Lockout Tagout does not effectively isolate explosion and injury

Lockout Tagout does not effectively isolate explosion and injury

In preparation for maintenance, the operator on duty assumes that the pump inlet valve is open by the position of the valve wrench. He moved the wrench perpendicular to the body, thinking he had closed the valve. But the valve is actually open.
Although mechanical engineers and operators performed Lockout tagout on the accident pump, they mistakenly believed that the pump had been isolated and relieved. They did not fully confirm that the pump was isolated or empty before Lockout tagout. Effective Lockout Tagout (LOTO) procedures include special requirements to inspect equipment to determine and confirm the effectiveness of locking equipment, Lockout tag equipment, and other energy control measures.

In interviews with operators, CSB found that they sometimes determine whether a valve is open or closed based on the position of the valve wrench. If the wrench is perpendicular to the valve direction, it is said to be closed. If the wrench is parallel to the valve direction, it is said to be open. Technically, the purpose of the wrench is not to indicate the position of the valve, as a position indicator is provided on the valve stem to indicate the valve on or off. However, some factory employees often determine the valve switch based on the position of the wrench, in part because the wrench is more obvious than the stem position indicator.