OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

March 29, 1995

Mr. Pat Reeves
Operations Co-Manager
A & K Railroad Materials, Inc.
2131 S. 74th Street
Kansas City, KS 66106

Dear Mr. Reeves:

This is in response to your letter of October 31, 1994 regarding the clarification of Standard, 29 CFR 1910.243, "Guarding of Portable Powered Tools."

With regard to your request for a clarification of the definition of an outer flange on an abrasive wheel, an outer flange is the flange which exerts pressure on the abrasive disc or wheel as a result of the tightening of the nut on the spindle.

Concerning your inquiry as to whether the regulation applies to type 27 wheels, please be advised that the regulation requires guarding for the type of wheel which is specified in your letter.

As you have noted, paragraph (c)(ii)(c) of the 1910.243 regulation states, "The spindle end, nut, and outer flange may be exposed on portable machines designed for, and used with, type 6, 11, 27, and 28 abrasive wheels, cutting off wheels, and tuck pointing wheels." This exemption from guarding applies only to those specific components, but not to the wheel itself.

Your understanding that the fiber glass "mesh-disk" is designed for the purpose of eliminating the shattering of the wheel is not supported either by this standard, or any other documentation in our files. Therefore, providing guards for this type of wheel would be required, so that any potential shattering would not injure the operator.

In addition, it appears that in your letter 1910.243(c)(6) and 1910.215(b)(12) are misinterpreted. The exclusion applies to "natural sandstone wheels and metal, wooden cloth or paper discs, having a layer of abrasive on the surface." Please note that this exclusion applies only to portable abrasive wheels.

Thank you for your interest in occupational safety and health. We hope that the above response is helpful to you.


Joseph A. Dear
Assistant Secretary