ASTM A358 EFW 347H Pipes

ASTM A358 EFW 347H Pipes

ASTM A358 EFW 347H Pipes are high-carbon, niobium (columbium) stabilized austenitic stainless steel pipes manufactured using the Electric Fusion Welding (EFW) process. The increased carbon content in 347H improves high-temperature strength and creep resistance compared to standard 347 grade.

These pipes are specifically developed for elevated temperature service in refineries, power plants, and chemical processing industries where enhanced mechanical strength and resistance to intergranular corrosion are essential.

Specifications

Standard	ASTM A358 / ASME SA358
Grade	347H
UNS Number	S34709
Manufacturing Process	Electric Fusion Welded (EFW)
Size Range	1/2" NB to 24" NB
Wall Thickness	Schedule 5S to Schedule 80S
Length	6 Meters Standard / Custom Length
Surface Finish	Annealed & Pickled, Polished, Matte Finish
End Type	Plain End, Beveled End, Threaded

Key Benefits

• Enhanced High-Temperature Strength: Higher carbon improves creep and stress rupture resistance.
• Niobium Stabilization: Prevents carbide precipitation and improves resistance to intergranular corrosion.
• Excellent Oxidation Resistance: Performs reliably in elevated temperature environments.
• Strong Weld Integrity: EFW manufacturing ensures uniform seam quality and durability.
• Long Service Life: Suitable for demanding refinery and power generation systems.

Chemical Composition (Typical)

Element	347H (%)
Carbon	0.04 – 0.10
Chromium	17.0 – 19.0
Nickel	9.0 – 13.0
Niobium (Columbium)	8xC Min – 1.00 Max

Applications

• Petroleum Refineries
• Boilers & Superheaters
• Heat Exchangers
• Power Generation Plants
• High-Temperature Chemical Processing

Quality Testing

• Hydrostatic Testing
• Ultrasonic Testing (UT)
• Radiographic Testing (RT)
• PMI Testing
• Dimensional Inspection

Conclusion

ASTM A358 EFW 347H Pipes provide superior high-temperature strength, excellent oxidation resistance, and dependable welded construction. Their high-carbon niobium-stabilized composition ensures reliable long-term performance in critical elevated temperature applications.