1. Sizes: 3-1/8 to 11 inches

2. Material: AISI 4145H

3. API Spec 7

Full-length heat-treatment processes ensure that mechanical propertiesmeet or exceed API Spec 7 requirements. Drill collar material and processtraceability are maintained from receipt of mills' certified raw material tocompletion of all the manufacturing. Serial numbers are die stamped on barbodies. Drill collar thread roots, as well as elevator recess upper radius, arecold-rolled. Cold rolling creates a compressive recess upper radius stresscondition that increases fatigue life by minimizing crack initiation. All tooljoint connections are phosphate-coated or copper plated to improve resistanceto corrosion. Optional slip and elevator recesses to improve handlingefficiency and safety are also available.