Oilfield Chain 1.Standards:ISO/ DIN/ ANSI 2.International Approvals:BV/ ISO/ ... API Approved Oil Field Chains : Why Choose Donghua Oilfield Chain ? 1. Hangzhou Donghua Chain Group Co., Ltd established in 1991, we have ... , driving chains, conveyor chains, dragging chains, agricultural chains; Oil field chain and so on;4. we have obtained ISO9001, ISO14001, ISO16969 ...