Issues regarding the use of Q355E in GB/T9948-2025 within GB150
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GB150-2024 specifies that for Q345E as defined in GB6479, when the outer diameter is greater than 76 mm and the thickness is greater than 6.5 mm, an impact energy of 47 J at -40 degrees Celsius is required; whereas GB/T9948 only sets specific requirements for grades 10 and 20 of carbon steel pipes. Is it necessary for Q355E under GB/T9948-2025 to meet the impact requirements specified for Q345E? Should we still follow the relevant regulations regarding standard codes without indication of the year, and assume that GB150 does not have any special requirements for Q355E?
I think for 9948-2025, the energy absorbed in the low-temperature impact test of Q355E steel pipes is only 40 J
Q355 is not specified in 9948-2013, nor is it mentioned in GB/T150.2; therefore, for the new material standard, Q355 corresponds to the requirements outlined in 6479 – without the impact test requirement, which means the standards have been relaxed
When standards conflict, it is safer to follow the higher requirements; do not force compliance with GB/T150.