Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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

April 2, 1976

Mr. J. D. Manney,
American Petroleum Institute
2101 L Street, N.W.
Washington, D. C. 20037

Dear Mr. Manney:

Assistant Secretary Morton Corn has asked me to respond to your letter of March 15, 1976, regarding Subpart O -- Machinery and Machine Guarding, Mechanical Power-Transmission Apparatus. In addition, this confirms a telephone conversation with a member of my staff.

Your correspondence indicates confusion exists regarding the height of guards for pumping units. The Occupational Safety and Health Administration (OSHA) standard that applies to the guarding of cranks and connecting rods is 29 CFR 1910.219(b)(2), which reads:

Cranks and connecting rods. Cranks and connecting rods, when exposed to contact, shall be guarded in accordance with paragraphs (m) and (n) of this section, or by a guardrail as described in paragraph (o)(5) of this section.

29 CFR 1910.219(b)(2) appears to be definitive enough. Where an employee is exposed to a moving crank and connecting rods, this hazard shall be guarded by a standard guard or guardrail as described in the appropriate standards.

Table 0-12--Table of Standard Materials and Dimensions in Part 1910 requires standard guards to be at least 7 feet in height from the floor or platform level. 29 CFR 1910.219(o)(5)(i) requires guardrails to be 42 inches.

According to the preceding OSHA requirements, there are three alternatives:

1. No employee exposure
2. A 7-foot minimum height standard guard.
3. A 42-inch-high guardrail.

Where panels in guardrails are fitted with expanded metal or wire mesh as noted in Table 0-12, the middle rails may be omitted.

Where a State is enforcing safety and health standards under an 18(b) plan with OSHA, its enforcement and standards are required to be at least as effective as OSHA standards. This, however, does not prohibit more stringent state standards.


Barry J. White
Associate Assistant Secretary
for Regional Programs