Command Tubular’s drill collars are made of modified AISI 4145H chromium molybdenum alloy steel. These drill collar bars are full-length heat treated and water quenched to obtain mechanical properties as specified by API Spec 7-1.
Full mechanical and chemical mill test certifications are supplied with all drill collars. These mill test certifications guarantee a hardness range of 285 to 341 BHN and an impact value of 40 ft-lbs at room temperature, one inch below surface.
All drill collar bars are trepanned then drifted to API specifications to ensure close tolerance bores. Drill collars are also supplied with the outer surface either machined or rough peeled.
All connections are precision-machined to API Spec 7-2 requirements. API relief groove pin and bore back box stress relief are available on request. Thread roots are cold-worked to offer a greater resistance to fatigue. At Command Tubular all connections are phosphate coated to minimize galling during makeup and thread storage compound is applied. Thread protectors are installed to ensure adequate joint protection during shipment.
Spiral Drill Collars
The spiral cut is added to a drill collar to prevent the likelihood of differential wall-sticking by reducing wall contact between the drill collar and the wall of the hole. The spiralling starts 22” from the bottom of the slip recess or 79” from the box end and ends 30” from the pin end. Adding spiralling to drill collars reduces the weight by approximately 4%.
Non-Magnetic Drill Collars
Command Tubular’s non-magnetic drill collars are an integral heavy duty joint that are constructed from a solid bar of austenitic stainless steel. Our non-magnetic drill collars are supplied with a machined surface finish condition.
All non-magnetic collars are hot/cold worked in order to provide them with the necessary mechanical properties. The bars are then trepanned, hot spot inspected and machined. An internal bore treatment is performed on the full length in order to achieve the proper compressive status of the internal diameter.
This provides the collar with optimal resistance to stress corrosion cracking. All of our drill collars are manufactured in accordance with API spec 7, Q1 and recommended practice 7G as applicable.
Slip and Elevator Recesses
Command Tubular offers slip and elevator recesses to improve handling efficiency and safety. Unless otherwise specified, slip and elevator recesses are machined in compliance with API RP7G latest edition guidelines and can be provided together or separately.
The five options for slip and elevator recesses’ for Command Tubular are:
- Slip Recess
- Slip and Elevator Recess
- API Configuration of 18” long slip recess
- Longer Elevator and Slip Recess with reduced OD’s
- One long recess with an 18 degree shoulder for use with drill pipe elevators