1. It is strictly prohibited to disassemble and disassemble the expansion flange at the pipeline construction site; It is strictly prohibited to stretch, press, shorten and expand at random. 2. The pipe at both ends of the telescopic valve shall be concentric, and the two flange surfaces of the p

1. Required equipmentA set of manual electric welding equipment, a handle angle grinder, an electric hammer, and a plane ruler.2. Preparation before welding1. Check and debug the equipment to ensure the normal operation of the equipment; 2. It is best to dry the φ4.0J402 electrode at 300℃-350℃ for o