ASTM A312 is a standard specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes, ASTM A312 material covers Austenitic stainless steels, and ASTM A312 pipe is manufactured in both welded and seamless processes.
ASTM A312 stainless steel pipe is widely used for high-temperature service and general service, with pipe sizes from 1/8 inch to 30 inch for outside diameter, and wall thickness from Schedule 5S to 80S.
ASTM A312 is equal to ASME SA312, in practice, ASME SA312 and ASTM A312 are dual-certified specifications. SA312 pipes can be seamless and welded, ASTM A312 material include TP304, TP304L, TP304H, TP310S, UNS S31254, TP316, TP316L, TP321, TP321H, TP347, TP347H, UNSN08810, UNSN08811, and many more grades.
ASTM A312 Material Chemical Requirements And Mechanical Properties
ASTM A312 material covers Austenitic stainless steels, including TP304, TP304L, TP304H, TP304LN, TP309S, TP309J, TP310S, TP310H, TP316, TP316L, TP316H, TP316TI, TP317, TP317L, TP321, TP321H, TP347, TP347H, these grades have unique composition and properties, common stainless steel grades with chemical composition and properties are specified as following.
ASTM A312 Material Chemical Composition
| Grade | Carbon | Silicon | Manganese | Chromium | Nickel | Molybdenum | Sulfur | Phosphorous |
|---|---|---|---|---|---|---|---|---|
| TP304 | 0,08 | 1,0 | 2.00 | 18.0 – 20.0 | 8.0 – 11.0 | – | 0,03 | 0,045 |
| TP304L | 0,035 | 1,0 | 2.00 | 18.0 – 20.0 | 8.0 – 13.0 | – | 0,03 | 0,045 |
| TP316 | 0,08 | 1,0 | 2.00 | 16.0 – 18.0 | 10.0 – 14.0 | 2.00 – 3.00 | 0,03 | 0,045 |
| TP316L | 0,035 | 1,0 | 2.00 | 16.0 – 18.0 | 10.0 – 15.0 | 2.00 – 3.00 | 0,03 | 0,045 |
| TP321 | 0,08 | 1,0 | 2.00 | 17.0 – 19.0 | 9.0 – 12.0 | – | 0,03 | 0,045 |
ASTM A312 Material Mechanical Properties
| Grade | UNS | Tensile Strength Min, Ksi [MPa] | Yield Strength Min, Ksi [MPa] |
|---|---|---|---|
| TP304 | S30400 | 75 [515] | 30 [205] |
| TP304L | S30403 | 70 [485] | 25 [170] |
| TP304H | S30409 | 75 [515] | 30 [205] |
| TP304N | S30451 | 80 [550] | 35 [240] |
| TP304LN | S30453 | 75 [515] | 30 [205] |
| TP309S | S30908 | 75 [515] | 30 [205] |
| TP310S | S31008 | 75 [515] | 30 [205] |
| TP316 | S31600 | 75 [515] | 30 [205] |
| TP316L | S31603 | 70 [485] | 25 [170] |
| TP316H | S31609 | 75 [515] | 30 [205] |
| TP316N | S31651 | 80 [550] | 35 [240] |
| TP316LN | S31653 | 75 [515] | 30 [205] |
| TP317 | S31700 | 75 [515] | 30 [205] |
| TP317L | S31703 | 75 [515] | 30 [205] |
What is ASTM A312?
The ASTM A312 standard developed by the American Society for Testing and Materials (ASTM), is a specification specifically for the manufacturing requirements and mechanical properties of seamless and welded austenitic stainless steel pipe. The standard covers from 1/8 inch (6.4mm) to 30 inches (760mm) diameter range pipe, thickness from the standard (SCH 5S) to form XXS (SCH XXS), to meet the different needs of different industries on the stainless steel pipe, ASTM A312 standard not only specifies the selection of materials, manufacturing methods, surface treatment, and mechanical properties of the pipe, and other basic requirements but also details a wide range of stainless steel pipe. Requirements, but also listed in detail a variety of stainless steel grades (such as TP304, TP304L, TP316, TP316L, etc.) of the chemical composition and mechanical properties of the parameters, to ensure the reliability and durability of the pipeline in actual use.
ASTM A312 Pipe Manufacturing
ASTM A312 Seamless Pipe
Pipe should be made from stainless steel billet in hot rolling or cold drawn, with no welding process during manufacturing, seamless pipe has better pressure to withstand, annealing solution and pickling finishing condition, applied for high temperature and corrosion environment.
ASTM A312 Welded Pipe
No additional metal using an automatic welding process for welded pipe, made from stainless steel strip or plate, using TIG, ERW, ERW and other welding methods to produce single welding and double welding pipes, small diameter and large diameter are available in annealing pickling finish.
ASTM A312 stainless steel welded pipe manufacturing process mainly includes raw material preparation, forming, welding, heat treatment surface treatment and other links. Raw materials need to be selected to meet the standard requirements of austenitic stainless steel plate or strip, after cutting, cleaning and other pre-treatment into the molding machine for roll or press forming. After forming the billet needs to be welded, welding can be automatic welding, manual welding, or a combination of welding methods to ensure the quality of the weld. After welding, heat treatment is also required to eliminate welding stress and improve the overall performance of the pipe. Finally, the internal and external walls of the pipe are mechanically polished, degreased, pickled and cleaned to achieve the required surface finish.
To ensure that the quality of ASTM A312 stainless steel welded pipe meets the standard requirements, manufacturers need to implement strict quality control measures. Firstly, raw materials need to be strictly inspected to ensure that their chemical composition and mechanical properties meet the standard requirements. Secondly, in the manufacturing process, the need for strict control of each process, such as forming accuracy, welding quality, heat treatment temperature and time, etc. need to meet the process requirements. At the same time, it is also necessary to carry out comprehensive testing and testing of the finished product, including mechanical properties test, intergranular corrosion test, hydraulic test, etc., to ensure the safety and reliability of the pipeline in actual use. In addition, the manufacturer also needs to establish a perfect quality management system, comprehensive monitoring and management of the production process to ensure the stability and consistency of product quality.
Heavily Cold-Worked (HCW) Pipe
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.
Welded pipe and HCW pipe of 14 and smaller than NPS 14 shall have a single longitudinal weld. After approval by the purchaser, the welded pipe and HCW pipe with an NPS greater than NPS 14 shall have a single longitudinal weld or shall be manufactured by forming and welding two longitudinal sections of flat stock.
Heat Treatment
All pipes shall be furnished in the heat-treated condition in accordance with the required heat-treating temperature and cooling requirements, pipes shall be individually quenched in water or rapidly cooled by other means (direct quenched).
The pipe shall be free of scale and contaminating exogenous iron particles. Pickling, blasting, or surface finishing is not mandatory when the pipe is bright annealed.
ASTM A312 Dimensional Tolerances
Outside Diameter
| Outside Diameter, NPS | Tolerance, Inch |
|---|---|
| 1/8 To 1-1/2, Incl | Over 1/16 Under 1/32 |
| Over 1-1/2 To 4, Incl | Over 1/32 Under 1/32 |
| Over 4 To 8, Incl | Over 1/16 Under 1/32 |
| Over 8 To 18, Incl | Over 3/32 Under 1/32 |
| Over 18 To 26, Incl | Over 1/8 Under 1/32 |
| Over 26 To 34, Incl | Over 5/32 Under 1/32 |
| Over 34 To 48, Incl | Over 3/16 Under 1/32 |
Wall Thickness
| NPS | Wall Thickness Tolerance, % |
|---|---|
| 1/8 To 2-1/2 Incl., All T/D Ratios | Over 20.2 Under 12.5 |
| Over 3 To 18 Incl., T/D Up To 5% Incl. | Over 22.5 Under 12.5 |
| Over 3 To 18, Incl., T/D > 5% | Over 15.0 Under 12.5 |
| 20 And Large, Welded, All T/D Ratios | Over 17.5 Under 12.5 |
| 20 And Large, Seamless, T/D Up To 5% Incl. | Over 22.5 Under 12.5 |
| >20 And Large, Seamless, T/D > 5% | Over 15.0 Under 12.5 |
ASTM A312 Pipe Dimensions
ASTM A312 stainless steel pipe sizes and dimensions should conform to ANSI B36.19, nominal pipe size (NPS) ranges from NPS 1/8 [10.29 mm] to NPS 30 [762 mm], Schedule number for wall thickness from Sch 5s to Sch 80s, more Pipe Schedule Sizes are specified for special applications, the value stated respectively for a specific size, average wall and minimum wall pipe are available.
Note that over NPS 12 sizes are actual sizes, unlike below NPS 12 size values.
| Nominal Size | OD | Wall Thickness, SCHEDULE | |||||
|---|---|---|---|---|---|---|---|
| NPS | DN | Mm | 5S | 10S | 40S | STD | 80S |
| 1∕8 | 6 | 10.3 | – | 1.24 | 1.73 | 1.73 | 2.41 |
| 1∕4 | 8 | 13.7 | – | 1.65 | 2.24 | 2.24 | 3.02 |
| 3∕8 | 10 | 17.2 | – | 1.65 | 2.31 | 2.31 | 3.2 |
| 1∕2 | 15 | 21.3 | 1.65 | 2.11 | 2.77 | 2.77 | 3.73 |
| 3∕4 | 20 | 26.7 | 1.65 | 2.11 | 2.87 | 2.87 | 3.91 |
| 1 | 25 | 33.4 | 1.65 | 2.77 | 3.38 | 3.38 | 4.55 |
| 1 1∕4 | 32 | 42.2 | 1.65 | 2.77 | 3.56 | 3.56 | 4.85 |
| 1 1∕2 | 40 | 48.3 | 1.65 | 2.77 | 3.68 | 3.68 | 5.08 |
| 2 | 50 | 60.3 | 1.65 | 2.77 | 3.91 | 3.91 | 5.54 |
| 2 1∕2 | 65 | 73 | 2.11 | 3.05 | 5.16 | 5.16 | 7.01 |
| 3 | 80 | 88.9 | 2.11 | 3.05 | 5.49 | 5.49 | 7.62 |
| 3 1∕2 | 90 | 101.6 | 2.11 | 3.05 | 5.74 | 5.74 | 8.08 |
| 4 | 100 | 114.3 | 2.11 | 3.05 | 6.02 | 6.02 | 8.56 |
| 5 | 125 | 141.3 | 2.77 | 3.4 | 6.55 | 6.55 | 9.53 |
| 6 | 150 | 168.3 | 2.77 | 3.4 | 7.11 | 7.11 | 10.97 |
| 8 | 200 | 219.1 | 2.77 | 3.76 | 8.18 | 8.18 | 12.7 |
| 10 | 250 | 273.1 | 3.4 | 4.19 | 9.27 | 9.27 | 12.7 |
| 12 | 300 | 323.9 | 3.96 | 4.57 | 9.53 | 9.53 | 12.7 |
| 14 | 350 | 355.6 | 3.96 | 4.78 | – | 9.53 | – |
| 16 | 400 | 406.4 | 4.19 | 4.78 | – | 9.53 | – |
| 18 | 450 | 457.2 | 4.19 | 4.78 | – | 9.53 | – |
| 20 | 500 | 508 | 4.78 | 5.54 | – | 9.53 | – |
| 22 | 550 | 558.8 | 4.78 | 5.54 | – | 9.53 | – |
| 24 | 600 | 609.6 | 5.54 | 6.35 | – | 9.53 | – |
| 26 | 650 | 660.4 | – | – | – | 9.53 | – |
| 28 | 700 | 711.2 | – | – | – | 9.53 | – |
| 30 | 750 | 762 | 6.35 | 7.92 | – | 9.53 | – |
Beveled Stainless Steel Pipe
Beveled end A312 stainless steel industrial pipe is used for joint fitting or other connectors, there are different angles and tolerances for special applications, it is easy to weld, saves installing time, and is cost-effective.
Testing And Inspection
- Mechanical Tests
- Grain Size Determinations
- Weld Decay Tests
- Transverse or Longitudinal Tension Test
- Hydrostatic or Nondestructive Electric Test
- Flattening Test (option)
- Radiographic Examination (option)
- Intergranular Corrosion Test (option)
- Weld Decay Test (option)
ASTM A312 Pipe Applications
ASTM A312 stainless steel pipe has an extremely wide range of applications. In the chemical industry, due to the excellent corrosion resistance of stainless steel, can effectively prevent the corrosion and contamination of chemical substances on the pipeline, so it is widely used in the manufacture, storage, and delivery of chemical substances piping systems. In the oil and gas industry, stainless steel pipelines can withstand the harsh conditions of high pressure and high temperature, as well as good anti-wear properties, become an important tool for drilling, extraction, and transport of oil and gas resources. In addition, in the food and pharmaceutical industries, stainless steel piping has become a key part of the production process because it is non-toxic, odorless, non-polluting, and easy to clean and disinfect.
Reference Documents
- ASTM A999 / A999M – Standard Specification for General Requirements for Alloy and Stainless Steel Pipe
- ASTM A1016 / A1016M – Standard Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes
- ASME B36.10 – Welded and Seamless Wrought Steel Pipe
- ASME B36.19 – Stainless Steel Pipe
- ASTM A312/A312M-22a PDF Free Download