Iron pipe sizes

[Bruce VoelkerdingParticipant @brucevoelkerding91659]

[Bruce VoelkerdingParticipant @brucevoelkerding91659]

I am an engineer in the States. While sketching a repair part for a Japanese machine which is endowed with BSPT pipe threads, a question arose wih regards to pipe sizes (NOT the difference between NPT and BSPT sizes). What is the outside diameter of iron pipe used in England ? In the USA, ordinary, non-galvanized, black iron pipe is as follows:

1/8" = .405" OD

1/4" = .540" OD

3/8" = .675" OD

1/2" = .840" OD

3/4" = 1.050" OD

1" = 1.315" OD

I found some references on the web, but the values were different than the OD's shown on some of the Japanese drawings. One reference, did state there was an OD difference, but it did not affect threaded joints. Interestingly, I have come across pipe from Chinese sources which at times have been .015" smaller than the values above.

thanks in advance,

Bruce

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