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fire protection pipe min thickness

fire protection pipe min thickness

fire protection pipe min thickness

(OP)
what is the reference for calculating the required minimum thickness for piping used in a fire protection system?

Also, would I still apply a corrosion allowance for carbon steel pipe?

thanks

RE: fire protection pipe min thickness

there are several NFPA standards that can be referenced depending upon application.  Please note the following NFPA standards:

NFPA 11    Standard for Low-, Medium-, and High-Expansion Foam  2002 Edition
 NFPA 11A    Standard for Medium- and High-Expansion Foam Systems  1999 Edition
 NFPA 12    Standard on Carbon Dioxide Extinguishing Systems  2000 Edition
 NFPA 12A    Standard on Halon 1301 Fire Extinguishing Systems  1997 Edition
 NFPA 13    Standard for the Installation of Sprinkler Systems  2002 Edition
 NFPA 13D    Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes  2002 Edition
 NFPA 13E    Recommended Practice for Fire Department Operations in Properties Protected by Sprinkler and Standpipe Systems  2000 Edition
 NFPA 13R    Standard for the Installation of Sprinkler Systems in Residential Occupancies up to and Including Four Stories in Height  2002 Edition
 NFPA 14    Standard for the Installation of Standpipe, Private Hydrant, and Hose Systems  2000 Edition
 NFPA 15    Standard for Water Spray Fixed Systems for Fire Protection  2001 Edition
 NFPA 16    Standard for the Installation of Foam-Water Sprinkler and Foam-Water Spray Systems  1999 Edition
 NFPA 17    Standard for Dry Chemical Extinguishing Systems  2002 Edition
 NFPA 17A    Standard for Wet Chemical Extinguishing Systems  2002 Edition
 NFPA 18    Standard on Wetting Agents  1995 Edition
 NFPA 20    Standard for the Installation of Stationary Pumps for Fire Protection  1999 Edition

Good Luck!
-pmover

RE: fire protection pipe min thickness

Hello pipe15,

Codes and Standards are voluntary (used at the discretion of the designer) UNTIL they are REQUIRED by the local jurisdiction - then they have the "force of law".  Various Codes and Standards are required by a jurisdiction when they refer to them in the local (municipal, city, county or state/province) building Code.  Regardless of what you read in discussion forums, you will have to look at the local building Code for the jurisdiction in which the piping system will be constructed to determine the piping design requirements.

I think you will find that in most USA jurisdictions the design of pressure piping systems (internal pressure of 15 psig or greater) of any type or use will refer to one of the ASME B31 Codes for Pressure Piping.  Once you know the requirement of the building Code you should look for the Code section that provides the rules for pressure design (e.g., if the Code requires the use of B31.3 or B31.9 look under "Pressure Design").  Read the section in its entirety so that you will understand the requirements for mill tolerance, corrosion allowance, etc.  In ASME B31.3 you would look at paragraph 304.

Regards, John.

RE: fire protection pipe min thickness

(OP)
I can appreciate what you are saying, but in the case of small bore threaded connection, B31.1 says the min wall should be S-80.  NFPA-13, 14, & 15 allow small bore threaded pipe using S-40 up to 300 psi.

RE: fire protection pipe min thickness

Hi pipe15,

"I can appreciate what you are saying, but in the case of small bore threaded connection, B31.1 says the min wall should be S-80.  NFPA-13, 14, & 15 allow small bore threaded pipe using S-40 up to 300 psi."

OK.  But first, B31.1 would only apply if your fire protection system were located in a power plant (the B31.1 requirement for the thicker wall piping would be to accommodate the loss of effective wall thickness due to threading - and B31.1 might also require "seal welds" over the threads).  It is very unlikely that your jurisdiction would require B31.1 if the system is not in a power plant.  If the system is not in a power plant, B31.3 (higher allowable stresses) and B31.9 would be more applicable.  NFPA-13, 14, & 15 are ALSO national standards that by themselves do not have the "force of law".  So, which Code to apply is really not your (or my) call to make.

Seems that the real issue here is what does your local jurisdiction require.  The local building Code most likely has a separate section that includes requirements for fire protection systems.  To get the correct answer, you are going to have to read the building code.  You might also consider (as an alternative to reading through the building code) calling your local jurisdiction, explain to them the apparent contradiction in the Codes and asking them for their requirement.  You could start by looking at the National Board's site to find the telephone number for your State/Province Chief Inspector at:

https://www.nationalboard.org/NationalBoard/Members/Default.aspx

Chief Inspectors are usually very approachable and your call would demonstrate your desire to "do the right thing" so the Chief will be glad to help you.

Regards, John.

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