SI057001_MNL - Gasoline Overfill Protection SIS IMMEAS-SIS1 Design Manual

Immingham East Terminal – Gasoline Overfill Protection

Safety Instrument System

P & I Design Ltd

DOCUMENT NO: SI277001_RPT

2 Reed Street, Thornaby, UK, TS17 7AF

ISSUE:

DATE: 31.10.14

Tel: + 44 (0)1642 617444

PAGE 10 OF 29

Fax: + 44 (0)1642 616447

6.3

Operation

The Safety Instrument Functions (SIF) are to prevent overfill of the storage tanks.

6.3.1 No. 4 East Tanks

There are six possible import routes. Although there are six pipelines, a batch import process

to any particular tank will only use a single pipeline. As there is no process control system

which confirms the route, this design will operate by closing the tank-side import valve on the

tank high high alarm activation.

For the No.4 East tanks, on detection of a tank high high level, fault or power supply failure,

the output will be removed to the actuator on that tank’s import valve, resulting in the ball

valve closing. The valve cannot be re-opened until the high high level, fault or power supply

failure are returned to a healthy state. Then on operation of a momentary reset pushbutton

(one on the SIS panel plus facility for remote operation) the actuated ball valve will open (if

selected to open at local pneumatic control station).

There is no requirement to override this SIF in the event of an activation of the high high

level switch as there is a dedicated export route using hoses under management procedures

which will allow for product to be removed from the tank. Management controlled use of this

is described elsewhere.

The valves will be operated, cycled, periodically on a monthly basis. This will provide a form

of regular stroke testing. Taking this into consideration, and the fact that only one valve will

be open to allow import to any one tank, the SIS shall be designed as a 1oo1 system

throughout, providing all clauses of BS EN 61511 are satisfied.