Fireline under building - Never a good idea but....

[SprinklerDesigner2]

NFPA #24 2013 Edition FIGURE A.10.6.3.1 Riser Entrance Location shows the maximum length of underground under a floor slab to be 10'-0" but this is the appendix not the standard.

I am looking at a project where the engineer is calling for an underground line to be installed under a building with a total of 50' under floor slab.

He has a post indicator on each side.

To say I don't like the idea is an understatement because if it ever busts loose guess whose fault it is that a two story medical building with patients .... well.. you get the picture.

Is there something somewhere else in the standards that prohibits underground from being installed under buildings? Seems I read something somewhere once but I don't remember where. Figure in the appendix shows 10'-0" Max and I have to think that came from somewhere.

Thank you.

 

[LCREP]

NFPA 13' 13 Ed

How about 2 below, I am sure that will go over well in a medical bld.

10.6.2 Where approved, pipe shall be permitted to be run
under buildings, and special precautions shall be taken, including the following:
(1) Arching the foundation walls over the pipe
(2) Running pipe in covered trenches
(3)Providing valves to isolate sections of pipe under buildings
[24:10.6.2]

 

[SprinklerDesigner2]

LCREP,

Thanks, I knew I saw that somewhere but I couldn't put my finger on it, time is running out and I panicked.

 

[cdafd]

Some reason for the fifty foot run??

Will it be totally buried or run exposed in a crawl space?

Is the riser going to be located at the fifty foot mark??


Is there an ahj, and if so are they going to buy off on this??

 

[SprinklerDesigner2]

I am getting to old to fight em anymore.

These drawings have an engineers signature and seal and I am going to do exactly as shown.

If something needs to be changed that is what change orders are made for, right?

 

[MatthewJWillis]

Wouldn't you think at a minimum you should ask for evidence of compliance with the trenching/etc?

If it does pop, the fact that you touched it will be enough to see you share the grief no?

If you had a piece of paper saying "I tried to tell them.." you may be safer me thinks..

R/
Matt

 

[TravisMack]

Art:

NFPA 13 direct from the standard:
10.6.3.1* The requirements of 10.6.2(2) and 10.6.2(3) shall not apply where fire service mains enter under the building no more than 10 ft (3 m) as measured from the outside edge of
the building to the center of the vertical pipe. [24:10.6.3.1]

So basically, if they want to run under the building, they have to meet 10.6.2 (2) and (3), unless they come in the building and run that section overhead. I don't see any wiggle room at all.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

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

 

[cdafd]

Is there building where the graphic scale is shown on the plans or is that open area??

Plus the line they are proposing looks like it is feeding a dead end fire hydrant??

 

[stookeyfpe]

Be advised these requirement became far more liberal under the 2016 edition of NFPA 13.

 

[jgailla]

From a civil perspective, you should case the line to at least 5 feet beyond the building foundation (probably more) and restrain all joints.
You don't want a pressurized line getting a leak underneath a structure.

 

[SprinklerDesigner2]

jgailla,

Years ago I seem to remember reading one of the largest losses ever sustained by IRI had to do with a fire line under a press pit building in Detroit that ruptured.

 

[chicopee]

What if the fire line is in a grated, cemented trench?

 

[cdafd]

chic

someone still has to figure out how to fix the break in the middle of the building!!!


Funny they are rerouting the gas line??? Why not run it under the building

 

[chicopee]

An open trench that is wide enough with the water pipe, with flange connections, high enough from the trench bottom and with a suitable drain, pipe repair should not be a problem. After all you are in the basement.

 

[cdafd]

Has to support the building!

With all that expense 200 more feet of pipe, and you around the exterior of the building.

If an ahj is involved, it is up to them to approve it.

 

[rconner]

With regard to the observation and question, "Funny they are rerouting the gas line??? Why not run it under the building", the answer to this may well be that many international and national codes prohibit this uncased, or require that the pipe be very specially encased in conduit (and in practice it may be realized with all the local requirements for same the latter may be easier said than suitably or dependably accomplished).
As many near premise underground gas lines have been installed in recent years as plastic (polyethylene) pipe, such types of pipe also bring some special concerns that are perhaps non-obvious to to at least laeity in the field. I noticed the state of Texas commission at

http://www.rrc.state.tx.us/media/8558/chap6-reapirsnewconstruction-natgas.pdf

e.g. states on pg VI-4 , "Plastic pipe is unsuitable for aboveground installation..." and, "Where the pipe is installed in a vault or other below-grade enclosure, it must be completely encased in gas-tight metal pipe with fittings that are protected from corrosion." Such statements and requirements are perhaps based on the realities that plastics are less robust from the standpoints of mechanical strength and puncture/fracture resistance than modern metal pipes (and exposure to some impacts/damage is hard to avoid in real world life cycles), they are weakened in at least the long-term by UV (where exposure is possible), and furthermore unlike metal pipes they over time also sort of effuse the gas outward into the environment through every square inch of the walls of the pipe itself. While chemical gas/hydrocarbon permeation behavior and mechanisms are non-obvious, and frankly unknown or unrealized by many of at least laity in the field, and the quantities of effused gas (at least if somehow effectively vented) are also quite small, over the long-term they can build up and all of us may be sort of reminded of this if we stick our nose e.g. in an enclosed shed or marine bilge containing polyethylene plastic gasoline tanks and/or polymeric transfer hoses etc.

 

[MatthewJWillis]

I believe the comment was give a little "tongue in cheek". Since our (Fire Protection) have special requirements as well.

R/
Matt