1. Cut the pipeline into shrimp sections by lofting, and then weld the shrimp sections together to obtain a 90-degree elbow;

2. Seal one end of the pipe, pour in another pile of clean and dry sand and beat it hard. After filling sand and tamping, seal the other end with a cork, knock it flat or weld it, and then bend the pipe to the required 90 degrees on the pile by heating and burning red.