ASTM A312 Stainless steel Pipe

ASTM A312 Stainless steel Pipe include Seamless and Welded Austenitic Stainless Steel Pipes. ASTM A312 Standard specification covers seamless, straight-seam welded, and heavily cold worked welded austenitic stainless steel pipe intended for high-temperature and general corrosive service.

ASTM A312 Stainless steel Pipe Specification

Outer Diameter :	1/8" NPS to 30" NPS
Thickness :	0.6 mm to 12.7 mm
Schedules :	SCH. 5, 10, 20, 30, 40, 60, 80, 100, 120, 140, 160, XXS.
Length :	Single Random, Double Random & Cut Length
End :	Plain End, Beveled End
Pipe Type	Seamless / ERW/ EFW / Welded / Fabricated Pipe

ASTM A312 Stainless steel Pipe Grades: TP304,TP304L, TP304H, TP316,TP316L,316Ti, TP316H, TP317, TP317L, TP321, TP321H, TP310S, Tp347, S31254, 254SMO, N08904, 904L, N08367, N08926 etc.


ASTM A312 Stainless steel Pipe Manufacture:

The ASTM A312 Pipe shall be manufactured either hot finished or cold finished.

The Seamless (SMLS) Pipe shall be made by a process that does not involve welding at any stage of production.

The Welded Pipe shall be made using an automatic welding process with no addition of filler metal during the welding process.

The Heavily cold-worked (HCW) Pipe shall be made by applying cold working of not less than 35 % reduction in thickness of both wall and weld to a welded pipe prior to the final anneal. No filler shall be used in making the weld. Prior to cold working, the weld shall be 100 % radiographically inspected in accordance with the requirements of ASME Boiler and Pressure Vessel Code.

The more details about the Material grades Chemical Requirements, Annealing Requirements, Tensile Requirements etc. please check the Standard ASTM A312 pdf.

The Dimensions of ASTM A312 Welded and Seamless Stainless Steel Pipe

ASTM A312 Stainless Steel Pipes OD Tolerance

Standard	OD（mm）
	OD（mm）	Tolerance
ASTM A312	10.29~48.26	+0.4/-0.8
	48.26~114.30	+0.8/-0.8
	114.30~219.08	+1.6/-0.8
	219.08~457.20	+2.4/-0.8

Heat treatment and surface treatment

All pipes must undergo a solution heat treatment: quenching in water after holding at 1040-1100°C to restore the corrosion resistance after cold working. For special grades such as 321/347, an additional stabilisation treatment (holding at 900°C) is required to fix the free carbon by means of titanium/niobium carbides. Surface treatment adopts a three-step method: electrolytic pickling to remove oxide skin → high-pressure water needle flow to remove slag → electrolytic polishing to form a nano-scale passivation film, surface roughness Ra ≤ 0.8μm
 

ASTM A312 standard upgrade:

1, testing technology innovation: the introduction of phased array ultrasonic testing (PAUT) instead of the traditional ray flaw detection, in the ethylene cracking plant pipeline inspection, defect detection rate The defect detection rate was increased by more than 40%. At the same time, the requirements of weld loss test are strengthened to ensure that the corrosion resistance of the welded area is consistent with that of the base material.
 

Tolerance control optimisation: differentiated management is implemented for pipelines with different thickness-to-diameter ratios (t/D). For example, when the t/D ratio is >5% (e.g. Sch80S thick-walled pipe), the wall thickness tolerance is tightened to +15%/-12.5%, which significantly improves the safety of high-pressure pipelines.
 

3, environmentally friendly process-oriented: the new version of the standard encourages the use of bright annealing technology to replace the traditional pickling process, reducing acid consumption by 30%, and the surface passivation effect is more Uniformity. At the same time clearly allow the use of digital radiography (DR) technology to reduce the darkroom treatment of chemical pollution.
 

Future Development of Pipelines

HT PIPE is committed to make a weak contribution to global environmental protection and sustainable development by adopting the latest cutting-edge technology in pipeline environmental protection and innovation:
 

Short flow process: Scrap - Electric Arc Furnace - Refining - Continuous Casting - Hot Rolling - Pipe making integrated plant, 40% carbon reduction compared to traditional processes
 

Acid-free surface treatment: laser cleaning + electrolytic polishing instead of acid washing, to achieve zero wastewater discharge
 

In the oilfield projects we serve, we creatively combine A312 TP316L steel pipe with API 5L X65 carbon steel pipe through metallurgy to make bimetallic composite pipe, with corrosion-resistant inner wall and pressure-bearing outer wall, which reduces the cost by 30%.
 

In addition, in order to cope with the energy transition, China has adopted stainless steel and carbon steel composite, nickel alloy and carbon steel composite in many energy projects to save costs and reduce the waste of resources.