Product Introduction
2¼Cr (2.25% chromium) electric fusion welded steel pipe under ASTM A691 standard is an alloy steel pipeline product designed for high temperature and high pressure conditions. Its core requirements are as follows:
The steel pipe is made of 2¼Cr-1Mo alloy steel (equivalent to A335 P22 material), and the chemical composition must be strictly controlled: chromium content 2.00-2.50%, molybdenum content 0.90-1.10%, carbon content ≤0.15%, and sulfur and phosphorus content is limited to ≤0.025%. Strict mechanical properties are required, with a minimum yield strength of 310MPa (45ksi), tensile strength ≥585MPa (85ksi), elongation ≥20%, and hardness controlled at ≤250HBW to ensure welding performance.
The manufacturing process requires the use of electric fusion welding (EFW) method for production, and a complete heat treatment process must be carried out after welding: first normalizing treatment in the temperature range of 900-1000℃, followed by tempering in the range of 680-760℃, and additional post-weld heat treatment (PWHT) of 700-760℃ is required for welded joints. All welds must pass 100% radiographic testing (RT) or ultrasonic testing (UT), and the testing standards are implemented in accordance with ASME specifications.
The product must pass strict high-temperature performance tests, including 540℃ high-temperature tensile tests. Impact toughness requirements are: Charpy V-notch impact energy ≥54J (40ft-lbf) at room temperature. In terms of dimensional tolerance control, the outer diameter is allowed to deviate by ±0.5%, and the wall thickness tolerance is +19%/-8%.
ASTM A691 2¼Cr-1Mo steel pipe is particularly suitable for harsh environments with service temperatures of 450-600℃, such as refinery hydrogenation units and power station high-temperature steam pipelines. Its excellent resistance to high-temperature oxidation and creep makes it the preferred material for high-temperature and high-pressure conditions. The standard also requires manufacturers to provide complete heat treatment records and third-party inspection reports to ensure the reliability of materials under high-temperature and long-term service.
While ASTM A691 2 1/4CR CL42 offers excellent performance, it requires strict adherence to applicable specifications during use. Key considerations include:
Welding Control: During on-site installation and welding, the same welding procedures as those used at the factory must be used. Preheating is required before welding, and the welding materials must be compatible with the parent metal.
Temperature Limit: The upper temperature limit for ASTM A691 2 1/4CR CL42 is 540°C. However, prolonged use above this temperature can lead to Mo precipitation, reducing creep resistance and shortening service life.
Corrosion Protection: While inherently corrosion resistant, additional protection is required for use in extremely harsh environments to effectively prevent intergranular corrosion.
Periodic Inspection: After 3-5 years of use, wall thickness should be inspected to monitor for changes in wall thickness and hardness due to long-term use, indicating the need for timely replacement.
Frequent purchasers of ASTM A691 2 1/4CR CL42 know that price is influenced by many factors, including raw material costs, whose price fluctuations significantly impact the cost of steel pipe. Advanced production processes and strict quality control also contribute to price increases. Furthermore, the diameter, wall thickness, and length of ASTM A691 2 1/4CR CL42 pipe also affect price. Generally speaking, larger diameters, thicker walls, and longer lengths increase production complexity and material usage, leading to higher prices.
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