5 things to consider when selecting a safety system

Performance requirements now drive the selection process

10/29/2013


Hazard management in places like offshore drilling is critical to the safety of people and property, and is one of five considerations when choosing a safety system. Courtesy: ABBSafety is among the top priorities in any manufacturing facility, and given the changes in the industry, technology and even standard, there are a lot of concerns starting with the selection of a safety system.

The performance based safety standards (IEC61508 and IEC61511/ISA84) have changed the way safety system selection should happen. Gone are the days of simply choosing a certified product, or selecting a preferred architecture; today’s system selection is driven by performance requirements. 

1: Hazard understanding

Correct, this has nothing to do with the safety system hardware. It is critical in the process to understand the scope of the process hazards and to determine the necessary risk reduction required. This should be done to create the Safety Requirements Specification (SRS) necessary to start a system selection. Even when replacing an existing system, this is critical as the risk profile of the plant may have changed since installation. 

2: The more diverse the better

Technology diversity: There has been a long standing requirement that a safety system must be different (or diverse) technology from its process automation counterpart to avoid common cause failures. But most safety systems rely on component redundancy (hardware fault tolerance, or HFT) to meet reliability and availability requirements, introducing a degree of common cause failure directly into the safety system.

Rather than redundancy, leading systems now provide diversity of technologies designed into logic solvers and I/O modules, along with a high degree of diagnostics, to allow a simplex hardware configuration to meet SIL3 requirements.

Product implementation diversity: The standards are imposing diversity on the way manufacturers deliver the product you buy. Even though most safety systems are manufactured by process automation vendors, organizational diversity between the two product teams is only the first level of separation.

Within the safety product team, leading suppliers will also be separating the design group from product development group and then again from product testing group. Ask your potential suppliers how diverse they really are? 

3: Systematic safeguards

This addresses how much protection against mistakes is built into the safety system. You should be asking for:

  • certified software libraries that offer functions according to the SIL requirements of the application,
  • compiler restrictions to enforce implementations according to the SIL requirements,
  • user security management to separate approved from non-approved users for overrides, bypass and other key functions,
  • and, audit trail capability to record and document changes to aid in compliance with functional safety standards 

4: Availability

As mentioned above, previous generations of safety systems met reliability requirements through HFT. This feature helped to provide availability and kept plants running in the event of a component failure with the safety system. Whether you needed it or not, you paid for it. Understand if you need high availability or not as some processes can easily tolerate shutdowns from spurious trips when using simplex configurations that still deliver appropriate SIL coverage.

If you know you need availability, look for a system supporting firmware update or upgrade and maintenance without disrupting the process. 

5: Separate, interfaced, or integrated?

Using the SRS and your business requirements, make a clear determination of one of these three requirements. Integrated offers many key benefits, drawing on common capabilities of the process automation system not related to the safety functions directly. But only being interfaced or even kept completely separate are options, and need to be thoroughly considered.

However, achieving the desired risk reduction involves more than just choosing a system. On our next posting we’ll cover implementation, security, operation, and maintenance of a safety system. 

Luis Duran is Product Marketing Manager at ABB for the Safety Automation System business.



The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
A new approach to the Skills Gap; Community colleges may hold the key for manufacturing; 2017 Engineering Leaders Under 40
Doubling down on digital manufacturing; Data driving predictive maintenance; Electric motors and generators; Rewarding operational improvement
2017 Lubrication Guide; Software tools; Microgrids and energy strategies; Use robots effectively
The cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Mobility as the means to offshore innovation; Preventing another Deepwater Horizon; ROVs as subsea robots; SCADA and the radio spectrum
Power system design for high-performance buildings; mitigating arc flash hazards
Research team developing Tesla coil designs; Implementing wireless process sensing
Commissioning electrical systems; Designing emergency and standby generator systems; Paralleling switchgear generator systems

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
Featured articles highlight technologies that enable the Industrial Internet of Things, IIoT-related products and strategies to get data more easily to the user.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Maintenance Manager; California Oils Corp.
Associate, Electrical Engineering; Wood Harbinger
Control Systems Engineer; Robert Bosch Corp.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me