NFPA 11 - Use of materials other than galvanized outside hazard area 1

[henryj3]

Forum,

I have been trying to interpret the revised 2010 NFPA 11 Section 4.7 - Piping for a while. My conversations with various AHJs have been conflicting to say the least.

Question:
Does piping outside of the hazard area need to be galvanized?

I can justify other materials/finishes are suitable based on the following:

4.7.1.3 - Pipe outside of the hazard area shall conform to the materials allowed by NFPA 24.
4.7.2.5(2) - Other C-values for corrosion resistant piping materials IAW NFPA 13.

So I believe it still provides an option to use other than galvanized pipe, but it is not straightforward. Looking at the previous issue and the report on proposals excerpts, it appears the Standard's committee fought back hard to make it a galvanized only standard. So why leave any room for interpretation/exceptions? If HDPE or cement lined pipe is acceptable outside the hazard area, why doesn't 4.7.2.5(2) reference NFPA 24 since HDPE and cement lined pipe are not included in NFPA 13?

For background - Our applications are typically flammable liquids storage tank protection, so we end up with both buried and above ground foam header piping >10" diameter, downstream of the proportioner, extending thousands of feet around tank farms. HDPE and painted, cement Lined CS are ideal materials for use outside of the hazard area for buried and above ground headers, respectively. To use anything else is hard to justify.

Thanks in advance for your replies.
JP

 

[pipesnpumps]

I say outside the hazard area it does not have to be galvanized.
I am not sure how an AHJ could reasonably disagree with that interpretation. 4.7.1.3 reads as clear as day..

The reference back to NFPA 13 is probably just to make it easier on the NFPA 11 committee.. Table 22.4.4.7 in NFPA 13 has alot more C values than NFPA 11-2005 had, so they are deferring to NFPA 13 to provide more thorough guidance..

For example consider than NFPA 11-2005 did NOT list any C values for plastic piping (HDPE). So how does one meet the standard? Assumes something. Referring back to NFPA 13 not makes that value known (C-150). Keep in mind that NFPA 24 does not list any c-values either.

The logic that because NFPA 11 refers to NFPA 13 for C values this somehow implies that you can only use piping materials that are approved for NFPA 13 systems is bizarre and illogical thinking.. It only refers to the C-value, and nothing more.

Read it for what it is. Materials per NFPA 24 when outside the hazard area. Look up C-values in NFPA 13.. Thats it.

 

[pipesnpumps]

should have read as: "Referring back to NFPA 13 NOW makes that value..."

One more thought, since I had to re-post.. You did not discuss 4.7.1.4 which states "Where exposed to corrosive influences, the piping shall be corrosion resistant or protected against corrosion."

Ok now what does that mean. Perhaps that any DI pipe exposed to the elements should be painted. Any PVC piping (material allowed by NFPA 24) would need to be painted for UV exposure.. If there are any special chemicals or other exposure that could harm the piping you'd need to address those as well. BTW this applies both inside and outside the hazard area.

 

[henryj3]

Thanks for the feedback PnP.

I see what you are saying wr2 4.7.2.5(2). I've never really been exposed to NFPA 13, and never saw Table 22.4.4.7 until now. Your input supports my interpretation that galvanized pipe isn't required outside of the hazard area.

4.7.1.4 is exactly the reason we are trying to stray from galvanized pipe. Buried plastic and lined CS aboveground. Easy Day!