Thrust Support for Pipes

[FPE22]

Good day all.

The contractor on our project has installed field-manufactured devices on the elbows and direction changes of the firefighting system in the basement floors. These devices were installed to account for any large thrust forces on the pipe fittings. I have the following questions:

1) Is it a requirement by NFPA 13 (2013 Edition) to install thrust supports for pipes if these pipes already have hangers/clamps installed? (All pipes are aboveground).

2) If these supports aren't required, but we decide to keep them installed:

a) Does keeping them installed damage the pipes in case of high forces resulting from water pressure?

b) NFPA 13, 9.3.4.9 mentions that " Clearance from structural members not penetrated or used, collectively or independently, to support the piping shall be at least 2 in." Can we consider these devices as structural members not used, therefore keeping them installed with a 2 in clearance from the pipes?

I attached a photo of the thrust devices used for your reference.

Appreciate your help.
Best regards,
Steve

 

[cdafd]

I would not call that a thurst block.

It looks like they put it there for some type of support???

If you look at the pipe above/change of direction, it does not appear there is a similar device there.

Also looks like it was fabbed in the field.

 

[cdafd]

Is there a fire pump on the system??

 

[MatthewJWillis]

No, no, and no.

13 has VERY specific requirements for hanging/bracing.
Top of the list is UL/FM approved for use in Fire Sprinkler Systems.

Aboveground Sprinkler systems are tested to 200psi (or 50 higher than anticipated if over 200).

This would not pass my inspection. "Foreign item attached to pipe"

BTW Section 9.3 referenced above in your post, is for earthquake zones.

R/
Matt

 

[cdafd]

Forgot to ask which state is this in?

 

[FPE22]

cdafd - True, they are using them to support the pipes against thrust forces. If you look closely (upper left), they are using a similar setup to support the above change in direction you mentioned. Yes it is a field fabricated setup. Also, there is a 220 psi fire pump used. This project is outside the US, and NFPA codes apply.

Matthew - Yes we are also taking into consideration protection of pipes against damage where subject to earthquakes. Based on this, I need to know if it is acceptable to keep this support setup installed after maintaining a clearance of up to 2 in. from the pipes in reference to NFPA 13 2013 Ed, 9.3.4.9.

 

[cdafd]

Ok I see the top one

This must be in California or similar

 

[stookeyfpe]

FPE22:

You have other NFPA 13 problems, namely the material of construction for the bracket, which may be aluminum:

9.1.1.6.2. Nonferrous components that have been proven by fire tests to be adequate for the hazard application, that are listed for this purpose, and that are in compliance with the other requirements of this section shall be acceptable.

As to this being acceptable, you need to talk to the structural engineer who determined what the seismic loads based on the building and soils. It is not possible for forum members to answer a site-specific structural engineering question.

 

[TravisMack]

If this is to be protected against earthquakes in accordance with 9.3, then that item is not in compliance with NFPA 13 criteria. They need to use a listed brace for seismic protection of fire protection systems.

Do some research on the seismic bracing components listed by the major manufacturers and you will find the information that you need.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

https://www.facebook.com/pages/MFP-Design-LLC/92218417692

 

[MGXFP]

If it touches the pipe it needs to be listed. If the intent is to prevent motion then perhaps a listed seismic brace is in order.

It looks like the intent is to make a snubber to prevent excess motion of the pipe.

Sometimes when fire pumps kick on during testing etc suspended sprinkler pipe will move/sway under flow conditions.

 

[FPE22]

stookeyfpe - Thank you for bringing this to my attention. Actually yes the bracket is made of Aluminum and this doesn't comply with NFPA 13 which requires it to be ferrous as this bracket is fabricated in the field, so needless to say it's not listed.

Travis/NewtonFP - Yes we might use seismic braces after consulting with the structural engineers. They seem to be the best option we have.