Question:
For CS and SS steel pipes we have ANSI 36.10 and 36.19. Then which standard control the tubes ? Can some one please explain ? And why does the ANSI 36.10 contains colomn headings only on some colomns, having the suffix S, as 5S, 10S, 40S, when there is already a separate standard available for ss pipes as 36.19 ??
Answer:
Wall thicknesses of carbon steel and stainless steel pipe are most commonly (but not exclusively; see later comments) described by a "Schedule Number". The wall thickness for a schedule varies
according to the pipe size and is given in tables in the relevant specifications. These schedules are derived from two different specifications, for carbon steels and for stainless steels, so although they share much there are some important differences. "S" schedules are specific to stainless steels and schedules without the "S" are intended for carbon steel.
WHERE CARBON STEEL SCHEDULES EQUAL STAINLESS SCHEDULES:
Up to DN 300 (NPS 12) all Sch 10 and Sch 10S wall thicknesses are the same.
Up to DN 250 (NPS 10) all Sch 40, Std Wt and Sch 40S wall thicknesses are the same.
Up to DN 200 (NPS 8) all Sch 80, XS and Sch 80S wall thicknesses are the same
THE DIFFERENCES BETWEEN CARBON STEEL AND STAINLESS PIPE:
In larger nominal sizes Std Wt and XS schedules remain constant, but schedules 10, 40 and 80
continue to increase with larger pipe sizes. (The ASME committee had hoped that these older Std Wt,XS and XXS wall thicknesses would gradually disappear, when the standard was revised – in 1939!)
The stainless steel "S" schedules are aligned with the Std Wt and XS series …
Sch 40S matches Std Wt and Sch 80S matches XS, throughout the full size range.
Sch 10S deviates from Sch 10 above DN 300 – there is no carbon steel equivalent to 10S.
In carbon steels there is a very rich range of schedules, including a thin wall Sch 5 (identical to
stainless steel Sch 5S). Only the common pipe sizes and schedules are held in stock.
STAINLESS STEEL PIPE WITH SCH 80?
Occasionally specifiers require larger size (over DN 200) stainless steel pipe with a heavier wall than
Sch 80S. This can be covered by calling for Sch 80. This is an uncommon but legitimate deviation and the dimensions are covered by ASME B36.10M. Stainless pipe to Sch 80 is a "special" that is not commonly stocked. There will be a price premium.
ISO 4200:1991(E)
Plain End Steel Tubes, Welded and Seamless - General tables of dimensions and masses per unit length.
ISO 1127:1992(E) Stainless Steel Tubes - Dimensions, tolerances and conventional masses per
unit length (presented with ISO 4200 data)
ISO 1129:1980(E)
Steel Tubes for Boilers, Super heaters and Heat Exchangers - Dimensions, tolerances and conventional masses per unit length (presented with ISO 4200 data)
ISO 5252 Steel Tubes - Tolerance systems.
Just go through the link given in the source.
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