Stainless steel pipe 20mm nominal diameter with plain ends in a standard length of 6. 0 to 6. 3 m for Freight stock conforming to rdso psec. No 04- abr- 2002 with amendment no 06 & Material to ASTM- A 312 Schedule 40 S Gr. TP 304 ( ERW ). thickness of pipes to be governed by IS: 1239 ( Part I ) Heavy C- class.