Q: What is the minimum zinc coating thickness for GB/T 3091 hot-dip galvanized welded pipes? A: For GB/T 3091 hot-dip galvanized welded pipes, the minimum zinc coating thickness is 86 μm (3.4 mils) for pipes with a nominal diameter ≤100 mm, and 100 μm (3.9 mils) for pipes with a nominal diameter >100 mm.
Q: Can GB/T 3091 welded pipes be used for underground water supply pipelines? A: Yes, GB/T 3091 hot-dip galvanized welded pipes are widely used for underground water supply pipelines because their zinc coating has excellent corrosion resistance against soil and groundwater.
Q: What is the difference between GB/T 3091 Grade Q235A and Q235B welded pipes? A: The main difference is the impact test requirement: Q235B requires a Charpy V-notch impact test at 20°C (minimum impact energy of 27 J), while Q235A does not require an impact test. Q235B is more suitable for low-temperature or dynamic load scenarios.
Q: What is the maximum operating temperature of ASTM A106 Grade B welded pipe? A: ASTM A106 Grade B welded pipe is designed for high-temperature service, with a maximum operating temperature of 427°C (800°F), making it suitable for boiler feedwater, steam, and high-temperature gas pipelines.
Q: Is ASTM A106 Grade C welded pipe a higher grade than Grade B? A: Yes, ASTM A106 Grade C has higher mechanical properties than Grade B: its minimum yield strength is 345 MPa (50,000 psi) (vs. 276 MPa for Grade B), and minimum tensile strength is 517 MPa (75,000 psi) (vs. 485 MPa for Grade B). It is used for higher temperature and pressure applications.
