1. What is the corresponding Chinese standard grade for ASTM A1011 Grade CS Type B welded pipe, and what are their differences in surface quality?
Answer: ASTM A1011 Grade CS Type B welded pipe (carbon steel hot-rolled welded pipe) corresponds to GB/T 3091 Q235B welded pipe in Chinese standard. In terms of surface quality, the two have differences: ASTM A1011 CS Type B allows slight surface defects (such as small scratches, pits) with a depth not exceeding 10% of the wall thickness, and has no strict requirements on surface roughness; GB/T 3091 Q235B has stricter requirements on surface quality, and surface defects such as scratches and pits are not allowed to exceed 5% of the wall thickness, and the surface roughness must meet the specified requirements. In addition, ASTM A1011 CS Type B is mainly used for general industrial and agricultural pipelines, while Q235B is more commonly used in domestic municipal and industrial pipelines with higher surface quality requirements.
2. Which Chinese standard welded pipe grade corresponds to ASTM A513 Grade 1 welded mechanical structural pipe, and what are their differences in formability?
Answer: ASTM A513 Grade 1 welded mechanical structural pipe corresponds to GB/T 6728 Q235B welded mechanical structural pipe in Chinese standard. In terms of formability, the two have obvious differences: ASTM A513 Grade 1 has excellent formability, can be bent, stamped and other forming processes without cracking, and is suitable for manufacturing mechanical parts, brackets and other structural parts that require complex forming; GB/T 6728 Q235B has good formability, but its bending and stamping performance is slightly worse than that of ASTM A513 Grade 1, and it is more suitable for manufacturing simple mechanical structural parts. In addition, ASTM A513 Grade 1 has higher requirements for the uniformity of the pipe's wall thickness, which ensures the stability of forming performance, while Q235B has more flexible requirements for wall thickness uniformity.
3. What is the corresponding relationship between API 5L X80 welded pipe and Chinese standard welded pipe, and what are their technical advantages in high-pressure long-distance pipelines?
Answer: API 5L X80 welded pipe corresponds to GB/T 9711.1 L690 welded pipe in Chinese standard. Both have significant technical advantages in high-pressure long-distance oil and gas pipelines: API 5L X80 has a minimum tensile strength of 800 MPa, a yield strength of not less than 555 MPa, high strength, high toughness and good weldability, which can reduce the wall thickness of the pipe, reduce construction costs, and improve the transportation efficiency of oil and gas; GB/T 9711.1 L690 has basically the same mechanical properties as API 5L X80 (tensile strength 720-860 MPa, yield strength ≥690 MPa), and is independently developed on the basis of API 5L standard, with better adaptability to domestic geological and climatic conditions, and higher requirements for low-temperature toughness (impact toughness at -20℃ ≥60 J), which is suitable for high-pressure long-distance pipelines in cold regions of China. In addition, both adopt advanced welding technology, ensuring the reliability and safety of the pipeline.
4. Does GB/T 9711.2 L290 welded pipe have a corresponding American Standard grade, and what are their differences in corrosion resistance?
Answer: GB/T 9711.2 L290 welded pipe (oil and gas transportation, sour service) corresponds to API 5L Grade B (sour service) welded pipe in American Standard. In terms of corrosion resistance, the two have differences: API 5L Grade B (sour service) has strict requirements on sulfur content (≤0.015%) and hydrogen-induced cracking (HIC) resistance, which is suitable for sour oil and gas (containing H2S) transportation pipelines; GB/T 9711.2 L290 also has HIC resistance requirements, but the sulfur content requirement is slightly lower (≤0.020%), and its corrosion resistance to sour gas is slightly worse than that of API 5L Grade B (sour service). L290 is more suitable for low-sulfur oil and gas transportation pipelines in China, while API 5L Grade B (sour service) is more suitable for high-sulfur sour oil and gas projects in international markets.
5. What is the corresponding Chinese standard grade for ASTM A333 Grade 3 welded pipe, and what are their differences in low-temperature impact performance?
Answer: ASTM A333 Grade 3 welded pipe (low-temperature carbon steel pipe) corresponds to GB/T 18984 10MnDG welded pipe in Chinese standard. In terms of low-temperature impact performance, the two have obvious differences: ASTM A333 Grade 3 can be used in low-temperature environments as low as -30℃, and the impact toughness requirement at -30℃ is not less than 27 J; GB/T 18984 10MnDG can be used in low-temperature environments as low as -35℃, and the impact toughness requirement at -35℃ is not less than 34 J. 10MnDG contains a certain amount of manganese and nickel elements, which have better low-temperature toughness than ASTM A333 Grade 3, while ASTM A333 Grade 3 has more stable performance in the range of -30℃ to -20℃. Both are used in low-temperature fluid transportation pipelines, such as cryogenic storage and transportation, cold region water supply pipelines.
