An operator went to purge a process tank per standard operating procedure. The operator reviewed the previous shift's purge time and determined the next required purge time. The operator found that the tank had been purged earlier than expected on the previous shift. Because the earlier purge time was not recognized, the 12-hour purge frequency was exceeded.
Background: On the previous day, during the night shift, an operator performed 12-hour hydrogen purges per the requirements of the standard operating procedure. Each of the hydrogen purges was completed within the required time limits. The operator correctly recorded the time and date that the next hydrogen purges would be required. The following morning, shift turnover was conducted. The direct and root cause of this occurrence is a management problem, work organization / planning deficiency. On 8/26/00, during the night shift, the 12-hour hydrogen purge was performed unusually early in the shift (19:10 hours to 19:15 hours) to accommodate other scheduled work activities. Performing the purge this early in the shift resulted in the next purge being required by 07:15 hours, immediately after morning shift change turnover, which usually occurs at approximately 07:00 hours. Poor planning led to the operator not purging one of the process vessels within the required 12-hour frequency. The operator that completed the procedure and performed the vessel hydrogen purge is qualified and routinely successfully performs these evolutions without error.
The night shift manager should have recognized that it would be difficult to meet the 12-hour purge frequency the following morning. The manager should have scheduled the hydrogen purge for later in the shift, or again prior to the end of the night shift so that it could reasonably be performed on the next shift.
This occurrence highlights the need for ensuring work is organized and planned in a manner that is practical and efficient. The primary lesson learned from this occurrence is that personnel must be cognizant of the impact of their actions on other shifts. Planning with thought on potential consequences is necessary to ensure work activities are performed safely and the appropriate actions are taken as required.