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Wall thickness for joining by threaded connections

Question asked by hubma on Jan 17, 2016

Hello, I'm looking for a help in following question:


If for example steel pipe DN25 has wall thickness 3,20 mm (which is according to tolerances 12,5%  allowed by ASTM A 53, but is less than 3,4 mm allowed by Schedule 40 ) is it proper steel pipe DN25 for joining by threaded connections?


According to point 6.3.3 NFPA 13 (2013 Edition)  for steel pipes DN25, DN32  joined by threaded fittings the minimum wall thickness shall be in accordance with Schedule 40 - minimum wall thickness for DN25 is 3,4 mm and for DN32 is 3,6 mm.

According to point NFPA 13 (2013 Edition) pipe shall meet or exceed one of the standards in Table or be in accordance with

Table - one of the Standard is ASTM A 53.

According to ASTM A 53 the minimum wall thickness at any point shall be not more than 12,5% under the specified wall thickness.


Thank you for help in advance