ASTM A520
ASTM A520 standard specification for supplementary requirements for seamless and electric resistance welded carbon steel tubular products for high temperature service conforming to iso recommendations for boiler construction .
If rimmed steel or other than killed steel is used in the manufacture of electric-resistancewelded tubes to the requirements of Specification A520 , the strip shall be rolled in single width and shall not be slit longitudinally except to trim the edges .
The yield strength values at the indicated elevated temperatures shall not be less than those given . The yield strength corresponding to a permanent offset of 0.2 % of the gage length of the specimen or to a total extension of 0.5 % of the gage length under load shall be determined .
For lots of 400 tubes or under , one tube for each 50tubes or 2 % of the total number of tubes , at the option of the manufacturer , shall be submitted to a tensile test , a flattening test , and a flaring or flanging test . For lots of more than 400tubes , one additional tube out of each 100 tubes or part thereof shall be tested .
The flaring and flanging tests apply only for tubes of outside diameter not greater than 6 in . ( 152.4 mm ) and a wall thickness not greater than 0.350 in . ( 8.89 mm ).
A lot is defined as a group of tubes of the same diameter and wall thickness from metal of the same specification and of the same manufacturer .