Overview of ASTM A335 P11 Alloy Steel Pipe

The ASTM A335 P11 alloy steel pipe is a seamless ferritic tube manufactured from low-alloy steel containing chromium and molybdenum. This specification falls under the ASME SA335 standard and is recognized globally for service in environments where carbon steel would suffer from premature failure due to heat exposure.

Grade P11 specifically refers to the 1.25Cr-0.5Mo composition. This material exhibits stable microstructure and mechanical properties when operated continuously within the temperature range of 400°C to 550°C. Unlike standard carbon pipes, the A335 P11 resists temper embrittlement and maintains tensile integrity under fluctuating thermal loads.

Engineers select this alloy for critical circuits where unexpected shutdowns carry high safety or financial risks. The seamless construction eliminates weld seam weakness, making it suitable for high-pressure fluid transmission including superheated steam, hot process liquids, and hydrogen-rich streams.

Features & Properties

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Creep Resistance: Maintains structural integrity under long-term heat exposure.

Oxidation Resistance: The Chromium layer prevents scaling up to 550°C (1022°F).

Weldability: Suitable for fusion welding with preheating (typically 150°C to 300°C) and post-weld heat treatment (PWHT).

Chemical Composition & Mechanical Properties

To meet the rigorous demands of high-pressure environments, the ASTM A335 P11 must adhere to strict chemical and mechanical standards. Below is the technical breakdown that engineers look for:

Chemical Composition

Element	Content (%)
Carbon (C)	0.05 – 0.15%
Manganese (Mn)	0.30 – 0.60%
Phosphorus (P)	≤ 0.025%
Sulfur (S)	≤ 0.025%
Silicon (Si)	0.50 – 1.00%
Chromium (Cr)	1.00 – 1.50%
Molybdenum (Mo)	0.44 – 0.65%

Mechanical Properties

Tensile Strength	Min 415 MPa (60,000 psi)
Yield Strength	Min 205 MPa (30,000 psi)
Hardness	≤ 85 HRB or ≤ 163 HBW

Applications: Where is A335 P11 Used?

If you are sourcing ASTM A335 P11 alloy steel pipe, you likely have one of the following applications.

Our material is field-proven in:

Power Plants

Superheater tubes, reheater tubes, and main steam lines.

Refineries

High-temperature crude oil transfer lines and catalytic reformers..

Chemical Fertilizer Plants

Synthesis gas (Syngas) piping.

Heat Exchangers

Shell and tube heat exchangers requiring chrome-moly strength.

Boiler Components

Headers and riser tubes.

Manufacturing & Standards

We ensure that every ASTM A335 P11 alloy steel pipe supplied complies with international quality control standards. Transparency in manufacturing guarantees that your project passes rigorous third-party inspections.

comparison of product parameters

Parameter	Specification
Dimension Standard	ASME B36.10M
Size Range	NPS 1/2″ to 24″ (DN15 to DN600)
Schedule	SCH 40, SCH 80, SCH 160 (Custom available)
Pipe Type	Seamless (Hot-finished or Cold-drawn)
Inspection	Hydrostatic test, Ultrasonic test (UT), Positive Material Identification (PMI), Hardness test, Intergranular corrosion test.
Certifications	EN 10204 3.1, NACE MR0175 (for H2S service), ISO 9001:2015

Why Choose Our ASTM A335 P11 Pipes?

With decades of experience in the steel trade, we understand that a failed pipe means costly downtime. Here is why procurement experts trust us:

1.Traceability

Every pipe comes with mill test reports (MTRs) traceable to the original heat number.

2.Stock Availability

We maintain a large inventory of A335 P11 in Schedule 40 and Schedule 80 for immediate shipment.

3.Value-Added Services

We offer precision cutting, beveling, threading, and heat treatment before delivery.

4.Third-Party Inspection

We welcome SGS, BV, or Lloyds inspections at our warehouse to verify your specifications.

Request a Quote for ASTM A335 P11 Alloy Steel Pipe

Don't compromise on safety and performance. Whether you need a standard 6-meter random length or custom dimensions, our team is ready to provide competitive pricing for high-quality ASTM A335 P11 alloy steel pipe.