30 CFR § 18.98 - Enclosures, joints, and fastenings; pressure testing.

---
identifier: "/us/cfr/t30/s18.98"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "30 CFR § 18.98 - Enclosures, joints, and fastenings; pressure testing."
title_number: 30
title_name: "Mineral Resources"
section_number: "18.98"
section_name: "Enclosures, joints, and fastenings; pressure testing."
chapter_name: "MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR"
subchapter_number: "B"
subchapter_name: "TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS"
part_number: "18"
part_name: "ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "30 U.S.C. 957, 961."
regulatory_source: "33 FR 4660, Mar. 19, 1968, unless otherwise noted."
cfr_part: "18"
---


# 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.