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Spiral drill collar
Spiral grooves of Drill Collar can reduce the surface contacting area between well and drill collar, and effectively lower the possibility of differential pressure block or sticking, let mud circulate freely around the drill collar to equalize pressure .
Every drill collar shall be left certain length uncut for both ends, 18"~42" from box shoulder and 12~40" from pin shoulder.
Sprial Groove size
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OD Range（In）
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4~4 3/8
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4 1/2~5 1/8
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5 1/4~5 3/4
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5 7/8~6 3/8
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6 1/2~7
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7 1/8~7 7/8
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8~8 7/8
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9~9 7/8
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Depth of cut（in）
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6/32±1/32
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7/32±1/32
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1/4±1/32
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9/32±1/16
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5/16±1/16
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11/32±1/16
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3/8±1/16
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13/32±3/32
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Spiral Pitch（in）
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36±1
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38±1
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42±1
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42±1
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46±1
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64±1
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68±1
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72±1
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