Event: Caustic burn Date/Time: 17 April 2003, 0815 hrs. Location: premix mud tank Shift and Team: Daylight tour Investigation Date(s): 17-18 April 2003 Report completed by: XXXXXXXXXXXXXXXXXXXXX
CONCLUSION:
The accident was preventable and results from:
Employee did not use proper procedure for mixing caustic soda.
Employee had his coveralls tucked inside the top of his boots.
He did not perform a short form JSA prior to mixing the chemical.
All potential hazards were not considered as employee moved the empty sacks.
Rubber boots should be worn for mixing chemicals with coverall/pant legs outside of boot top.
Chemical resistant pants should be worn along with apron.
Incident Information:
XXXXXX employee began work tour at 0700 hrs. He was instructed by the mud engineer to add two sacks of caustic soda to one of the premix tank compartments as preparation to mix additional mud. The mud engineer assisted the XXXXXXXXXX employee in getting two bags of caustic from the bulk pallet. The plastic cover was replaced over the stored chemical on the pallet. The mud engineer left the tank to attend other duties while the mud mixer applied the caustic. He indicated that he was gone no more than about 10 minutes. The first person to see the mud mixer in distress was a XXXXXXXXXXXXXXXX dump truck driver, who responded by getting additional help from the rig personnel. The employee was in severe distress at the rig site. After washing his foot, he was transported to the XXXXXXXXX clinic at XXXXXXXXX. He was treated and transported by the XXXXXXXXXXXXX ambulance to a clinic in XXXXXX, where continued treatment was administered. It appears that the employee had completed mixing the two sacks of caustic soda, had picked up the sacks, proceeded down the stairs off the premix tank and deposited the sacks in the proper disposal bin. Evidently, as he was carrying the sacks to dispose of them, a small volume of the caustic soda fell out of an "empty " sack and into the top of his boot. The employee then returned to the top of the tank where he evidently started washing down the excess soda on the tank grating with a short drain hose below the wash basin. In doing so, he got water in his boot, which reacted with the caustic soda. As his foot became irritated, the employee sat down on the tank grating, removed his boot, and started washing his foot and at the same time starting yelling for help.
Post Incident:
An immediate investigation was initiated at the rig site. The XXXXXXXXXXXXXXX management and safety personnel conducted interviews to determine the cause of the accident. There were no witnesses to the actual event. It was not possible to get a statement from the injured employee at the rig site. He was interviewed at the clinic in XXXXXXXXXXX later in the evening.
Investigation Team Activities:
Interviews, Inspection (17April03) Final review meeting at PD 738 (19April03) to elaborate investigation report.
Reviewed current JSA for chemical mixing.
Employee had received training (documented) in handling hazardous substances. He said he didn’t remember getting the training.
Failed to use proper PPE. Employee was wearing safety glasses instead of safety goggles as required by Pd’s JSA. This was not a contributing factor to this incident, but did reflect non-conformity to the JSA. Also, the use of goggles was discussed.
Failed to follow JSA for mixing caustic soda. The chemical was mixed directly into the tank, which contained only water. The JSA states that all caustic should be mixed in the chemical barrel and then added to the system. The review team discussed this issue and found that it was common for the caustic soda to be added directly to the system in our operations. The team felt that mixing the chemical directly to the system may, in this case, actually be safer than mixing in the barrel. Adding caustic to an active mud system requires that the caustic be dissolved in water prior to adding to the system. In this case, the entire sack can be added to a compartment containing only a large volume of water without creating a problem. There is less handling and the task is completed quicker, thereby minimizing exposure.
Failed to follow XXXXXXXX policy. Employee had pants legs tucked into the top of his boots, violating the policy. Had his pant legs been outside the boots, it is very unlikely that the chemical could have entered his boot top. This policy was not strictly enforced.
Inadequate water supply on the tank. The team felt that the premix tank did not have an adequate water supply available on top of the tank for this activity and may have contributed the accident. Had there been a water outlet available with a longer hose, the use of the short drain hose under the wash basin probably would not have been necessary to wash off the tank, thereby reducing the chances of getting water into the top of the boot.
Employee indicated that he had not reported past near misses involving mixing the chemical. As a result of the incident, the team also recommends that the empty caustic soda bags by segregated in a specific place instead of being thrown into the trash container with other bags. There is a good probability of someone receiving a chemical burn when removing the trash by residues falling from the bags.
Root Cause: Failure to follow XXXXXXXXXXXXXX policy and wear pant legs outside of boots. This left the top of the boot open and allowed the caustic powder to enter the boot.
Recommendations:
As a result of the team review, it was decided that an emergency shower would also be installed on the premix tank with the additional water connections. The team felt as though another water outlet should be available with a hose.
The team recommended that all personnel on location would now be required to wear pants leg outside of boot uppers. To manage this issue in only limited areas of the work location did not seem feasible.
The JSA for mixing caustic soda will be reviewed further and possibly changed.
PPE requirements will be reviewed. Other types or styles of PPE will be reviewed.
The team felt that a full-face shield would be a better solution to goggles, which have a tendency to fog up. Adjusting goggles also tends to bring the gloved hands closer to the face and eye area, bringing contaminated gloves in contact with the facial area.
The JSA for mixing other chemicals will be reviewed.
The team felt that there was lack of policy enforcement.
The condition of the workers coveralls might have to be taken into consideration.
As a result of this incident, it became apparent that the safety rescue equipment was stored at various locations around the rig site. It was decided that all response equipment would be stored in the safety-training trailer.
The use of a buddy system for mixing chemicals was discussed and will be reviewed further. The use of a barrier crème was discussed and will be reviewed further.
All near misses should be reviewed more stringently on a monthly basis. This review would include the rig manager and drilling supervisors.
