Drill Collar is manufactured from AISI 4145H modified quenched and tempered steel and is heat treated along its entire length for uniform toughness and durability. Strict metallurgical tests are performed per specifications to ensure that the heat treatment produces consistent and maximum hardness through the depth of the bar.
A hardness range of 285 to 341 BHN and a Charpy impact value of 40 ft-lbs are guaranteed for evenly distributed 16 points in any cross sections at room temperature;
Connections are phosphate coated after machining to protect the threads from corrosive elements and to prevent galling upon initial make-up;
Thread roots are cold rolled on API and H-90 connections;
Pressed steel thread protectors are supplied for all drill collar that are equipped with standard connections