Stainless Steel 347/347H Pipes Manufacturer
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Stainless Steel 347 and 347H pipes are niobium and tantalum stabilised austenitic stainless steel grades for long-term high-temperature service. They resist intergranular corrosion and maintain structural integrity when exposed for long durations at temperatures between 425°C and 875°C. Midland Alloys Inc. is one of the established 347 stainless steel pipes suppliers, offering high-quality products for demanding industrial applications.
The high carbon 347H grade offers better creep strength and high temperature mechanical properties that make it suitable for equipment for thermal processing, chemical processing plants, pressure vessels and power generating systems. We are one of the most reputable stainless steel 347 pipes manufacturers and suppliers. We have been supplying customers with certified products and that too, with consistency in quality and full traceability of material.
Benefits of Stainless Steel 347 Seamless Pipes
- Excellent stabilization against chromium carbide precipitation
- Enhanced resistance to intergranular attack in oxidizing environments
- Performs well under continuous operation above 800°C
- Non-magnetic in annealed condition
- Superior weldability with low risk of sensitization
- Maintains tensile strength at elevated temperatures
- Composed of chromium-nickel with added niobium for enhanced stability
- Suitable for forming, bending, and deep-drawing processes
Difference Between Stainless Steel 347/347H Pipes and Stainless Steel 316 Pipes
Feature / Property | Stainless Steel 347/347H Pipes | Stainless Steel 316 Pipes |
Primary Stabilizing Element | Niobium & Tantalum additions | Molybdenum addition |
Carbide Precipitation | Highly resistant during high-heat service | Vulnerable in the 425°C to 875°C range. |
Elevated Temperature Limits | Superior creep strength up to 875°C | Lower creep threshold; degrades faster under heat |
Chloride Resistance | Moderate atmospheric and chemical defense | Excellent protection in marine/saline environments |
Primary Applications | Thermal circuits, boiler tubes, pressure vessels | Marine hardware, chemical pumps, coastal piping |
What Makes SS 347 and 347H Different from Conventional Stainless Steel Pipes?
SS 347 and 347H stainless steel pipes are distinguished from the regular grades by the niobium stabilization that binds the structural matrix to survive longer than traditional alloys when exposed to extended heat. This addition avoids chromium depletion and intergranular corrosion during the essential operations and hence no post-weld heat treatment in the heat-affected zone is required. Moreover, the 347H version provides a superior carbon profile that results in excellent high-temperature strength, stress-rupture properties, and consistent tensile strength under extreme service circumstances.
Technical Specifications of Stainless Steel 347 / 347H 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 347 / 347H 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 347/347H 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
| Grade | Ni | Mn | Si | S | C | Cr | P | Mo | N | |
| TP347 | min. | 9.0 | – | – | – | – | 17.0 | – | 2.00 | – |
| max. | 13.0 | 2.0 | 1.00 | 0.030 | 0.08 | 20.0 | 0.045 | 3.00 | – | |
| TP347H | min. | 9.0 | – | – | – | 0.04 | 17.0 | – | 3.00 | – |
| max. | 13.0 | 2.0 | 1.00 | 0.030 | 0.10 | 19.0 | 0.045 | 4.00 | – | |
| Grade | Tensile Strength minimum (MPa) | Yield Strength 0.2% Proof minimum (MPa) | Elongation minimum (% in 50mm) | Hardness | |
| Rockwell B (HR B) maximum | Brinell (HB) maximum | ||||
| 347 | 515 | 205 | 40 | 95 | 201 |
| 347H | 515 | 205 | 40 | 92 | 201 |
| GRADE / MATERIAL | UNS (USA) | WERKSTOFF NR. (Germany) |
| ASTM A312 347 | S34700 | 1.4550 |
| TP 347H | S34709 | 1.4961 |
Stainless Steel Pipe Grades We Also Offer
Stainless Steel 347/347H 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 347/347H 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 SS 347 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 AISI 347 Stainless Steel Pipe
AISI 347 and 347H Stainless Steel Pipes are commonly used in industries requiring high heat resistance, mechanical strength, and corrosion protection. These pipes have high temperatures in aircraft exhaust systems without losing their structural integrity. They move aggressive gases and fluids in chemical processing facilities without experiencing corrosion fatigue. For high pressure and high-temperature cracking operations where material integrity is crucial petroleum refineries depend on 347H pipes. For long-term, safe operation under continuous heat exposure and pressure cycling, these pipes are also utilized in high-pressure boilers, superheaters and reheaters.
Why Choose Midland Alloys Inc. for ASTM A312 TP347H Stainless Steel Pipe
We are known for precise manufacturing in accordance with ASTM A312, EN, and ISO-certified standards. A well known manufacturer and exporter of high-quality 347/347H stainless steel pipes from India. Our facilities provide complete customization including non standard schedules, surface treatments, special end finishes and cut-to-length. We provide dependable logistics and compliance while meeting a variety of project needs in the Gulf, Europe, Africa, and Southeast Asia.
In addition to undergoing extensive internal testing, which includes hydrostatic pressure, PMI and flattening tests, each pipe is supplied with Mill Test Certificates (MTC) and, upon request, third-party inspections. We accommodate project-specific delivery schedules and are equally skilled in handling bulk and small-batch orders. Our commitment lies in building long-term partnerships, maintaining product integrity, and ensuring total client satisfaction. All pipes are clearly marked as per ASTM/ASME specifications (e.g., ASTM A312 / SA312) and are accompanied by Mill Test Certificates (MTCs) that verify full chemical and mechanical compliance.
Frequently Asked Questions (FAQs)
Every batch undergoes strict hydrostatic testing, ultrasonic examinations, Positive Material Identification (PMI), and intergranular corrosion (IGC) tests to ensure faultless structural performance.
Seamless and welded pipes are available in nominal sizes from 1/8″ to 24″ with standard schedules from Sch 5S to Sch 160 and XXS.
They are made and certified to common worldwide standards, including ASTM A312, ASME SA312 and the like EN/DIN international plumbing standards.
