... 4.supplier of sinopec and petrochina 20/40 high grade proppant sand Intertek Refractories Co., Gongyi City, ... company has strong technical force and advanced production testing equipment, has a production plant of 40, ... types of technical personnel, has developed a high-density, medium density, low density and many ... 9 ≥9 ≤7.5 ≤100 ≤6.5Of testing equipment: To meet the demands of domestic oil Wells ...