Stainless steel 304H seamless pipe is a high-carbon modification of Grade 304 manufactured under ASTM A312 as TP304H, with the UNS designation S30409. Its controlled carbon content of 0.04–0.10% provides improved creep and stress-rupture strength during elevated-temperature service. The chromium-nickel composition also provides useful oxidation resistance, general corrosion resistance, strength, and toughness.
Manufactured without a longitudinal weld seam, ASTM A312 TP304H seamless pipe is commonly selected for high-temperature pressure piping, refinery process lines, steam systems, furnace equipment, and power-generation installations. Unlike 304L, which is primarily selected to reduce the risk of intergranular corrosion after welding, 304H is intended for applications where long-term mechanical strength at elevated temperatures is the main material-selection requirement.

304H stainless steel seamless pipe begins with a solid TP304H billet whose controlled carbon content is verified before production. The billet is heated and pierced into a hollow section, then cold drawn or cold rolled to achieve the specified outside diameter and wall thickness. After forming, the pipe is solution annealed under controlled conditions to obtain the required microstructure and grain characteristics for elevated-temperature service. It is then straightened, cut to length, pickled, and inspected for dimensional accuracy, mechanical properties, and material traceability. Learn more in our stainless steel seamless pipe manufacturing process guide.
ASTM A312 TP304H seamless pipe is manufactured for elevated-temperature and general corrosive service. Its controlled carbon content and required material properties make it suitable for pressure piping where creep and stress-rupture strength are important.

1. Elevated-Temperature Strength

The controlled carbon content of TP304H helps the material retain useful
mechanical strength at elevated temperatures, making it suitable for
high-temperature pressure and process piping.

2. Creep and Stress-Rupture Resistance

Compared with 304 and 304L, Grade 304H provides improved creep and
stress-rupture performance during prolonged exposure to elevated temperatures
and sustained mechanical loads.

3. Oxidation and Corrosion Resistance

Its chromium-nickel composition provides good resistance to oxidation and
general corrosion in many industrial environments. Suitability should be
evaluated carefully for chloride-containing or strongly corrosive service.

4. Seamless Pressure Integrity

The seamless construction eliminates a longitudinal weld seam and provides a
continuous pipe wall, making TP304H seamless pipe suitable for demanding
high-temperature and pressure-bearing systems.

Why Choose us as Your 304H Stainless Steel Seamless Pipe Manufacturer & Supplier?

1. Extensive Inventory

We maintain approximately 2,000 tons of stainless steel products in commonly requested grades, sizes, and wall thicknesses. This inventory allows us to respond efficiently to urgent orders and different purchasing quantities.

2. In-House Manufacturing

With established production equipment, experienced workers, and controlled manufacturing processes, we produce 304 stainless steel seamless pipes according to applicable standards and customer specifications.

3. Reliable Lead Times

In-house production, available inventory, and coordinated production scheduling give us better control over order progress. Lead times are confirmed according to the required size, quantity, testing, and finishing requirements.

4. Quality Assurance and Documentation

Our quality team conducts material verification, dimensional inspection, and applicable mechanical and nondestructive testing. EN 10204 3.1 inspection certificates and heat-number traceability can be provided with each order.

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