1. Learning bulletin – Sundridge Lost time incident and dangerous occurrence
Failure of Auxiliary valve
While checking stock levels in the Chlorine and Sulphur dioxide store at Sundridge one of your colleagues became concerned over the condition of the pressurised pipework, when he examined this more closely the connection coupling failed and Chlorine was released into the room.
Your colleague promptly evacuated the room and activated the emergency shutdown system which effectively stopped the release.
The emergency services ( Fire , Police and Ambulance ) Attended and your colleague was taken to hospital and detained overnight for observation.
Why did it really happen?
Small weeps and leaks of Chlorine will corrode pipework, if external damage can be seen there may be a deeper cause for concern.
Investigating any concern by touching pipework can worsen the situation a proper completion of the point of work risk assessment did not occur.
An unplanned/ unscheduled task was undertaken by the individual
What can I do differently?
Never touch or physically adjust any pressurised pipework on the gas delivery line while working alone. Always have a second man
Check your emergency procedures are up to date and are well rehearsed.
Make sure you are confident and up to date with the controls and standards in our risk assessment.
When you have a concern with the gas system, leave the room and arrange to address this concern with the proper ppe, tools and manning levels.

2. Learning bulletin – Opening of stiff valves
What happened?
A part of the MANDAT of the Chlorguard system is testing to ensure that in the event of a leak the system would shut in the cylinder to stop the leak. During July there have been 2 occasions where the cylinder valves have sheared during the inspection of the chlorguard system. On both occasions BOC (our supplier) have attended site to isolate the cylinder, complete a repair or remove the cylinder from site.
Why did it really happen?
Two issues have been identified:
A tool, typically known as a spider has been used to open the valves, which has resulted in excessive force being applied and the valve being jammed in the open position. When the Chlorguard tried to operate the valve it sheared it from the cylinder.
The torque setting on the Chlorguard system is checked to a task spec measuring the pressure of the air supplied in bar (1.5) we are working with BOC and Chlorguard to verify 1.5 bar limits the torque delivered to 5-7 nm – a further update will be provided.
What can I do differently?
TAKE CARE and TAKE YOUR TIME
No tools are to be used to open valve’s on toxic gas cylinders. All “spider” tools are to be handed in to your local H&S advisor for disposal.
Once fully opened by hand the valve should be turned one half turn back .
Chlorguard MANDATs need to be completed when the cylinders have been isolated and the Chlorguard removed.
Should you encounter a stiff valve, then follow the procedure for opening which is detailed in appendix 6 of HSP1 Managing Toxic Gas rooms – available from the H&S section of the Thames Water portal.
Any incidents involving stiff valves to be reported.