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.

October 15, 1981

Mr. Terry Warren
3400 48th Avenue North
Minneapolis, Minnesota 55429

Dear Mr. Warren:

This is in response to your letter requesting a clarification of the applicability of your steel backed cup abrasive wheels as they relate to the guarding requirements of the OSHA regulations.

As you are aware, 29 CFR 1910.215(b)(1)(iii) permits revolving cup guards to be used for the protection of workers when those guards are made of steel or other material of adequate strength and enclose the wheel sides upward from the back for one-third of the wheel thickness. The guards are separate from the wheel and are therefore required to be mounted with a clearance of not more than one-sixteenth inch to assure that a pinch point is not created.

Although a guard as an integral part of the abrasive cup wheel, such as you describe, is not specifically addressed in the standards, the consideration for operator safety is accommodated if the steel backing is of adequate strength to contain the wheel upon fragmentation. Certainly, the fact that the guard cannot be inadvertently removed is a distinct safety feature. Adequate guards of the integral type would not be in violation of OSHA requirements for safeguarding, but are considered a technical violation of a de minimis nature. De minimis violations are those which do not effect the safety or health of employees and the equipment or procedures used are at least equivalent or exceed the requirement of the regulations. A copy of OSHA Instruction CPL 2.11A, regarding a de minimis violations is enclosed.

We thank you for your concern for the safety of your customers' employees. If we may be of further assistance, please call or write.


John K. Barto Chief,
Division of Occupational Safety Programming