ASTM A312 (ASME SA312) is a widely used standard for stainless steel pipes, covering seamless, welded, and heavily cold-worked pipe types. It is commonly applied in high-temperature and general corrosive service environments. The standard includes multiple stainless steel grades to meet different application requirements, with typical grades such as TP304 (S30400), TP316 (S31600), TP304L (S30403), and TP316L (S31603).
As a professional and reliable stainless steel pipe supplier in China, Botop Steel is committed to providing high-quality stainless steel pipe products with competitive pricing and fast delivery for your projects. Contact us to receive dedicated support from our experienced team.
Material furnished under ASTM A312 shall conform to the applicable requirements of the current edition of ASTM A999 unless otherwise provided herein.
Requirements such as chemical composition, mechanical properties, hydrostatic testing, non-destructive testing, and dimensional tolerances shall all comply with the relevant provisions of A999.
All grades in ASTM A312 are stainless steels, and therefore their chemical composition contains relatively high amounts of chromium (Cr) and nickel (Ni) to ensure corrosion resistance, high-temperature strength, and overall durability in various service conditions.
| Grade | Composition, % | |||||||
| C | Mn | P | S | Si | Cr | Ni | Mo | |
| TP304 | 0.08 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 18.00 ~ 20.00 | 8.0 ~ 11.0 | — |
| TP304L | 0.035 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 18.00 ~ 20.00 | 8.0 ~ 13.0 | — |
| TP316 | 0.08 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 16.00 ~ 18.00 | 11.0 ~ 14.0 | 2.0 ~ 3.0 |
| TP316L | 0.035 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 16.00 ~ 18.00 | 11.0 ~ 14.0 | 2.0 ~ 3.0 |
For welded TP316 pipe, the nickel (Ni) ranges shall be 10.0 to 14.0%.
| Mechanical Properties | TP304 / TP316 | TP304L / TP316L | |
| Tensile Requirements | Tensile Strength | 75 ksi [515 MPa] min | 70 ksi [485 MPa] min |
| Yield Strength | 30 ksi [205 MPa] min | 25 ksi [170 MPa] min | |
| Elongation in 2 in. or 50 mm |
Longitudinal: 35 % min Transverse: 25 % min |
||
| Flattening Test | Flattening tests shall be conducted on 5% of the pipes from each heat-treated lot. | ||
| Weld Decay Test | The weld metal to base metal loss ratio shall be 0.90 to 1.1. (The test is not required unless specified in the purchase order) |
||
When the impact test criterion for a low-temperature service is 15 ft-lbf (20 J) energy absorption or 15 mils [0.38 mm] lateral expansion, grades TP304 and TP304L are accepted by the ASME Pressure Vessel Code, Section VIII, Division 1, and by the Chemical Plant and Refinery Piping Code, ANSI B31.3, for service at temperatures as low as -425°F [-250°C] without qualification by impact tests.
Other AISI stainless steel grades are usually accepted for service temperatures as low as -325°F [-200°C] without impact testing.
Manufacturer Process
ASTM A312 TP304, TP316, TP304L, and TP316L pipes can be manufactured by three methods: seamless (SML), automatic welding process (WLD), and heavily cold worked (HCW), and can be either hot-finished or cold-finished as required.
Regardless of the welding method, no filler metal shall be added during welding.
Welded pipe and HCW pipe of NPS 14 and smaller shall have a single longitudinal weld. Welded pipe and HCW pipe of a size larger than NPS 14 shall have a single longitudinal weld or shall be produced by forming and welding two longitudinal sections of flat stock when approved by the purchaser. All weld tests, examinations, inspections, or treatments shall be performed on each weld seam.
Heat Treatment
All ASTM A312 steel pipes shall be furnished with heat treatment.
The heat treatment procedure for TP304, TP316, TP304L, and TP316L shall include heating the pipe to a minimum of 1900°F (1040°C) and quenching in water or rapidly cooling by other means.
The cooling rate must be sufficient to prevent carbide reprecipitation and can be verified by the ability to pass ASTM A262, Practice E.
For A312 seamless pipes, immediately after hot forming, while the pipe temperature is not less than the specified minimum solution treatment temperature, each pipe shall be individually quenched in water or rapidly cooled by other means.
Each pipe shall be subjected to the nondestructive electric test or the hydrostatic test. The type of test to be used shall be at the option of the manufacturer, unless otherwise specified in the purchase order.
The testing methods shall be carried out in accordance with the relevant requirements of ASTM A999.
For piping with fittings equal to or larger than NPS 10, a system test may be used instead of hydrostatic testing. If hydrostatic testing is not performed, the marking must include "NH".
The finished pipes shall be reasonably straight and shall have a workmanlike finish.
The pipe shall be free of scale and contaminating exogenous iron particles. Pickling, blasting, or surface finishing is not mandatory when pipe is bright annealed. The purchaser is permitted to require that a passivating treatment be applied to the finished pipe.
Removal of imperfections by grinding is permitted, provided the wall thicknesses are not decreased to less than that permitted in Section 9 of ASTM A999.
| NPS Designator | Tolerance, % form Nominal | |
| Over | Under | |
| 1/8 to 2 1/2 incl., all t/D ratios | 20.0 | 12.5 |
| 3 to 18 incl. t/D up to 5% incl. | 22.5 | 12.5 |
| 3 to 18 incl. t/D ＞ 5% | 15.0 | 12.5 |
| 20 and larger, welded, all t/D ratios | 17.5 | 12.5 |
| 20 and larger, seamless, t/D up to 5 % incl. | 22.5 | 12.5 |
| 20 and larger, seamless, t/D ＞ 5 % | 15.0 | 12.5 |
t = Nominal Wall Thickness; D = Order Outside Diameter.
Botop Steel provides multiple packaging options for your projects, ranging from woven bag packaging and plastic bag packaging to wooden case packaging, ensuring safe handling, protection during transportation, and compliance with project requirements.
Material: ASTM A312 stainless steel pipes and fittings;
Grade: TP304, TP316, TP304L, and TP316L
Size: 1/8" to 30", or customized according to your requirements;
Length: Random length or cut to order;
Packaging: Woven bags, plastic bags, wooden cases, etc.
Support: EXW, FOB, CIF, CFR;
MOQ: 1 m;
Payment Terms: T/T or L/C;
Price: Contact us for the latest prices.
