alloy steel pipes

All you need to know about ASTM A335 P11 Seamless Pipes

What is Alloy Steel?

Different metallic and non-metallic elements are added to Carbon Steel in a particular amount, the properties of Carbon Steel change. We can change the percentages of alloying elements in steel to improve its properties over plain Carbon Steel.

Alloy steel can be further subdivided into

  • Low alloy steels: which have a total alloying material content of less than 5%.
  • High alloy steels: which have a total alloying material content of more than 5%.


The most popular alloy steel grade that you can come across is shown here.

ASTM A335 Pipes: Gr P1, P5, P11, P9 

ASTM A234 Wrought Fittings: Gr.WP5, WP9, WP11 

ASTM A182 Forged Fittings: F5, F9, F11


What are the different Grades of Alloy-Steel ASTM A335 Pipes

Alloy Steel includes steel grades from P1 to P5 as well as P9, P11, P12, and P91. P11 & P12 , P91 & P92 grades are widely used in Power Plants, whereas A335 grade P5 and P9 are mainly used in petrochemical industry.

What is Alloy A335 Pipes?

Alloy pipes are tubular with higher concentrations of alloying elements such as Molybdenum (Mo), Chromium (Cr), Nickel (Ni), and so on than normal carbon steel pipes.  ASTM A335 P11 Seamless Steel Pipes has a good tensile strength and fine resistance to high temperature and corrosion. This standard applies a Low Alloy  steel pipes with a total amount of alloying elements of less than 5%.The addition of higher percentages of alloying elements (for example, nickel and chromium) transforms steel into higher alloys such as Stainless Steel, Super Steel, Duplex Steel and Alloyed materials such as Hastelloy, Monel, Inconel and so on.

What is P11 Seamless Pipes?

P11 Seamless Pipe has a high concentration of Cr (chromium) and Mo (molybdenum). Chrome improves high temperature tolerance, and increases tensile yield, increases oxidation resistance and hardness at room temperature. Elasticity, Wear resistance, impact properties, and hardness of Mo (molybdenum) boots. It strengthens chromium’s resistance to softening, prevents grain forming, and reduces embrittlement.

P11 Seamless Pipe Chemical Composition

  • Molybdenum – 0.44% – 0.65%
  • Manganese – 0.30% – 0.60%
  • Phosphorus, max – 0.025%
  • Sulfur, max – 0.025%
  • Carbon – 0.05% – 0.15%
  • Silicon – 0.50% – 1.00%
  • Chromium – 1.00% – 1.50%

Alloy Steel ASTM A335 P11 Seamless Pipes Specifications

  • Yield Strength, Minimum – 30,000 (205)
  • Tensile strength, Minimum– 60,000 (415)

Applications of A335 P11 Seamless Pipes

Along with iron’s Ferrimagnetic properties, a few steel alloys in A335 P11 Seamless Pipes can be used in applications where magnetism reactions are essential. Which includes transformers and electric motors. P11 Seamless Pipe is also a common grade for a variety of applications, including:

  • Turbine blades of Jet Engine
  • Nuclear Reactors
  • Off-Shore Oil Drilling Companies
  • Power Generation
  • Heat Exchangers
  • Condensers
  • Petrochemicals
  • Gas Processing
  • Pharmaceutical Equipment
  • Chemical Equipment
  • Spacecraft
  • Sea Water Equipment

All you need to know about ASTM A335 P11 Seamless Pipes

by admin time to read: 2 min