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In-trench butt fusion welding
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Author:  GeneralQuestion [ April 7th, 2016, 8:38 am ]
Post subject:  In-trench butt fusion welding

I am interested in butt-fusion welding HDPE pipe in the trench. I have a gravity sewer project using 10" SDR-17 pipe, and there are connections to HDPE manholes every 200 - 300 feet (the MHs are stubbed out). The client would like the pipe to be seamless as much as possible--the liquid is leachate, and a leak opens a world of trouble and fines. So, the solution was to use in-trench butt-fusion welding, but the installer is recommending mechanical joint couplings instead. I understand his position, the MJ couplings will allow for misalignment between the manhole stub and sewer pipe, simplifying installation. But is this the 'A' job that the client is paying for?

If the physical aspect of getting the butt-fusion equipment into the trench is overcome, there is still the issue of having enough movement to allow for alignment, clamping, and joining--if the pipe has enough movement, the joint can be made. I've talked to some installers and it's possible to weld to the MH out of the trench, and then lower it in place. Is this a practical alternative? Has anyone done this? It seems like the most important factor is the installer's sequencing.

I am interested to hear how manhole connections are actually fashioned in the field. What is the BEST way to make the joint, and what is TYPICAL? How should the installer sequence the project to minimize the number of MJ couplings or electrofusion couplings? Thanks to anyone who can help.

Author:  Ben Murphy [ June 8th, 2016, 2:24 pm ]
Post subject:  Re: In-trench butt fusion welding

I hope you managed to get a hold of one of us by now, but if not, I am sorry that we didn't get in touch with you sooner.

A good butt fusion joint is the most reliable, least expensive, and longest life joint and should be used everywhere possible. In those cases where you can’t, I would recommend the Hymax Grip® mechanical fitting or EF.

It is easier and more productive to fuse above ground and then lower the line in the ditch. In cases where you need to fuse in the ditch, the Pit Bull® is available, or the carriage from the 4 wheel cart or TracStar® can be removed and operated in the ditch.

You mentioned that the “MHs are stubbed out”, so I assume that the outlets are fused to the MH. (Note: If the outlets are only clamped on, we offer Sidewall fusion machines to make that joint leak free.) If the stub is long enough to clamp with one fixed clamp and allow for face off, then the pipe could be fused directly to the stub, at least at one end. Typically the last joint between MH’s is done with a mechanical fitting or EF.

The line of Hymax fittings is manufactured by Krausz of Israel and is a member of the PE Alliance.

Hope that this is of some help. Please contact us via our Tech Support phone line (918)831-9224 anytime we can be of service.

Best Regards,

Ben Murphy
Technical Service Specialist
McElroy Mfg, Inc.

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