Process Safety Management - Universitas...

Process Safety Management

Dr. Ir. Yulianto S Nugroho, MSc.Department of Mechanical Engineering University of Indonesia

Industrial Safety Series

2 ©Dr. Ir. Yulianto S Nugroho, MSc

Outline of talk

• Introduction : what is process safety ?• Inherently safer and more user-friendly design• Incident investigation and human error• Institutional memory• Process safety analysis• Hazard analysis• Risk analysis• Project review and audit process• Safety devices• Hazardous material and conditions

Reference :Perry’s Chemical Engineering Handbook, 1999Charles A. Wentz, Safety, Health and Environmental Protection, MGH, 1998.


Introduction

In recent years there has been an increased emphasis on process safety as a result of a number of serious accidents. This is due in part to the worldwide attention to issues in the chemical industry brought on by several dramatic accidents involving gas releases, major explosions, and environmental incidents. Public awareness of these and other accidents has provided a driving force for industry to improve its safety record.

Hazards from combustion and runaway reactions play a leading role in many chemical process accidents. Knowledge of these reactions is essential for control of process hazards. It is important that loss of containment be avoided.


Introduction (con’t)

Process safety differs from the traditional approach to accidentprevention in a number of ways.

There is more concern with accidents that arise out of the technology.

There is more emphasis on foreseeing hazards and taking action before accidents occur.

There is more emphasis on a systematic rather than a trial-and error approach.

Traditional practices and standards are looked at more critically.


Inherently safer and more user-friendly design

For many years the usual procedure in plant design was to identify the hazards, by one of the systematic techniques or by waiting until an accident occurred, and then add on protective equipment to control future accidents or protect people from their consequences. This protective equipment is often complex and expensive and requires regular testing and maintenance. It often interferes with the smooth operation of the plant and is sometimes bypassed. Gradually the industry came to realize that, whenever possible, one should design user-friendly plants which can withstand human error and equipment failure without serious effects on safety (and output and efficiency).


Inherently safer and more user-friendly design (con’t)

Rather than add on equipment to control hazards or to protect people from their consequences, it is better to design user-friendly plants which can withstand human error and equipment failure without serious effects on safety, the environment, output, and efficiency.

The most effective way of designing user-friendly plants is to avoid, when possible, large inventories of hazardous materials in process or storage.

“What you don’t have, can’t leak.”

Plants in which we avoid a hazard, by reducing inventories or avoiding hazardous reactions, are usually called inherently safer.



The principle ways of designing inherently safer plants:Intensification

This involves using so little hazardous material that it does not matter if it all leaks out.

Substitution If intensification is not possible, then an alternative is to consider using a safer material in place of a hazardous one. Thus it may be possible to replace flammable solvents, refrigerants, and heat-transfer media by non-flammable or less flammable.

Attenuation Another alternative to intensification is attenuation, using a hazardous material under the least hazardous conditions.



Limitation of Effects of Failures Limitation can be done by equipment design or change in reaction conditions, rather than by adding on protective equipment.

Simplification Simpler plants are friendlier than complex ones, as they provide fewer opportunities for error and less equipment which can fail.

Knock-on Effects Plants should be designed so that those incidents better

that do occur do not produce knock-on or domino effects.

Avoiding Incorrect Assembly Plants should be designed so that incorrect assembly is difficult or impossible.



Status Clear It should be possible to see at a glance if equipment has been assembled or installed incorrectly or whether a valve is in the open or shut position.

Tolerance Whenever possible, equipment should tolerate poor installation or operation without failure.

Low Leak Rate If friendly equipment does leak, it does so at a low rate, which is easy to stop or control.

Ease of Control Processes with a flat response to change are obviously friendlier than those with a steep response.

Software In some programmable electronic systems (PES), errors are much easier to detect and correct than in others.


Incident investigation

Although most companies investigate accidents (and many investigate dangerous incidents in which no one was injured), these investigations are often superficial, and we fail to learn all the lessons for which we have paid the high price of an accident. The facts are usually recorded correctly, but often only superficial conclusions are drawn from them.


Institutional memory

Most accidents do not occur because we do not know how to prevent them but because we do not use the information that is available. The recommendations made after an accident are forgotten when the people involved have left the plant; the procedures they introduced are allowed to lapse, the equipment they installed is no longer used, and the accident happens again.


Institutional memory (con’t)Many accidents have occurred because the two procedures below were unsatisfactory or were not followed.

Preparation of Equipment for Maintenance :

Isolation of the equipment under maintenance, Identification of the equipment, Freeing from hazardous materials, Jobs which raise special problems, Handover, Change of intent, .

Control of Plant and Process Modifications

Many accidents have occurred because plant or process modifications had unforeseen and unsafe side effects. No such modifications should therefore be made until they have been authorized by a professionally qualified person who has made a systematic attempt to identify and assess the consequences of the proposal, by hazard and operability study or a similar technique.


Process safety analysis

Hazard analysis :

The meaning of hazard is often confused with risk. Hazard is defined as the inherent potential of a material or activity to harm people, property, or the environment. Hazard does not have a probability component.

Process Hazard Analysis Methods Listed in the OSHA Process Safety Management Rule


Process safety analysis (con’t)System for hazard identification :


Risk analysis

Risk is a measure of economic loss or human injury in terms of both incident likelihood (frequency) and the magnitude of theloss or injury (consequence).

Risk analysis The development of an estimate of risk based on engineering evaluation and mathematical techniques for combining estimates of incident consequences and frequencies. Incidents in the context of the discussion in this chapter are acute events which involve loss of containment of material or energy.


Risk analysis (con’t)The components of a risk analysis involve the estimation of the

frequency of an event, an estimation of the consequences (the extent of the material or energy release and its impact on population, property, or environment), and the selection and generation of the estimate of risk itself.

A risk analysis can have a variety of potential goals:1. To screen or bracket a number of risks in order to prioritise them

for possible future study 2. To estimate risk to employees 3. To estimate risk to the public 4. To estimate financial risk 5. To evaluate a range of risk reduction measures6. To meet legal or regulatory requirements 7. To assist in emergency planning


HAZOP example




Date post:	16-Apr-2018
Category:	Documents
Upload:	ngotram
View:	217 times
Download:	2 times

Process Safety Management - Universitas...

Documents