1. First of all, it is best to punch or grind the groove of the eight-meter round pipe with 100 thick wall before welding, so that it can be welded through.

2. Secondly, secondary welding can be used and the downward welding method should be used. A groove or gap should also be left before welding.

3. Thin-walled pipes do not need to be beveled, they can be welded directly, so that they will not collapse.