Working as a plumber to replace metal pipes with polymer ones during major overhauls, I developed certain skills for working with a grinder, and also absorbed the experience of my older comrades.
One of the operations to replace metal pipes is to dismantle it. Usually all pipes are welded, threaded connections are rare. Especially on the risers. And there is no point in unwinding stuck threads. Cutting an old pipe with a grinder is one of the fastest and most effective ways to remove old pipes.
An ordinary person, occasionally working with a grinder with a metal profile, might think: "What's so complicated, you cut out a pipe and that's it, metal and metal in Africa". But it was not there. One of the problems of risers and wiring in the apartment is their "tension":
During the initial installation, the pipe can be bent "cold" by a fitter or a welder and subsequently welded. That is, there is potential energy in the pipe, which tries to return it to its previous position upon release. We call such a pipe "energized".
One more point. If the installation of risers is carried out without sufficient fasteners, then the pipes from the last floors begin to put decent pressure on the pipes from the lower ones. Accordingly, there is also a "tension"
Therefore, when cutting out old pipes, two methods are used for safe work, now I will clearly demonstrate them to you. At the stand that has prepared for the readers of the channel.
First way:
Two cuts are made in the pipe, the pipe is not cut to the end.
3-4 mm of metal remains.
Further, this piece is gnawed out with a gas wrench.
Thus, pipes under load do not bite the disc. And it will not fly into the face, neck or body of the Fortune operator.
Second way
It should only be used by experienced locksmiths and welders who are fluent in angle grinders.
If in the first method two cuts were made, then in this the pipe is cut at a time, without working with a gas wrench.
The pipe is cut at an oblique angle, to the end.
If there was tension in the pipe. Bending, or closing, then such an angle allows the disc to jump out of the cut without consequences, preventing clamping, biting and subsequently scattering of the disc.
Why is this happening? Apparently the clamping area increases and the disc tolerates the impact well. In addition, the angular cut allows the load to pass tangentially.
For any work with angle grinders, protective equipment should be used. Overalls, masks, glasses. In addition, these methods should be used by experienced and confident users.
I am sure that this information has broadened your horizons in metalworking. In addition, I prepared a video for my subscribers about these methods. It will be released a little later. Not to be missed subscribe.