NFPA-11 galvanized pipe - inside or outside?

[IFRs]

NFPA-11 states 4.7.2.1* Galvanized pipe shall be used and 4.7.3.5* Galvanized fittings shall be used. For a tank farm (not a marine system), is the intent to require the use pipe that is galvanized on the inside? Can the pipe be field welded and touched up on the outside only?

 

[cdafd]

from the 2010 edition

4.7.2 Foam System Piping.

4.7.2.1* Galvanized pipe shall be used.

looks like they mean outside only:::


A.4.7.2.1 Corrosive atmospheres could require other coatings.


PLUS::::

4.7.2.2 Pipe carrying foam concentrate shall not be galvanized.



4.7.2.3 Piping in constant contact with foam concentrates shall be constructed of material compatible with and not affected by the concentrate.



4.7.2.4 Piping in constant contact with foam concentrate shall not have a detrimental effect on the foam concentrate.

not a welder but::
just says welding shall

4.7 Piping.

. 4.7.4.3* Welding shall conform to the requirements of AWS D10.9. 4

 

[IFRs]

I agree, but then they go and give the friction factor for galvanized pipe, suggesting that they expect it to be galvanized inside. What do you think?

 

[cdafd]

Sorry that is as far as I go, not an engineer

Scott should give an answer sometime soon

 

[cdafd]

agree, but then they go and give the friction factor for galvanized pipe, suggesting that they expect it to be galvanized inside. What do you think?

do you have a section reference for above???

 

[IFRs]

4.7.2.5 For the purpose of computing friction loss in foam
solution piping, the following C-values shall be used for the
Hazen–Williams formula:
(1) Galvanized steel pipe — 120
(2) Other C-values for corrosion-resistant piping materials in
accordance with NFPA 13

 

[stevenal]

Since the pipe must be submerged in hot zinc, galvanizing just the outside would be challenging (expensive). I would assume they mean the commonly available stuff that is galvanized inside and out.