Back off sub also called releasing spear, was used to releasing drill stem above the stick point druing drilling and workover operation. Specifications:
OD(mm)
Connection(LH)
Fishing Connection(RH)
DKJ105
105
NC31
DKJ121
121
NC38
DKJ165
165
NC50
NC46
5 1/2 FH
NC56
DKJ178
178
6 5/8 REG
DKJ203
203
NC61
7 5/8 REG
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