Ductile Iron fittings (connecting to existing DI pipe) - Eng-Tips

Great, thanks to all for the replies.

Stevewag, I have as-builts to go by, which may or may not be accurate. An alternative would be test holes - but the client doesn't always want to pay for them. They keep telling me they have As-Builts, so why the need for test holes? ha!

Maury, good point although my hope is this is something a reputable contractor would know how to handle. I have the US Pipe Ductile Iron Pipe booklets which detail how to field cut and assemble the various joints - I would hope the contractor has these also!

rconner, I hadn't considered bell direction. Thanks for that. It seems the additional cost of a coupling is worth it, considering the benefits and potential issues which can be avoided by their use.

My question stems from two sources: One - a coworker doing the peer (QA/QC) review on my design was asking why I didn't use a coupling for a particular connection. His comments couplings were the only fitting to be used for DI to DI connections. Two - the various contractors I've been dealing with as of late do not seem very knowledgable in the use of the couplings I've spec'ed ( the EJPrescott and Smith-Blair, both very similar to the Dresser couplings but NSF and AWWA approved). Their comments were causing me to wonder how they were connecting DI to DI and what fittings they were using.

Thanks again for the responses. s0eebuch,

I would not use a coupling on an ductile to ductile connection. I would use one when I had no other alternative such as connecting ductile (or C 900) to an over or undersized pipe, or when making a repair from a main break. Instead I specify that a solid sleeve be used if not using another type of MJ fitting to connect to an existing main. The solid sleeve is normaly between 8 and 12" long versus the 6 inches normally availible with a coupling. This give much more pipe gap availible to get a group of fittings into place. This fitting should be in the online EJP catalog, I have the paper (page B-4) one in my office.

When I do need to use a coupling, instead of the "dresser" syle coupling I use one like the Romac Macro As sold by EJ Prescott rather than the Romac 501 from the catalog cut sheet. These couplings (and the Viking-Johnson equivelent) do not have to be disasembled to slide onto the pipe, have a torque spec for the bolts, only two bolts no to tighten, the gaskets can be (and need to be) field modifided to fit a wide range of pipe outside diameters without having a variety of gaskets and endrings on hand.

I never liked tightening the dresser style couplings to the point that the bolts are starting to bow. Also I have been around main breaks where the bolts rusted away after a few decades causing a leak.

I would question a pipe laying crew putting MJ fittings in the ground (and conecting to existing mains) if there was no torque wrench on site since most (there may be an exception) MJ glands now manufactured have instructions that require specific tourquing. Also they should have an outside diameter or pi tape on hand to measure and verify the outside diameter of any pipe.

The book I prefer to have on hand is the Clow (McWane) "Pipe Economy" it has great detail on pipe installation and availible fittings that the McWane corporation produces with all of its subcompanies.

I am both the engineer and owner on my projects, so I have a vested interest that the work goes well. If not, I do hear it from my coworkers.

Good Luck!

Jefferson