The number you're doing and the contractor you choose also have a big impact.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rconner]

It is interesting that while many, including up into the hallowed halls of Congress and some special interest industry, were quick to blame e.g. some gray cast iron pipes with ancient joining technology (that had incidentally provided at least some level of service since the time of Grover Cleveland) for the unfortunate, deadly and initially well-publicized East Harlem gas pipeline blast last March, some information that has dribbled out in the more than a year since have indicated maybe, "Not so fast...."
The article e.g. at

http://www.wsj.com/articles/probe-into-east-harlem-explosion-focuses-on-gas-line-1426713337

e.g. says there may well have been some involvement with separation of a "T-shaped connector" in a relatively brand new (~3 years old) plastic pipe and service installation near the scene. While apparently some very small leaks were also found in the surrounding main area, it will be interesting to see (the final report may still not be out in this matter after more than a year!) what exactly is involved here, as electrofusion is in general attempted not only in socket type, but also for lateral/service connections.
In this regard, it appears from at least the preliminary "Operations Group Factual Report" this year, I also happened to see not long ago at

http://puc.sd.gov/commission/PSOT/2015/presentation/public_57000-57499_57111_569281.pdf

, that the East Harlem "T-shaped connector" that separated from the main had in fact been "electrofused" in at least some extent to the plastic main. I had noticed this reported separation was described by the third-party gas pipeline safety consultant in the WSJ report as, "This is going to leak a lot of gas,"
For any not familiar, there are various requirements for different butt fusion and electrofusion joining procedures and fusers of plastic pipes in the Code of Federal Regulations (CFR).

 

[bimr]

Federal investigators said a poorly welded joint in a Con Edison gas line and a break in an old city sewer line were the likely causes of the blast.

They say the joint’s weakness was exposed when the soil beneath it was undermined by the sewer break.

 

[BigInch]

I would have included within the recommendations to prevent this from happening in future to provide adequate support, maybe something like a steel pipe half casing laid under the plastic pipe, when spanning sewer pipes, or any area where soil erosion and loss of natural support may occur.

 

[bimr]

The gas main actually ran parallel to the sewer pipe. The cause of the blast; from improper training, installation, emergency response, utility operations, you name it. Any number of separate acts could have prevented the explosion or prevented the loss of life. For example, the sewer had a major leak for 8 years that was known to the City and not repaired. The gas smell was observed the night before and nobody reported it. The Street has a major failure and nobody investigated further. The piping was never tested.

Events like this should not be occurring. The report should also have called for more spending on infrastructure. There was a 100 year old water main and a brick sewer.