ASTM A213 TP347H / UNS S34709 Stainless Steel Seamless Tube Heat Exchanger Tube

Pickled And Annealed Stainless Steel Seamless Tube, ASME SA213 TP347H Heat Exchanger Tube

ASTM A213 TP347H stainless steel seamless tube, which is an austenitic stainless steel modified with the addition of columbium and tantalum. This modification enhances the tube's high-temperature strength and prevents sensitization and intergranular corrosion. Its used in high-temperature environments, such as in power generation plants, chemical processing industries, and oil refineries. They can withstand temperatures up to 1000°C (1832°F) without losing their mechanical properties. A213 TP347H seamless tubes undergo various inspection and testing procedures to ensure their quality and performance. These may include visual inspection, dimensional inspection, mechanical tests (such as tensile strength and hardness), and non-destructive tests (like ultrasonic testing or eddy current testing).

Chemical Composition of 347 Stainless Steel Pipes and Tubes

Resistance to Corrosion of 347 Stainless Steel Pipes and Tubes
General Corrosion
Alloys 321 and 347 offer similar resistance to general, overall corrosion as the unstabilized chromium nickels Alloy 304. Heating for long periods of time in the chromium carbide precipitation range may affect the general resistance of Alloys 321 and 347 in severe corrosive media.

In most environments, both alloys will show similar corrosion resistance; however, Alloy 321 in the annealed condition is somewhat less resistant to general corrosion in strongly oxidizing environments than annealed Alloy 347. For this reason, Alloy 347 is preferable for aqueous and other low temperature environments. Exposure in the 800⁰F to 1500⁰F (427⁰C to 816⁰C) temperature range lowers the overall corrosion resistance of Alloy 321 to a much greater extent than Alloy 347. Alloy 347 is used primarily in high temperature applications where high resistance to sensitization is essential, thereby preventing intergranular corrosion at lower temperatures.

Physical Properties of 347 Stainless Steel Pipes and Tubes
The physical properties of Types 321 and 347 are quite similar and, for all practical purposes, may be considered to be the same. The values given in the table may be used to apply to both steels.
When properly annealed, the Alloys 321 and 347 stainless steels consist principally of austenite and carbides of titanium or columbium. Small amounts of ferrite may or may not be present in the microstructure. Small amounts of sigma phase may form during long time exposure in the 1000⁰F to 1500⁰F (593⁰C to 816⁰C) temperature range.
The stabilized Alloys 321 and 347 stainless steels are not hardenable by heat treatment.
The overall heat transfer coefficient of metals is determined by factors in addition to thermal conductivity of the metal. In most cases, film coefficients, scaling, and surface conditions are such that not more than 10 to 15% more surface area is required for stainless steels than for other metals having higher thermal conductivity. The ability of stainless steels to maintain clean surfaces often allows better heat transfer than other metals having higher thermal conductivity.

Mechanical Properties of 347 Stainless Steel Pipes and Tubes
Room Temperature Tensile Properties
Minimum mechanical properties of the stabilized Alloys 321 and 347 chromium-nickel grades in the annealed condition (2000⁰F [1093⁰C], air cooled) are shown in the table.
Elevated Temperature Tensile Properties
Typical elevated temperature mechanical properties for Alloys 321 and 347 sheet / strip are shown below. Strength of these stabilized alloys is distinctly higher than that of non-stabilized 304 alloys at temperatures of 1000⁰F (538⁰C) and above.

High carbon Alloys 321H and 347H (UNS32109 and S34700, respectively) have higher strength at temperatures above 1000⁰F (537⁰C). ASME maximum allowable design stress data for Alloy 347H reflects the higher strength of this grade in comparison to the lower carbon Alloy 347 grade. The Alloy 321H is not permitted for Section VIII applications and is limited to 800⁰F (427⁰C) use temperatures for Section III code applications.

Heat Treatment of 347 Stainless Steel Pipes and Tubes
The annealing temperature range for Alloys 321 and 347 is 1800 to 2000⁰F (928 to 1093⁰C). While the primary purpose of annealing is to obtain softness and high ductility, these steels may also be stress relief annealed within the carbide precipitation range 800 to 1500⁰F (427 to 816⁰C), without any danger of subsequent intergranular corrosion. Relieving strains by annealing for only a few hours in the 800 to 1500⁰F (427 to 816⁰C) range will not cause any noticeable lowering in the general corrosion resistance, although prolonged heating within this range does tend to lower the general corrosion resistance to some extent. As emphasized, however, annealing in the 800 to 1500⁰F (427 to 816⁰C) temperature range does not result in a susceptibility to intergranular attack.For maximum ductility, the higher annealing range of 1800 to 2000⁰F (928 to 1093⁰C) is recommended.

Here are some advantages of stainless steel 347H:

1. High Temperature Resistance: One of the significant advantages of stainless steel 347H is its excellent resistance to high temperatures. It can withstand prolonged exposure to elevated temperatures without losing its mechanical strength and corrosion resistance. This makes it suitable for applications in heat exchangers, furnace components, and other high-temperature environments.

2. Improved Creep and Stress Rupture Properties: Stainless steel 347H exhibits improved creep and stress rupture properties compared to standard austenitic stainless steel grades. This means it can withstand higher stress and load for longer periods without deformation or failure, making it suitable for applications involving sustained high temperatures and mechanical stresses.

3. Enhanced Corrosion Resistance: Stainless steel 347H offers better corrosion resistance compared to standard austenitic stainless steel grades like 304 and 316. It contains a higher amount of chromium, which forms a protective oxide layer on the surface, providing excellent resistance to corrosion from many corrosive substances, including acids, alkalis, and chloride environments.

4. Resistance to Sensitization and Intergranular Corrosion: Sensitization is a phenomenon where chromium carbides can precipitate at grain boundaries during certain high-temperature processes, leading to intergranular corrosion and reduced corrosion resistance. Stainless steel 347H contains niobium (columbium) and tantalum, which form stable carbides, preventing sensitization and intergranular corrosion.

5. Weldability: Stainless steel 347H exhibits good weldability and can be easily welded using standard welding techniques and processes. This makes it convenient for fabricating complex structures and components that require welding during the manufacturing process.

6. Versatility: Stainless steel 347H offers versatility in terms of its range of applications. It is commonly used in industries such as chemical processing, petrochemical, oil and gas, power generation, and aerospace, where high-temperature and corrosion resistance are required.

Application

1. Petrochemical Industry

2. Power Generation

3. Heat Exchangers

4. Boiler Tubes

5. Chemical Processing