Code Basis for Replacement of 3/4" Branch Pipe?

4/25/2022

We have a project in an old building (historic city) that has 3/4-inch branch pipe in their sprinkler system. We've recommended, based on good practice, to change these out for minimum 1-inch due to the potential of obstructions, and that NFPA 13 has not recognized 3/4-inch branch pipe for over 50 years now.

The client is pushing back asking for a reference stating that 3/4-inch lines need to be replaced. I cannot find anything in NFPA standards which would "require" it.

Do you have any helpful references on this that would help educate the client here?

Thanks in advance.

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13 Comments

Pete H

4/25/2022 06:54:29 am

Nothing too concrete off the top of my head. You could claim that there's no listed steel fire sprinkler pipe currently less than 1" in diameter, and pursuant to NFPA 13 Chapter 6 (2016 edition and prior) the pipe has to be listed for fire protection, but I haven't double checked that there isn't any 3/4" pipe that's listed for fire protection, so maybe they could catch you with your pants down there.

You could also claim that if this is a hydraulically designed retrofit on a previously pipe schedule system, the current calculations and current water does not work for 3/4" branch piping, but I don't see your calcs and have no way to verify if that's true.

You could claim that you're trying to install flexheads for obstructions and adding the friction loss of the flexhead is why you need the 1" pipe sizing for your calculations.

You could claim if it is not a hydraulically designed retrofit that you're following current NFPA 13 rules regarding pipe schedules systems (It's around Chapter 23.7 in NFPA 13 2016, but you might have to look for the exact section) and the chart showing pipe sizing and heads that can be fed doesn't include 3/4" showing 3/4" is not an acceptable pipe size on current pipe schedule retrofits.

Hopefully someone else provides you with something more concrete.

Alex

4/25/2022 07:01:53 am

Hi,

I don’t believe there is a code section that states it needs to be replaced. Once touched, it needs to be brought up to 1” minimum but if you aren’t modifying it, then it can stay. Even if you are just replacing heads, I would replace the entire line. You touch it, you own it.

If you aren’t modifying it, I would still call for the piping to be internally inspected per NFPA 25 Chapter 14. Since the system is over 50 years, you are running an increased risk of build up over time. If foreign organic or inorganic material is found, I would replace the piping with a larger size contingent on hydraulic calculations.

Lastly, if the sprinklers are still original, they must either be replaced or a representative sample from the area must be tested (NFPA 25 5.3.1.1.1). This would in turn trigger replacing the ¾” lines.

Hope this helps!
Alex

Jesse link

4/25/2022 08:08:41 am

I'm with Alex here. I'm guessing this is an old pipe schedule system. If you're not modifying the lines, you could make the case for the 3/4" pipe to remain. But, if you're modifying it, it needs to be changed.

The case to replace it is strong. You may need to hydraulically calculate it to ensure any changes in the water supply don't render it inadequate.

Finally, depending upon who there property insurer is, the underwriter and Loss Control engineer may not allow 3/4" branch lines at all. I know of at least 3 insurers that don't allow it.

Matt C

4/25/2022 08:20:02 am

If you're going to hydraulically calculate the system at all, you can use 23.4.1.2. (in the 2013 ed.) which states ferrous piping shall be no less than 1".

Anthony C. Brown

4/25/2022 08:25:08 am

check with the AHJ. Some have code that will allow the last section of an existing system to remain 3/4" with the balance being replaced. Some AHJ will defer to their State Building Code on percentage of work being done for system replacement, i.e. If 50% (or some other benchmark amount) of a system is being replaced, then the entire system must be brought up to current code. Just be careful because I have seen several Municipalities use the base amount of the actual cost of construction, not the current cost of construction.

If all else fails then as has been suggested, use the 50 Year inspection and check the 3/4" pipe for sludge blockage. I bet you'll find it...

Craig Montoya

4/25/2022 08:53:36 am

I would have a conversation about the risks of doing a hydrostatic test at 200 PSI on the existing branch lines, and if that failed I would talk to the AHJ privately and tell them your concerns.

If this will mainly be a new system I think it is completely acceptable for an AHJ to use section of 1.4 on this project and make the owner replace these.

Joe Chadwick

4/25/2022 08:57:03 am

If this is part of a larger renovation, and the work is regulated by the Existing Building Code (IEBC), sprinklers may be required to comply with current code.
The Owner’s insurance carrier might have something to say.

David Kendrick

4/25/2022 09:38:57 am

Ask for the system internal inspection documentation. The smaller size pipe works until its filled with rust, corrosion or other debris.
Upon finding no documentation recommend a representative sample internal inspection.
Truly you touch it you own a certain responsibility.
The sprinkler business has a mantra taken from the real estate industry.

Documentation, documentation, documentation.

Personal opinion.

Karsten Smith link

4/25/2022 09:40:36 am

The first question I have is what is your scope of work for this project? Are you doing a TI, an addition, etc?

When submitting this to the AHJ will they require that you upgrade the pipe? If so, have the conversation with the AHJ before hand, discuss the project and they may provide you with local amendments/requirements that state you need to bring the
"affected area" or "entire system" up to current code.

Hope this helps.

John

4/25/2022 09:55:10 am

It appears that at the time of the original installation, three-quarter inch pipe was acceptable. Even though the current codes do not allow for this, the system in essence is grandfathered in. The owner isn’t obligated to upgrade the pipe sizes unless there is a serious physical reason to do so.

Please be mindful that unless a PE makes this type of recommendation, a fire protection contractor, cannot act in an engineering capacity. This may expose you to legal issues in the future

Dan Wilder

4/25/2022 11:08:50 am

Need some more info as to your scope and your scope language. If your scope includes changing the 3/4" lines to 1" due to hydraulic needs, then anything within your scope would need to be changed out (based on hydraulics proving the other pipe sizes all work). It would then fall onto a letter of recommendation that the areas outside your scope be changed (again, with a proof hydraulic calculation showing the pipe sizing all works to the end of the system),

If your scope includes changing sprinklers (with the same K-Factor in the case of a change out) but do not include a hazard change (see 29.4 below) you should be OK but not required to change pipe sizing.

When was the last internal inspection performed on the system? Since it's an old system, it probably looks like the day it was installed but it's a possible option. The other push may be that the AHJ has written in something requiring the change out for pipe schedule systems (I've seen this in older AHJ's to weed out the older systems).

NFPA 13-19'
19.3.2.3 - Pipe schedule is allowed based on the 4 criteria
27.5 - Allows Pipe Schedule systems if the original system was based on that design criteria
29.4.1 - Allows pipe schedules systems to be revamped.

Robert Hughes

4/25/2022 12:16:31 pm

Have the owner sign something stating they are dis-regarding your company's recommended standards and industry practice.

Eric Rieve

4/27/2022 12:12:42 pm

If the system was designed per pipe schedule, does the sprinkler riser have a backflow preventer that was retrofitted into the original riser arrangement? If so, how old is the backflow, and is there a hydraulic plate to show that the system was recalculated when it was installed?

We recently came across a similar situation where a backflow had been installed without a calc being performed, and this gave us an easy way to state that the tenant space needed to be recalculated which then found the 3/4" pipe to be lacking.

Code Basis for Replacement of 3/4" Branch Pipe?

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