Given the global necessity to get products to markets more quickly and on demand, nothing is as crucial as the safe, uninterrupted operation of a manufacturing facility.
Safety benchmarks from domestic and international standards organizations comprise the path to safe operation. Domestic organizations include the American National Standards Institute (ANSI); the Instrumentation, Systems and Automation Society (ISA); and the National Electrical Manufacturers Association (NEMA).
Among independent testing-and-assessment services in Europe is TÜV Rheinland Berlin Brandenburg Group. Globally, there are the European-based International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC).
Front-burner issues receiving attention include functional safety in process industries and in programmable electronic systems, as well as criticality determinations relating to shutdowns. Also being developed is a safety-related bus system for the process sector through collaboration of end-users, manufacturers and a certification agency.
Some of those groups are also working together—or are taking other’s standards and adapting them—to address various hot-topic concerns such as integrated systems manufacturing and robotics.
ISA adapts IEC standards
Underway at ISA is a high-priority effort to facilitate transition from ANSI/ISA S84.01-1996 to S84.01-2003 which will correspond to IEC 61511. That transition will be addressed by a new guidelines task team, says Vic Maggioli, president of Feltronics Corp., Newark, Del., and vice president of ISA’s standards and practices department.
“Heavy user participation in this development is assuring that the guideline will address the process-sector needs. The goal is to have this done in 2004.”
IEC 61511 provides a three-part functional safety standard for safety-instrumented systems (SISs). “Part 1 is normative. Part 2 is informative, providing guidance for the application of Part 1. And Part 3 is informative, providing overviews on key global hazard-and-risk analysis methods,” says Maggioli. “IEC 61511-1 and 61511–3 were published this year. The IEC 61511-2 publication date is imminent.”
This ISA work is being done so there will be a global functional safety standard, says Angela Summers, Ph.D., President at Sis-Tech Solutions LLC, a Houston, Texas, consulting and engineering firm. “It will apply to SISs and will facilitate the implementation of safety-instrumented functions and safety integrity levels (SILs),” says Summers, who is ISA task team leader for the project.
Team meetings are scheduled for September and October, says Summers. “We’re prepared to do whatever we have to do. ISA’s intent in developing the guide is not to duplicate anything within IEC 61511-2, but simply to assist end-users in transitioning to the new standard.”
ISA’s SP84 committee work will add one clause to IEC 61511-1 that will “grandfather” S84.01-1996 systems, says Summers, who is also co-chair of the technical advisory committee at Texas A&M University’s Mary Kay O’Connor Process Safety Center. “That will make the standard compliant with the U.S. Occupational Health and Safety Administration’s 21 Code of Federal Regulations Part 1910.119 standards on process safety management.”
However, “ANSI approval will be sought for S84.01-2003,” Maggioli notes. Technical report TR91.00.02-2003 is available from ISA, he says. “This document provides guidelines and an instrumentation-classification scheme in addressing the discrete-parts and machine-tool industry.”
To support design and end-user implementation of safety systems that will conform to international standards, the Fieldbus Foundation is writing specifications and guidelines for safety-instrumented systems.
“Fieldbus Foundation-Safety Instrumented Systems (FF-SIS) will enable manufacturers to provide Foundation fieldbus instruments that comply with standards such as IEC 61508. A third-party agency will certify the SIL capability of the instruments, and the foundation will perform the usual ‘checkmark’ registration process,” says David Glanzer, Foundation director of technology.
The foundation’s board of directors approved this project in October 2002, after the foundation’s End-user Advisory Council identified FF-SIS as a strategic need. “Users want the same benefits in safety systems that they see in the standard fieldbus, including interoperable devices from various suppliers.”
The project kickoff was hosted by safety-equipment manufacturer Hima in January 2003, Glanzer reports. “On that team are end-users, including DuPont, Shell, Saudi Aramco, ExxonMobil, integrator Kellogg Brown & Root and major instrument and control manufacturers. ABB is providing the program management.”
Glanzer says TÜV is an active participant. “We picked them because Hima and TÜV have a working relationship. We need to make sure that what we’re doing can be safety certified.”
TÜV will develop a technical report on the evaluation of the SIS protocols and applications. “This will enable instrument manufacturers to develop equipment compliant with IEC 61508. Also, those instruments will be able to be certified by any safety agency.”
ANSI, ISO take on cells
Also undergoing a major revision is ANSI B11.20, says Roberta Nelson Shea, safety business development manager of Honeywell’s Sensing and Control Division, Freeport, Ill.
Safety of Manufacturing Systems/Cells, the original standard, was created in 1990. “The revision is a requirement from ANSI, that a standard must go to an update or reaffirmation, or it has to be withdrawn.”
Nelson Shea, who is ANSI’s Technical Expert on the ISO committee and worked on the original standard, says the reaffirmation process takes a few months. Reaffirm means “that members vote if the standard is still applicable. What has been discovered is that there are additional needs, questions and issues.”
This has been compounded by the evolution of technology. “New safety controls and new control technology affects what an integrated manufacturing system looks like and what its safety characteristics are.”
The standard, which addresses combining various kinds of machines and equipment, “concerns itself with how these operate as a whole and the safety aspects,” she says. “For instance, you may have 10 machines. Six of them might be used in one configuration. So you’re faced with figuring out how to have the six operate together and the other four operate together.”
Six of those may be used for production, she says. “You may have some being maintained. You have to figure out how to have this occur and manage the risks that might be present for people.”
Risk assessment, the process of determining the safety strategy of these configurations, is used to optimize designs to include safety. “If safety is part of the original design, that’s the most cost-effective solution.”
Nelson Shea says that “the goal of the standard is to have a more productive system by thoughtfully and thoroughly conducting a risk assessment that addresses all the anticipated tasks that may need to be performed in design, layout, production, maintenance, everything.”
It’s an iterative process. “A great deal of attention is being focused on risk assessment, especially task-based, and in the design. That means giving a great deal of attention to the layout of the equipment—not just the location, but also the orientation—and to understand and address the multiple uses that may go on simultaneously with this complex system.”
Individual machines have their own safety standards that will still apply. “This is very consistent with what is happening, in general, with technology. That means consistency in providing flexibility in manufacturing, yet controlling hazards and risks to personnel.”
The ANSI standard has participation from major manufacturing concerns, machinery manufacturers and safeguarding device manufacturers, says Nelson Shea. “That’s a broad range of interests being represented.”
Occurring simultaneously is new activity in International Organization for Standardization (ISO) standard 11161, Safety of Integrated Manufacturing Systems. “There is a revision being drafted for this standard, which is the international version of ANSI B11.20.”
Nelson Shea says the intention of the standard “has been to harmonize an international standard. We’re not done yet, but we’re very, very close. The committee hopes that a draft will be completed by the end of this calendar year,” she says.
Span of Control
Major B11.20 and ISO 11161 highlights, according to Nelson Shea, “are risk assessment and also introducing a span of control as it relates to individual machines, zones, modes and specific control devices. That could include emergency stop, enabling devices and safeguarding or protective devices.”
What is being encouraged in both ANSI B11.20 and ISO 11161 is to design in modes that will automatically group safeguarding for that mode of operation, Nelson Shea says. “This is a new concept that should apply to one or two machine combinations, multiple machines or all the machines.”
See sidebar to this article: IEC developing, reviewing other standards
See sidebar to this article: Robots setting lead for safety
