Product List

Inspection of Alloy Steel Pipes

Outer Diameter and Wall Thickness: Measurements are taken using a Vernier caliper or micrometer, typically at multiple points across different cross-sections of the tube to ensure accuracy. Some modern production lines utilize automated inspection equipment for continuous measurement.

Length: Measurements are taken using a steel tape measure to ensure the tube length meets order specifications.

End Faces: Inspect the beveled edges and cuts at both ends of the tube to ensure they are flat, smooth, and free of burrs.

Spectral Analysis: Spectral analysis is a non-destructive testing method used to determine the chemical composition of alloy steel tubes. By analyzing the content of specific elements in the steel, it can be confirmed whether it meets the grade standards.

Wooden box packaging: Wooden box packaging is primarily used to protect alloy steel tubes during long-distance transportation, especially during sea transport. For tubes with special surface treatments or precision components, the interior of the wooden box is filled with cushioning materials such as foam or bubble wrap to prevent the tubes from colliding with each other.

ASTM A335 Alloy Steel Pipe Specification

ASTM A335 Alloy Steel Pipe Chemical Composition

Tensile Requirements of Alloy Steel Pipes 

ASTM A335 Standard Ordering Information

Orders for material under this specification should include the following, as required, to describe the desired material adequately:

1. Quantity (feet, metres, or number of lengths),

2. Name of material (seamless alloy steel pipe),

3. Grade (Table 1),

4. Manufacture (hot-finished or cold-drawn),

5. Size using one of the following

6. NPS and schedule number

7. Outside diameter and nominal wall thickness

8. Outside diameter and minimum wall thickness

9. Inside diameter and nominal wall thickness, and

10. Inside diameter and minimum wall thickness.

11. Length (specific or random),

12. End finish (Ends Section of Specification A999/ A999M),

Alloy Steel Pipe Dimension

What is ASTM A335 Material?

ASTM A335 is a standard for seamless alloy steel pipes established by the American Society for Testing and Materials (ASTM), primarily used in pipeline systems operating under high-temperature and high-pressure conditions. This standard covers various grades of chromium-molybdenum alloy steel, such as P1, P5, P9, P11, P22, P91, etc., which exhibit excellent high-temperature strength, creep resistance, and corrosion resistance. They are widely applied in fields such as power plant boilers, petrochemical plants, refining facilities, and heat exchangers.

Advantages of Alloy Steel Pipes

High Strength and Toughness: Alloying elements significantly increase the yield strength and tensile strength of steel pipes, enabling them to withstand higher pressures and loads. At the same time, they maintain good toughness, making them less susceptible to brittle fracture.

Excellent High and Low-Temperature Resistance: Alloying elements enhance the pipe’s long-lasting strength and oxidation resistance at high temperatures, ensuring it retains excellent mechanical properties even at extremely low temperatures.

Excellent Corrosion Resistance: The addition of elements such as chromium and nickel significantly enhances the corrosion resistance of alloy steel pipes.

Wear Resistance: Some alloy steel pipes exhibit excellent wear resistance, effectively resisting erosion and wear caused by flowing media, extending their service life.

Applications of Alloy Steel Pipes

Oil and Gas Industry

Power Industry

Chemical and Pharmaceutical Industry

Aerospace and Automotive Industry

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ASTM A335 P91 alloy steel pipe is a highly specialized type of pipe widely used in high-temperature applications.

ASTM A335 / ASME SA335 Pipe named chrome moly pipe as they have a high level of Chromium and Molybdenum.

Chromium will increase oxidation resistance and provides high-temperature strength, along with the better tensile & yield strength and proper hardness at room temperature. When the chromium content increased more than 12%, it can be classified as stainless steel.

Molybdenum increases the overall strength, resistance, elasticity, hardenability and overall quality, moly ensures that the material is more resistant to softening, restrains the growth of grains and lessens the chances of embrittlement. It is the single additive that is responsible for the increase in high temperature resistance (to 540-750°C) and it also improves the corrosion resistance to steel.

What is a P91 pipe?

ASTM A335 P91 pipe is a type of high-temperature alloy steel pipe, used in applications requiring excellent strength and resistance to creep at elevated temperatures, commonly found in power plants for critical components like boilers and heat exchangers.

High-temperature application:

P91 is specifically designed to maintain strength at very high temperatures, making it suitable for extreme conditions in power generation.

Creep resistance:

This alloy has excellent resistance to “creep,” a phenomenon where a material slowly deforms under constant stress at high temperatures.

Chemical composition:

The “P91” designation refers to its primary alloying elements: 9% chromium and 1% molybdenum.

Standard specification:

P91 pipes are typically manufactured according to ASTM A335 standard.

What is ASTM A335 P91 material?

ASTM A335 P91 is a ferritic alloy steel that’s used for high-temperature applications. It’s also known as 9 Cr 1 Mo steel or chrome moly pipe.

Composition

Carbon, manganese, phosphorus, sulfur, silicon, chromium, molybdenum, vanadium, nitrogen, nickel, aluminum, columbium, titanium, and zirconium

Properties

High strength

Creep resistant

Resistant to corrosion, oxidation, and erosion

Can withstand temperatures up to 600 °C

Has a minimum yield strength of 415 MPa and a minimum tensile strength of 585 MPa

Uses power plants, chemical plants, and other industrial facilities.

Pipe types

Seamless pipes are drawn from a single billet of raw material

Welded pipes are welded from a strip or sheet

Other designations UNS #: K91560, ASME Specification alloy steel Pipes, and ASME SA335 Grade P91 Pipes.

Heat treatment

The pipes are normalized at 1500°C to enhance creep strength and durability

ASTM A335 P91 Pipe Specification

Standard Scope

This specification covers nominal wall and minimum wall seamless ferritic alloy-steel pipe intended for high-temperature service. Pipe ordered to this specification shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Selection will depend upon design, service conditions, mechanical properties, and high-temperature characteristics.

Materials and Manufacture

 Pipe may be either hot finished or cold drawn with the finishing treatment as required.

Heat Treatment:

All pipe shall be reheated for heat treatment and heat treated in accordance with the requirements of Table 2.

NOTE 3—It is recommended that the temperature for tempering should be at least 100 °F [50 °C] above the intended service temperature; consequently, the purchaser should advise the manufacturer if the service temperature is to be over 1100 °F [600 °C].

NOTE 4—Certain of the ferritic steels covered by this specification will harden if cooled rapidly from above their critical temperature. Some will air harden, that is, become hardened to an undesirable degree when cooled in air from high temperatures. Therefore, operations involving heating such steels above their critical temperatures, such as welding, flanging, and hot bending, should be followed by suitable heat treatment.

Alloy Steel P91 Pipes Chemical Composition

Alloy Steel P91 Pipe Mechanical Properties

ASTM A335 P91 Pipe Heat Treatment Requirements

What are the grades of ASTM A335?

ASTM A335 is a standard for seamless alloy steel pipes that come in many grades, including P1, P5, P9, P11, P22, P91, and P92. These pipes are used in many industries, including power plants, chemical plants, and nuclear reactors. 

Common grades 

P5: Used in the petrochemical industry

P9: Used in the petrochemical industry

P11: Used in power plants, nuclear reactors, and jet engines

P22: Used in power plants and chemical plants

P91: Used in power plants and chemical plants

P92: Used in high-pressure boilers for power generation

Properties

ASTM A335 pipes are made of chrome-molybdenum alloy steel, and are designed for high-temperature and high-pressure applications. They can be bent, flanged, and welded. 

ASTM A335 Chrome Moly Pipe Dimension

Permissible Variations in Outside Diameter of Alloy Steel Pipes

1) For pipe ordered to NPS [DN] or outside diameter, variations in outside diameter shall not exceed those specified .

2) For pipe ordered to inside diameter, the inside diameter shall not vary more than +/- 1 % from the specified inside diameter.

What is the difference between A335 P91 Type 1 and Type 2?

A335 P91 Type 1 and Type 2 are both grades of alloy steel pipe under the ASTM A335 standard, but the main difference lies in their chemical composition, with Type 2 generally having stricter limitations on elements like manganese, sulfur, silicon, and nitrogen, resulting in enhanced creep strength and making it better suited for high-temperature applications with sustained stress; essentially, Type 2 offers improved performance under extreme conditions compared to Type 1. 

Chemical Composition:

Type 2 has tighter tolerances on certain elements like manganese, sulfur, silicon, and nitrogen, leading to better creep resistance.

Application:

Type 2 is often preferred for applications requiring high creep strength, like power generation boilers and high-pressure pipelines operating at elevated temperatures.

Overall Performance:

While both types have excellent high-temperature strength and corrosion resistance, Type 2 generally performs better in demanding environments with sustained stress. 

Key Features

Alloy Steel Composition:

P91 is a ferritic alloy steel, meaning it contains chromium and molybdenum, among other alloying elements.

The “91” designation indicates its specific chemical composition, which includes approximately 9% chromium and 1% molybdenum.

These additions provide enhanced strength, corrosion resistance, and high-temperature performance.

High-Temperature Service:

This pipe is designed for use in environments with extremely high temperatures, making it ideal for power generation, petrochemical, and other industries.

It exhibits excellent creep strength, meaning it can withstand high stresses over extended periods at elevated temperatures without significant deformation.

Seamless Construction:

ASTM A335 P91 pipes are typically manufactured as seamless pipes, which provides superior strength and resistance to pressure.

This is very important for high pressure applications.

Applications:

– Power generation

– Petrochemical plants

– Oil and gas industry

– High-temperature piping systems.

Key Advantages

Enhanced Creep Strength:

P91’s composition allows it to maintain its strength at high temperatures, reducing the risk of failure.

Improved Corrosion Resistance:

The chromium content provides excellent resistance to oxidation and corrosion.

Long Service Life:

Its durability and high-temperature performance contribute to a long service life, reducing maintenance and replacement costs.

You can get an offer for products in below material forms:

-Pipe and Tube (EN 10216-5, ASTM A213, ASTM A249, A312, A790,)

-Forged Fitting and Flange (ASTM A182 , ASTM A105,ASTM B564 )

-Butt Weld Fittings (ASTM A234, ASTM A403,ASTM A815)

-Round bar , Billet (ASTM A276, ASTM A479)

– Plate, Sheet, Strip(ASTM A240, EN 10028-7, A480)

-Bolting, Nuts（ASTM A193, A194, A320）

ASTM A335 P91 Alloy Steel Pipe Exported Countries

We Export ASTM A335 P91 Alloy Steel Pipe to Saudi Arabia, United Arab Emirates, Qatar, Bahrain, Oman, Kuwait, Turkey, Egypt, Yemen , Syria, Jordan, Cyprus, Singapore, Malaysia, Indonesia, Thailand, Vietnam, South Korea, Japan, Sri Lanka, Maldives, Bangladesh, Cambodia, Argentina, Bolivia, Brazil, Venezuela, Colombia, Ecuador, Guyana, Paraguay, Uruguay, United States Of America, Canada, Mexico, Panama, Jamaica, Bahamas, Denmark, Norway, Germany, France,Italy, United Kingdom, Spain, Belgium, Greece, Czech Republic, Portugal, Hungary, Albania, Austria, Finland, Ireland, Croatia, Malta, Nigeria, Algeria, Angola, South Africa, Libya, Egypt, Sudan,  Europe, Africa, Asia, North America, South America, Middle East.etc

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