Near-miss: Cement tank hatch failure

A member has reported an incident in which the hatch on a cement tank failed under pressure. The incident occurred when the cement tank was being pressurised to verify the integrity of the system prior to loading dry bulk during a forthcoming port call. Following the pressurisation of the cement tank to approximately 4 bar, a loud bang was heard and the cement tank pressure was rapidly lost.

Fortunately, no one was present within the cement room at the time and there were no injuries. This incident was considered a high potential near miss. Had any persons been in the cement space at the time of the incident, the potential for a serious injury was high.

Our member’s investigation revealed the following:

• The original cement tank hatch securing dogs had been removed and replaced by nuts. When this replacement had taken place was not known;
• It was discovered that the most likely reason for the change of the securing dogs with nuts was to provide greater clearance for personnel access between the cement tank hatch and the pillar;
• Although the cement tank hatch thread bar was 27mm, the diameter of the nuts was 30mm and, although of a differing size, it was still possible to secure these 30mm nuts on the 27mm thread bar;
• The change had not been properly documented or dealt with through a ‘management of change’ process;

Our member reported that a thorough investigation of this high potential incident is currently being undertaken and that the detailed findings from this investigation will be revealed in due course.