Drill collar

A component of a drill string that provides weight on bit for drilling. Drill collars are thick-walled tubular pieces machined from solid bars of steel.

All our equipment is manufactured to conform to NS-1™ and can support any NS-2 ™, DS1 cat 3-5 and API operations. Ongoing investment in new equipment enables HEMS to provide rental equipment that is in immaculate order and within spec. Our Drill Collars are manufactured from Non Magnetic and AISI 4145 H-MOD 30-36RC material in Slick, Spiral and Flexi profile.

Drill collars are extremely heavy duty industrial tubulars used to drill into the ground, and are used in conjunction with drill pipe. While drill pipe makes up the majority length of a drill string, drill collars make up only a small amount. For example: a 10,000ft drill string may be comprised of 9,000ft of drill pipe, and only 500ft of drill collars. Much like drill pipe, drill collars are made in 31ft lengths and are screwed together vertically on the drilling rig. In contrast to drill pipe, drill collars are thick walled and heavy, with very limited flexibility. Drill collars are used at the bottom of the drill string, just above the drill bit. They are used mainly for weight on the drill bit but also work as a shock absorber to dampen the vibrations and impact forces caused by drilling. There are two main types of drill collars, slick or spiral grooved, however both styles accomplish the same task. Spiral groove drill collars were introduced in more recent years and are thought to help prevent the drill string from getting stuck in the hole by allowing drilling debris and lubricant to pass more freely around the drill collar.


We provides a full range of slick and spiral drill collars manufactured in AISI 4145H-modified steel, Sour Service and Arctic Grades and non-magnetic alloys. Drill collars are available with the following features:

  • ODs from 2-7/8" to 14"
  • Slick or spiral
  • Mechanical properties guaranteed to 1" below the steel's surface at ambient temperature
  • Enhanced fatigue resistance (threads cold rolled, pin-relief groove and box bore back for API  connections)
  • Phosphate-coated threads to prevent galling
  • Slip & elevator recess
  • API stress-relief and bore back
  • Hardbanding and internal plastic coating upon request
  • Proprietary connections optional
  • Pressed steel thread protector
  • NS-1 & DS-1


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 Energy 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 Energy’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 Energy 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 Energy are:

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