ASTM A270

ASTM A270 / A270M – Standard Specification for Seamless and Welded Austenitic and Ferritic/Austenitic Stainless Steel Sanitary Tubing, this specification covers grades of seamless, welded, and heavily cold worked welded austenitic and ferritic/austenitic stainless steel sanitary tubing intended for use in the dairy and food industry, commonly, having polishing surface finishes.

ASTM A270 standard equivalent specification is ASME SA270, download free.

Stainless steel grades have TP304 (S30400), TP304L (S30403), S31254, TP316 (S31600), TP316L (S31603), N08926, N08367, S31803, 2205 (S32205), S32750, S32003.

The most used grades and chemical composition (max, %)

Grade C Si Mn Cr Ni Mo S P
TP304 0,08 1,0 2 18 – 20 8 – 11 0,03 0,045
TP304L 0,035 1,0 2 18 – 20 8 – 12 0,03 0,045
TP316 0,08 1,0 2 16 – 18 10 – 14 2 – 3 0,03 0,045
TP316L 0,035 1,0 2 16 – 18 10 – 15 2 – 3 0,03 0,045

ASYM A270 Tubing Dimensions

ASTM A270 covers tubing sizes up to and including 12 inch (300 mm) in outside diameter, custom OD have 25.4, 38.1, 50.8, 60.3, 76.2, 89, 159 mm, wall thickness ranges from 0.8 to 3.48 mm.

Tighter outside diameter and wall tolerances conform to ASTM A270, we can offer tighter tolerance than standard specified to provide high quality tubes.

ASTM A270 tolerance in outside diameter, wall thickness and length

OD Tolerance WT Tolerance Length Tolerance
≤ 25.4mm ± 0.13mm ± 12.5% OD ≤ 101.6mm, +3.2mm-0mm
OD > 101.6mm, +4.8mm-0mm
> 25.4mm, ≤ 50.8mm ± 0.20mm
> 50.8mm, ≤ 76.2mm ± 0.25mm
> 76.2mm, ≤ 101.6mm ± 0.38mm
> 101.6mm, < 139.7mm ± 0.38mm
> 139.7mm, ≤ 203.2mm ± 0.76mm
> 203.2mm, < 304.8mm ± 1.27mm

Manufacture

Seamless tubes shall be manufactured by a process that does not involve welding at any stage.

Welded tubes shall be produced using an automated welding process with no addition of filler metal during the welding process, we use TIG welding method to form sanitary tubing, for ASTM A270 sanitary tubing, welded tubing is required most compared to seamless tubing.

All tubes shall be furnished in the heat-treated condition, minimum solution temperature is 1040° C, and rapidly cooling.

Surface finish:

The following surface finishes may be specified: mill finish, mechanically polished surface finish, finish No. 80, finish No. 120, finish No. 180, finish No. 240, electro polished finish, and maximum roughness average surface finish.

  • Mill Finish — A finish without additional polishing or operations intended to smooth the surface.
  • Finish No. 80 — A ground finish produced by polishing a tube with an abrasive media impregnated with No. 80 grit.
  • Finish No. 120 — A ground finish produced by polishing a tube with an abrasive media impregnated with No.120 grit.
  • Finish No. 180
  • Finish No. 240
  • Electropolished Finish—A bright reflective finish produced by electropolishing. The manufacturer may use other polishing operations prior to electro polishing.
  • Maximum Roughness Average (Ra) Surface Finish—The customer may specify a maximum Ra on the inside surface, outside surface, or both. The measurement of surface roughness shall be in accordance with ASME B46.1.

Testing and Inspection

  • Mechanical Tests Required – Reverse Flattening Test
  • For welded tubes, one reverse flattening test shall be made on a specimen from each 1500 ft (457 m) of finished tubing.
  • Hydrostatic or Nondestructive Electric Test (Eddy current test commonly.)