Method for preventing scrap iron from backflushing in pressurized tapping new pipe connecting process of gas high-pressure pipeline

The invention discloses a method for preventing scrap iron from backflushing in a pressurized tapping new pipe connecting process of a gas high-pressure pipeline. The method comprises the following steps that step 1, parts are installed, specifically, a holding pipe of a tapping part is connected with a mother pipe, and a branch pipe of the tapping part is connected with a new pipe; step 2, part and new pipe pressure test is carried out, specifically, the fluctuation range of the operating pressure of the mother pipe is observed, and the maximum operating pressure of the mother pipe at the gas consumption peak is obtained according to the observation; step 3, a sandwich valve is installed, specifically, a blind plate is disassembled and the sandwich valve is installed; step 4, a tapping machine is installed; and step 5, the new pipe rises to the running pressure of the mother pipe. According to the method for preventing the scrap iron from backflushing in the pressurized tapping new pipe connecting process of