Plant Layout

Plant layout is often a compromise on a number of factors including:

* Need to keep the distance to the transfer of materials between plant / warehouse units to minimize cost and risk reduction.

* Geographical limitations of the site;

* Interaction with existing or planned facilities, such as existing roads, sewers and utility lines;

* Cooperation with other plants in the field;

* Need plant and utility maintenance;

* Need to hazardous materials resources on site boundaries and the local population lives in the neighborhood to install;

* The need for the prison where leakage of flammable materials may occur to prevent

* The need for access to emergency services;

* The need to escape on-site staffing;

* The need for acceptable working conditions for operators.

The most important factor in changing the plant layout, as long as opinions are concerned about the safety,

* Prevention, reduction and / or easing the tensions related events (Domino);

* Provide a safe place in occupied buildings;

* Controlling access by unauthorized persons;

* Improving access to emergency services.

Defining plant layout designers must take into account the factors described in the following paragraphs.

Built-in safety

The main principle is to eliminate the inherent danger to safety together. The best way to achieve this is to reduce the inventory of hazardous substances so that no more serious threat is presented. But it is not often easily accessible and by definition not a COMAH facility did not do this. Other possible methods are intrinsically safe design:

* Reduction of the activation of reserves;

* Substitution of hazardous substances with less hazardous alternatives

* Relax in an attempt to adverse conditions, temperature, pressure reduction;

* A simple systems / processes to the potential loss of content or restrict any errors cause dangerous event;

* Fail-safe construction as positioner failure.

Plant layout considerations relating to the achievement of security first and foremost for those who are concerned about the domino effect (see below).

Dow / Mond indices

These are useful indicators of the risk assessment of processes or software, they are senior to the existing facilities and the assignment of incident classifications. They provide the comparative size of a fire and explosion process are useful tools for plant layout development, because they objective distance distances to be considered at all stages.

Method for making a quick method for ranking, based on the Dow / Mond index detailed ILO PIACT greater practical risk management handbook, 1988.

Although this useful rule of thumb methods for primary plant layouts change, they do not replace the risk assessment from the distance between power devices use these systems are based on technical evaluations, and to some extent the experience rather than a detailed analysis.

Domino effect

Risk assessment of the site layout is very important for controlling the effects of loss and opportunities to ensure sastkatsats minimized. Domino is a fire, explosion (shock wave and missiles), or toxic gases causing loss of control government actions in a different location.

Four

A fire in four ways.

* Direct ignition, such as running liquid fires);

* Convention;

* Radiation;

* Conduct.

Spread of fire in other parts of its territory, the origin be prevented by vertical and horizontal sections using fire walls and floor. More information can be found in BS 5908 '1990 [8]. Taking into account the need to spread through the flammable substances list, piping and ventilation systems. Delayed ignition of the release could lead to the spread of fire through such systems the combustible gas to disperse vapors.

Protection against Domino effects by convention, heat conduction and radiation can achieve enhanced security principles, namely to ensure that the distance between the plant elements are sufficient to heat related plants compromising the safety of the plant. If it is not possible because of other constraints, other methods such as fire walls, active or passive fire protection are considered.

Explosion

Extension of an explosion may directly or indirectly from pressure waves of missiles. If fires are inherently safe methods to be considered:

* Organize distances, so that damage to adjacent plants was not even in the worst case;

* Display obstacles blast walls, placement of a strong building;

* Protection of plants against damage, for example, the thicker walls of vessels;

* Management Explosion relief vents away from sensitive areas such as other plants or buildings, roads around the place outside.

But the latter can no practical solutions, in particular missile, and risk analysis may be required to provide adequate security to show.

Toxic Gas Releases

Toxic gas released, a domino effect of related plants cause in making useless and injuring operators. Prevention / mitigation of such effects may affect the supply of automated systems using the principles of inherently safe and comfortable control room (see below occupied buildings).