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ASTM A312 TP347H Welded Stainless Steel Pipes for High Temperature & Pressure Service

TP347H welded stainless steel pipes are high carbon, niobium-stabilized austenitic pipes engineered for enhanced creep strength and structural reliability in elevated temperature pressure systems.

Product Overview – ASTM A312 TP347H Welded Pipes

ASTM A312 TP347H is the high carbon version of 347 stainless steel. The increased carbon content improves high-temperature strength, while niobium stabilization prevents chromium carbide precipitation during welding and thermal exposure.
TP347H welded pipes are manufactured using precision ERW welding methods and are solution annealed, hydro tested, and inspected as per ASTM A312 specifications.

This grade is widely specified for superheaters, pressure vessels, refinery piping, and thermal power plant systems where elevated temperature performance and creep resistance are critical.
Compared to standard 347, TP347H offers improved strength retention under sustained high heat and pressure conditions.

Standard & International Identification - ASTM A312 TP347H Welded Pipes

Standard ASTM A312 / ASME SA312
Grade TP347H
UNS S34709
EN 1.4961

Technical Specifications – TP347H Welded Pipes

Pipe Type: Welded / ERW Stainless Steel Pipe
Available Sizes: 1/8″ NB to 36″ NB
Wall Thickness: SCH 5S to SCH 160
Standard Length: 6m, 12m, Custom Length
Surface Finish: Pickled, Annealed, Industrial Finish
Pipe Ends: Plain End (PE), Beveled End (BE)
Testing: Hydrostatic, Weld Seam Testing, PMI
Certification : EN 10204 3.1 / 3.2 MTC
Dimensional compliance: ASME B36.19M.

All specifications are in accordance of ASTM A312 / ASME SA312 standards. Mechanical and chemical values are as per standard limits. Mill Test Certificates (MTC) available upon request.

Chemical Composition of TP347H Welded Pipes

(As per ASTM specification)
ElementMax (%)
Carbon (C)0.04 – 0.10%
Manganese (Mn)2.00 %
Silicon (Si)1.00%
Phosphorus (P)0.045 %
Sulfur (S) 0.030 %
Chromium (Cr)17.0 – 19.0%
Nickel (Ni)9.0 – 13.0%
Niobium (Nb + Ta):10xC min to 1.00% max
Iron :Balance
Note: Higher carbon improves creep strength at elevated temperatures.

Mechanical Properties – TP347H Welded Pipes

PropertyMinimum Value
Tensile Strength≥ 515 MPa
Yield Strength≥ 205 MPa
Elongation35%
TP347H provides improved creep resistance and structural integrity in high-temperature applications.

High Temperature & Pressure Performance Advantages- ASTM A312 TP347H Welded Pipes

SS 347H welded pipes offer:

🔸 Enhanced creep strength
🔸 Reliable performance in high-pressure steam systems
🔸 Niobium stabilization for intergranular corrosion resistance
🔸 Good oxidation resistance at elevated temperatures

For refinery and thermal power systems operating under heat and pressure, TP347H is a preferred specification.

Major Industrial Applications of TP347H Welded Pipes

  • 🔸Thermal power plants
  • 🔸Boiler and superheater systems
  • 🔸Oil & gas refineries
  • 🔸Petrochemical units
  • 🔸Pressure vessels
  • 🔸High temperature steam lines

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Key Advantages of TP347H Welded Pipes

High carbon for elevated temperature strength Niobium stabilized structure Improved creep resistance Suitable for pressure-intensive environments Industrial and export-grade reliability

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Frequently Asked Questions

–ASTM A312 TP347H Welded Pipes

What is the difference between 347 and 347H?
347H has higher carbon content, providing improved high-temperature strength and creep resistance.
What sizes are available in TP347H ERW pipes?
Sizes typically range from 1/8″ NB to 36″ NB in various wall thicknesses as per ASME standards.
Is TP347H suitable for high-pressure steam systems?
Yes. It is widely used in superheater and pressure vessel applications.
What is the UNS number of SS 347H?
The UNS designation is S34709.
Can 347H welded pipes be used in refineries?
Yes. They are commonly specified for refinery and petrochemical piping systems.
Do you supply ASTM A312 TP347H welded pipes in India?
Yes. We supply and export TP347H welded stainless steel pipes from Mumbai with certified inspection reports.