In the second half of 2016, Jiangsu administrative bureau for industry and commerce organised an inspection in the circulation domain in Jiangsu province. The inspected samples includes all the pipes and fitting parts of PVC-U pipe systems. The products of Tonzo are all qualified during this inspection.

The inspection was based on the standard of GB/T5836.2-2006 "hard polyvinyl chloride (PVC-U) pipes for drainage in buildings" and GB/T5836.1-2006 "building drainage with a hard polyvinyl chloride (PVC-U) pipe" . Huaian, Nantong, Suzhou, Taixing, Taizhou, Suqian, Yangzhou and other 7 cities were involved. And the values of size, density, VEKA softening temperature, etc. were inspected.