First, Basic Characteristics of ASME SA-106Gr.B Steel Pipe
1. Standards and Applications of ASME SA-106Gr.B Steel Pipe
ASME SA-106Gr.B seamless steel pipe is produced in accordance with the American Society of Mechanical Engineers (ASME) standard SA-106/SA-106M and is Grade B. It is primarily used in piping systems operating in high-temperature and high-pressure environments, such as in the oil, gas, chemical, and power industries.
2. Chemical Composition of ASME SA-106Gr.B Steel Pipe
Carbon: ≤0.30% (controlled to 0.18%-0.25% in some applications), ensuring a balance between weldability and toughness.
Manganese: 0.29%-1.06% (typically 0.60%-0.90%), strengthening the ferrite matrix and improving strength and impact resistance. Phosphorus/Sulfur: ≤0.035%, strictly limited to prevent inclusion formation and ensure material purity.
Silicon: 0.10%-0.50%, deoxidizes and enhances steel strength.
Alloying Elements: Trace amounts of chromium, molybdenum, and other elements may be added to improve corrosion resistance and high-temperature strength.
3. Mechanical Properties of ASME SA-106Gr.B Steel Pipe
Tensile Strength: ≥415MPa (≥485MPa required in some applications), capable of withstanding the tensile forces of high-pressure fluids.
Yield Strength: ≥240MPa, ensuring only moderate plastic deformation under pressure.
Elongation: ≥22% (≥30% in some applications), imparting excellent toughness to the material and buffering impact energy.
Low-Temperature Toughness: Verified through impact testing, suitable for use in extreme environments ranging from -29°C to 565°C.
Second, NACE MR0175 Standard Requirements
1. Standard Background: NACE MR0175 is a standard developed by the National Association of Corrosion Engineers (NACE). Its full title is “Metallic Materials Resistant to Sulfide Stress Cracking for Oilfield Equipment.” In 2003, the standard was revised and renamed NACE MR0175/ISO 15156, “Petroleum and Natural Gas Industries—Materials for Use in H₂S-Containing Environments in Oil and Gas Production.”
2. Chemical Composition Limits:
- Sulfur Content: For seamless products, the sulfur content shall not exceed 0.01%; for rolled products (steel plates), the sulfur content shall not exceed 0.003%; for forged products, the sulfur content shall be less than 0.025%. Reducing the sulfur content in steel can increase resistance to sulfide stress corrosion.
- Phosphorus Content: Generally, phosphorus should be ≤ 0.020%. Excessive phosphorus content can reduce the toughness and corrosion resistance of the steel. – Carbon Content: Carbon content is generally required to be ≤0.10%. Excessively high carbon content increases the steel’s hardness and reduces its toughness, making it less resistant to sulfide stress corrosion cracking.
- Nickel Content: The nickel content in carbon steel and low-alloy steel is less than 1%. Excessively high nickel content may increase the steel’s susceptibility to sulfide stress corrosion cracking.
3. Mechanical Properties and Hardness.
- Hardness: The hardness of carbon steel and low-alloy steel should not exceed 22 HRC (Rockwell hardness). Forgings produced according to ASTM A105 should not exceed 187 HBW (Brinell hardness); for ASTM A234 WPB and WPC, the hardness should not exceed 197 HBW (Brinell hardness). The maximum hardness of the weld zone should not exceed 250 HV (Vickers hardness) or 22 HRC (Rockwell hardness).
- Strength: The tensile strength and yield strength should be consistent with those of general steel pipes in accordance with the relevant standards and must meet the mechanical property requirements under actual service conditions.
4. Heat Treatment and Manufacturing Process.
The base material should be non-free-machining steel and be in one of the following heat treatment conditions: hot rolling (carbon steel only), annealing, normalizing, normalizing and tempering, austenitizing, quenching, and tempering. Carbon steel and low-alloy steel should be subjected to stress relief heat treatment (not less than 595°C) after rolling, cold forging, or other manufacturing processes that result in permanent outer fiber deformation exceeding 5%. However, cold-worked line fittings of ASTM A53 B, ASTM A106 B, API 5L X42, or equivalent grades do not require heat treatment if the cold deformation does not exceed 15% and the hardness does not exceed 197 HBW.
Third, the integration of ASME SA-106Gr.B steel pipe with the NACE MR0175 standard.
1. Chemical composition adjustment: To meet the NACE MR0175 standard, ASME SA-106Gr.B steel pipe must further reduce sulfur and phosphorus contents and control the contents of elements such as carbon and nickel to improve resistance to sulfide stress corrosion cracking.
2. Mechanical property verification: The steel pipe’s mechanical properties, such as tensile strength, yield strength, elongation, and low-temperature toughness, are verified through tensile and impact tests to ensure stability in H₂S-containing environments.
3. Hardness control: The steel pipe’s hardness is strictly controlled to ensure it does not exceed 22 HRC (Rockwell hardness) to reduce the risk of sulfide stress corrosion cracking.
4. Heat treatment and manufacturing process optimization: According to the requirements of the NACE MR0175 standard, the steel pipe undergoes appropriate heat treatment (such as annealing, normalizing, and tempering) to eliminate internal stress, adjust hardness, and improve microstructure. At the same time, the manufacturing process is optimized to avoid excessive deformation during processing and reduce stress concentration.
Post time: Sep-23-2025