Thursday, October 9, 2014

Coupling Guards - OSHA Requirements

Coupling Guard
Yes, couplings are required to be guarded or protected under OSHA regulations... but what exactly does that mean? What exactly are those regulations?

OSHA (Occupational Safety & Health Administration) is an organization under the United States Department of Labor that was created under the Occupational Safety and Health Act of 1970 "to assure safe and healthful working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education and assistance." More specifically, OSHA touches power transmission couplings and coupling guarding through its broad Code of Federal Regulations (CFR). Under these regulations, there exists a section, 29 CFR 1910 Subpart O, titled "Machinery and Machine Guarding".

"Machinery and Machine Guarding" (which is likely relevant to you on numerous components above and beyond just couplings) is broken out into the following subcategories:

While the concepts throughout "Machinery and Machine Guarding" are broadly applicable to couplings, it is within the last subcategory, "Mechanical power-transmission apparatus" (1910.219), that couplings are specifically called out by name. Section 1910.219(i)(2) reads: "Couplings. Shaft couplings shall be so constructed as to present no hazard from bolts, nuts, setscrews, or revolving surfaces. Bolts, nuts, and setscrews will, however, be permitted where they are covered with safety sleeves or where they are used parallel with the shafting and are countersunk or else do not extend beyond the flange of the coupling."

While other sections of the regulation may not specifically call out couplings by name, the concepts of these sections (aimed at keeping workers safe from potential hazards of machinery) do still apply to the use of keeping an employee safe from the dangers posed by rotating couplings. Fully communicating the concepts covered in these other sections requires quite a bit of real estate, but, fortunately, OSHA has designed several great resources to help facilitate this information on to you. The following four links are some of their best tools:
(OSHA's digital book is surprisingly readable, their checklist hits on a lot of issues quickly, and their bibliography offers a bunch of further great links .) 

Translating OSHA speak/lingo into industry speak/lingo, "safety sleeve" is often termed "coupling guards"... and "coupling guards" come in many forms. The most traditional view is probably the one pictured above: a piece of sheet steel bend over and around the coupling and shaft...with edges sometimes bend down or with added welded u-shape pieces to more fully encapsulate the coupling.(Disclaimer: This article is a research piece only, and Lovejoy is not using this article to specifically endorse or exclude any coupling guard product in regards to it's regulatory compliance and/or appropriate use for any specific coupling application.) In hydraulic applications, the safety sleeve feature is achieved through a pump motor mount (sometimes also referred to as a "bellhousing" or "flower pot" based on the devices shape). Pump motor mounts connect the frame of a pump and motor together (and in vertical installation cases bearing the motor weight)... while also providing guarding around the coupling. (Note: In full disclosure, Lovejoy does sell hydraulic pump / motor mounts, as pictured left.)

In addition to these two classic guarding methods, various entities have developed and marketed a number of different proprietary and unique guarding methods. (Note: OSHA does not specifically "approve" any manufacturer's coupling guarding solutions. They only issue regulations and enforce/audit facilities for compliance.) Most of these coupling guard manufacturers will tell you that they have reviewed the regulations, and, that their product, when used correctly, will allow you to be compliant with the regulations. These manufacturers (whose business is selling a better mouse trap) are well versed on the standards and can/will speak to additional standards including ANSI B11.19-201 (titled "Performance Criteria for Safeguarding") and ANSI Z535.4 (which is a Safety Signs and Labels standard).

And In Canada? Like the US, Canada has its own set of distinct coupling guarding regulations & standards. The following link is one of the better articles we found covering guarding in Canada, as it breaks out rules and regulation for each specific province... which are different. The overriding primary standard in Canada appears to be CSA Standard Z432, Safeguarding of Machinery, but please consider clicking on the first link above... to determine what specifically applies to your part of Canada... before diving into the standard.)

Recommended Follow-On Reading: Given you are on a standards roll, how about reviewing the active coupling bore & keyway standards: Active Coupling Bore and Keyway Standards - What Are They & Where Can I Find Them?

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