Check that the entire circumference of the pipes at both ends of the pipe fittings should have scraping marks; check that the melt during the fusion process does not seep out of the pipe fittings; check that the pipe fittings should be in the middle of the positioning lines of the pipes on both sides; check that the fusion indicator pin (if there is such a device) has been raised; ; Check that the pipes and fittings are aligned.
