ZDM back off sub is a special tool for backing off the jammed boring toll underground. In the
operation, we can use the tool with out safety apparatus joint. and work above ground to
exit buckle. Using the toll is at a relatively low cost to fishing in comparison with back taper, and
can not cause the accident such as die tap breaking.
the type and main parameter
|
type |
name |
length |
Water hole |
O.D. |
Upper connection |
Under connection |
applicability |
ultimate load KN |
|
ZDM46 |
4 3/4″Inverted Button fishing spear |
670 |
12 |
121 |
NC38LH |
NC38 |
3 1/2″Drill pipe |
350(35) |
|
ZDM46S |
4 3/4″Double deduction is Flip spear fishing |
670 |
12 |
12l |
NC38 |
NC38 |
3 1/2″Drill pipe |
350(35) |
|
ZDM62 |
6 1/4″Drill down Button fishing spear |
670 |
28 |
159 |
NC50LH |
NC50 |
4 1/2″～5″Drill pipe |
500(50) |
|
ZDM62S |
6 1/4″Double deduction is Flip spear fishing |
670 |
28 |
159 |
NC50 |
NC50 |
4 1/2″～5″Drill pipe |
500(50) |
|
ZDM70 |
7″Flip spear fishing |
700 |
32 |
178 |
5 1/2FHLH |
5 1/2FH |
5 1/2″Inch drill pipe |
700(70) |
|
ZDM70S |
7″Double spear fishing is buckle down buckle |
700 |
32 |
178 |
5 1/2FH |
5 1/2FH |
5 1/2″Drill pipe |
700(70) |
|
ZDM80 |
8″Flip drill spear fishing |
750 |
32 |
203 |
6 5/8REGLH |
6 5/8REG |
8″Drill Collar |
800(80) |
|
ZDM90 |
9″Flip Fishing spear |
750 |
32 |
229 |
6 5/8REGLH |
7 5/8REG |
9″Drill Collar |
800(80) |
Construction and operating principle
ZDM back off sub is made of pike, expansion mandrel and expansion slip. There is drill connection
on the top of the pike, the pike is connected to the expansion mandrel , the expansion slip
is installed in the cone of expansion mandrel, and there is a guide awl under the expansion
mandrel, to help expansion slip flawlessly into the joint of the fish. The expansion slip can catch
the fish firmly by the pull. If the top of boring tool is right hand thread, the upper connection of
the tool is right hand thread too.
method of application
On the top of fish should be the female thread to suit for the under connection of the back off sub.
Check the tool by follow-up procedure seriously before descent down hole.
operating procedure
ZDM back off sub is advanced by left hand drill pipe. If we use double right hand back off sub ,
link it with right hand drill pipe. After the awl plug in water hole of fish, take right hand direction
5 or 6 turns to make the expansion slip coupled with the top of fish
Pick up the boring tool, the expansion slip has been swell by expansion mandrel, and couple
with the fish tightly. The pulling-up power had better be the sum of the weight of the boring tool
and fishing boring tool. In the ordinary course of events, we can back off the boring tool under
the fish with 100～200KN（10～20tf）
According to customer requirements ,We can design and manufacture other serial specification products
