[Code of Federal Regulations]
[Title 30, Volume 1]
[Revised as of July 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 30CFR18.33]

[Page 98]
 
                       TITLE 30--MINERAL RESOURCES
 
  CHAPTER I--MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
 
PART 18--ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES--Table of Contents
 
             Subpart B--Construction and Design Requirements
 
Sec. 18.33  Finish of surface joints.

    Flat surfaces between bolt holes that form any part of a flame-
arresting path shall be plane to within a maximum deviation of one-half 
the maximum clearance specified in Sec. 18.31(a)(6). All metal surfaces 
forming a flame-arresting path shall be finished during the 
manufacturing process to not more than 250 microinches. A thin film of 
nonhardening preparation to inhibit rusting may be applied to these 
finished metal surfaces as long as the final surface can be readily 
wiped free of any foreign materials.

[57 FR 61210, Dec. 23, 1992]