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MLTI Private Limited (Moonlight Tube Industries) manufactures and supplies Stainless Steel 321H Pipe from our facility in Gujarat, India. We have manufactured stainless steel pipe since 2008, with a stated plant capacity of approximately 8,000 MT per year. ASTM A312 / ASME SA-312 Grade TP321H is the higher-carbon variant of Type 321 stainless steel, developed for improved elevated-temperature strength and creep resistance.
Carbon in 321H is controlled between 0.04 and 0.10%, compared with a maximum of 0.08% for standard Type 321. The higher controlled carbon range contributes to improved high-temperature strength and creep resistance. The grade contains 17.0 to 19.0% chromium and 9.0 to 12.0% nickel, with titanium added for stabilisation. The minimum tensile strength is 515 MPa (75 ksi), the minimum yield strength is 205 MPa (30 ksi), and the minimum elongation is 35%. These values apply to welded pipe at all wall thicknesses and to seamless pipe up to 9.5 mm wall; heavier seamless walls are governed by the reduced values in ASTM A312.
We manufacture SS 321H pipe to ASTM A312 / ASME SA-312 and dimension it to ASME B36.19M. Sizes range from 1/8" NB to 10" NB in SCH 10S to SCH 80S, with SCH 5S available from 1/2" NB upward, with lengths up to 24 ft (7.3 m). We supply Stainless steel 321H seamless pipes, which are pierced and drawn from solid billets to carry high pressures without joints. Welded 321H pipe is formed from stainless steel strip and longitudinally welded, including ERW variants produced by electric resistance welding without filler metal. Typical applications include refinery process lines, power-generation piping, steam systems, and high-temperature exhaust applications. Each length is subjected to either a hydrostatic test or a nondestructive electric test in accordance with ASTM A999/A999M, as permitted by ASTM A312. Hydrostatic testing to a specific requirement can be confirmed at the time of order. Our company holds ISO 45001 and ISO 14001, BIS registration, IBR and EIL approval, with PED 2014/68/EU compliance.
We supply ASTM A312 TP321H pipe in round sections with a mill finish as standard. The following table summarises the applicable standards, dimensions, manufacturing forms, and conditions.
| Parameter | Value |
|---|---|
| Applicable Standard | ASTM A312 / ASME SA-312: Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes |
| Dimensional Standard | ASME B36.19M |
| Size Range | 1/8" NB to 10" NB (6 mm to 250 mm) |
| Schedule | SCH 10S, SCH 20S, SCH 40S, SCH 80S across the full range; SCH 5S from 1/2" NB upward |
| Wall Thickness | 1.24 mm to 12.70 mm, depending on NB and schedule |
| Length | Up to 24 ft (7.3 m); single random, double random and cut lengths |
| Manufacturing Form | Seamless and Welded (ERW) per ASTM A312 |
| Section Profile | Round, Square, and Rectangular |
| Finish | Mill finish, solution annealed and pickled |
| End Type | Plain end; bevelled ends to order |
The controlled carbon range is one of the defining chemical requirements of Type 321H. The composition limits for UNS S32109 are provided below.
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.04 to 0.10 |
| Manganese (Mn) | 2.00 max |
| Phosphorus (P) | 0.045 max |
| Sulphur (S) | 0.030 max |
| Silicon (Si) | 1.00 max |
| Chromium (Cr) | 17.0 to 19.0 |
| Nickel (Ni) | 9.0 to 12.0 |
| Nitrogen (N) | 0.10 max |
| Titanium (Ti) | 4 × (C + N) min, 0.70 max |
| Iron (Fe) | Balance |
Design calculations and material acceptance for 321H pipe use the mechanical requirements specified by ASTM A312 / ASME SA-312. The principal tensile and elongation requirements are listed below.
| Property | Welded pipe, all wall thicknesses | Seamless pipe, t ≤ 9.5 mm | Seamless pipe, t > 9.5 mm |
|---|---|---|---|
| Tensile Strength, min | 515 MPa (75 ksi) | 515 MPa (75 ksi) | 480 MPa (70 ksi) |
| Yield Strength, min | 205 MPa (30 ksi) | 205 MPa (30 ksi) | 170 MPa (25 ksi) |
| Elongation in 50 mm, min, longitudinal | 35% | 35% | 35% |
| Elongation in 50 mm, min, transverse | 25% | 25% | 25% |
ASTM A312 applies reduced tensile and yield requirements to seamless ASTM A312 / ASME SA-312 TP321H pipe in nominal wall thicknesses greater than 9.5 mm (3/8 in.). Within our size range this affects 6" SCH 80S, 8" SCH 80S and 10" SCH 80S. Welded pipe retains the full 515 MPa / 205 MPa requirement at all wall thicknesses.
321H may appear under different designations on international drawings and procurement documents. The principal designations are listed below.
| Standard or System | Designation |
|---|---|
| UNS | UNS S32109 |
| Europe (EN / W.Nr.) | 1.4878 |
A distinction between Type 321 and Type 321H is important when reviewing European designations. EN 1.4541 corresponds to Type 321, while 1.4878 corresponds to the higher-carbon 321H composition.
321H pipe is available in different manufacturing forms. The manufacturing route affects the product characteristics, applicable standard and typical application.
Seamless 321H pipe is manufactured from a solid billet that is pierced and subsequently reduced to the required dimensions without a longitudinal weld seam. It is available for applications where seamless construction is specified.
SS 321H welded pipe is formed from stainless steel strip, joined along a longitudinal seam, heat treated, and finished to specification. This includes electric resistance welding (ERW), which fuses strip edges without filler metal; under ASTM A312, ERW is classified as a welding method, not a separate product class (WLD).
Round 321H pipe is the primary profile covered by the ASME B36.19M dimensional range specified for this product line.
Square
Square stainless steel sections are manufactured and specified separately from ASTM A312 pipe, remaining subject to their own unique applicable product and dimensional standards.
Rectangular
Rectangular stainless steel sections are fabricated independently of standard piping specs, adhering strictly to their own designated dimensional requirements and structural product standards.
We supply 321H pipe from 1/8" NB to 10" NB in SCH 5S, 10S, 20S, SCH 40S and SCH 80S, with SCH 5S available from 1/2" NB upward. The outside diameters and nominal wall thicknesses corresponding to these nominal pipe sizes are provided below.
| Nominal Bore (mm) | Nominal Bore (INCH) | Outside Diameter (mm) | Sch-5S Thickness (mm) | Sch-10S Thickness (mm) | Sch-20S Thickness (mm) | Sch-40S Thickness (mm) | Sch-80S Thickness (mm) |
|---|---|---|---|---|---|---|---|
| 6 | 1/8 | 10.30 | - | 1.24 | 1.50 | 1.73 | 2.41 |
| 8 | 1/4 | 13.70 | - | 1.65 | 2.00 | 2.24 | 3.02 |
| 10 | 3/8 | 17.10 | - | 1.65 | 2.00 | 2.31 | 3.2 |
| 15 | 1/2 | 21.34 | 1.65 | 2.11 | 2.30 | 2.77 | 3.75 |
| 20 | 3/4 | 26.70 | 1.65 | 2.11 | 2.55 | 2.87 | 3.91 |
| 25 | 1 | 33.40 | 1.65 | 2.77 | 3.00 | 3.38 | 4.55 |
| 32 | 1 1/4 | 42.20 | 1.65 | 2.77 | 3.00 | 3.56 | 4.85 |
| 40 | 1 1/2 | 48.30 | 1.65 | 2.77 | 3.00 | 3.68 | 5.08 |
| 50 | 2 | 60.30 | 1.65 | 2.77 | 3.00 | 3.91 | 5.54 |
| 65 | 2 1/2 | 73 | 2.11 | 3.05 | 4.00 | 5.16 | 7.01 |
| 80 | 3 | 88.9 | 2.11 | 3.05 | 4.00 | 5.49 | 7.62 |
| 100 | 4 | 114.3 | 2.11 | 3.05 | 4.50 | 6.02 | 8.56 |
| 125 | 5 | 141.3 | 2.77 | 3.4 | 5.00 | 6.55 | 9.53 |
| 150 | 6 | 168.3 | 2.77 | 3.4 | 6.35 | 7.11 | 10.97 |
| 200 | 8 | 219.1 | 2.77 | 3.76 | 6.35 | 8.18 | 12.7 |
| 250 | 10 | 273.1 | 3.4 | 4.19 | 6.35 | 9.27 | 12.7 |
Schedule 5S is not defined in ASME B36.19M for NPS 1/8 and smaller, so the lightest listed schedule at 3/8" NB is 10S.
This comprehensive weight chart provides precise metrics per metre for S321H pipes across various schedules.
| Nominal Bore (mm) | Nominal Bore (INCH) | Sch-5S Weight (Kg/mt) | Sch-10S Weight (Kg/mt) | Sch-20S Weight (Kg/mt) | Sch-40S Weight (Kg/mt) | Sch-80S Weight (Kg/mt) |
|---|---|---|---|---|---|---|
| 6 | 1/8 | - | 0.28 | 0.33 | 0.37 | 0.47 |
| 8 | 1/4 | - | 0.49 | 0.58 | 0.631 | 0.8 |
| 10 | 3/8 | - | 0.63 | 0.74 | 0.845 | 1.1 |
| 15 | 1/2 | 0.8 | 1 | 1.08 | 1.27 | 1.62 |
| 20 | 3/4 | 1.03 | 1.28 | 1.52 | 1.68 | 2.2 |
| 25 | 1 | 1.3 | 2.09 | 1.94 | 2.5 | 3.24 |
| 32 | 1 1/4 | 1.65 | 2.7 | 2.90 | 3.38 | 4.47 |
| 40 | 1 1/2 | 1.91 | 3.11 | 3.35 | 4.05 | 5.41 |
| 50 | 2 | 2.4 | 3.93 | 4.24 | 5.44 | 7.48 |
| 65 | 2 1/2 | 3.69 | 5.26 | 6.81 | 8.63 | 11.4 |
| 80 | 3 | 4.51 | 6.45 | 8.37 | 11.3 | 15.2 |
| 100 | 4 | 5.84 | 8.36 | 12.18 | 16.07 | 22.3 |
| 125 | 5 | 9.47 | 11.57 | 16.81 | 21.8 | 31.97 |
| 150 | 6 | 11.32 | 13.84 | 25.36 | 28.3 | 42.7 |
| 200 | 8 | 14.79 | 19.96 | 33.31 | 42.6 | 64.6 |
| 250 | 10 | 22.63 | 27.78 | 41.77 | 60.5 | 96 |
321H stainless steel pipe is selected for applications where elevated temperature, creep resistance and resistance to intergranular corrosion after high-temperature exposure are important.
Refineries and petrochemical plants use 321H pipe for selected hot process lines, reformer-related piping, thermal oxidiser connections and other elevated-temperature services. The stabilised composition is useful where the material experiences temperatures associated with sensitisation during operation or thermal cycling.
321H pipe is used in selected high-temperature steam, superheater and reheater piping where the service temperature and mechanical design requirements justify the use of the H grade. Its controlled carbon content provides higher elevated-temperature strength than standard 321.
Chemical-processing plants use 321H pipe for selected hot process lines, gas lines and high-temperature services. The titanium-stabilised composition helps reduce the risk of intergranular corrosion following exposure to sensitising temperatures.
321H stainless steel is used in selected engine, exhaust and hot-gas applications where resistance to elevated temperature and thermal cycling is required. The specific grade and wall thickness are selected according to the operating temperature and mechanical requirements.
321H pipe can be used in selected high-temperature utility systems, sterilisation equipment and drying systems where the temperature exceeds the preferred operating range of conventional grades. The required surface finish, cleanliness and product standard depend on the application.
ASTM A312 / ASME SA-312 specifies solution heat treatment requirements for Type 321H pipe. Hot-finished 321H pipe is solution treated at a minimum temperature of 1050°C (1925°F), while cold-finished pipe is solution treated at a minimum of 1100°C (2000°F), followed by rapid cooling.
The exact heat-treatment procedure must comply with the applicable edition of the product standard and the manufacturing condition.
321H stainless steel pipe can be welded using conventional austenitic stainless steel welding processes. The titanium-stabilised composition reduces the susceptibility to intergranular corrosion associated with chromium carbide precipitation during welding.
Post-weld heat treatment is not normally required for standard welded joints, although the welding procedure and any project-specific requirements should always be reviewed before fabrication.
321H provides general corrosion resistance comparable to Type 304 stainless steel in many environments. Its titanium stabilisation improves resistance to intergranular corrosion following exposure to elevated temperatures.
However, 321H is not a high-pitting-resistance alloy. Chloride-containing environments can cause pitting and stress corrosion cracking, particularly at elevated temperatures. The grade should therefore not be selected solely for high-temperature service when the process also contains significant chloride concentrations.
We prepare Stainless Steel 321H Pipe for domestic and export transportation.
Stainless steel 321H pipe prices in India typically range from about ₹260–₹400/kg for standard seamless sizes, with higher values for small diameters, thick schedules or special certifications; international quotes often sit around US$4–6/kg depending on mill, size and Incoterms.
Buyers return to Moonlight Tubes for certified material, approved grades and stock that ships on schedule. Every order is backed by documented quality, a wide size range and delivery commitments we hold to.
321H has a controlled carbon range of 0.04 to 0.10%, while standard 321 permits carbon up to 0.08% without a minimum. The higher controlled carbon content gives 321H improved elevated-temperature strength and creep resistance, making it suitable for applications where these properties are important.
Stainless Steel 321H Pipe is designated as ASTM A312 TP321H, ASME SA-312 TP321H, AISI 321H and UNS S32109. Its European material number is 1.4878.
There is no single maximum service temperature that applies to every 321H application. Allowable temperature depends on pressure, design conditions, environment, exposure duration and applicable design code. 321H is specifically used for elevated-temperature service where creep and stress-rupture properties are important.
321H can generally be welded without post-weld heat treatment. Titanium stabilisation reduces the risk of chromium carbide precipitation associated with welding. However, project specifications and the qualified welding procedure should be followed where additional heat treatment is required.
321H provides good general corrosion resistance and improved resistance to intergranular corrosion after elevated-temperature exposure. However, it is susceptible to pitting and other forms of corrosion in chloride-containing environments. Material selection should therefore consider the complete chemical and temperature conditions.
No. 321H is an Austenitic Stainless Steel and cannot be hardened by conventional solution heat treatment or precipitation hardening. Its strength can be increased through cold working, although the allowable amount of cold work depends on the product and application.
We manufacture 321H Pipe from 1/8" NB to 10" NB in SCH 5S, SCH 10S, SCH 20S, SCH 40S and SCH 80S, with dimensions based on ASME B36.19M. Lengths up to 24 ft (7.3 m) are available subject to manufacturing and transport requirements.
Yes. EN 10204 3.1 mill test certificates can be supplied with the material, providing heat identification, chemical composition and mechanical test results. Additional testing and documentation can be arranged according to the purchase specification.