A member has reported a near-miss which could have been a potentially serious incident, which occurred during the stacking of lengths of pipe. The pipe joints were being off-loaded from the transport vehicle, and were being stacked pending further loading into U-frames for delivery to the pipelay vessel.
The procedure specified a stack with a maximum height of 8 layers of the 10″ pipe joints. When placing the seventh layer on a stack, the front end pipe joint in the bottom layer slipped out of the restraining chock, pushing the other chocks ahead of it. This was followed by a slow slippage of the entire base layer, causing the rest of the pipe stack to slump. The slippage of pipes continued until it came to rest against a fork lift truck that was parked in front of the stack.
The area in front of the stack was used as an inspection area, but at the time of the incident no people were in the area and, as a result, nobody was injured and there was only negligible damage.
The method employed for stacking the pipe had been used on several projects without any previously recorded incidents.
The investigation showed that the pipe coating was smooth, not sintered as expected, with little or no friction. This had been noted upon reception of the pipe joints, but not considered a problem. A subsequent sensitivity analysis, conducted as part of the investigation, revealed that the smooth surface more than doubled the forces that the wooden restraining chocks would have to withstand.
The discovery of the smooth pipe coating should have resulted in the initiation of a management of change process, which would have led to further engineering and a new risk assessment for the pipe stacking. This was not done.
As a result of this incident, a new method was employed to secure the bottom layer. Four lengths of pipe were inserted into pipe joints and these were secured with chains and turnbuckles (see photo below).
The company involved has noted the lessons learned from this incident as including:
- Always use a management of change process when things are different than expected;
- Pipe stacks should be located so that work in front of/or behind the stack is avoided;
- The method of stacking pipe should be evaluated for each type of pipe, taking into account the coating, to determine if securing the stack with wooden chocks is sufficient or other methods have to be adopted.