... 4.supplier of sinopec and petrochina 20/40 high grade proppant sand Intertek Refractories Co., Gongyi City, ... types of technical personnel, has developed a high-density, medium density, low density and many ... 30 / 50 mesh and other specifications, product quality inspection by the authority of the department are up ... number of oil units, due to excellent quality, our products get the user units alike ...