What is a Pipe?
The term pipe covers a specific range of sizes laid down by ANSI specifications. Any sizes not covered by these specifications are tube.
Stainless Steel Pipe dimensions determined by ASME B36.19 covering the outside diameter and the Schedule wall thickness. Note that stainless wall thicknesses to ANSI B36.19 all have an ‘S’ suffix. Sizes without an ‘S’ suffix are to ANSI B36.10 which is intended for carbon steel pipes.
Pipe Specifications - Seamless/Welded
ASTM A312: Seamless and straight-seam welded austenitic pipe intended for high temperature and general corrosive service. Filler metal not permitted during welding.
ASTM A358: Electric fusion welded austenitic pipe for corrosive and/or high temperature service. Typically only pipe up to 8 inch is produced to this specification. Addition of filler metal is permitted during welding.
ASTM A790: Seamless and straight-seam welded ferritic/austenitic (duplex) pipe intended for general corrosive service, with a particular emphasis on resistance to stress corrosion cracking.
ASTM A409: Straight-seam or spiral-seam electric fusion welded large diameter austenitic light-wall pipe in sizes 14” to 30” with walls Sch5S and Sch 10S for corrosive and/or high temperature service.
ASTM A376: Seamless austenitic pipe for high temperature applications.
ASTM A813: Single-seam, single- or double- welded austenitic pipe for high temperature and general corrosive applications.
ASTM A814: Cold-worked welded austenitic pipe for high temperature and general corrosive service.
Note: Welded pipes manufactured to ASTM A312, A790 and A813 must be produced by an automatic process with NO addition of filler metal during the welding operation.
Markings on the Pipe
The full identification of the pipe should be continuously marked down its whole length, including:
~ Nominal Pipe Size (Nominal Bore)
~ Schedule (Wall Thickness)
~ Specification
~ Grade
~ Method of Manufacture (Seamless or Welded)
~ Heat Number
~ Manufacturer’s Name or Symbol
Welded Pipe Specifications
Usually it will be to ASTM A312. If it is to ASTM A358 then there are various Classes available as shown below. The Class Number dictates how the pipe is welded and what non-destructive tests:
~ Class 1: Pipe shall be double welded by processes employing filler metal in all passes and shall be completely radiographed.
~ Class 2: Pipe shall be double welded by processes employing filler metal in all passes. No radiography is required.
~ Class 3: Pipe shall be welded in one pass by processes employing filler metal and shall be completely radiographed
~ Class 4: Same as Class 3 except that the welding process exposed to the inside pipe surface may be made without the addition of filler metal.
~ Class 5: Pipe shall be double welded by processes employing filler metal in all passes and shall be spot radiographed.
This Data is indicative only and must not be seen as a substitute for the full specification from which it is drawn. In particular, the mechanical property requirements vary widely with temper, product and product dimensions. The information is based on our present knowledge and is given in good faith. However, no liability will be accepted by the Company is respect of any action taken by any third party in reliance thereon.
Any advice given by the Company to any third party is given for that party’s assistance only and without liability on the part of the Company. Any contract between the Company and a customer will be subject to the Company’s Conditions of Sale. The extent of the Company’s liabilities to any customer is clearly set out in those Conditions; a copy of which is available on request.