There are also many procedures for product quality inspection, such as anti-aging experiment, pressure resistance experiment, corrosion resistance experiment, Vicat softening experiment, short crack tensile experiment, heavy hammer impact experiment and so on.
Crushing experiment: 50% of the external diameter of the pipe is extruded according to the national standard (for example, the external diameter is 1 10, and the external diameter is extruded to 55), and 9 random samples of 10 are considered as qualified. Most of them are caused by the high proportion of recycled raw materials or calcium carbonate. If the unqualified products are put into use, they will be very brittle, and it is easy for some or even the whole coffin to crack.
Needless to say, pressure resistance! Too much trouble! Just 30 points is not worth it!