Alloy Steel Tube ASTM A335 Chrome-Moly Alloy Seamless Pipe Grade P9 P22

Main Applications of ASTM A335 P9 Tubes

ASTM A335 P9 seamless tube is a ferritic heat-resistant alloy tube containing 9% chromium and 1% molybdenum. It can be used continuously at high pressure within 550～593°C, with excellent high-temperature oxidation resistance, high-temperature sulfide corrosion resistance and creep resistance. It is widely applied in thermal power, oil refining cracking, hydroprocessing and chemical high-temperature & high-pressure equipment.

1. Thermal Power Industry (Most Common Application)

•  Boiler superheater and reheater tube bundles

They heat saturated steam into high-temperature superheated steam under high temperature of 550–600°C and high pressure of 16–26 MPa.

• Main steam pipelines, headers and steam lead pipes

Large-diameter thick-walled P9 tubes connecting boiler outlets to steam turbines, serving as core high-temperature pressure-bearing pipelines of power generating units.

• High-pressure heaters and high-temperature sections of economizers.

2. Oil Refining & Steam Cracking Units

(1) Ethylene Steam Cracking Plants

• Outlet pipelines of cracking furnace radiation sections, quench pipelines and high-temperature fractionator pipelines;
• Transport high-temperature cracked oil and gas, and resist high-temperature sulfide corrosion.

(2) Hydroprocessing Units (Hydrocracking & Catalytic Reforming)

• Inlet and outlet pipelines of hydroreactors, furnace tubes of process heaters, and tube bundles of high-temperature heat exchangers;
• Tolerate high-temperature, high-pressure hydrogen and H₂S media, and perform much better than carbon steel and P22 in resisting hydrogen corrosion and hydrogen embrittlement.

(3) Delayed Coking & Fluid Catalytic Cracking (FCC) Units

• Furnace tubes of heaters, transfer lines and high-temperature side pipelines of fractionators;
• Deliver sulfur-containing residual oil and oil-gas at 450–520°C, and have far longer service life than ordinary carbon steel.

(4) High-temperature side pipelines of atmospheric and vacuum distillation units, asphalt heating pipelines.

3. High-temperature Equipment for Chemical & Coal Chemical Industries

• High-temperature reformer pipelines for ammonia and methanol synthesis plants;

• High-temperature heat exchangers, shell-and-tube heaters and tube bundles of waste heat boilers;

• High-temperature process pipelines for coal-to-liquid and coal-to-olefin projects.

4. Auxiliary Pipelines for Conventional Island of Nuclear Power Plants

High-temperature feedwater and auxiliary steam pipelines of the secondary loop of nuclear power plants, cooling medium transmission pipelines with stable anti-oxidation and anti-radiation properties.

5. Other High-temperature Industrial Scenarios

• Furnace tubes for metallurgical heating furnaces and heat treatment furnaces;

• Main high-temperature pipelines for thermal oil furnaces;

• High-temperature nozzles matched with pressure vessels, as well as supporting thick-walled fittings (elbows, tees, reducers of P9 material).

Comparison Table of A335 P9 / P22 / P91 Materials

Basic Chemical Composition & Maximum Long-Term Service Temperature

Chemical composition(%):

Mechanical properties: