Views: 5 Author: Site Editor Publish Time: 2025-07-07 Origin: Site
The ASTM A335 alloy steel pipes standard is a very important standard specification that covers seamless ferritic alloy steel pipes for use in high temperature environments. These tubes are popular for their excellent high-temperature strength, creep resistance, and resistance to a wide range of corrosive media, and are widely used in demanding industries such as power, petrochemical, and refining.
ASTM A335 is the American Society for Testing and Materials (ASTM) standard for seamless ferritic alloy steel pipe for high-temperature service, known as Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High- Temperature Service. Temperature Service). The standard covers a variety of alloy steel pipe, different types of alloy steel pipe by adding chromium (Cr), molybdenum (Mo), vanadium (V) and other alloying elements, giving the pipe special properties to meet the petroleum, chemical, electric power and other industries in the use of high-temperature and high-pressure environment needs. Contact us
Processing Method: | Seamless and Welded |
Size Range | 1/8” - 48” / DN6 - 1200 |
Thickness Schedule | SCH 20- SCH 160, XXS |
Length | 6m or 12 m or Random |
Standard | ASME B36.10 |
Surface Treatment | Blasting and Painting, Epoxy Powder FBE, 2PE, 3PE Coating |
Material Grade | ASTM A335 P11 / P12 / P 5 / P9 / P91/ P92, A213 T11 / T12 / T22 / T5 / T9 / T91 / T92. 15CrMoG, 12Cr1MoVG, 12Cr5Mo, 1Cr5Mo, Cr9Mo, 10CrMo910, 12CrMo4-5 |
This specification covers nominal wall and minimum wall seamless ferritic alloy-steel pipe intended for hightemperature 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.
Note 1: Ferritic steels in this specification are defined as low- and intermediate-alloy steels containing up to and including 10 % chromium.
(A) New designation established in accordance with Practice E527 and SAE J1086, Practice for Numbering Metals and Alloys (UNS).
(B) Grade P 5c shall have a titanium content of not less than 4 times the carbon content and not more than 0.70 %; or a columbium content of 8 to 10 times the carbon content.
(C) Alternatively, in lieu of this ratio minimum, the material shall have a minimum hardness of 275 HV in the hardened condition, defined as after austenitizing and cooling to room temperature but prior to tempering. Hardness testing shall be performed at mid-thickness of the product. Hardness test frequency shall be two samples of product per heat treatment lot and the hardness testing results shall be reported on the material test report.
1. Carbon (C)
Carbon is a key element in determining the basic properties of steel. In the production of ASTM A335 alloy steel pipes, according to the requirements of the use of steel pipe, precise control of carbon content, to ensure the strength at the same time, taking into account the toughness and welding performance.
2. Silicon (Si)
Silicon in the ASTM A335 alloy steel pipes mainly as a deoxidizer exists, silicon has a certain ability to improve the antioxidant steel, it can promote the formation of a dense layer of oxidation film on the surface of steel, slowing down the oxidation rate of steel in the high temperature environment.
3. Manganese (Mn)
Manganese is also commonly used as a deoxidizer and alloying element. In terms of performance enhancement, manganese expands the austenite zone and increases the strength and toughness of steel. The right amount of manganese can refine the grain, so that the organization of the steel is more uniform, thus improving the overall mechanical properties of steel.
4. Phosphorus (P)
phosphorus in the ASTM A335 alloy steel pipes belongs to the harmful elements, its content is strictly limited, phosphorus can be dissolved in ferrite, resulting in a strong solid solution strengthening effect, to a certain extent, to improve the strength and hardness of steel.
5. Sulfur (S)
Sulfur is also ASTM A335 alloy steel pipes in the harmful elements, in order to reduce the harm of sulfur, in addition to strict control of its content, but also through the addition of manganese, so that manganese and sulfur combined to form a high melting point of manganese sulfide (MnS), to improve the hot working properties of steel.
6. Chromium (Cr)
Chromium is the key element that gives ASTM A335 alloy steel pipes excellent oxidation and corrosion resistance. Chromium in the steel surface can react with oxygen to generate a dense layer of oxide film (Cr₂O₃), this layer of oxide film has good chemical stability and barrier, can effectively prevent oxygen and other corrosive media and steel matrix contact, thus significantly improving the antioxidant and corrosion resistance of steel.
7. Molybdenum (Mo)
Molybdenum in the ASTM A335 alloy steel pipe is mainly used to enhance the high temperature strength and creep resistance. Each in the process of long-term service at high temperatures, steel is prone to creep deformation, and the presence of molybdenum can effectively inhibit creep, improve the reliability of the steel pipe at high temperatures and high pressures.
Grade | P-5 | P-9 | P-11 | P-12 | P-22 | P-91 | P-91 shall also include the following: | |
Element | UNS Designation | K41545 | S50400 | K11597 | K11562 | K21590 | K91560 | |
Carbon | 0.15 max | 0.15 max | 0.05 - 0.15 | 0.05 - 0.15 | 0.05 - 0.15 | 0.08 - 0.12 | V at 0.18 - 0.25 | |
Manganese | 0.30 - 0.60 | 0.30 - 0.60 | 0.30 - 0.60 | 0.30 - 0.61 | 0.30 - 0.60 | 0.30 - 0.60 | N at 0.030 - 0.070 | |
Phosphorous, max | 0.025 | 0.025 | 0.025 | 0.025 | 0.025 | 0.02 | Ni at 0.40 max | |
Sulfur, max | 0.025 | 0.025 | 0.025 | 0.025 | 0.025 | 0.01 | Al at 0.02 max | |
Silicon | 0.50 max | 0.25 - 1.00 | 0.50 - 1.00 | 0.50 max | 0.50 max | 0.20 -0.50 | Cb at 0.06 - 0.10 | |
Chromium | 4.00 - 6.00 | 8.00 - 10.00 | 1.00 - 1.50 | 0.80-1.25 | 1.90 - 2.60 | 8.00 - 9.50 | Ti at 0.01 max | |
Molybdenum | 0.45 -0.65 | 0.90 - 1.10 | 0.44 - 0.65 | 0.44-0.65 | 0.87 - 1.13 | 0.85 - 1.05 | Zr at 0.01 max | |
Seamless | ||||||
P-5 | P-9 | P-11 | P-12 | P-22 | P-91 | |
Tensile Strength, min., psi | ||||||
ksi | 60 | 60 | 60 | 60 | 60 | 85 |
MPa | 415 | 415 | 415 | 415 | 415 | 585 |
Yield Strength, min., psi | ||||||
ksi | 30 | 30 | 30 | 32 | 30 | 60 |
MPa | 205 | 205 | 205 | 220 | 205 | 415 |
P-91 | |
Tensile Strength, min., psi | |
ksi | 85 |
MPa | 585 |
Yield Strength, min., psi | |
ksi | 60 |
MPa | 415 |
P91 shall not have a hardness not exceeding 250 HB/265 HV [25HRC].
High Temperature Performance
ASTM A335 alloy steel pipe has excellent high temperature performance. Under high temperature environment, it can maintain high strength and hardness, and effectively resist creep deformation.
Mechanical Properties
At room temperature, ASTM A335 alloy steel pipe also has excellent mechanical properties. Its tensile strength, yield strength and elongation indicators are better than ordinary carbon steel.
Corrosion Resistance
Due to the addition of alloying elements, ASTM A335 alloy steel pipe in a variety of corrosive environments show good corrosion resistance. The oxidized film on its surface and the synergistic effect of alloying elements, preventing the corrosive medium and the steel matrix contact, extending the service life of the pipe.
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.
NPS [DN] Designator | Over | Under | ||
in. | mm | in. | mm | |
1/8 to 1 1/2 [6 to 40], incl. | 1/64 (0.015) | 0.4 | 1/64 (0.015) | 0.4 |
Over 1 1/2 to 4 [40 to 100], incl. | 1/32 (0.031) | 0.79 | 1/32 (0.031) | 0.79 |
Over 4 to 8 [100 to 200], incl. | 1/16 (0.062) | 1.59 | 1/32 (0.031) | 0.79 |
Over 8 to 12 [200 to 300], incl. | 3/32 (0.093) | 2.38 | 1/32 (0.031) | 0.79 |
Over 12 [300] | +/- 1% of the specified outside diameter | |||
NPS [DN] Designator | Tolerance, % from Specified | |
Over | Under | |
1/8 to 2 1/2 [6 to 65] incl., all t/D ratios | 20.00% | 12.50% |
Above 2 1/2 [65], t/D < or = 5% | 22.50% | 12.50% |
Above 2 1/2 [65], t/D > 5% | 15.00% | 12.50% |
(t = Specified Wall Thickness; D = Specified Outside Diameter) | ||
1. Quantity (feet, metres, or number of lengths), | 7. Outside diameter and nominal wall thickness |
2. Name of material (seamless alloy steel pipe), | 8. Outside diameter and minimum wall thickness |
3. Grade (Table 1), | 9. Inside diameter and nominal wall thickness, and |
4. Manufacture (hot-finished or cold-drawn), | 10. Inside diameter and minimum wall thickness. |
5. Size using one of the following | 11. Length (specific or random), |
6. NPS and schedule number | 12. End finish (Ends Section of Specification A999/ A999M), |
Comparison of Alloy Steel Tubes with EN 10216-2
EN 10216-2 is a European standard for alloy steel tubes for pressure applications. Compared with ASTM A335 standard, EN 10216-2 standard has some similarity in the alloy composition system, but there are some unique features. In terms of performance requirements, EN 10216-2 standard pays more attention to the stability of mechanical properties and long-term service performance of steel pipe at different temperatures. In terms of production process and quality control, the two standards also have their own characteristics and requirements, and these differences reflect the level of industrial development in different regions and the characteristics of the technical standard system.
High-temperature and high-pressure steam pipes in the power industry
Petrochemical refining equipment
Boiler piping systems
Nuclear power plant heat exchangers
Ultra-supercritical power plant main steam and reheat steam pipelines
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