During splicing, only radial and circumferential weld directions are allowed. This requirement may be cancelled for large stainless steel pipe caps in the future. The splicing distance shall be greater than 3 δ, And not less than 100mm (the welding heat affected zone is a high stress zone, and the chemical composition in this zone will be burned. Therefore, it is necessary to avoid the high stress zone, which is related to the thickness. According to practical experience, the stress attenuation length is greater than 3 δ, And not less than 100mm). However, refrigeration equipment is difficult to meet this requirement, which has its particularity. For the head formed after splicing, the splicing weld shall be subject to 100% radiographic or ultrasonic testing, and the qualification level shall follow the equipment shell. The final formed weld detection level and proportion are the same as that of the equipment shell, which is high waste. Example: if the equipment shell is 20% tested, III is qualified.