Stainless Steel 347 & 347H Welded Pipes Manufacturer
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Midland Alloys Inc. is a trusted manufacturer and supplier of stainless steel 347 and 347H welded pipes. We specialise in precision-welded stainless steel piping designed for high-temperature, corrosion-critical applications. Our production team prioritises consistency, metallurgical control and weld integrity at all stages. Stainless Steel 347 and 347H welded pipes are niobium-stabilised austenitic stainless steel grades developed to perform where heat and pressure work together over long cycles. SS 347 uses niobium stabilisation to resist intergranular corrosion during welding and service, while SS 347H is the high-carbon variant engineered for added strength at elevated temperatures. We manufacture pipes to ASTM A312, ASTM A358, ASME, and EN standards, covering controlled size ranges, wall thicknesses, and surface finishes. These welded pipes serve high-temperature industrial piping, heat exchangers, power plants, and chemical processing units. With ready stock, ISO certification, and export capability, Midland Alloys Inc. supports global project schedules without compromise. Precision matters here.
What is SS 347 / 347H Welded Pipe?
SS 347 and 347H welded pipes are produced by rolling stainless steel plates or coils into a cylindrical form, and welding the longitudinal seam using controlled heat input. The SS 347 welded pipe grade uses niobium stabilisation to prevent chromium carbide production, which enhances resistance to intergranular corrosion after welding. The stainless steel 347H welded pipe has a larger carbon content, which improves creep strength and mechanical stability at elevated temperatures. Both grades show good oxidation resistance, reliable high-temperature strength, and excellent weldability without post-weld cracking issues. The welded process allows tight dimensional control, consistent wall thickness, and a clean internal surface when manufactured correctly. A 347 welded stainless steel pipe performs well in high-temperature and corrosive conditions, such as power-generating lines, refinery systems, and chemical processing pipes, where thermal cycling and pressure are constant. These pipes handle stress calmly. No surprises in service.
Benefits of Welded 347 & 347H SS Piping
Using welded 347 and 347H stainless steel piping adds long-term value in systems exposed to heat, pressure, and aggressive media. These grades balance strength, corrosion resistance, and fabrication ease without overengineering.
- SS 347 welded pipe advantages include niobium stabilisation against intergranular corrosion
- Stable performance during repeated thermal cycling and welding operations
- Good oxidation resistance in elevated temperature operating zones
- SS 347H high-temperature pipe supports higher creep strength under pressure
- Reliable mechanical properties for long-duration high-temperature service
- 347 welded pipe benefits include consistent weld quality and dimensional accuracy
- Suitable for boilers, superheaters, and heat exchanger tubing systems
Specification of Stainless 347 & 347H Welded Pipes
The following specifications define the manufacturing, dimensional tolerance, and inspection requirements for stainless steel 347 and 347H welded pipes used in high-temperature and pressure service.
Seamless Pipe OD : 1/8 -12" NPS
ASTM A312 / ASME SA312
Welded
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 347H & 347 Welded Pipes
SS 347 and 347H welded pipes are available in multiple forms to match structural, process, and temperature-driven requirements. Fabrication remains straightforward, even for complex layouts. Corrosion resistance stays intact.
These pipes perform well in high-temperature industrial and structural applications where fabrication ease and material stability matter.
Pipe Forms
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Round PipeUsed for high-temperature fluid transport and process piping.
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Square PipeUsed in structural frameworks and fabricated assemblies.
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Rectangular PipeUsed in construction supports and load-bearing structures.
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Polished PipeUsed in architectural and controlled-environment applications.
- Industrial Process Pipe
Used in chemical, power, and heat transfer systems.
Contact us today to discuss how Stainless Steel 347/347H Welded 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
Chemical composition control ensures resistance to intergranular corrosion, oxidation stability, and predictable mechanical behaviour during long-term exposure to heat.
| 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 | – | |
Mechanical properties focus on tensile strength, yield strength, elongation, and creep resistance, particularly for pressure systems operating at elevated temperatures.
| 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 |
Stainless Steel Welded Pipe Grades We Also Offer
How SS 347 Welded 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
Industrial Applications for SS 347 & 347H Welded Pipes
SS 347 and 347H welded pipes are used in industries where high temperatures, pressure, and corrosive media coexist. Common applications include power plant boiler lines, superheaters, and reheaters that operate under constant thermal stress. Chemical processing plants use these pipes for reactors, transfer lines, and heat exchangers that handle harsh fluids. Refineries use them in high-temperature hydrocarbon systems. Fertiliser units, petrochemical plants, and thermal processing facilities also specify these grades for long-term stability. The material choice reduces weld-related failures. That matters in continuous operations.
Why Choose Midland Alloy's SS 347 And 347H Welded Pipes
Midland Alloys Inc. manufactures welded stainless steel piping for demanding thermal and pressure environments where material stability matters more than short-term cost. SS 347 suits stabilised corrosion-resistant service, especially in welded systems exposed to thermal cycling. SS 347H supports high-temperature pressure systems, where creep strength becomes critical over time. Our manufacturing processes ensure controlled weld parameters, constant wall thickness, and clean internal surfaces. Weldability remains excellent even with complex configurations. These pipes provide a long service life, consistent performance, and low maintenance requirements. As an ISO-certified company, we provide export-quality materials with complete traceability and compliance. We operate globally as a stainless steel 347h welded pipe supplier known for technical consistency, not marketing hype.
FAQs
SS 347 uses niobium stabilisation to resist intergranular corrosion, while 347H has higher carbon for improved high-temperature strength.
Niobium prevents chromium carbide formation during welding and service, protecting corrosion resistance.
Yes. SS 347H is designed for elevated temperature pressure systems requiring higher creep strength.
