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Wellhead isolation tool
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Patent number 6,920,925
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Issue date Jul 26, 2005
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Duhn Oil Tool, Inc.
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Rex E. Duhn
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E21 - EARTH DRILLING MINING
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Coil tubing hanger system
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Patent number 6,588,510
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Issue date Jul 8, 2003
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Duhn Oil Tool, Inc.
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Gary A. Card
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E21 - EARTH DRILLING MINING
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Well tubing rotator
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Patent number 6,543,533
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Issue date Apr 8, 2003
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Duhn Oil Tool, Inc.
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Robert K. Meek
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E21 - EARTH DRILLING MINING
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Drilling quick connectors
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Patent number 6,199,914
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Issue date Mar 13, 2001
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Duhn Oil Tool, Inc.
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Rex E. Duhn
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E21 - EARTH DRILLING MINING
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Ring seal packer
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Patent number 5,303,774
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Issue date Apr 19, 1994
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Duhn Oil Tool, Inc.
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Jay C. Duhn
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E21 - EARTH DRILLING MINING
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Ground subsiding wellhead
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Patent number 4,974,676
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Issue date Dec 4, 1990
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Duhn Oil Tool, Inc.
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Rex E. Duhn
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E21 - EARTH DRILLING MINING