Normal Drill Collars
Drill Collars are integral heavy wall joints that are manufactured from a solid bar of modified alloy steel. The solid bars are quenched and tempered to obtain the required mechanical properties, then trepanned, drifted and threaded. Drill collars are furnished as slick or spiraled in 30 or 31 foot lengths.
Traceability
From receipt of mill’s certified raw material to the completion of all the processing, in each process of which complete traceability mechanism work craft. Serial numbers are die stamped on bar bodies.
Routine and strict inspection procedures
All our drill collars are inspected to comply with the API standards. These inspections include fluorescent magnetic-particle detection and inner ultrasonic flaw detection and hardness detection over the entire body of the drill collar as well as other mechanical performance detection.
Cold rolling process
The thread roots, and the elevator recess, shall be cold-rolled. Cold rolling creates such compressive upper radius stress that increases fatigue resistance by minimizing crack initiation.
Phosphate-coated or copper plating
All connections shall undergo phosphate-coated or copper plating process to ensure corrosion resistance, so as to avoid galled thread.
Slip groove, elevator groove and size
Our company offers optional slip and elevate and accepts reprocesses orders, improving the handling efficiency and guarantee safety. Unless special specification is required, slip and elevator are processed in compliance with API rp 7G guidelines.
Thread protectors
Steel, cast steel, and plastic steel thread protectors for the drill stem products are subject to your requirements.
SPIRAL DRILL COLLARS
Spiraled drill collars have grooves machined in the outside surface. The spiral grooves promote even flow of drilling fluid around the collar diameter, equalizing pressure and reducing the occurrence of differential sticking
Spiral grooves make mud circulate freely around the drill collar to equalize pressure for sake of drill pipe sticking. It reduces the probability of sticking occurrence due to different pressure through reduction of touching area. Spiral drill collar is widely used because of its special structure. The special grooves decrease the volume of the contact with the well wall. It leads to the decrease of the sticking and turning of the drill pipe string.
The weight of Spiral drill collar will be reduced approximately 4%-6% by spiral conversion. Inspections for spiral drill collars: According to API SPEC, each collar undergoes inspections, including thread fluorescent magnetic-particle detection and full-length ultrasonic flaw detection and to ensure the quality.
NON-MAGNETIC DRILL COLLAR
Adopts a kind of chrome manganese alloy steel as material, low carbon obtained by combining a proprietary chemical analysis and rotary hammer process. The material is resistant to corrosion crack, with low magnetic conductivity, with no tendency to galling and high wear proof performances.
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