Is Use of C900 for Fire Service Entry Acceptable?

2/16/2023

We have a building that is constructed. It has a very deep footing.

The contractor originally submitted an Ames In-Building Riser, but it's too deep for the in-building riser in the building's (essentially) existing condition.

They proposed using C900 to come under the footing, without a sleeve, going below the 12" footing and then stubbing up into the riser room without thrust blocks.

We have concerns about restraint and a change of direction underneath the foundation.

NFPA 13 applies and C900 is a permitted material, which is what the contractor has suggested makes it acceptable.

Is routing C900 under a building footing, changing direction, and then stubbing into the building acceptable?

16 Comments

James Phifer

2/16/2023 08:17:35 am

I don't think it's a good idea, but NFPA 13, 2022 ed A6.4.3.1.1 states: The individual piping standards should be followed for load and bury depth, accounting for the load and stresses imposed by the building foundation.

Seems like a lot of weight to put on the C900 pipe.

Jesse

2/16/2023 08:18:14 am

I have concerns as well. Primarily the lack of restraint and thrust blocking at the change of direction. How are they expecting the pipe to not separate?

Anthony

2/21/2023 01:10:36 pm

This, Nothing worse than having your underground blow out during testing especially under a footer that's supporting the building.

Glenn Berger

2/16/2023 08:18:25 am

Using C900 piping below a footing w/o a sleeve may or may not be permissible. First consult the applicable authorities if this is allowed in this jurisdiction.

Since this is an existing building, I would be more accepting of this condition, than if it was for a new building. Restraints and thrust blocks would still be required.

David Kendrick

2/16/2023 08:20:05 am

!. Adequate clearance between C900 and footing.
2. If change in direction means the spigot rising through floor then change in direction is acceptable. There are industry practices as well as products approved for the purpose of restraining the joints.

If this is a product substititution you are probably justified to propose new practices to protect the piping. If it were my choice bringing a ductile pipe through the floor and floor sleeve is a good start.

We have in the past used Ductile Iron Pipe both under the footing and absolutely for the spigot through the floor.

James Evans

2/16/2023 08:21:39 am

You need to transition @ 5'-0" out from the building to Cement Lined Ductile Iron with mechanical Joint Fittings. This has been done for years and is still acceptable. I know the fashion is the new in building riser but go back to the old trusted way. It still works well.

2/16/2023 08:36:32 am

James,

Could you please elaborate on the specific conditions where the jointed, cement-lined DIP riser is preferable to the Ames-type in-building riser? Thanks!

James Evans

2/16/2023 10:16:34 am

I did not say it was "Preferable", I do love the in building riser, however it does not meet every need. I will say that cement lined ductile iron is preferable over C900 going under a footing and slab.

It is never a good idea to run plastic pipe under a footing. Even in residential occupancies they prefer you use copper pipe when entering the residence.

Plastic under a footing is just calling for problems in the future.

J.James

2/16/2023 09:04:20 am

I agree with James. The riser / stub-in / lead-in should be ductile. If you choose to use C-900, it should be sleeved. I have seen a few instances where a fork truck has hit and snapped the C-900 at its base.

2/16/2023 08:43:46 am

Have you considered using an In-Building Riser? All one piece stainless steel. AMES makes them from 4-inch up to 12-inch. and it will connect to the C900. You can order it in a length that will put the connection past the footing bearing zone.

James B

2/16/2023 08:48:29 am

We have had Ames make custom lengths from the factory in the past. Check into that option as well.

Ryan Hinson

2/16/2023 10:40:58 am

Every joint between pipe and fitting must be restrained against separation per NFPA 24 (2022) Section 10.6 which may include thrust blocking (10.6.1), or more likely; restrained joint systems (10.6.2), or other connection methods (10.6.3).

Of additional consideration are the limitations imposed on private fire service mains beneath buildings per NFPA 24 Section 10.4.3 regarding distance inside the building footprint, pipe joints not being under footings, and clearances between the pipe and footing.

The IBR is an ideal option for this scenario and has custom lengths for both lateral and vertical legs and already includes restraint attachments for both up- and downstream piping. See also NFPA 24 Figure A.10.4.3 which shows an acceptable riser entrance detail inclusive of no joints underneath the footing, minimum distance below the bottom of the footing, and not exceeding the allowable 10 ft distance into the building.

If using PVC or DI, the restraint requirement at the 90 el, and access to provide it, remains the same. Since this elbow is already welded on the IBR, no access is needed to it, just the room to get it installed.

Though allowed per NFPA 13 Section 6.1.4 and NFPA 24 Section 10.1.4, I would not recommend stubbing plastic pipe of any type above the floor inside the building. I have seen melted risers in riser rooms. This allowance also directly contradicts plastic pipe mfgrs' listing indicating it is only for UG FW use.

Unless this is a seismically-protected system, no sleeve through the floor slab is required per NFPA nor do you want your riser moving around inside the building. I would use the IBR and poor the floor slab patch right up to the edge of the IBR.

Mark Harris

2/16/2023 12:35:26 pm

James covered this well. Transition from PVC to ductile iron five foot outside building and several have mentioned restraint which you also have to be concerned with the Ames stainless steel riser installs.

Water material supplier will probably not have a 11 or 12 foot long flange by plain end so most likely will be a piece of ductile pipe with a MJ 90 at the base and a uniflange to transition to steel above floor.

If in a seismic area need to look at proper core or sleeve sizes for both the foundation and floor.

Casey Milhorn

2/16/2023 03:00:20 pm

I agree with changing to DI pipe at 5'-0" out. This may not be code driven, but it's definitely a good idea. Also, I'm not sure how cost compares in other parts of the country, but where I am, there is very little cost difference now between C900 and DI pipe. It used to be 50% to 70% in savings to go C900.

Chris

2/17/2023 08:54:15 am

Have them use ductile iron from the interior flange installed at a minimum height of 1'-0" AFF down under the footing and then a minimum of 5'0" from the outside face of the footing. IIRC code says piping within 5' of the building exterior shall be of a type resistant to mechanical damage, or something to that effect. And But Ames does make the IBR with different lengths of legs if you do want to stick with Ames.

James Art. FPE

2/22/2023 11:56:06 am

J.James, and R Hinson:
You both mentioned what sounded like EXPOSED* PVC (intended as underground) above the ground.
Fork lift hit the pipe? Melted pipes?

*I do not believe the PVC is listed to be used exposed like that,
which is why such pipe should be metallic!

Perhaps someone can find the code references.

Yes, there is listed CPVC, but it is small, and for very limited applications, not large commercial risers! Even that is better if protected behind or inside walls or ceilings!

Is Use of C900 for Fire Service Entry Acceptable?

Leave a Reply.

ALL-ACCESS

SUBSCRIBE

COMMUNITY

YOUR POST

PE EXAM

FILTERS

ARCHIVES

PE PREP SERIES