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Are open cans of oil allowed on the flightline?

No. Oils, solvents and fuels are flammable or combustible liquids, and every service requires them to be kept in original closed containers, approved safety cans, or approved portable tanks — open containers are prohibited outright, and glass is prohibited with them. The rule is written into the Air Force's DAFMAN 91-203 and mirrored in each service's safety manual, so an open can sitting out on the line is a finding wherever you are.

Readers asked this on CheckMyRegs and CheckMyAFI 17 times — this page answers it from the official catalogs and the publications’ own text.

The controlling publication in each branch

BranchControlling publicationDatedSource
Air ForceDAFMAN 91-203 Current
Consolidated occupational safety manual; chapter 22 is the controlling text
2026-02-24Official link
Coast GuardCOMDTINST M5100.47D Current
Safety and Environmental Health Manual
2021-07-27Official link
ArmyAR 385-10 Current
Army Safety Program
2023-07-24Official link
NavyOPNAVINST 5100.23H Current
Navy Safety and Occupational Health Program
2020-06-05Official link
Marine CorpsMCO 5100.29C VOLUMES 1-9 w/CH-2 Current
Marine Corps Safety Management System
2022-02-08Official link
DoD-wideDoDI 6055.01 Current
DoD-wide safety and occupational health policy above all of them
2014-10-14Official link
Publication numbers, dates, and statuses resolve live against each branch’s official catalog every time this page loads — when a service revises its reg, this page follows. Quotes below are extracted verbatim from the official PDFs. Verify the controlling copy before citing it.

What the regulation actually says

Closed containers only

Flammable and combustible liquids must be in their original closed container, an approved safety can, or an approved portable tank — open or glass containers are not authorized at all.

“27.6.2. Containers. Flammable or combustible liquids brought into spray finishing rooms will be in original closed containers, approved portable tanks, approved safety cans, or by a properly arranged system of piping. (T-0) Containers will be marked IAW AFI 90-821. (T-1) Open or glass containers will not be used. (T-0)”

Transfer through a closed path

Draw or transfer liquid only through closed piping, from a safety can, through a top-mounted device, or by gravity through an approved self-closing valve — never by pouring from an open vessel.

“22.8.6. Handling Flammable and Combustible Liquids at Final Point of Use. Flammable and combustible liquids will be drawn from or transferred into vessels, containers, or portable tanks within a building only through a closed piping system, from safety cans, by means of a device through the top, or from a container or portable tanks by gravity through an approved self - closing valve. (T-0) Transferring by means of air pressure on the container or portable tanks is prohibited. Refer to 29 CFR § 1910.106 for additional information.”

Operations stay observed

Any operation using fuels or solvents must be watched continuously, and open solvent or fuel containers near electrical equipment or pilot lights are called out by name as a hazard.

“22.2.4. Operations where fuels, solvents or other flammable liquids are used must be constantly observed to avoid unsafe practices. (T-0) It is hazardous to use fuels (such as gasoline) to clean floors or clothing or use open solvent or gasoline containers near electrical equipment or pilot lights. The use of low-flashpoint petroleum solvents will be avoided, when possible. (T-0) Open flames, heaters, equipment not properly grounded and non -explosion proof electrical equipment will not be used in the prese nce of flammable or combustible liquids. (T-0) Refer to NFPA 30 for additional guidance.”

Bond and ground before pouring

Anyone dispensing flammable or combustible liquid has to be trained on static electricity hazards — the static generated by pouring is enough to ignite vapor.

“22.3.1.3. Individuals involved in dispensing of flammable or combustible liquids are instructed on hazards of static electricity. (T-0)”

Fifty feet from ignition

Containers stored outside must be protected from heat sources, and no open flame or smoking is permitted within fifty feet of a flammable or combustible liquid storage area.

“22.8.3. Outside Storage. All containers having flammable or combustible materials will be protected from heat sources to prevent the content expanding and pressurizing the container, which could rupture the container. (T-0) Open flame or smoking will not be permitted within 50 feet of flammable or combustible liquid storage areas. (T-0)”

Locked up at end of shift

Coast Guard policy is explicit that these liquids are stored in approved lockers at the end of the workday, and that all ignition sources are prohibited where they are handled.

“b. All sources of ignition shall be prohibited in areas where flammable and combustible liquids are stored, handled and/or processed. Appropriate “NO SMOKING, MATCHES, or OPEN FLAME” signs shall be posted in all such areas as required. c. Flammable and combustible liquids shall not be used in areas where open flames or heating devices are present and shall be properly stored in approved lockers at the end 18-5 of the workday. Flammable and combustible liquids shall not be stored in areas used for exits, stairways or safe passage of people.”

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Updated 2026-08-01. CheckMyRegs is an unofficial index — always cite the official publication.