Machine Safety: Which takes precedence, a Type-B or a Type-C safety standard?
In the hierarchy of Type A, B, and C safety standards, doesn’t a Type B safety standard take precedent over a Type C safety standard? Over the past several years Standards Development Organizations (SDOs), like ANSI, have been rolling out A, B, and C level standards here in the U.S. The European Union (EU) has been structured this way for many years. Below is a general guideline for the U.S. structure:
Type A — basic / general safety requirements that can be applied to machinery
Examples: ANSI B11.0, OSHA 1910.212, ISO 12100, CSA Z432
Type B — generic safety standards addressing certain aspects of safeguarding across a sub-set or range of machinery types
Examples: ANSI B11.19, OSHA 1910.147, ISO 13849, IEC 60204
Type C — safety standards addressing a specific type or related group of machines
Examples: ANSI B11.1, OSHA 1910.217, ISO 10218, CSA Z434
Specific guidelines for the three types (levels) of safety standards can be obtained from the SDOs; however, it seems rather clear that a hierarchy exists between the three types of standards. So, wouldn’t it seem clear that a Type B general machine safety standard like ANSI B11.19 would require compliance priority over a Type C specific machine safety standard for mechanical metal forming machines like ANSI B11.1?
The most common understanding I’ve learned from safety experts is:
If a Type C safety standard does exist, and there are discrepancies between the related Type B and Type C safety standards, the Type C safety standard will generally take precedence over the Type B standard.
The general background behind this position, in my opinion, follows:
1. A Type B safety standard generally covers safeguarding over a range of machinery types and by definition will be a bit more generic as it relates to any specific machine type.
2. A Type C safety standard will cover a specific type of machine and all included requirements will be specific to that type of machine.
3. The working committee for a Type C safety standard will likely have members vertically involved with that type of machine, whereas the working committee for a Type B safety standard will tend to have members horizontally involved across the range of machinery types.
What is your opinion or understanding on this issue? Has this presented you with any new perspectives? Do you have some specific topic or interest that we could cover in future blog posts? Add your comments or thoughts to the discussion by submitting your ideas, experiences, and challenges in the comments section below.
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