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 http://www.osha.gov.

Jan 22, 2013

Mr. Robert Ricaud
Senior Consultant
Applied Technical Services
1049 Triad Court
Marietta, GA 30062

Dear Mr. Ricaud:

Thank you for your November 8, 2011, letter, to the Occupational Safety and Health Administration (OSHA), in which you requested a clarification of the requirements of 29 CFR 1910.261(g)(12)(ii)1. This constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any question not delineated within your original correspondence.

Your scenario and questions are paraphrased and our responses follow.

Scenario/Background: Many valve manufacturers make valves with threaded cap bolts on two-part body valves and on the clean-out covers of the check valves.

Question #1: Please define digester piping. Does digester piping include only the blow lines (from the digesters to the blow tank), or does it also consist of all piping attached to the digester (such as the heater circulation line)?

Response #1: Digester piping includes all piping that is attached to the digester vessel.

Question #2: Does digester piping include equipment attached to the pipe, such as heat exchangers with cap bolts holding on the heads?

Response #2: No. The requirement only applies to piping.

Question #3: Where on the piping are cap bolts not allowed? Are they not allowed on the connection/flanges, or are they not allowed anywhere on the system (such as the clean-out covers)?

Response #3: All digester piping must be secured with through bolts (not cap bolts), pursuant to 29 CFR 1910.261(g)(12)(ii).

Question #4: Can cap bolts be used on the reducing flanges (threaded flanges that reduce the piping size without the need for transition piping)?

Response #4: No. Reducing flanges that are attached to piping connected to the digester must have through bolts, pursuant to 29 CFR 1910.261(g)(12)(ii).

Thank you for your interest in occupational safety and health. We hope you find this information helpful. OSHA's requirements are set by statute, standards, and regulations. Our letters of interpretation do not create new or additional requirements but rather explain these requirements and how they apply to particular circumstances. This letter constitutes OSHA's interpretation of the requirements discussed. From time to time, letters are affected when the Agency updates a standard, a legal decision impacts a standard, or changes in technology affect the interpretation. To assure that you are using the correct information and guidance, please consult OSHA's website at https://www.osha.gov. If you have further questions, please feel free to contact the Office of General Industry Enforcement at (202) 693-1850.


Thomas Galassi, Director
Directorate of Enforcement Programs

1 1910.261(g)(12)(ii)Through bolts instead of cap bolts shall be used on all digester pipings.