Hazards

Hazard Definition:
There are many definitions of a hazard:

•	Def Stan 00-56 [MOD95], "A physical situation, often following from some initiating event that can lead to an accident".
•	MIL-STD-882C [DOD93], US Department of Defence: "....freedom from those conditions that can cause death, injury, occupational illness, or damage to, or loss of, equipment or property or damage to the environment".

In the simplest of terms, it is "Something that has the potential to cause harm"

The identification, assessment and mitigation of hazards are fundamental processes in the management of safety and are integral to the design, build and operation of safe systems. Where there is human involvement with activities there will always be an element of risk. One of the aims of a Safety Management System is to reduce the risks to a level that is tolerable, or ALARP (As Low As Reasonably Practicable).

Hazards - Identification Techniques
There are a variety of techniques that can be used to identify hazards in a system. T&IP Ltd is experienced in the following:

1. Structured What If Technique (SWIFT).
2. Failure Mode & Effects Analysis (FMEA).
3. Hazard and Operability Analysis (HAZOP).
4. Zonal Hazard Analysis.

1.Structured What If Technique (SWIFT)

As the name implies, this process is based around a series of structured and well-defined questions aimed at brainstorming possible failure mechanisms for the system at an early stage of the design. Possible questions might be:
What if;

>   A specific item of equipment fails?
>   The operator fails to carry out the correct procedure?
>   The level Control fails to operate?
>   A fire occurs in a particular part of the plant?
>   A flood occurs?

The success of the process is reliant, primarily, on the experience of the personnel conducting the review.  T&IP Ltd have wide ranging expertise and system knowledge covering high energy hydraulic and pneumatic systems as well as cooling water and steam systems. All associates can also demonstrate extensive system operational experience on these types of system.

We have successfully developed and implemented a strategy to conduct Zonal Hazard Identification for the Astute Class Submarine presently under Design by BAE SYSTEMS Marine Limited.

2. Failure Mode and Effects Analysis (FMEA)
FMEA is used to identify the ways in which a system might fail and the effects those failures could have on the system. An individual or a team of experts can carry out the analysis. The steps involved in conducting an FMEA are:

1. Select a component.
2. Identify its function.
3. Identify its possible failure modes.
4. Identify the unmitigated local effects of the failure.
5. Identify the overall unmitigated system effects of the failure.
6. Identify methods of protection from the effects of the failure (Mitigation).

Identify fault modes for components		Assess plant consequences of component failures
FMEA	Identify possible failure modes and assess the consequences of these failures

T & IP Ltd has the knowledge, expertise and experience to conduct FMEA on a wide range of high-energy fluid and gas systems. In addition we can provide expertise in Electrical System and Control & Instrumentation Failure Modes and Effects Analysis to complement the Mechanical Systems demonstrated above.

3. Hazard and Operability Analysis (HAZOP)
A Hazard and Operability Analysis (HAZOP) is a formal systematic approach to hazard identification. It is a team-based technique, which allows the members to brainstorm opinions and viewpoints using the experience from within their own fields of expertise. The methodology is structured to ensure a thorough and consistent coverage of any system design. It examines the components of the system, and the interactions between components and explores whether deviations from the design intent are possible, and if so what the possible cause may be and the possible effects to the system and plant. It is used primarily for analysis of new system design but is just as valid, if not more so, on system modifications, re-design or fully operational systems. Although a HAZOP may be conducted at any stage of the plant life cycle the maximum benefit will be derived during the design phase when changes are relatively easily made.

HAZOP -

Working from the fault in both directions, to determine possible causes and effects

T&IP Ltd have been intimately involved in the HAZOP process when conducting hazard identification procedures for BAE SYSTEMS Marine Limited, on the design of new systems associated with the Astute Class submarine:

• Hydraulic systems
• High-energy pneumatic systems
• Cooling water systems
• High-energy steam propulsion systems
• Lubricating oil systems
• Refrigeration systems
• Diesel Engine systems
• Hotel and Domestic services

4. Zonal Hazard Analysis
This technique is used to look at the complex interactions that can occur between high-energy systems and is specifically concerned with their physical position in relation to each other. The process has been successfully developed and implemented by T&IP Ltd in the Astute Class submarine project hazard identification process. It has been particularly useful in identifying possible common cause hazards i.e. where failure of a component, or part of a system, may cause associated hazards in the immediate area.

For example: a steam leak could cause the area, in which isolation of the leak can be affected, to be untenable to the operator. The leak is therefore unisolable. The identification of this particular hazard would lead to the recommendation to provide a remote isolation facility that is protected from the effects of the steam leak.

The Zonal Hazard Analysis techniques are also used to assess the effects of the proliferation of hazards into adjacent physical areas or compartments. They can be used to identify the routes by which the hazards may spread and in so doing, solutions can be developed to control and mitigate the effects of the hazard.

Checklists can be utilised in the process to identify hazards, they can also be used to check that designs comply with certain standards and codes of practice, or that protective measures are correctly employed. They are however, reliant on the knowledge and experience of those persons compiling the lists and T&IP Ltd can demonstrate relevant experience that will provide significant safety benefits for your systems and equipment.

Individuals, or teams, of people may utilise checklists to assist as part of the Zonal Hazard Analysis process, to identify hazards at any stage of the design process.

T&IP Ltd has the expertise and experience to carry out a Zonal Hazard Analysis and compile relevant and appropriate checklists to meet our customer's requirements for the analysis of the complex interactions that can occur between high-energy systems within a confined spatial environment.

How Hazard Identification Techniques Complement Each Other
Experience has shown, and best practice dictates, the use of a combination of hazard identification techniques.  There is no one technique that can claim to produce complete identification of all hazards.  The use of two or more techniques such as FMEA and HAZOP, will complement each other. FMEA starts with the failure mode of a component and examines the effects of that fault.  HAZOP starts with a deviation from normal system operation and examines how that deviation might occur and the consequences should such a deviation occur.

Risk Assessment
When hazards have been identified, there is a need to assess the risks they may present. Risk assessment is the determination of how often the event is likely to occur (frequency), and what the consequences would be if the event did occur, (perhaps injuries or even fatalities). The resultant risk is measured as a number of fatalities in any period of one year. There are several methods of determining risk; two of the most popularly used methods being Fault Tree Analysis (FTA), and Event Tree Analysis (ETA). Both techniques have been successfully employed by T&IP Ltd to determine risk levels of hazards.

The analysis technique in its simplest form makes use of 'And' and 'Or' logic gates to produce a tree structure. It starts at the Top Level event, and branches out through the logic gates to the base events.

Fault Tree Analysis - Working outwards from Top Level Event to identify individual cause or base events.

Fault tree analysis is a deductive technique, and requires a different and separate fault tree for each Top Level event.

Event Tree Analysis complements Fault Tree Analysis in much the same way as FMEA complements HAZOP.  Event Tree Analysis starts with a hazard, but instead of working backwards as in the Fault Tree, it works forward to describe all the possible subsequent events and so identify the event sequences that could lead to a variety of possible consequences.

Event Tree Analysis - Working from hazard events to identify consequences.

How Fault Tree analysis & Event Tree analysis complement each other

FTA - Working from the hazard to identify individual causes.
ETA - Working from the hazard to identify the consequences