Changes Coming in New Edition of CSA Z142-10 Press Standard
April 1, 2010
Later this month the Canadian Standards Association (CSA) will release the most recent edition of the CSA Z142 power press standard.
It has been seven years since the release of the 2002 code that set the bar very high for press safety and became one of the more popular CSA safety standards.
At the five-year review the technical committee met to determine if a new edition of the standard was needed. During this review phase, there were several key revisions that played a major role in the decision to update the existing standard.
The first was to introduce requirements for the safe pressurizing of hydraulic tie rod nuts along with guidance on devices to be used for these tasks. The second major issue was the introduction of laser-actuated active optoelectronic protective devices (AOPDs) use on press brakes, which have been used throughout Europe for many years.
During our review process the American National Standards Institute (ANSI) B11.1 was also being updated, so it was important for the committee to make an effort to harmonize where possible with any applicable changes in ANSI’s new edition. Three issues that ANSI was addressing were the expanded use of slide locks, introduction of servo press technology for use on mechanical presses, and the introduction of risk assessment for auxiliary items that make up the complex press system.
Facing these tasks, the CSA technical committee went to work developing the new edition.
New to the Standard
Tie Rod Nuts. Probably the most important issue for the technical committee to address was to develop new guidelines for the safe use of hydraulic tie rod nuts in response to a coroner’s report on the death of a worker. In the response to the coroner’s findings, CSA agreed that the accident had application to both the CSA Z142 and the CSA Z460 standard for control of hazardous energy - lockout and other methods, but that neither standard specifically recognized the quick-coupler devices that were the cause of the accident in question.
CSA also recognized that even though many presses have been retrofitted with hydraulic tie rod nuts, no standards in Canada specifically apply to these devices. CSA then recommended that “guidance be provided in a future edition of CSA Z142 on both the design of safe pressure relief devices around these tie rods and the procedures to be followed in the release of hazardous stored energy when a malfunction occurs.”
Quick-coupler Devices. The new edition has an added a section for the design of quick-coupler devices to be used when pressurizing hydraulic tie rod nuts. These devices need four ports available: one port for attaching to the hydraulic line to increase pressure to the tie rod nut, one port with a permanently installed bleeder that bleeds to the atmosphere, a port with a pressure indicator capable of displaying the pressure range of the device, and a port for attaching directly to the tie rod nut itself.
All fittings are required to be rated to the pressure they will be subjected to, and the device should be portable and need not be permanently installed on each tie rod nut.
The purpose of these requirements is to add as little additional cost as possible to the end user. It is also important to note that while this device is a new technical requirement to the standard, it is required only when pressurizing of the tie rod nuts is needed.
Harmonizing With Other Standards
AOPDs. When CSA committees develop new editions of standards, it is very important that they always make an effort to harmonize with other standards. A European standard already exists for laser-actuated AOPD safeguarding devices (EN 12622), so this standard became the model for an entirely new section in the CSA standard.
It was important to the committee members that these new device requirements be given their own section rather than being added to the section on safeguarding devices. The reason for this is that these devices have a very limited scope of application and do not use the safe-distance calculations that other safeguarding devices are subject to.
The other major difference with these new devices is that they use safe speed as nonhazardous movement, which is contrary to the 0.25 in. (6 mm) being used as nonhazardous in the safeguarding section.
Slide Locks. The other issue of harmonization was focused on the current ANSI B11.1, which was also under development at the time. One of the additions that CSA included was regarding safety blocking devices - the use of slide locks as a substitute for ram blocks.
The U.S.’s Occupational Safety and Health Administration (OSHA) directive CPL 02-01-043 recognizes slide locks as a slide-support means for lockout. The committee used this criterion when updating our section on safety blocking devices. The Z142 now provides separate requirements for manually installed safety blocking devices and slide locks.
While the slide lock mechanism still must meet the static load holding requirements of manually placed blocks, specific requirements govern interlock and indication since many slide locks cannot be visualized because of their location or the size of the press on which they are installed.
Servo Presses
Since the previous edition of the press standard was released, a new type of mechanical press was introduced to the North American market. Servo or direct-drive presses have been used outside of North America for many years but in the last several years, they have begun to represent a large percentage of new press sales.
Servo presses operate in much the same way their mechanical counterparts do but transmit their energy via a servo drive mechanism instead of a conventional clutch and brake. Using servo drives to transmit power to the press drive system, these new presses can be programmed with several speed changes and multiple hits per cycle.
These presses can also dwell during the stroke with full energy. Because these presses have no clutch and brake mechanism, the focus has been placed on the control system and on the monitoring of communication between the controller and the slide monitoring devices.
Because the servo drive also controls the stopping of the press motion, a holding brake is a requirement for use when the servo drive and motor systems are de-energized.
The technical committee also adapted other sections from ANSI B11.1. A new section is an inclusion and exclusion list under the scope of use for determining which machines should be considered power presses and which should not.
An expanded section on auxiliary press equipment hazards includes a reference to risk assessment to address these hazards. It was important to recognize all hazards associated with the press system rather than just the press itself.
Two other noticeable changes include the removal of radio frequency (RF) devices as a point-of-operation safeguarding device and the elimination of requirements for stopping performance monitors or brake monitors on presses equipped with devices that are not dependent on safeguarding devices that signal a stop.
The updated version of CSA Z142 has passed the final technical review and is expected to be released in early April 2010. It will be available to purchase online at www.shopcsa.ca.
For more information, visit www.tekpress.ca.
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