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Overburden Drill Systems and Accessories

Stratex
Stratex
Drop-off Ring System

The Standard of Excellence and Durability for Over 30 Years

The Stratex Drill System

The Stratex Drill System (SDS) is an overburden drilling system designed for conditions where a cased hole is required. Collapsing holes tend to make overburden drilling expensive, with lost drilling equipment and down time.

In cooperation with drillers and drilling contractors, the SDS was developed to overcome these problems. The patented eccentric design and the Drop Off Ring (DOR) drill bits enable the drill string and casing to be lowered in the hole simultaneously with a conventional hammer drilling system.

The SDS eccentric designed bit rotates outward and drills a larger diameter hole than the casing, avoiding cave-ins, wash-outs, and other problems common in normal drilling operations in soft and gravel-type strata or loose rock. Since 90% of the world's overburden drilling is in loose strata, potential utilization of the SDS is enormous.

After reaching the designated depth, the SDS reamer-bit is retracted by reversing the direction of the rotation and by applying tension on the reamer-bit, which has a taper and will retract into the casing for easy removal of the entire drill-string. This leaves the casing in place for other applications or for removal at a later date. The SDS method is designed for use with flush joint threaded pipe or welded-type casing and provides a bit size for a wide variety of different casing wall thicknesses.

Advantages of SDS:

  • Low capital investment
  • High drilling performance
  • No rotation of the casing
  • Compatible with most drilling rigs
  • Virtually no casing stress
  • Casing is simultaneously lowered by the guide device and to deeper depths than other methods allow
  • Cost and on-site time reduced due to better penetration rates, easier bit changes, and stable hole conditions
  • Smaller pilot bit for faster and better penetration

Applications:

  • Blast holes
  • Water supply wells
  • Bridge and building foundations
  • Standard slant or horizontal drilling
  • Mining air holes
  • Environmental monitoring wells
  • Grouting operations
  • Seismic shot holes
  • Soil sample and geotechnical applications
  • Ground anomaly and tiebacks
  • Storage caverns and dam

Man with Stratex

Accessories Available with SDS:

  • Drop Off Ring (DOR)
  • Drill pipe and subs
  • Threaded casings
  • Casing drive shoes
  • Hydraulic casing pullers
  • Stabilizers
  • Discharge heads
  • Casing wing-nuts
  • Shock subs
  • Drill bits
  • Fishing tools
  • Air swivels

 

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Overburden Drill System

Assembly of the Stratex System

The Stratex Drilling Method is used with air rotary drilling rigs and most manufacturers' downhole hammers. The drill rod is connected to the rig top drive using a changeover sub or swivel sub. The drill rod is then connected to the down-hole hammer by the same method. The chuck nut and split rings are removed to insert the guide device shank and secured by replacing the split rings and chuck nut.

The reamer bit, in the closed position, is now inserted into the casing shoe. Since the percussion hammer is at the bottom of the hole, working directly above the drill bit, the force to pull down the casing tube is transferred by way of the casing shoe. The exhaust air from the drill redirects the loose cuttings up through the groves on the guide device, forcing them up between the drill rod and the casing wall out through the discharge head, which is attached to the casing tube. By using a discharge head, drilling is not only safer but also environmentally cleaner. Stratex can be used with foam or water to aid in cutting removal.

Good Flushing

Good Flushing is essential with any successful drilling operation or in using an overburden drilling system. The Stratex System provides air jets above and below the guide device, creating a vacuum across the face of the reamer bit, removing the cuttings with greater annular velocity. The gauge carbides along the side of the pilot and reamer bit act to crush the cuttings into finer particles, the majority of which are removed from the hole. The remaining cuttings are forced back into the walls of the cavity, leaving less material to be extracted from the hole.

Stratex System assembly
Stratex cutaway

Advantages:

  • Efficient removal of cuttings from above the guide device, which prevents the hammer from jamming and torque problems
  • Removal of fine cuttings from around the bit system and casing creates less friction and achieves deeper depths and easier casing removal
  • Reduction in losses due to circulation problems by increased vacuum in cutting removal
  • For unique applications, the annular velocity can be increased by changing the airflow in the reamer pilot system

 

  1. One-piece reamer and pilot bit
  2. One-piece guide device and shank
  3. Casing with shoe sleeve
  4. Casing
  5. Wing-nut centralizing system
  6. Drill rod
  7. Casing adapter
  8. Discharge head
  9. Swivel sub

Air velocity is important for efficient hole cleaning. A minimum return air velocity of 4000 feet per minute is desirable. Annular space between drill pipe and the drilled hole as well as compressor capacity determines the air velocity. The annular air velocity in foot per minute can be calculated with the following formula if air consumption and annular area are known:

annular air velocity (fpm) =
  free air consumed (cfm) x 144
    annular area (sq. in.)*

*annular area = .7854 x (hole diameter - drill pipe OD)

The following flushing mediums are also useful:

  • Air with water injection
  • Air with foam injection

NOTE: Foam has the ability to lift cuttings and stabilizes the wall of the hole and provides lubrication for easier casing penetration. Foam also has good drilling performance in most types of clay.

The Stratex Drill System        

Drilling Rod

Stratex Drill System cutaway

 

 

Wiper Cover
Wipers

Discharge Body

Discharge Clamp
Adapter

Blank Casing End

Adapter Clamp

Replaceable Grippers

Pin End

Box End

Casing

Hammer Shank

Guide Device

Casing Shoe

Reamer Bit

The Stratex System utilizes a one-piece reamer and pilot bit that moves outward to full open position on an eccentric shaft by rotating a half turn to the right.

This reamer pilot bit system opens a larger diameter hole than the diameter of the casing. The casing is simultaneously lowered into the hole as the reamer pilot bit drills. The pilot bit is rotated at 10 to 40 rpm while drilling with the hammer.

When the designated drilling depth is reached, the reamer pilot bit system is retracted into the casing by applying slight tension and reversing the direction of the drilling rotation. The design of the reamer pilot bit system incorporates a closed bearing method that makes the loss of the pilot bit virtually impossible. This bit system, in the closed position, is easily removed through the casing shoe and casing.

Working
Position

Working position

Retracted
Position

Retracted position

Stratex

Telescopic Drilling

Using a telescoping drilling method can achieve deeper depths.

Some string samples are as follows:
365
240
190
140
90
 
365
215
165
115
 
 
365
215
140
90
 

Casing depths with Stratex can reach 500 feet or more with the down-hole hammer versions depending on the type of formation, drilling equipment, and drilling personnel experience.

Hole Depth

Stratex System (mm)
70
80
90
115
140
165
190
215
240
365

Normal Max - Hole Depth (ft)

200
250
300
500
500
500
500
-
-
-

The Stratex Drilling Method

The Ultimate Drilling Method

The Overburden Drilling Method that was designed by drillers for drillers. Overburden material strikes when least expected. Be prepared. Use Stratex!

The PATENTED Stratex Drill System:

Stratex cutaway
  1. One-piece shank and guide device manufactured from the highest quality material with stringent quality control.
  2. Air jets are used to prevent any malfunction of the opening and retraction of the reamer pilot bit operation and the clearing of cuttings above the reamer pilot bit system.
  3. Sealed bearing system for ease in rotating the eccentric bit outward or retracting it into the casing.
  4. Casing with shoe: Casing may be supplied with plain or threaded ends.
  5. Grooved bypass directly above the lock system to clear cuttings and ensure complete drilling face contact.
  6. Tapered shoulder on the reamer bit eliminates casing binding and assists in the retracting of the reamer bit into the casing.
  7. One-piece reamer and pilot bit manufactured from the highest quality material, with stringent quality control.
  8. Gauge protection carbides on heavy duty, one-piece pilot and reamer bit.
  9. Dome carbides on heavy duty pilot and reamer bit.

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The Stratex

ECCENTRIC UNDER REAMER

Used for a large range of diameter requirements:

Eccentric Under Reamer
  • High performance drilling
  • One-piece reamer
  • One-piece guide device
  • Made from tough heat-treated alloy steel
  • Studded with an aggressive array of tungsten carbide inserts
  • Lower drilling costs per foot
  • Guaranteed performance*
  • Guaranteed service
  • Large range of accessories
  • Manufactured under strict quality-controlled conditions

*When used in conjunction with manufacturer's recommendations and specifications.

Casing

Hammer

Guide Device

Casing Shoe

Reamer Bit

Under Reamer cutaway
"Performs comfortably with
any system out there. We
stock and sell with ease."


-Bill Johnson Equipment

The Stratex

DROP-OFF RING UNDER REAMER

Drop-Off Ring Under Reamer

Used when concentric drilling is a requirement:

  • High performance drilling
  • One-piece reamer
  • One-piece guide device
  • Made from tough heat-treated alloy steel
  • Studded with an aggressive array of tungsten carbide inserts
  • Lower drilling costs per foot
  • Guaranteed performance*
  • Guaranteed service
  • Large range of accessories
  • Manufactured under strict quality-controlled conditions

*When used in conjunction with manufacturer's recommendations and specifications.

Drop-Off Ring Under Reamer

Tool
Size
Casing
OD (IN)
a
Nominal
Casing Size
(IN)
Casing
Wall
Casing
Show i/d
b
Hole
Dia.
c
70 mm
3.5
3.0
.216
2.75
3.75
80 mm
4.0
3.5
.266
3.125
4.875
90 mm
4.5
4.0
.237
3.625
5.0
115 mm
5.563
5.0
.258
4.5
6.125
140 mm
6.625
6.0
.280
5.5
7.5
165 mm
7.625
7.0
.301
6.5
8.75
190 mm
8.625
8.0
.322
7.5
9.75
210 mm
9.625
9.0
.342
8.350
11.0
215 mm
10.0
9.5
.350
8.625
11.125
240 mm
10.75
10.0
.365
9.525
11.25

TOOLS OF EXCELLENCE AND DURABILITY FOR OVER 30 YEARS

Air Pressure Gauge

Recommended Maximum Air Pressure for Stratex Drill Systems

The maximum recommended air pressure for Stratex drilling with down-hole hammers is 12 bar, which equals 210 psi.

Rotation speed depends on the size of the Stratex bit and the formation being drilled. The rotation speed may have to be varied as the formation changes. The table shows recommended rotation speeds for the various Stratex sizes.

Recommended Rotation Speeds

Stratex System (mm)
70
80
90
115
140
165
190
215
240
280
Speed (rpm)
20 - 40
10 - 25

Drill rigs must have sufficient torque for drilling with Stratex. The table shows recommended rotation speeds for the various Stratex bit sizes.

Hole Depth

Stratex System (mm)
70
80
90
115
140
165
190
215
240
280
Minimum Torque (ft/lb)
570
600
663
1470
2200
2950
4000
4000
4000
7000

"Stratex provides the widest range of flexibility when it comes to casing wall size
thickness, which makes it a high demand by users. All systems complete and ready for
resale within a week or two, a time frame that cannot be met by other manufacturers."


-LLC Supply AZ, USA

Stratex Over Burden Drilling Tool: Size and Technical Chart

Tool Size
Casing Sizes
Drive Shoe I.D.
(B)
Drive Shoe Length
(C)
Guide to Casing Distance
(D)
Reamed Diameter
(E)
Bit
Size
(F)
Guide to Casing Distance
(D)
Nominal Size
O.D.
(A)
Walls
(S)
70
3
3.50
.216
2.750
2.5
4.25
3.75
2.75
2.968
80
3.5
4.0
.237
3.156
2.75
4.5
4.375
3
3.437
90
4
4.5
.247
3.650
3.5
5
5
3.5
3.937
110
5
5.562
.375
4.375
5.5
7.50
6.125
4.25
4.75
115
5
5.562
.258
4.575
5.5
7.50
6.125
4.25
4.937
132
6
6.625
.432
5.188
5
7.75
7.5
4.875
5.593
140
6
6.625
.280
5.575
5
7.75
7.5
5.125
5.937
142
7
7
.498
5.575
5
7.625
7.875
5.25
5.875
150
7
7
.272
5.937
5
7.625
7.875
5.25
6.375
160
7
7.625
.500
6.036
5.5
8.25
8.75
6.125
6.500
165
7
7.625
.301
6.575
5.5
8.25
8.75
6.25
6.937
180
8
8.625
.500
7.075
6
8.75
10
6.75
7.535
190
8
8.625
.277
7.575
6
8.75
10
7.375
7.937
200
9
9.625
.500
7.937
6
9
11
7.625
8.437
210
9
9.625
.342
8.312
6
9
11
8
8.845
215
10
10
.250
8.625
6
9
11
8
9.250
230
10
10.75
.500
9.050
7
10.25
11.75
8.75
9.625
235
10
10.75
.365
9.275
7
10.25
11.75
9
9.890
250
11
11.75
.500
10
7
10.75
13.25
9.625
10.62
260
11
11.75
.375
10.25
7
10.75
13.25
10
10.87
280
12
12.75
.500
10.937
7
11
14.5
10.625
11.56
300
13.37
13.375
.430
*
8
12
15
10.625
*
310
14
14
.500
12.25
8
12
15.75
12
12.87
360
16
16
.500
14.25
10
14.25
18
14
14.87
410
18
18
.500
*
10
*
20
15
*
420
18.62
18.62
.430
*
10
*
20.37
15
*
455
20
20
.500
*
11
*
22
17.5
*
510
22
22
.500
20.075
11
16
24
18
*
560
24
24
.500
22.075
11
16.5
26
20
22.75
610
26
26
.500
23.875
12
17
28
22
*
660
28
28
.500
25.875
12
17.5
30
24
*
710
30
30
.500
27.875
12
19
32.5
26
*
760
32
32
.500
29.875
14
21
34.5
28
*
810
34
34
.500
31.875
14
21.5
36.5
30
32.62
860
36
36
.500
33.75
14
23
38.5
32
*
1000
42
42
.500
39.375
16
*
44.5
38
*
1150
48
48
.500
45.375
16
*
51
42
*

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Overburden Drill System

THE STRATEX CENTRO*

Stratex Centro

The latest concentric under reamer used for large diameter requirements:

  • High performance drilling
  • Five retractable wings
  • Made from tough heat-treated alloy steel
  • Studded with an aggressive array of tungsten carbide inserts
  • Lower drilling costs per foot
  • Guaranteed performance**
  • Guaranteed service
  • Large range of accessories
  • Qualified, dedicated staff
  • Manufactured under strict quality-controlled conditions
  • Sizes from 20"
  • Custom sizes available

  *Patent pending
**When used in conjunction with manufacturer's recommendations and specifications

Tool Size
Casing Sizes
Drive Shoe
Drive Shoe Length
Guide to Casing Dist.
Reamed Diameter
Guide O.D.
DIM
(mm)
Nominal Size
O.D.
Max
Wall
         
460
20
20.000
0.500
18.125
9.000
14.00
21.250
18.750
510
22
22.000
0.500
20.125
10.000
15.50
23.250
20.750
560
24
24.000
0.500
22.125
10.000
15.50
25.250
22.750
610
26
26.000
0.500
24.125
11.000
16.50
27.250
24.750
660
28
28.000
0.500
26.125
12.000
17.50
29.250
26.750
710
30
30.000
0.500
27.875
12.000
19.00
32.500
*
760
32
32.000
0.500
29.875
14.000
21.00
34.500
*
810
34
34.000
0.500
31.875
14.000
21.50
36.500
36.620
860
36
36.000
0.500
33.750
14.000
23.00
38.500
*
1000
42
42.000
0.500
39.375
16.000
*
44.500
*
1150
48
48.000
0.500
45.375
16.000
*
51.000
*

AWDS Logo

The Stratex

THREADED CASING, DRILL RODS, AND CONNECTIONS

Threaded Casing, Drill Rods, and Connections
  • LH/RH thread
  • Alloy steel threaded casing ends
  • Flush joints
  • API and custom-threaded specs available
  • Casing sizes from 70 mm
  • Metric and Imperial sizes available
  • Drill rod sizes from 2"

Overburden Drill Systems

ACCESSORIES

  • Drop-off Ring (DOR) bits
  • Drill pipe and subs
  • Left threaded casings (left-hand HT allow ends)
  • Casing drive shoes
  • Stabilizers
  • Hydraulic casing pullers
  • Discharge heads
  • Casing wing-nuts
  • Shock subs
  • Drill bits
  • Fishing tools
  • Air swivels

Manufactured under ISO 9001 quality control

Overburden accessories

Very happy with the Stratex Eccentric
and Casing Puller System. Excellent turn
around time and knowledgeable staff. Highly recommended to users and distributors."

-N&N Drilling Supply, PA, USA