Why safety in chemical engineering

Question 1

Consider plant lifecycle

Answer 1

Phases of lifecycle from manufacture through use to dismantling and disposal

Question 2

Design for safe erection and installation of the plant

Answer 2

Risk relating to installation and erection of the plant controlled by:

• Designing the plant so it is stable when left freestanding prior to installation
• Making it structurally stable even without ‘adjustment’, that is, before all the nuts have been tightened,
• Providing special supports that can be used to give stability prior to and during installation,
• Providing attachment points for lifting and handling.

Question 3

To facilitate safe use

Answer 3

• User physical characteristics
• The maximum number of tasks an operator can be expected to perform at any one time,
• The complexity of those tasks, and the pace at which they can be performed
• The need to minimise long periods of physical or repetitive activity and constrained posture
• The layout of the workstation or environment in which the plant may be used
  Instrumentation and its layout - easy to understand layout, not too much info to cause confusion

Question 4

Physical characteristics of users

Answer 4

• The plant should accommodate the range of physical characteristics of each user: the range of human dimensions and capabilities such as height, reach and weight to provide an optimum match between plant and user.
• The principles of ergonomics should be applied to minimise the physical and mental demands on the plant operator in order to reduce potential discomfort, fatigue, error and injury under the intended conditions of use.

Question 5

Consider intended use and reasonable foreseeable misuse

Answer 5

The plant is used for tasks not designed or originally intended

Question 6

Design for safe maintenance

Answer 6

Worker difficulties when maintaining and repairing the plant, locate other maintenance points out with the possible danger zones

Question 7

Design so the plant ‘fails to safety’

Answer 7

Types of failure or malfunctions and design the plant to fail in a safe manner, leaks and spills are contained, fire and explosions don’t lead to runaway reactions

Question 8

Chemical engineers involvement

Answer 8

Process specification, design, relief systems, shutdown routines, emergency plans, change legislation, physical effect
=>There are a number of strategies which should be considered during design:
Stable, non-toxic, non-flammable chemical processes used for making a product must be one of the objectives of the conceptual design.
Then considering how Inherent Safe Design may be planned, followed by Layers of Protection through relief &control systems. Finally the Operation Management through controlling management of change, permits, hazid and hazop