UNS S34709 Pipe

1. Standard: ASTM A213, ASME SA312
2. Size: 1/2''~48''
3. Thickness: SCH5~SCHXXS
4. Service: Cutting, Welding, Fabricated, Customized

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Product Introduction

UNS S34709 pipe is an austenitic chromium-nickel stainless steel, stabilized by the addition of niobium and tantalum and by increasing the carbon content. The "H" suffix indicates high-temperature applications, with the carbon content controlled within the range of 0.04% to 0.10% to ensure higher strength at high temperatures. HT PIPE is a 347h stainless steel Pipe supplier with 15+ export experience. Contact us for more information and quotes for free!

We offers UNS S34709 pipe in a variety of forms, including:

Bar
Wire
Sheet
Plate
Forgings
Pipe fittings
Flanges
Seamless & Welded pipe
Seamless Tube & Welded tube
Weld Rod

Standards and Specifications of ss347h

ASTM A213/A213M: Standard specification for seamless tubes of ferritic and austenitic alloy steels for boilers, superheaters, and heat exchangers.

ASTM A269/A269M: Standard specification for seamless and welded tubes of austenitic stainless steel for general service.

ASTM A312/A312M: Standard specification for nominal tubes of seamless and welded austenitic stainless steel.

ASME SA213: This is the version adopted by the ASME Boiler and Pressure Vessel Code, which is crucial for pressure equipment.

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ASTM A312 TP347H Chemical Composition

Element	SUS 347H
Chromium	17.00 min.-19.00 max.
Nickel	9.00 min.-13.00 max.
Carbon	0.04 min.-0.10 max.
Manganese	2.00
Phosphorus	0.045
Sulfur	0.03
Silicon	0.75
Columbium & Tantalum	8 x (C + N) min.-1.00 max.
Iron	Balance

ASTM A312 Gr 347H Seamless Pipe Mechanical Properties

HeatTreatment		Solution
Temperure	Min.	1900 (1040) º F(º C)
Tensile Strength	Ksi (MPa), Min.	75(515)
Yield Strength	Ksi (MPa), Min.	30(205)
Elongation %, Min		35

Manufacturing Process of uns s34709 pipe

Seamless Tubes (SMLS): Manufactured from pierced round billets or extruded solid billets. Pipes produced using this process have no weld seams and exhibit uniform overall performance, making them the preferred choice for high-pressure and high-temperature applications.

Welded Pipes: UNS S34709 welded pipe are made by rolling and welding steel plates or strips. Welded pipes require cold rolling (cold working) and solution annealing to ensure the weld performance matches that of the base material. Welded pipes are generally less expensive than seamless pipes.

Comparison with Other Materials

Comparison with 304/304H: While 304H also has a high carbon content, it lacks stabilizing elements. Therefore, its resistance to intergranular corrosion is significantly lower than that of UNS S34709 pipe after welding or prolonged exposure to sensitization temperatures. 347H also exhibits superior high-temperature strength compared to 304H.

Comparison with 321/321H: 321H uses titanium (Ti) as a stabilizing element. Titanium may partially fail due to oxidation during welding, and titanium carbides may dissolve at very high temperatures, re-initiating the risk of sensitization. Niobium carbides, on the other hand, are more stable, making 347H more reliable during long-term high-temperature service.

Compared to 316/316H: 316H has added molybdenum (Mo), which improves its resistance to pitting and crevice corrosion, especially in chloride environments. However, for purely high-temperature creep-resistant applications, 347H is generally the better choice.