Typical Hydrant Installations

[EngWade]

Why are tie rods often times specified with hydrant installations? As an example, suppose you have an 8" water main, and you tie into it with an 8x8x6 Tee Joint. Then between that Tee and the Hydrant, there is typically a gate valve installed. My question is, why are tie-rods specified around this gate valve? In the past, I've seen it done with "anchor pipes." Could someone shed a little light on this, and explain if there is any real difference between the two?

Thanks a lot for your help.

 

[bimr]

Underground joints for hydrants should be fully restrained back to and including the water main. In the past, thrust blocks were used, but mechanical joints are more common at the present time.

Tie rods are not mandatory but may be used as part of the mechanical joint restraining system. The tie rods may be part of some utilities standards.

 

[greggy]

We use to use bell collars and threaded bar stock to restrain hydrant runs, but we now use anchor pipe and fittings in the event in the future the street is widened, then extending the restrained hydrant run is a much simpler matter without having to shut down the whole main plus offering confidence the hydrant valve and fittings will hold the thrust.

 

[CarlB]

FWIW, the local utility standard up until a few years ago was tie-rods & a thrust block. Even though rods were coated there were enough corrosion problems they now use restrained joint pipe & fittings, such as "megalug". Then for corrosion mitigation, wrap pipe with 8-mil poly and provide anodes on every other pipe joint. For freeze protection, insulation is provided over the hydrant leg.

 

[EngWade]

Greggy,

The anchor pipes method is the one I have been most familiar with. What is the mechanism that restrains the hydrant connection with the anchor pipes? Meaning, are the anchor pipes just a thicker, less flexible material than typical waterline materials (e.g. DIP)? Thanks.

 

[rconner]

A veritable smorgasbord of restraints in these areas is available from many vendors. As I suspect the OP is dealing with mechanical joint piping items, in that regard Swivel Tees or anchor pipes are sometimes used to fasten mechanical joint shut-off valve close to the main (e.g. see

http://www.acipco.com/adip/fittings/mechanical/glands.cfm).

Of course many styles of mechanical joint “retainer glands” have also been alternatively used with basically just “plain end” pipes for similar purpose at any mechanical joint of fittings, valves, hydrants, etc. Even other types of mechanical joint piping restraints that do not employ gripping retainer glands are also available (e.g. as shown at

http://www.acipco.com/adip/pipe/restrained/mj.cfm

).

 

[greggy]

EngWade....the anchor pipe is just like an MJ pipe joint, only there is a metal ring welded onto the spigot end that is restrained by the follower gland and T-head bolts. The anchor pipe lengths are in 6 inch increments. There are anchor fittings also (tees and 90 degree bends).