Drill Collars are the most important parts of all drilling string elements. The performance of drill collars will effect the efficiency of drilling. Shenlong's mission is to provide our clients with most cost-effective products, not only price, but also products' performance. So Quality is most valued in Shenlong. We assure every piece of Drill Collar leaving our facility conform to the requirements of API SPEC 7-1. When producing,Traceability are maintained from the receipt of raw material to completion of final products. Serial numbers are die-stamped on each bar body. During each manufacturing process, test and inspection are performed. We do Ultrasonic Testing and Magnetic Partical Testing before and after Heat Treatment. Specimen have been taken from each bar after heat-treatment to make Tensile Test and Impact Test. We assure the Mechanical Properties of our products comply with or exceed the requirements of API. All connections are made according to API SPEC 7-1 and are phosphate-coated to improve resistance to corrosion. API Stress Relief Pin and Boreback Box are available according to clients' requirements. We provide steel thread protector for free. In order to improve handling efficiency, We offer Slip Recess and Elevator Recess.