This standard specifies the technology and acceptance level for using magnetic particle testing methods to detect surface defects in welds of ferromagnetic materials (including heat-affected zones). Appendix A describes basic technical factors that can provide higher or lower detection sensitivity. Appendix B recommends acceptance levels for display. More information on indicating acceptance levels can be found in the product or application standards. The basic rules that should be followed when applying non-destructive testing specified in GB/T 5616 apply to this standard.