Darron Drill Collars are manufactured from Chromium, Molybdenum Alloy Steel conforming to AISI 4145 H Modified. Fully heat treated and supplied in accordance with A.P.I. Specification 7-1.

Quality Control and Ultrasonic Inspection

State of the art measurement and ultrasonic techniques are used to ensure that the highest control standards within the industry are maintained.

Every Darron Drill Collar is subject to full length, full section ultrasonic examination. Thread connections machined and gauged in accordance with A.P.I. Specification 7-1 and RP7G are individually examined within our own inspection department as an integral part of final inspection procedures.

Individual characteristics of each thread such as stand off, taper, pitch, etc., are fully documented on in-house documentation.

Thread Connections

All connections are machined to the highest possible accuracy and conform to the requirements of A.P.I. Specification 7-1& 7-2.

To improve fatigue resistance all connections are cold rolled and to prevent galling during make up all connections are phosphated. Connections are coated with a thread compound conforming to the thread protectors are fitted.

Precision Boring

Drill Collars are deep precision bored to ensure tight tolerances that eliminate wall thickness variation along the bar length and drifted to A.P.I. Specifications. In addition to the standard ranges shown on following page, special sizes, bores, connections and lengths can be made to meet customers' specific requirements.

Surface Finish

The surface finish, linear straightness, roundness and O.D. tolerances conform to A.P.I. Specification.

Identity Markings

Licensed to apply the A.P.I. monogram Darron also mark the Drill Collars unique identification serial number, O.D., I.D., size and style of connections.


Downhole Tools: Heavy Weight Drill Pipe (Integral)

Darron's supplier in India offers a complete range of heavyweight drill pipe is integral and manufactured from AISI 4145H fully heat-treated steel that conforms to all API Spec. 7-1 standards


Downhole Tools: Rotary Crossover Subs

Darron Drill Stem Substitutes are manufactured from Alloy Steel AISI 4145 H Modified conforming to the requirements of A.P.I. Specification 7-1.


Downhole Tools: Lift Subs & Lift Plugs

The Darron Lift Subs are manufactured from AISI 4145 H Modified Steel, fully heat treated and supplied in accordance with A.P.I. Specification 7-1.


Downhole Tools: Circulating Subs

The Darron Circulating Subs have been designed to achieve increased mud circulation by placement in the B.H.A., either above the bit or down hole motor to pump materials in case of lost circulation.