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A335 P11

ASTM A335

PipelineASTM Alloy Pipe

A335 P11 is a pipeline steel (Alloy Pipe family) to ASTM A335. It has a specified 0.2 % proof stress of 205 MPa and a typical tensile strength of about 415 MPa, with a uniform elongation of 30 %. Nominal carbon content is around 0.05 %. For nonlinear FEA, a bilinear model uses E = 210 GPa up to yield and a tangent modulus of 707 MPa above it. It is a general-purpose wrought steel selected on strength, cost and availability.

0.2% proof Rp0.2
205MPa
UTS Rm (typ)
415MPa
Uniform elong. εu
30.0%
Condition / basis
seamless, Cr-Mo

Bilinear material model — nonlinear FEA

Elastic modulus E
210GPa
0.2% proof Rp0.2
205MPa
UTS Rm (typ)
415MPa
Tangent modulus Et
707MPa

Uniform elongation εu = 30.0% · conservative analysis limit ½εu = 15.0%

Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.

Ratings — engineering judgement

Weldabilitygood

Low carbon (~0.05%) gives good weldability by all common processes; preheat rarely needed in thin sections.

Machinabilitymoderate

Soft and gummy at low carbon — sharp tooling helps surface finish.

Corrosion resistancepoor

No inherent corrosion resistance — protect by paint, galvanising or plating in exposed use.

Hardenabilitylow

Limited hardenability at low carbon — surface hardening is possible but through-hardening is not.

Toughnessmoderate

Adequate toughness for general use at ambient temperature.

Indicative ratings derived from composition and family — engineering guidance, not specification values.

Physical properties

Density7850kg/m³
Elastic modulus210GPa
Shear modulus80.8GPa
Poisson's ratio0.30
Thermal expansion12.0×10⁻⁶/°C
Thermal conductivity48W/(m·K)
Specific heat470J/(kg·K)
MagneticYes

Typical values for astm alloy pipe steel — use the mill certificate for the specific product.

Chemical composition (wt %)

C
0.05–0.15
Si
0.50–1.00
Mn
0.30–0.60
Cr
1.00–1.50
Mo
0.44–0.65

Typical composition per ASTM A335.

Available forms

pipeexcellent
seamless & welded line pipe
Primary form to the line-pipe standard.
plategood
for welded pipe
Coil/plate feedstock for pipe making.

Common applications

  • Oil and gas transmission line pipe
  • Water and slurry pipelines
  • Structural and pressure piping

History

The chromium-molybdenum (and later high-chromium) creep-resisting steels were developed for power-station boilers and refinery reactors that run red-hot for decades — chromium for oxidation and hydrogen resistance, molybdenum (and vanadium/niobium) for creep strength. EN 10028-2/EN 10302 and ASTM A335/A213 carry the family.

  1. 1930
    Cr–Mo steels adopted for high-temperature boiler and refinery service
  2. 1970
    2¼Cr–1Mo (10CrMo9-10 / P22) becomes the refinery workhorse
  3. 1985
    Modified 9Cr–1Mo (Grade 91) enables higher-efficiency supercritical plant

This profile is generated from the grade's core data and family. Composition is decoded from the designation where its naming system defines it; physical properties are family-typical and ratings are indicative. Confirm critical values against the governing standard or the mill certificate. Equivalents, historical designations and hand-written expert notes are added per grade over time.