[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: 30CFR18.32]

[Page 97-98]
 
                       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. 18.32  Fastenings--additional requirements.

    (a) Bolts, screws, or studs shall be used for fastening adjoining 
parts to prevent the escape of flame from an enclosure. Hinge pins or 
clamps will be acceptable for this purpose provided MSHA determines them 
to be equally effective.
    (b) Lockwashers shall be provided for all bolts, screws, and studs 
that secure parts of explosion-proof enclosures. Special fastenings 
designed to prevent loosening will be acceptable in lieu of lockwashers, 
provided MSHA determines them to be equally effective.
    (c) Fastenings shall be as uniform in size as practicable to 
preclude improper assembly.
    (d) Holes for fastenings shall not penetrate to the interior of an 
explosion-proof enclosure, except as provided in paragraph (a)(9) of 
Sec. 18.34, and shall be threaded to insure that a specified bolt or 
screw will not bottom even if its lockwasher is omitted.
    (e) A minimum of \1/8\-inch of stock shall be left at the center of 
the bottom of each hole drilled for fastenings.

[[Page 98]]

    (f) Fastenings used for joints on explosion-proof enclosures shall 
not be used for attaching nonessential parts or for making electrical 
connections.
    (g) The acceptable sizes for and spacings of fastenings shall be 
determined by the size of the enclosure, as indicated in Sec. 18.31.
    (h) MSHA reserves the right to conduct explosion tests with standard 
bolts, nuts, cap screws, or studs substituted for any special high-
tensile strength fastening(s) specified by the applicant.
    (i) Coil-thread inserts, if used in holes for fastenings, shall meet 
the following:
    (1) The inserts shall have internal screw threads.
    (2) The holes for the inserts shall be drilled and tapped consistent 
with the insert manufacturer's specifications.
    (3) The inserts shall be installed consistent with the insert 
manufacturer's specifications.
    (4) The insert shall be of sufficient length to ensure the minimum 
thread engagement of fastening specified in Sec. 18.31(a)(6) of this 
part.

[33 FR 4660, Mar. 19, 1968, as amended at 57 FR 61210, Dec. 23, 1992]