CFR
- Title 1 - General Provisions
- Title 2 - Grants and Agreements
- Title 3 - The President
- Title 4 - Accounts
- Title 5 - Administrative Personnel
- Title 6 - Domestic Security
- Title 7 - Agriculture
- Title 8 - Aliens and Nationality
- Title 9 - Animals and Animal Products
- Title 10 - Energy
- Title 11 - Federal Elections
- Title 12 - Banks and Banking
- Title 13 - Business Credit and Assistance
- Title 14 - Aeronautics and Space
- Title 15 - Commerce and Foreign Trade
- Title 16 - Commercial Practices
- Title 17 - Commodity and Securities Exchanges
- Title 18 - Conservation of Power and Water Resources
- Title 19 - Customs Duties
- Title 20 - Employees' Benefits
- Title 21 - Food and Drugs
- Title 22 - Foreign Relations
- Title 23 - Highways
- Title 24 - Housing and Urban Development
- Title 25 - Indians
- Title 26 - Internal Revenue
- Title 27 - Alcohol, Tobacco Products and Firearms
- Title 28 - Judicial Administration
- Title 29 - Labor
- Title 30 - Mineral Resources
- Title 31 - Money and Finance: Treasury
- Title 32 - National Defense
- Title 33 - Navigation and Navigable Waters
- Title 34 - Education
- Title 35 - Panama Canal
- Title 36 - Parks, Forests, and Public Property
- Title 37 - Patents, Trademarks, and Copyrights
- Title 38 - Pensions, Bonuses, and Veterans' Relief
- Title 39 - Postal Service
- Title 40 - Protection of Environment
- Title 41 - Public Contracts and Property Management
- Title 42 - Public Health
- Title 43 - Public Lands: Interior
- Title 44 - Emergency Management and Assistance
- Title 45 - Public Welfare
- Title 46 - Shipping
- Title 47 - Telecommunication
- Title 48 - Federal Acquisition Regulations System
- Title 49 - Transportation
- Title 50 - Wildlife and Fisheries
57.22217—Seals and stoppings (I-A, I-B, and I-C mines).
All seals, and those stoppings that separate main intake from main return airways, shall be of substantial construction and constructed of noncombustible materials, except that stoppings constructed of brattice materials may be used in face areas.
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