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.

July 30, 1993

Ms. Julie A. Emmerich
Frank L. Pellegrini
Law Offices
701 Market Street,
Suite 390
Gateway One on the Mall
St. Louis, Missouri 63101

Dear Ms. Emmerich:

Thank you for your letter of July 6, in which you requested our opinion of an apparent conflict between the requirements of 1910.252(b)(4)(iv) and an example contained in Appendix C of the recently promulgated Occupational Safety and Health Administration (OSHA) standard on Permit-Required Confined Spaces (1910.146).

Section 1910.252(b)(4)(iv) requires that an attendant be stationed outside a confined space which a welder must enter through a manhole or other small opening "to observe" the welder at all times. However, Appendix C of 1910.146 lists "tapping or rapping codes on tank walls" as an example of an adequate means of communication and observation between an attendant and a welder working in a permit-required confined space.

The present requirement in 1910.252(b)(4)(iv) is based upon a similar requirement in an out-of-date voluntary standard (ANSI Z49.1-1967). The most recent version (1988) of the same ANSI standard contains language which is slightly different than that contained in the older version. The newer voluntary standard states that the attendant shall "observe the workers inside or be in constant communication with them." We believe, as indicated in Appendix C of the Permit-Required Confined Spaces Standard, that "tapping on tank walls" can be an adequate means of communication between an entrant and an attendant. As it is OSHA policy to accept compliance with a provision in a current national consensus standard (ANSI) which provides equivalent protection to a provision of the OSHA standard which is based upon an earlier version of the same national consensus standard, OSHA will accept the use of the tapping procedure on the walls of tanks in lieu of the more burdensome requirement in the current 1910.252(b)(4)(iv).

Although the contents of the appendices to 1910.146 are non-mandatory, the inclusion of the "tapping procedure" as an example of an adequate procedure to accomplish the required communication between a permit-required confined space entrant an outside attendant indicates that OSHA believes that the use of this procedure is in compliance with the the mandatory communication provision of the standard. Since this standard is much more recent than the welding standard (1910.252) and reflects current OSHA views on the communications issue, we believe it is appropriate for an employer to follow the example communications procedures outlined in the Permit-Required Confined Spaces standard in lieu of the outdated equivalent provisions in the OSHA welding standard.

We trust that this response will be helpful in your efforts to comply with OSHA requirements. Please feel free to contact us if you require further information or assistance.


Thomas J. Shepich Director,
Directorate of Safety Standards Programs