Page 4 • Fishing Bumper Subs • Manual D450
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Logan Fishing Bumper Sub
ASSEMBLY
Check all parts to ensure that they are
in good working condition before begin-
ning assembly. Make sure the tool is the
proper size for the operation.
Thoroughly clean and lubricate parts. If
the tool will be stored for a long period,
paint or lubricate the exterior surfaces
to prevent corrosion.
NOTE:
Do not paint or lubricate the
seals. Paint, sunlight, solvents, and
most lubricants are harmful to rub-
ber products.
Refer to the photographs on page 5
and proceed with the knocker seal/ring
assembly installation as follows. If using
the optional chevron packing set, skip
to step 5.
1. Starting with the lowest groove, re-
place the knocker seals.
a. Carefully examine and thoroughly
clean each groove. Smooth out
any nicks or burrs with emery
cloth.
b. Matching the bevel of the non-
extrusion ring to the bevel of the
groove, slide the non-extrusion
ring over the knocker. Carefully
expand the non-extrusion ring
to fit over the outside diameter of
the knocker.
Do not expand the
non-extrusion ring more than
is absolutely necessary.
2. Press the seal protector ring into
the groove next to the non-extru-
sion ring with the thumbs until the
ring is firmly seated in the groove.
3. Install the O-rings:
a. Stretch the O-ring until it is large
enough to fit around the knocker.
b. Insert the O-ring between the seal
protector ring and non-extrusion
ring.
OPERATION
The Logan Fishing Bumper Sub is
typically run directly above the spear,
overshot, screw-in sub, or safety joint.
The tool is designed to allow a verti-
cal stroke — upward or downward
— whether it is rotating or not, and is
always available to the operator. The
Fishing Bumper Sub will transmit full
torque at all times during rotation and
bumping operations.
When lift load is applied, the Fishing
Bumper Sub will slide open until the
knocker hits the mandrel body. Slack-
ing weight off the string will cause the
mandrel to slide back down the man-
drel body until the bottom shoulder of
the mandrel hits the top shoulder of the
mandrel body.
Fishing Operations
A Fishing Bumper Sub should be in-
cluded in the fishing string whenever a
releasing type fishing tool will be used.
If it becomes impossible to pull the fish,
the operator will have means available
to release the fishing tool. The Fish
-
ing Bumper Sub will deliver a sharp
blow and transmit the torque required
to disengage and release a fishing tool
from the fish.
A properly made-up Fishing Bumper
Sub is generally placed immediately
above the fishing tool, safety joint, or
unlatching joint.
Drilling Operations
The Fishing Bumper Sub is generally
installed in the drill string immediately
above the drill collars.
Applying a Downward Blow
At the surface, mark the pipe to indicate
the open and closed positions of the
Fishing Bumper Sub. Raise the fishing
string to open the full stroke length
(20 – 60 inches depending on the size
of the tool) and allow for extra string
stretch.
To deliver a sharp downward blow,
sharply drop the string and abruptly
stop with the brake approximately four
(4) to six (6) inches above the closed
position of the Fishing Bumper Sub. To
deliver a solid downward blow, drop the
full weight of the fishing string without
braking. This will cause the lower end of
the fishing string to drop downward and
the Fishing Bumper Sub will close. If the
fishing string has sufficient stretch and
elasticity, the Fishing Bumper Sub will
then deliver a series of downward blows
to the tool below.
Applying an Upward Blow
At the surface, mark the pipe to indicate
the open and closed positions of the
Fishing Bumper Sub. Raise the fishing
string to open the bumper sub and allow
for additional string stretch. Drop the
string by the amount of the stretch only
and stop it abruptly with the brake. As
the pipe rebounds at the bottom of the
hole, the Fishing Bumper Sub will quick-
ly reopen. This will cause the knocker to
strike the lower end of the mandrel body
with a solid upward blow.
Feeding-Off
When employing a Logan Fishing Bum-
per Sub as a feed-off tool, install the
Fishing Bumper Sub in a cutting string
several joints above a Logan Internal
Cutter. In this operation, a Fishing Bum-
per Sub with a 20-inch stroke will pick
up ten inches of the cutting string after
the cutter is set. Only the predetermined
weight of the pipe between the internal
cutter and the Fishing Bumper Sub
is applied to the cutter, thus ensuring
smooth operation of the cutter.
