Sharing Machine Safety Knowledge

The conference was well attended by a mixture of OH&S, engineering and maintenance professionals from around Australia.  Topics were an interesting mix of case studies, presentation of standards and legislative issues and application experience.

 ICT engineers Mark Crittenden and Michael Bagnara accepted an invitation to present an interactive workshop.  The workshop was structured as a number of topics from which the attendees could nominate selections for discussion.  This provided an opportunity to raise a variety of issues of specific relevance and interest to the audience.  Active discussion ensued with excellent interaction from the floor. 

Part 1: Critical Aspects Of Machine Safety In Planning And Engineering Of Machinery And Equipment

Topic 1: Overview of the Concept for Risk Control under AS4024.1.Introduction

AS 4024.1 is currently our core reference for machine safety.  It is a broad and very detailed standard with much useful guidance information and many requirements.  As a direct result of this we feel there is a danger of people getting lost in that detail and losing sight of what is to us the core methodology.

 This introductory topic looks at an overview of the core methodology of AS 4024.1 and a summary of the steps involved in its implementation.

 ICT Machinery Safety Workshop April 2011 - Part 1 Topic 1.pdf (PDF 1 MB)

Topic 2: Risk Assessment to Risk Control – How do I Determine if I need additional Risk Controls?

The requirement for Risk Assessment is well documented and enshrined in Australian OH&S legislation.  Standards describing Risk Assessment methods (including AS 4024.1) are fairly general however and a wide variety of forms and approaches are used in industry.

 In approaching the assessment and control of risks on a machine or process, it is sometimes unclear how to decide whether additional engineered risk controls are required.  This topic illustrates some different methods of quantification of level of risk and considers how we might decide whether additional risk controls are required.  The concepts of the “Hierarchy of Controls” and “Reasonably Practicable” are considered.

 ICT Machinery Safety Workshop April 2011 - Part 1 Topic 2.pdf (PDF 1 MB)

Topic 3: AS4024.1 – Discussion of the Process of Selection of Categories

AS4024.1 is somewhat unspecific in its guidance for selection of Categories for Safety Related Parts of Control Systems.  Words like “Seldom to quite often, and a short exposure time” can be interpreted differently by different assessors. 

 This topic reviews the intended purpose of the process of selection of categories and considers some practical guidelines. 

 ICT Machinery Safety Workshop April 2011 - Part 1 Topic 3.pdf (PDF 713 KB)

Topic 4: Dangers of Blanket Conservative Category Classification

Do all parts of a machine necessarily have the same classification?

 Is it safer to classify conservatively?  For example, should I simply classify my machine as Category 4? This eliminates the possibility that my assessment can be questioned from a safety point of view but what are the consequences?

 When undertaking a category assessment as defined in AS4024.1, blanket and conservative assessments can create significant problems in terms of implementation.  This topic will consider the pros and cons of blanket and conservative category classifications.

 ICT Machinery Safety Workshop April 2011 - Part 1 Topic 4.pdf (PDF 560 KB)

Topic 5: AS4024.1 – Consideration of Validation requirements

AS4024.1502 “specifies the procedures and conditions to be followed for the validation by both analysis and testing of the safety functions provided, and the category achieved for the safety related parts of the control system in compliance with AS 4024.1501”

 This topic will consider what validation means in the context of a safety system and how to achieve validation.

 ICT Machinery Safety Workshop April 2011 - Part 1 Topic 5.pdf (PDF 1 MB)

 Part 2: The Use Of Advanced Control And Protection Systems To Optimise Plant Safety And Performance

Topic 1: Machine Safety versus Process Safety – How do they Differ?

Safety Related Control System equipment and information tends to refer to applications in either Machine Safety or Process Safety.  This topic looks at:

The history behind this distinction

How relevant is this distinction in current safety system engineering?

Which standards relate to these areas and how are the standards evolving? 

What are the implications for the selection of control equipment for the two areas and to what extent are they merging?

 ICT Machinery Safety Workshop April 2011 - Part 2 Topic 1.pdf (PDF 569 KB)

Topic 2: How do Safety PLCs / Controllers Differ from Standard PLCs?

Over the past 10 years or so we have seen a variety of “Safety PLCs” or “Fail Safe PLCs” adopted for widespread use.  This topic explains how Safety PLCs differ from conventional PLCs.  The important difference between Availability and Integrity is also considered.

 ICT Machinery Safety Workshop April 2011 - Part 2 Topic 2.pdf (PDF 359 KB)

 Topic 3: What are the Pros and Cons of Safety PLCs over Safety Relays?

What is a safety relay and what is a safety PLC?  When would I use a safety relay and when would I use safety PLC?  What benefits can a safety PLC bring to my application?

 This topic will consider the pros and cons of the safety relays vs. safety PLCs and will include a number of example applications to demonstrate the pros and cons of each option.

 ICT Machinery Safety Workshop April 2011 - Part 2 Topic 3.pdf (PDF 1 MB)

Topic 4: Risk Controls - Operator convenience and safety should not be mutually exclusive.

A constant focus in our implementation of safety systems is to “make the easiest way the safest way”.

If a well-designed safety system facilitates all aspects of operation and maintenance then there will be little incentive to defeat or bypass the system.  This concept and its potential benefits for productivity are explored through some examples.

 ICT Machinery Safety Workshop April 2011 - Part 2 Topic 4.pdf (PDF 2 MB)

Topic 5: Risk Controls – Automatic checks boost system integrity and Reduce Maintenance Requirements

What is an automatic check?  How can an automatic check boost the safety integrity of my system and at the same time, reduce my maintenance costs?

 When specifying, designing and installing a safety system, consideration must be given to how the system will be maintained in order to ensure that it continues to deliver the required safety integrity over the life of the system.

 By designing safety systems that automatically check their safety functionality, we can reduce the time required to perform routine maintenance checks on our safety system.  This topic will explore how automatic safety checks can be designed into a safety system to reduce maintenance costs and at the same time, improve the safety integrity.

  ICT Machinery Safety Workshop April 2011 - Part 2 Topic 5.pdf (PDF 480 KB)

Topic 6: Productivity gains through safety system diagnostic displays

What is a safety system diagnostic display and how can such a display improve my productivity?

 This topic will explore the options for implementing safety systems and how the provision of diagnostic displays in the safety system design can significant reduce down time and thus improve productivity.

 ICT Machinery Safety Workshop April 2011 - Part 2 Topic 6.pdf (PDF 488 KB)