Is Q235-B used for impact tests?

According to standard 10.5.6.5, when the shell material is Q235-B or C, it is not necessary to take impact specimens from the product’s welding test plates for impact testing. The reason is that the base material undergoes impact test inspections upon leaving the factory, and it has been proven that after the casing is manufactured, its impact performance meets the standard requirements; therefore, no such requirements are imposed regarding the sampling for impact tests.

The base material is the base material, and the weld is the weld! They should be two different things! Welded test plates should undergo impact testing!

The base metal does not require impact testing, while the weld impact testing should be determined based on the operating temperature.

How could this happen? Article 10.5.6 of GB150 refers to: (requirements for manufacturing product test plates and welded joints). Article 10.5.6.5 stipulates that the dimensions of the test plates and the requirements for sampling shall be in accordance with those specified in Appendix E (the standard appendix). If the shell material (Q235-B, except for C) has impact requirements, impact specimens should also be taken from the test plate for impact testing. My understanding is that, apart from (Q235-B, C) materials, if the shell material has impact requirements, impact specimens should also be taken from the test pieces for impact testing. This regulation should be quite clear, and the boiler inspection agencies here all recognize it. Why do you still want to do it?

According to 10.5.6.5, impact testing is not required for Q235-B steel plates; however, there is no such requirement regarding welds. Please advise

It is specified in either the Code of Practice or the Standard (I can’t remember exactly) whether an impact test is required based on the operating temperature.

Of course it’s easy to do; the material standards require it!

For the welding procedure qualification of Q235-B, retesting of the base material is required, including impact testing. Welding procedure qualification is carried out to verify the correctness of the welding process; although impact testing covers a narrower range of thicknesses, it includes more types of Class I steel. In the retesting of the base material, impact testing is an important criterion for determining compliance, as it serves to verify whether the mechanical properties of the material meet the required standards. Product welding test plates do not require impact testing (GB150 10.5.6)

Impact testing is not required for product test plates, but it is necessary for welding procedure qualification specimens.

Is there a basis for requiring impact tests on weld procedure qualification specimens? Why are the process evaluations and product test plates not consistent?

GB150 specifies clearly: 4.1.7. When the steel is used at temperatures below -20°C, impact testing shall be conducted. The allowable operating temperature for Q235B is 0~350°C, therefore an impact test is not required. Although the reports from steel plate manufacturers include impact values, those are required by material standards. Independent of the container. 4.2.7. Impact testing is required for certain combinations of material temperature and thickness, and Q235B is not included among them. 10.5.8. Impact requirements for product welding test plates do not apply to Q235B; the same applies to Article 78 of the Acceptance Criteria. The requirements for welding process qualification are the same as those for product test plates; impact testing is not required. (Of course, the factory is willing to do it; no one can stop them. The problem is that the design documents don’t specify what the test temperatures and acceptable criteria are – how can you determine those?) ) Conclusion: When used in pressure vessels, Q235B can only be employed at temperatures ranging from 0 to 350°C; when used for vessel shells, its thickness should not exceed 20 mm. Neither the Code for Pressure Vessels nor GB150 requires impact testing on its raw materials, product welding test plates, or welding procedure qualification test plates. If the design unit or the owner has special requirements for conducting impact tests, the impact temperature and acceptance criteria must be specified.