Reverse circulation (RC) drill pipe is a dual wall pipe used for uncontaminated, representative and continuous samples. It is also used to reduce air requirements and maintain uphole velocity in larger diameter drilling applications. RC Inlet air passes between the inner tube and outer barrel. Cuttings are evacuated through the center tube.

Foremost manufactures a complete range of reverse circulation drill pipe and accessories including air swivels, saver subs, bit subs, interchanges, wear sleeves, blow-down and blow-back subs and open center bits.

Foremost's patented inner barrel suspension and retention system eliminates problems arising from the transfer of vibration and torque loads applied to the outer pipe. The inner pipe is suspended within the outer barrel and is relatively unstressed. The o-ring retainers absorb percussion forces and allow for replacement of the inner barrel in the field if required.

To suit customer requirements, Foremost offers various drill pipe configurations, with or without connector tubes:

Concealed Inner Pipe (CIP) - Incorporates a dual tube design, using both an outer barrel and a concealed inner tube. Connector tubes are not required when using CIP drill pipe. The inner tubes are sealed when the outer barrels are threaded together.

Connector Tube Pipe (CTP) - A dual tube design, incorporating an outer barrel and a concealed inner tube. Connector tubes are required when using CTP and are manually connected.

Protruding Inner Pipe (PIP) - A dual tube design using both an outer barrel and an inner tube, which protrudes from the pin tool joint. Connector tubes are not required when using PIP drill pipe. The inner tubes are sealed when the outer barrels are threaded together.

RC Hammer Pipe - The inner tube protrudes from the box tool joint and connector tubes are not required. The inner tubes are sealed when the outer barrels are threaded together.

SeriesDiameterWorking TensionYield TensionMax. TensionWorking TorqueWeight
CIP4"139,200 lbs244,200 lbs301,700 lbs7,000 ft-lbs146 lbs @ 10' length
4½"127,680 lbs210,100 lbs286,500 lbs8,900 ft-lbs421 lbs @ 20' length
9 5/8"285,500 lbs466,000 lbs635,700 lbs97,700 ft-lbs1,347 lbs @ 20' length
10¾"467,900 lbs843,000 lbs1,053,700 lbs100,000 ft-lbs1,760 lbs @ 20' length
CTP4½"127,680 lbs210,100 lbs286,500 lbs8,900 ft-lbs417 lbs @ 20' length
5½"127,700 lbs206,900 lbs282,100 lbs15,500 ft-lbs548 lbs @ 20' length
7"283,000 lbs466,000 lbs583,000 lbs30,500 ft-lbs804 lbs @ 20' length
PIP3¾"93,500 lbs200,600 lbs242,700 lbs4,800 ft-lbs124 lbs @ 10' length
5½"127,700 lbs206,900 lbs282,100 lbs15,500 ft-lbs540 lbs @ 20' length
Hammer Pipe6 5/8"282,800 lbs454,300 lbs628,300 lbsNot Applicable480 lbs @ 10' length
9"343,800 lbs556,800 lbs770,000 lbsNot Applicable580 lbs @ 10' length
10¾"615,200 lbs1,124,000 lbs1,405,000 lbsNot Applicable870 lbs @ 10' length
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