ASTM A312 Stainless Steel 347H Seamless Pipe Manufacturer

SS 347H Seamless Pipe Manufacturing Process

We manufacture 347H seamless stainless steel pipe by first taking a solid stainless-steel billet. Then, we heat and pierce/ extrude that billet to make a hollow shell. Later, it is rolled on a mandrel/plug or in an extrusion mill to get the required diameter. Once cold-drawing is done, the pipe goes through a solution-annealing process to dissolve precipitates and restore ductility. At the end, the pipe is pickled and straightened to prepare it for diameter checks and various quality tests.

What are the Key Features of 347H Stainless Steel Pipe

The 5 main characteristics that make 347H different from others are high-carbon content, stabilised alloy, high-temperature performance, enhanced creep resistance, and oxidation resistance.

• High-Carbon ("H" Grade): The high carbon content (0.04-0.10) in this pipe improves high temperature strength and creep resistance. This makes it suitable for many industries, which we will study in the coming section of applications.
• Stabilised Alloy: The stabilising elements (niobium and tantalum) present in this alloy make it more resistant to intergranular corrosion. This helps the pipe perform better in high-temperature environments.
• High-Temperature Performance: Due to the involvement of niobium (also known as columbium), the alloy remains stabilised. This prevents chromium carbide precipitation, which causes brittleness and corrosion at elevated temperatures.
• Enhanced Creep Resistance: The H in 347H alloy signifies higher carbon content. This, when combined with columbium, boosts strength and prevents creep when exposed to heat or stress.
• Oxidation Resistance: The 347H SS pipe has around 17 to 19% chromium. This helps the pipe to form a layer of oxide when it faces high temperatures. Due to this property, TP347H is extensively used in power plants and petrochemicals.