Use Hot-Dipped Steel Pipe for Foam Concentrate?

7/1/2021

NFPA 11 identifies several materials for foam concentrate pipe & valves, including brass, bronze, stainless steel (304 or 316), or other material in accordance with foam concentrate manufacturer's certification of compatibility with the foam concentrate as approved by the AHJ. [NFPA 11-2016 4.7.1.1]

Can we use hot-dipped carbon steel pipe to meet this requirement after the foam pump to the foam chamber of the cone roof tanks?

The distance is more than a mile long (1.2 miles, 2 km). Thanks in advance.

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7 Comments

Mike

7/1/2021 08:15:59 am

Reference NFPA 11- '16 -para 4.7

John Galante

7/1/2021 08:28:57 am

"Foam systems 101"--never use galvanized anything on foam concentrate or foam water system. It literally dissolves the galvanize and creates sledge , over time, which will clog the sprinklers. Viking literature for their galvanized trim makes you aware with their valves.
Also---never use red rubber gaskets, as the foam cincentrate/ water systems degrades, makes them brittle, and they blow out under pressure.
( trained with National Foam in the 60 s--6 months)

Dan Wilder

7/1/2021 08:55:55 am

Both Carbon Steel & Galvanized (regardless of method of application) piping are not allowed per 4.7.1.2 & 4.7.1.3

Brad K

7/1/2021 10:37:02 am

Foam concentrate is the pure concentrate between foam storage container and proportioning device. Once mixed with water, the mixture is then routed to the discharge device and Galvanized pipe should be acceptable. Always check with manufacturer requirements first. Ensure pipe drains appropriately.

Mike

7/1/2021 11:58:34 am

Per NFPA 11, galvanized steel is permitted for SOLUTION

4.7.2* Foam Solution Pipe Materials.
4.7.2.1* Foam solution pipe shall be made of one of the fol-lowing materials:

(1) Galvanized steel

Always check with manufacture if in doubt.

I have seen the galvanized coating create corrosion and blockage to the proportioner and check valve and it did not flow. Blue nasty stuff. Had to take it apart and replaced with red brass nipple.

Franck

7/2/2021 09:02:50 am

It is always interesting to have a look on the Annex section of NFPA standards.

A.4.7.1
This section addresses the pipe section that contains foam concentrate from the foam concentrate storage tank to the side inlet of the proportioner or eductor.

A.4.7.2
This section address the pipe section(s) that contains foam solution located from the flow-through outlet of the foam concentrate proportioner or eductor to the discharge device.

So, if you are between the proportioner/educator to the discharge device, you can apply chapter 4.7.2 (as well as 4.7.3.2 for the fittings - roughly the same material):

4.7.2.1 *
Foam solution pipe shall be made of one of the following materials:

(1) Galvanized steel
(2) Stainless steel
(3) Copper nickel 90/10
(4) Internal/external corrosion-resistant pipe in accordance with the foam manufacturer’s specification for compatibility and acceptable to the authority having jurisdiction
(5) Unprotected carbon steel pipe when filled with foam solution or water and the discharge devices are closed to the atmosphere

On the other hand, all above mentioned warning regarding corrosion and possible issue inside your piping system are correct.
The issue is more important with foam concentrate (thus the specifications of 4.7.1), but is still present with the foam solution.

Again, the annex section indicates:
A.4.7.2.1
Most deluge type foam water systems are subject to harsh environmental conditions, which can subject the foam solution feed line piping to internal to external corrosion. Types of systems that fall into this category include open head sprinklers, foam spray nozzles, monitors, foam chambers, fixed foam makers, fixed medium expansion foam makers, and high expansion foam systems. These systems are typically utilized for protection of fuel storage tanks, diked fuel containment areas, LNG facilities, truck and rail car loading racks, aircraft hangars, warehouses, marine docs, interior fuel storage tanks, refineries and manufacturing/processing areas

The foam solution piping on these systems is exposed to thermal changes, air movement, and other environmental conditions that can cause condensation, and the resulting corrosion can lead to the formation of debris and pipe scale. This material can inhibit proper function of the foam system discharge devices due to blockage. To alleviate the problem of foam systems with piping that is normally open to the surrounding atmosphere, these types of systems are to be constructed using pipe fitting materials identified in 4.7.2.1 and 4.7.3.2.1. Corrosive atmospheres could require other coatings.

M King

7/5/2021 05:07:46 pm

Concentrate - no.

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Use Hot-Dipped Steel Pipe for Foam Concentrate?

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