Home » Shutdown Philosophy
Safety Instrumented System (SIS)

Shutdown Philosophy

The Emergency Shutdown (ESD) System is designed to protect the personnel, plant, equipment and the environment against pollution.

The purpose of the ESD system is to monitor process safety parameters and activate or shutdown the process system and/or the utilities if these parameters deviate from normal conditions.

Shutdown Philosophy

Emergency Shutdown System Philosophy

This is the most important document associated with the Combined Safety System in that it lays down the philosophy applicable to it. In this document are listed the hierarchical shutdowns.

One must not lose sight of the fact that although the system has the ability to implement very critical shutdown features it also implements less critical unit and process shutdowns.

For instance on offshore platforms the usual stages of shutdown are as follows:-

UNIT SHUTDOWN

This, the lowest level of shutdown, causes the individual units to stop.

PROCESS TRAIN SHUTDOWN

An individual Process Train will shutdown on occurrence of any applicable trip.

PROCESS SHUTDOWN

On this process shutdown occurrence, the complete process stops but utilities remain running, in effect it is a process ‘stop’ with NO BLOWDOWN in order to facilitate a easier startup on rectification of the problem.

EMERGENCY SHUTDOWN

This action results generally from fire or Gas being sensed on the platform, obviously a fire in the Galley or in a room in the accommodation does not cause a ESD but more serious events in the Process, Wellhead or other critical areas will result in an ESD.

An ESD is actually a Process Shutdown with Blowdown and isolation of the platform trunkline. The blowdown results in flaring of the gas component of the platform inventory whilst the liquid component is maintained within the various process vessels. When co-incident fire detection in the process or wellhead areas occurs one of the two strategically placed firepumps start and deluge occurs automatically.

On some platforms main power is shutdown and the emergency generator starts when an ESD occurs whilst on others main power is maintained by the generators switching to Diesel except when there is fire in a critical area such as the wellheads.

This approach is advocated in that maintaining lighting ensures that at night the firefighting crew can see what they are doing.

TOTAL PLATFORM SHUTDOWN

This shutdown hopefully will never require operation during the life of the platform since it usually is the result of abandonment.

There are generally only two or three TPSD pushbuttons which are under the control of the Platform Operations Manager.

The result of this action is total blackout of the platform including isolation of batteries except for some navaids which continue to run.

The intent of this shutdown is to maintain some battery power for when the ‘black start team’ reboard the platform.

Articles You May Like :

Deluge System for Transformer

Process Interlocks and Trips

Fuse in a Electrical Circuit

Redundant Power Supply 

What is a Mimic Panel ?

Related Articles

Emergency Shutdown System Philosophy

S Bharadwaj Reddy

Process Safety and Instrumentation

S Bharadwaj Reddy

Safety Instrumented System Engineer Interview Questions

S Bharadwaj Reddy

What is Maintenance Override Switch (MOS) ?

S Bharadwaj Reddy

Voting Logic in Safety Instrumented System (SIS)

S Bharadwaj Reddy

Emergency Shutdown Valve : Advantages

S Bharadwaj Reddy

1 comment

kumar January 17, 2019 at 11:42 am

A Safety Shutdown System shall be independent of and in addition to other systems and equipment used for normal operation, control and monitoring, and shall act as a safety barrier in case of malfunction or maloperation of these systems and equipment.

The Safety Shutdown System is logically divided into three main levels of shutdown:

Process Shutdown (PSD)
Emergency Shutdown (ESD)
Abandon Platform Shutdown (APS)

Basic system philosophy is that a shutdown on a certain level shall never initiate shutdowns on higher levels, but shall always include shutdowns on lower levels.

Reply

Leave a Comment

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

Shutdown Philosophy

WordPress Image Lightbox

Send this to a friend