Safety Alert - Snake Grip Failure on OIL Drill
Line AT A PLATFORM RIG IN THE GULF OF MEXICO
While conducting stringing down block operations on a platform
rig in the Gulf of Mexico, a member of a four man work crew was struck with the
1 3/8” drill line when it failed to remain in the snake grip. The Injured Person (IP) was manning the
hydraulic drill line spool winch control at the time of the incident. As the drill line cable attached to the snake
grip was going through the last deadman sheave in the crown block, an “all
stop” was given by another member of the work crew when he noticed the drill
line cable coming out of the snake grip. Approximately ten to thirty seconds
after the “all stop” was given, the drill line cable came free from the snake
grip and fell toward the hydraulic drill line spool winch striking the IP on
the left shoulder and right hip. The IP
was put into a litter and lowered to the main deck, where he was treated by the
Rig Medic. He was then transported to
the closest hospital for treatment.
An investigation of the accident concluded the following
factors contributed to the incident:
• It was determined that the drill line cable was not properly
degreased before being inserted into snake grip.
• The proper clamping method recommended by the manufacturer’s
specifications was not utilized for the snake grip. Instead, manila rope and duct tape were used
to secure the snake grip which may have prevented the drill line cable and
snake grip from going through the block smoothly and contributing to the injury
incident.
We recommend the following when installing snake grips on to
the drill line cable:
•
Assure the manufacturer’s specifications and
instructions for use of a snake grip are followed completely.
•
Verify the correct sized snake grip is utilized
for actual drill line diameter during operations.
•
Drill line cables must be thoroughly degreased
before insertion into snake grip.
•
Use the proper manufacturer recommended clamps
and tools to secure the snake grip to the cable.
•
Maintain a safe operating speed on the drill
line winch to ensure safety observers have adequate time to relay any and all
safety concerns during operation.
•
Be assertive in personnel placement while
conducting this type operation. When possible, keep personnel clear of drop
zones of all the overhead equipment and work.
NOTE:
• The International Association of Drilling Contractors (IADC)
issued Safety Alert #11-20 titled, “DRILL LINE PULLS THROUGH WIRE ROPE SNAKE
WHILE STRINGING BLOCKS.” Safety Alert #11-20 was issued August 2011. This
Safety Alert addressed the importance of properly degreasing the wire cable
prior to utilizing the snake grip equipment.
• Snake Grips are also known as: ‘Chinese Finger Locks’ or
‘Socks’.
• Below are examples of the proper banding and taping
applications.
Drill Line Pulls Through
Wire Rope
Incident date
01 August 2011
Summary
While in the process of stringing the travelling blocks with
brand new drill line, the 1-3/8 inch drill line came free from the Wire Rope
Wire Mesh Snake Grip and dropped to the rig floor from approximately 20 meters. The line and snake grip had been reeved
through all three sheaves on the off driller’s side and had passed through the
first two sheaves on the driller’s side of the travelling block. There was one
last sheave on the travelling block to spool.
Incident consequence
HIPO
Cause of accident or
incident
Moving, flying or falling object
Location
Onshore construction/rig repair yard
Activity
Catering / hotel services
Description
While in the process of stringing the travelling blocks with
brand new drill line, the 1-3/8 inch drill line came free from the Wire Rope
Wire Mesh Snake Grip and dropped to the rig floor from approximately 20 meters.
The line and snake grip had been reeved through all three
sheaves on the off driller’s side and had passed through the first two sheaves
on the driller’s side of the travelling block. There was one last sheave on the
travelling block to spool.
The snake grip was in good condition and was the correct type
for the line. The drill line had been fully inserted into the 1 inch - 1-1/2
inch snake grip right to the rubber boot and then 3 x hose clamps were used to
secure the snake grip. The clamps were then covered with tape for about 6
inches on each. The snake grip was then attached to a 3/8 inch wire rope line
by back splicing the line’s dead end through the snake grip's soft eye. The 3/8
inch wire rope is used to pull the drill line through the crown and travelling
block sheaves.
There were four essential people involved in the job on the rig
floor but none were near the drop zone. The pre job held emphasized the need
for the rig floor to be clear. There was no potential for injury.
Specific Equipment
Wire Rope Snake and drilling line
Lessons Learnt
Not
following procedure:
A procedure is in place for the "Installation and use of a
Lewis Snake".
One step in the procedure is to "make sure the cable is
clean and free of grease and oil in the areas that will be loaded into the
snake grip”. The manufacture procedure says: “The grips cannot grip an oily
line no matter how hard they are compressing or squeezed. A high grade
degreaser and heavy duty disposable towels are recommended for this task."
Hazard not identified:
This task has been performed by the crew many times before but
the change was the line was new and coated with an oily type preservative. No
one who was spoken to during the investigation was aware that cleaning the line
was critical.
Hose clamp failure:
When the tape covering the hose clamps was removed after the
incident two
Recommendations
Rig personnel were instructed to follow the snake grip manufacture’s
recommended “Band It® Clamp” so that the preferred method of securing the snake
is used.
Distributed an internal safety alert to all rigs so that
everyone is aware of the hazards of using a snake with oily or grease coated
drill line.
Reinforced to all rigs to follow standard operating procedures
so that all of the agreed and necessary
GUIDELINES FOR PROPER
INSTALLATION AND USE OF LEWIS TYPE "LSG SNAKE" ROPE & CABLE
CONNECTOR GRIP
1.
Safety is always No. 1. Make sure no one
is under the line as it is being pulled through the blocks and crown. DO NOT
stand below or near the drilling line under tension, severe injury or death
could occur. KEEP BACK
2.
Be sure that the right size range grips are
being used for the line or rope being pulled. For example, for 13/8” drilling
line, use the LSG 1 - 11/2” snake. When pulling a larger line with a smaller
line (replacing the smaller with the larger), make sure the smaller line
has the correct size grip and that the new larger diameter line has the correct
size grip as well. LSG snakes are available with any required size range on
either side.
3.
Make sure the cable is clean and free of grease
and oil in the area that will be loaded into the LSG snake. A high grade
degreaser and heavy duty disposable towels are recommended for this purpose.
4.
When loading the cable into the grip, be certain
the cable is inserted all the way into the grip until the grip is fully loaded
(into the plastic boot area below the pulling eye of the grip). Also examine
both grips for cable abrasion or broken cables. An LSG snake showing any signs
of cable fraying, broken cables or distorted hardware should be immediately
discarded and replaced. Inspect the LSG Snake Grip prior to each use.
5.
Once the snake is loaded properly, Band AND Tape
(use electrical tape) over the tail end of each grip using a BAND-IT® brand
banding tool. Apply a Second Band AND Tape 4 to 6 inches apart from the first.