Product Description

WEIGAO Drill collars are made of AISI ***5 H modified alloy steel or non-magnetic material. Other grades are available on request. WEIGAO drill collars are used successfully for sour gas wells. After forging or rolling, the bars are peeled, heat treated, stress relieved, ultrasonically inspected and straightened to API specifications, to ensure that each bar will meet the physical properties.
 
Drill Collar:
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1. Thick walled pipe used to provide weight on bit(WOB) to keep drill pipe in tension.
2. Drill pipe has relatively low stiffness, make it susceptible to buckling when under compression.
3. Buckling may lead to failure.
4. Failure eliminated by keeping neutral point (point of zero tension and zero compression) below drill pipe.
5. *0% to *5% of buoyant weight of drill collar put under compression for safety factor of 1.*5.
6. Manufactured in an average length of *1ft.
7. Pin and box are cut from the body of the pipe.
8. Connection has tapered threads jack screw.
9. Threads are normally strengthened by cold-working the thread roots.