This is a very good strategy, actually.
The key is NOT welding the door.
If you weld the door, he will shoot it with a rocket, detonating the pipes prematurely, and quite possibly killing you and all of your teammates in the process.
The rocket can detonate the pipes on the other side of the door, and if the door is closed when the rocket detonates, then even if the door breaks on the first shot, the damage from the pipes will not penetrate the door to his side.
If, however, you close, but DO NOT WELD the door, he will stand right up against the other side of the door and open it, causing the pipe bombs to go off immediately with him standing right on top of them