LNG STS/bunkering compatibility - Why Emergency Shut Down envelopes are so important?

When Cryosafe assess any LNG STS or bunkering operation, one of the items we consider is the Emergency Shut Down envelope.

This is vital in ensuring a safe transfer to ensure that the transfer is secured and ERCs released before the hoses would become taught.

There have been a number of ESD2 events within the industry and the ERC systems have operated correctly preventing damage and uncontrolled release of cargo.

In order for the systems to operate correctly it is important that the hose lengths and operating envelopes are calculated correctly.

The envelope can differ depending upon a number of parameters. Vessels involved in the operation, location and operating conditions. Operators/owners/charterers/customers should have complete confidence that the ESD envelope has been configured for the exact transfer:

• Is the hose length sufficient to allow movements prior to shut down depending upon vessel types, fendering, location and metocean conditions?

• Have the vessel ESD valves timings been set for the STS?

• What is the delay between the ESD trigger and signal to the vessel?

• Is there a risk of the hose touching the water? If so has resulting BOG generation been accounted for?

• Have the transfer location and conditions been taken into account for the envelope?

• Does the envelope take into account the full draft range of the vessels?

• Is there any manifold offset vertically or horizontally?

• Is there any contingency distance for unforeseen circumstances?

If you would like to know more about this service or training please contact gw@cryosafe.co.uk.