Stainless Steel 321/321H Pipes Manufacturer & Supplier
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Midland Alloys Inc. is a trustworthy stainless steel pipe manufacturer and supplier from India offering high performance solutions to a variety of industries. Stainless steel 321 and 321H pipes, which are known for their superior corrosion resistance and thermal stability are part of our inventory. Titanium stabilizes SS 321 pipe after heat treatment, preventing intergranular corrosion. It is a modified version of SS 304 that is stronger and more resistant to oxidation at high temperatures. However, the higher carbon SS TP 321H Seamless Pipes, also known as UNS S32109, are engineered to have better creep resistance and higher temperatures. Niobium is added to 321H stainless steel to improve its performance in pressure-containing and structural applications, especially at temperatures above 1000°F.
Benefits of Stainless Steel TP 321 / 321H Seamless Pipes
- Excellent resistance to intergranular corrosion post-welding
- Withstands high-temperature exposure up to 1500°F
- Superior creep resistance compared to SS 304 pipes
- Titanium stabilisation ensures structural integrity after heat treatment
- Outstanding weldability with no need for post-weld annealing
- Good toughness at both high and cryogenic temperatures
- High mechanical strength and oxidation resistance in dynamic environments
- Available in seamless, welded, and cold-drawn finishes
Technical Specifications of Stainless Steel 321 / 321H Pipes
Seamless Pipe OD : 1/8 -12" NPS
Welded Pipe OD : 6.35 to 114.3 mm
EFW Pipe Size : 6″ NB – 24″ NB
ASTM A312 / ASME SA312
Seamless, ERW, Welded, Fabricated
Round, Square, Rectangular, Hydraulic Etc
Single Random, Double Random & Cut Length.
Plain End, Beveled End, Treaded
SCH5, SCH10, SCH20, SCH30, SCH40, STD, SCH80, SCH 80S, SCH60, SCH80, SCH120, SCH140, SCH160, SCH XXS, SCH XS
No. 2B - Mill finish/ Matte finish, No.8 - Mirror finish, No. 4 - Brushed finish, Bright, Annealing, Polished, Mirror
Types of Stainless Steel 321 / 321H Pipes
Manufacturing Types
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Seamless PipeWeld-free, perfect for even strength and sizing precision.
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Welded PipeWelded from flat-rolled steel, widely used where economy and large sizes are required.
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ERW PipeElectric Resistance Welded (ERW) pipes provide neat, high quality weld seams and are ideal for medium-pressure applications.
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EFW PipeElectric Fusion Welded (EFW) pipes are welded by fusion welding, usually applied in larger diameters and high-demand processes.
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LSAWLongitudinal Submerged Arc Welded (LSAW) pipes provide straight seam welding which is favored for thick-wall pieces and structural requirements.
Pipe Forms
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Round PipeThe most common shape for fluid and gas transport.
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Square PipeUsed in architectural and structural applications requiring angular profiles.
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Rectangular PipeProvides greater strength in load-bearing regions and flat structures.
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Hydraulic PipeDesigned to provide precise dimensional control for fluid systems under pressure.
Contact us today to discuss how Stainless Steel 321/321H Pipes can benefit your application. Whether you need guidance in selecting the right pipes or have specific requirements, our team of experts is here to help you find the optimal solution.
Technical Details & Delivery Condition
| Element | C | Mn | P | S | Si | Cr | Ni |
| Grade 321 | ≤ 0.08 | ≤ 2.0 | ≤ 0.045 | ≤ 0.03 | ≤ 1.0 | 17.0 – 19.0 | 9.0 – 12.0 |
| Grade 321H | 0.08 – 0.10 | ≤ 2.0 | ≤ 0.045 | ≤ 0.03 | ≤ 1.0 | 17.0 – 19.0 | 9.0 – 12.0 |
| Property | Tensile Strength (Rm) | Yield Strength (0.2% Rp) | Elongation (50 mm gauge length) | Hardness (HB) |
| Grade 321 | 515 – 720 MPa | 205 – 275 MPa | 40% | ≤ 200 |
| Grade 321H | 515 – 750 MPa | 240 – 275 MPa | 35 – 40% | ≤ 200 |
| AISI / ASTM | EN / DIN | JIS | UNS | BS | ISO |
| 321 / 321H | 1.4541 / 1.4878 | STS 321 / STS 321H | S32100 / S32109 | 321 / 321H | 321 / 321H |
Stainless Steel Pipe Grades We Offer
Stainless Steel 321/321H Pipe Dimensions
| Stainless Steel OD mm | Pipe WT mm | in. | Sch | Kg/m |
| 13.72 | 1.65 | 1/4 | 10S | 0.50 |
| 13.72 | 2.24 | 1/4 | 40S | 0.64 |
| 13.72 | 3.02 | 1/4 | 80S | 0.81 |
| 17.15 | 1.65 | 3/8 | 10S | 0.64 |
| 17.15 | 2.31 | 3/8 | 40S | 0.86 |
| 17.15 | 3.20 | 3/8 | 80S | 1.12 |
| 21.34 | 2.11 | 1/2 | 10S | 1.02 |
| 21.34 | 2.77 | 1/2 | 40S | 1.29 |
| 21.34 | 3.73 | 1/2 | 80S | 1.65 |
| 26.67 | 2.11 | 3/4 | 10S | 1.30 |
| 26.67 | 2.87 | 3/4 | 40S | 1.71 |
| 26.67 | 3.91 | 3/4 | 80S | 2.23 |
| 33.40 | 2.77 | 1 | 10S | 2.13 |
| 33.40 | 3.38 | 1 | 40S | 2.54 |
| 33.40 | 4.55 | 1 | 80S | 3.29 |
| 33.40 | 6.35 | 1 | 160 | 4.30 |
| 42.16 | 2.77 | 1¼ | 10S | 2.73 |
| 42.16 | 3.56 | 1¼ | 40S | 3.44 |
| 42.16 | 4.85 | 1¼ | 80S | 4.53 |
| 42.16 | 6.35 | 1¼ | 160 | 5.69 |
| 48.26 | 2.77 | 1½ | 10S | 3.16 |
| 48.26 | 3.68 | 1½ | 40S | 4.11 |
| 48.26 | 5.08 | 1½ | 80S | 5.49 |
| 60.33 | 2.77 | 2 | 10S | 3.99 |
| 60.33 | 3.91 | 2 | 40S | 5.52 |
| 60.33 | 5.54 | 2 | 80S | 7.60 |
| 60.33 | 8.74 | 2 | 160 | 11.29 |
| 73.03 | 3.05 | 2½ | 10S | 5.35 |
| 73.03 | 5.16 | 2½ | 40S | 8.77 |
| 73.03 | 7.01 | 2½ | 80S | 11.59 |
| 88.90 | 3.05 | 3 | 10S | 6.56 |
| 88.90 | 5.49 | 3 | 40S | 11.47 |
| 88.90 | 7.62 | 3 | 80S | 15.51 |
| 88.90 | 11.13 | 3 | 160 | 21.67 |
| 101.60 | 3.05 | 3½ | 10S | 7.53 |
| 101.60 | 5.74 | 3½ | 40S | 13.78 |
| 101.60 | 8.08 | 3½ | 80S | 18.92 |
| 114.30 | 3.05 | 4 | 10S | 8.50 |
| 114.30 | 6.02 | 4 | 40S | 16.32 |
| 114.30 | 8.56 | 4 | 80S | 22.67 |
| 114.30 | 13.49 | 4 | 160 | 34.05 |
| 141.30 | 6.55 | 5 | 40S | 22.10 |
| 141.30 | 9.53 | 5 | 80S | 31.44 |
| 141.30 | 15.88 | 5 | 160 | 49.87 |
| 168.28 | 3.40 | 6 | 10S | 14.04 |
| 168.28 | 7.11 | 6 | 40S | 28.69 |
| 168.28 | 10.97 | 6 | 80S | 43.21 |
| 168.28 | 14.27 | 6 | 120 | 54.75 |
| 168.28 | 18.26 | 6 | 160 | 68.59 |
| 219.08 | 8.18 | 8 | 40S | 43.20 |
| 219.08 | 12.70 | 8 | 80S | 65.63 |
| 219.08 | 18.23 | 8 | 120 | 91.30 |
| 219.08 | 23.01 | 8 | 160 | 112.97 |
Stainless Steel 321/321H Thickness Chart
| Nominal size [inches] | Outside diameter [inches] | Outside diameter [mm] | Wall thickness [inches] | Wall thickness [mm] | Weight [lb/ft] | Weight [kg/m] |
| 1/8 | 0.405 | 10.3 | 0.095 | 2.41 | 0.31 | 0.47 |
| 1/4 | 0.54 | 13.7 | 0.119 | 3.02 | 0.54 | 0.8 |
| 1/2 | 0.84 | 21.3 | 0.147 | 3.73 | 1.09 | 1.62 |
| 3/4 | 1.05 | 26.7 | 0.154 | 3.91 | 1.47 | 2.2 |
| 1 | 1.315 | 33.4 | 0.179 | 4.55 | 2.17 | 3.24 |
| 1 1/4 | 1.66 | 42.2 | 0.191 | 4.85 | 3 | 4.47 |
| 1 1/2 | 1.9 | 48.3 | 0.2 | 5.08 | 3.63 | 5.41 |
| 2 | 2.375 | 60.3 | 0.218 | 5.54 | 5.02 | 7.48 |
| 2 1/2 | 2.875 | 73 | 0.276 | 7.01 | 7.66 | 11.41 |
| 3 | 3.5 | 88.9 | 0.3 | 7.62 | 10.25 | 15.27 |
| 3 1/2 | 4 | 101.6 | 0.318 | 8.08 | 12.5 | 18.63 |
| 4 | 4.5 | 114.3 | 0.337 | 8.56 | 14.98 | 22.32 |
| 5 | 5.563 | 141.3 | 0.375 | 9.53 | 20.78 | 30.97 |
| 6 | 6.625 | 168.3 | 0.432 | 10.97 | 28.57 | 42.56 |
| 8 | 8.625 | 219.1 | 0.5 | 12.7 | 43.39 | 64.64 |
| 10 | 10.75 | 273 | 0.594 | 15.09 | 64.43 | 96.01 |
| 12 | 12.75 | 323.8 | 0.688 | 17.48 | 88.63 | 132.08 |
| 14 | 14 | 355.6 | 0.75 | 19.05 | 106.13 | 158.1 |
| 16 | 16 | 406.4 | 0.844 | 21.44 | 136.61 | 203.53 |
| 18 | 18 | 457 | 0.938 | 23.83 | 170.92 | 254.55 |
| 20 | 20 | 508 | 1.031 | 26.19 | 208.87 | 311.17 |
| 24 | 24 | 610 | 1.125 | 30.96 | 296.58 | 442.08 |
How Stainless Steel 321/321H Pipes Are Manufactured
Round Bar
Analytic
Cut to Length
Centering
Heating
Perforation
Inspection of Size
Pickling
Inspection of Surface
Lubricating
Cold Drawing (Cold Rolling)
Degreasing
Annealing
Straightening
Cut
Pickling / Passivating
Inspection
Analytic
Marking
Packing & Shipping
Applications of ASTM A312 TP 321 Pipes
Stainless Steel 321/321H Pipes are extensively used in high-temperature and corrosive environments across several sectors. In oil refineries, these pipes are essential for equipment exposed to intense heat and chemical processing. Industrial boilers, pressure vessels, and chemical processing heat exchangers rely on 321/321H’s strength and corrosion resistance. The pharmaceutical and chemical industries utilise these pipes in the fabrication of equipment that demands cleanability and structural durability. They are also used in petrochemical plants for high-temperature handling systems and process piping, guaranteeing long-term reliability and security in harsh environments.
Why Choose Midland Alloys Inc. for Stainless Steel 321/321H Pipes
Midland Alloys Inc. is a leading Indian manufacturer and exporter of SS 321/321H Pipes, committed to precision manufacturing and compliance with ASTM A312, EN 1.4541, and ISO-certified standards. We offer schedules, finishes, and lengths which are customized to the demands of the project. Each pipe goes through to internal quality testing, and on request by third-party agencies on request. Products have Mill Test Certificates (MTCs) confirming to chemical and mechanical compliance and are labelled following ASTM/ASME standards. We guarantee on time delivery, technical assistance, and reliable, long-term partnerships thanks to our robust global supply network spanning Europe, the Gulf, and Asia.
FAQs – Stainless Steel 321/321H Pipes
SS 321 can handle continuous service up to 900°C (1650°F) and intermittent service up to 815°C (1500°F).
No, both SS 321 and 321H cannot be hardened by heat treatment but can be strengthened through cold working.
SS 321H is equivalent to UNS S32109, EN 1.4878, and DIN 1.4550 in other international specifications.
Both grades show excellent corrosion resistance, especially to oxidation and intergranular attack, even after heat exposure.
In annealed conditions, SS 321/321H is generally non-magnetic but may become slightly magnetic after cold working.
