Restrain Service Pipe by Bolt to Friction Clamps?

6/8/2022

I have a job where the plans have a detail of the underground fire service entry into the building that shows us bolting to friction clamps. I've always used the 90-degree I bolts on the flange to shields.

Looking for some detail on this - are there other methods I should be considering? Is this acceptable?

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7 Comments

David Kendrick

6/8/2022 08:46:19 am

I think we called them Star Bolts. A 3/4" rod with a bent eye on one end and bolt thread on the other.

There are details of using a friction clamp with threaded rod. I just can't seem to locate one at the moment.

The friction clamp has "ears" that extend past the gland and bell of the fitting. Rod is laid into the gap between the ears after securing the clamp bolts.

We would use a special cast iron washer that had a pointed pin on one side that when placed over the rod with the pin between the fitting hub and bolt would hold the restraining rod in position. A nut would then secure the washer in the assembly.

It does require an equal fastener at the other end of the rod such as a dead man or fitting assembly.

As you can tell from the description Star bolts have less parts and are simpler to install.

Remember coat exposed steel or bag the pipe and restraint to reduce future corrosion.

Also good resource is the Ductile Iron Pipe Research Association.

www.dipra.org

I'd recommend requesting an installation guide from them.

Paul Pinigis

6/8/2022 10:07:04 am

Are you referring to a ductile iron retaining gland like Mega-Lug?

David Kendrick

6/8/2022 10:55:28 am

Megalug is a whole different product. A good product for that is made for ductile and plastic pipe.

www.DIPRA.org discusses restraint methods and calculations. Really good resource.

As far as the cast iron washer:

www.empireindustries.com

Figure 599 Socket Clamp Washer

We also would fabricate these out of welded flat plate with a 1/2" square rod about 1 1/2" long welded on the end for restraint of the washer.

https://www.asc-es.com/products/599-socket-clamp-washer

This is a picture of the Fig 599 washer with a Fig 600 restraint clamp.

Lots of product choices.

Toothed push gaskets are very useful on straight runs.

Jack G

6/8/2022 10:16:07 am

I would use an accessory at each slip joint, a gland I called tiger teeth. Had little teeth imbedded in the gland that held the joint together. Eliminates thrust blocks if entire run / service has restrained joints. Was about 35 bucks for 8 inch gland.

DAVID

6/8/2022 11:10:20 am

My boss was the expert in UG, not me, but we did as the other David described above, always going for redundant restraint/blocking, Star-bolts, MegaLugs, etc. (For the actual entry into the building, a one-piece stainless AMES In-Building-RIser (IBR) sometimes makes sense, especially in a retrofit.) Is the detail you have been provided old and generic?

Check the starpipeproducts restraint catalog, or ebaa-dot-com

There are several sentences and requirements regarding the use of clamps in NFPA 24 starting with this (2020):

10.6.2* Restrained Joint Systems. Private fire service mains
using restrained joint systems shall include one or more of the
following:
(1) Locking mechanical or push-on joints
(2) Mechanical joints utilizing setscrew retainer glands
(3) Bolted flange joints
(4) Pipe clamps and tie rods
(5) Other approved methods or devices

Cliff Schulze

6/8/2022 01:11:04 pm

Here is the only link I could find. Years back, the old fitters used to install this way all the time.
https://www.trumbull-mfg.com/products/joint-restraint-products/socket-clamps/

KRowe

6/9/2022 08:23:41 am

The use of a friction clamp (Water Main Clamp) is very common.
A single water main clamp behind the hub of underground pipe with Dog Ear washer. You would rod both sides through dog ear and use a concrete anchor to the wall.
If the water main clamp is in the middle of pipe, not behind a hub, restraining a fitting, you would need two water main clamps. The term used is to Mutt & Jeff the clamps. That is two varying lentghs of rod, say 2'-6" & 3'-6", one rod to each clamp, so that the water main clamp is cutting the pipe or crooked on the pipe. A single water main clamp in the middle of the pipe slides, no matter how tight you think you can tighten it.
This is what we you do if someone specified using an older method.

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Restrain Service Pipe by Bolt to Friction Clamps?

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