Fawley Site Event 3rd March Update

Dear Community Member

We wanted to take the opportunity to share with you the findings of our investigation into the cause of the loud bang that was heard from our Site on evening of 3^rd March.

We absolutely recognise that this was a loud and unique sound and we, again, apologise for any concern caused.

The cause:

As we directly communicated on the evening itself, the noise was caused by the sudden release of high pressure air from a fracture in a metal pipe.

At the time, we had taken one of our units offline to conduct routine annual maintenance – a standard process we have undertaken many times before – which requires pipework to be flushed of hydrocarbons before atmospheric air is pushed through at pressure.

The loud bang occurred when the pipe fractured and there was a sudden and concentrated release of air travelling at very high speed. The bang was essentially a release of energy.

The fracture of the pipe was caused by a chemical reaction between the air and a very small amount of residual hydrocarbons that had unexpectedly remained in the line following the purging process. This caused a small, very localised, combustion point leading to a break in the pipe and the sudden release of energy – hence the flash and loud bang.

The event lasted about 1 second, nobody was injured, there was no subsequent impacts and the community was not at risk.

Action taken:

We subsequently completed the maintenance work and the unit was safely returned to normal service.

While this was an incredibly rare occurrence that we could not have foreseen or planned for, we have now revised our process for this routine work to remove the risk of a repeat in the future. We have also followed up on our findings with the HSE, working with them throughout.

We hope this insight is helpful and again we apologies for any concern this has caused.

Nick Bone

Plant Manager

ExxonMobil Fawley