CFR > Title 30 - Mineral Resources > CHAPTER I—MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR > SUBCHAPTER B—TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS (parts 5 to 36) > PART 18—ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES > SUBPART E—Field Approval of Electrically Operated Mining Equipment (§18.90 to §18.99) > 18.98—Enclosures, joints, and fastenings; pressure testing.

18.98—Enclosures, joints, and fastenings; pressure testing.

(a) Cast or welded enclosures shall be designed to withstand a minimum internal pressure of 150 pounds per square inch (gage). Castings shall be free from blowholes.
(b) Pneumatic field testing of explosion-proof enclosures shall be conducted by determining:
(1) Leak performance with a peak dynamic or static pressure of 150 pounds per square inch (gage); or
(2) A pressure rise and rate of decay consistent with unyielding components during a pressure-time history as derived from a series of oscillograms.
(c) Welded joints forming an enclosure shall have continuous gastight welds.