Seamless and welded austenitic stainless steel pipe to ASTM A312 in TP304, TP304L, TP316, TP316L, TP321, TP347 and TP310S.
- Standard: ASTM A312, ASME B36.19, ASME B36.10
- Grades: TP304, TP304L, TP316, TP316L, TP321, TP347, TP310S, TP317L
- Certificate: EN 10204 3.1 with every order, 3.2 on request
Mejor Steel is the export agent for the mills that make your material: one contract, one delivery date, and the mill named on the quotation. How we supply
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Specifications
| Outer diameter | 1/8" - 30" (10.3 - 762 mm) |
|---|---|
| Wall thickness | SCH 5S - SCH XXS |
| Schedule | SCH 5S, 10S, 40S, 80S |
| Length | SRL, DRL, 20 FT, 40 FT, or custom |
| Ends | Plain, beveled, threaded |
| Surface treatment | Pickled and passivated, polished, bright annealed |
| Manufacturing process | Seamless, ERW welded, EFW welded |
| Pressure rating | Corrosive and high purity service |
Choosing Between 304 and 316
TP304 is the general purpose austenitic stainless steel, containing 18 percent chromium and 8 percent nickel. It offers excellent resistance to a wide range of organic and inorganic chemicals and to atmospheric corrosion. TP316 adds 2 to 3 percent molybdenum, which substantially improves resistance to chlorides and to pitting and crevice corrosion. The practical rule is: use 304 for benign chemical environments and general industrial duty; use 316 wherever chlorides are present, including seawater, brine, coastal atmospheres and many process streams. The L grades (304L and 316L) have a maximum carbon content of 0.035 percent, which prevents sensitization, that is the precipitation of chromium carbides at grain boundaries during welding, and are therefore preferred for welded construction.
As a stainless steel pipe supplier, Mejor Steel supplies ASTM A312 pipe from China — TP304 and TP316 with the L grades, the stabilised TP321 and TP347, and TP310S for high-temperature service — seamless or welded, in the sizes and schedules set out on this page.
Seamless or Welded Stainless Pipe?
ASTM A312 permits both seamless and welded pipe, and welded pipe may be supplied either as-welded or cold worked to meet the same mechanical requirements. For most corrosive service the welded product performs equivalently to seamless, provided the weld is properly made and the pipe is solution annealed and pickled. Welded pipe is considerably more economical in larger sizes and thinner walls. However, some end users and specifications still restrict stainless pipe in critical service to seamless construction, and for high pressure or cyclic service seamless remains the conservative choice. If your specification permits welded, confirm whether the weld seam must be radiographed and whether the pipe will be supplied in the annealed condition.
A312 pipe: pick the grade from the corrosion, not from the price
ASTM A312 covers austenitic stainless pipe and the grades differ in what they resist rather than in how strong they are. 304 is the general purpose grade, 316 adds molybdenum for chlorides, 321 and 347 are stabilised for service in the sensitising range, and 310S is the high temperature grade. A wrong grade is not fixed by a thicker wall.
| Service condition | What it decides | What to state on the enquiry |
|---|---|---|
| General chemical or water service | TP304 or TP304L is normally sufficient | whether the low carbon grade is mandatory |
| Chloride bearing or marine service | TP316 or TP316L, for the molybdenum content | the chloride level and the operating temperature |
| Service in the sensitising range | TP321 or TP347, stabilised against sensitisation | the service temperature, so the stabilised grade can be confirmed |
| High temperature, oxidising service | TP310S for the higher nickel and chrome content | the temperature, and whether a cast grade is expected instead |
| Welded construction | The L grades and the stabilised grades weld differently | whether the pipe is seamless or welded, and the welding procedure |
| Sour or offshore service | Stainless may still be specified to NACE, or duplex used instead | NACE MR0175, and whether duplex is acceptable |
| Heat exchanger duty | A312 is pipe; A213 and A249 are the tube specifications | whether tube rather than pipe is required |
What does the S in SCH 10S mean?
The S suffix denotes stainless steel schedules as defined in ASME B36.19. Stainless pipe uses thinner wall thicknesses for a given nominal size because the material has higher corrosion resistance and does not need a corrosion allowance in the same way carbon steel does. SCH 10S is thinner than SCH 10, and SCH 40S is thinner than SCH 40. Note that not all schedules have an S equivalent: SCH 5S, 10S, 40S and 80S are defined, but there is no SCH 20S or 60S. Always specify both the schedule and the outside diameter when ordering.
Can stainless steel pipe be used for high temperature service?
Yes, but grade selection matters. TP304 and TP316 have useful strength to about 540 to 565 degrees C. TP321 and TP347 are stabilized grades containing titanium or niobium respectively, which prevent sensitization by tying up the carbon, and are used for high temperature service where creep and intergranular corrosion are concerns. TP310S with 25 percent chromium and 20 percent nickel has the best high temperature oxidation resistance in the family and is often used in furnace and reformer service where temperatures exceed 800 degrees C.
Grades supplied and minimum properties
The grade fixes the minimum strength and the chemistry. The table below gives the requirements that separate the ASTM A312 grades ordered most often; the full composition and mechanical table for each grade is on its own page.
| Grade | Yield strength | Tensile strength |
|---|---|---|
| TP304 | 205 MPa min (30,000 psi) | 515 MPa min (75,000 psi) |
| TP304L | 170 MPa min (25,000 psi) | 485 MPa min (70,000 psi) |
| TP316 | 205 MPa min (30,000 psi) | 515 MPa min (75,000 psi) |
| TP316L | 170 MPa min (25,000 psi) | 485 MPa min (70,000 psi) |
| TP321 | 205 MPa min (30,000 psi) | 515 MPa min (75,000 psi) |
| TP347 | 205 MPa min (30,000 psi) | 515 MPa min (75,000 psi) |
| TP310S | 205 MPa min (30,000 psi) | 515 MPa min (75,000 psi) |
The complete chemistry and mechanical table for each grade, with the notes that qualify it, is on the individual grade page – for example ASTM A312 TP316 pipe. The L suffix denotes the low carbon version, which can be welded in most service without post-weld solution annealing.
Source: specified minimum yield and tensile strength for each grade, per ASTM A312 / ASME SA312. The standard is the governing document.
Download ASTM A312 Stainless Steel Pipe data sheet (PDF) One page: supply range, grades and key sizes, what to state on the enquiry, and the inspection documents that come with the order. The standard is the governing document.
Materials
- Austenitic stainless steel
Typical applications
- Chemical and petrochemical process piping
- Food, dairy and pharmaceutical piping
- Desalination and seawater systems
- Pulp and paper processing
- Heat exchanger and condenser tubing
Inspection & testing
- Eddy current testing
- Ultrasonic testing
- Hydrostatic pressure test
- Intergranular corrosion test (ASTM A262)
- PMI positive material identification
- Third-party inspection (SGS, BV, TUV)
| Packaging | Sea-worthy export packing: bundled by size, plastic caps on both ends, corrosion protection on request, stencilled with size, grade and heat number. |
|---|---|
| MOQ | One bundle or one truckload; mixed sizes within a bundle accepted. |
| Lead time | Stock sizes: 7-15 days. Mill run / non-stock: 4-6 weeks after order confirmation. |
Payment: T/T 30% deposit with the balance before shipment; L/C at sight also accepted. Final terms are confirmed on the quotation.
How we supply: sourced through partner mills; the producing mill is named on the quotation. How we supply sets out who is accountable for the order.
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