Plugs, Adapters, & Vents
Drum plugs and adapters help control dispensing, venting, and connectivity for steel, plastic, and fiber drums used throughout industrial, chemical, food processing, and manufacturing operations. Selecting the proper drum fitting is important for maintaining product integrity, improving transfer efficiency, and ensuring compatibility with pumps, faucets, hoses, and other drum accessories. BASCO offers a variety of drum plugs, reducers, adapters, and conversion fittings designed to help connect different thread sizes and support a wide range of liquid handling applications.
How to Pick the Right Drum Plug.
Selecting the correct drum plug, thread type, and closure configuration is critical for safety, compliance, and product integrity. Below are answers to common questions regarding drum bungs, plugs, flanges, threads, compatibility, and UN/DOT considerations.
Does a steel drum need to be recertified for UN/DOT Compliance when steel plugs are replaced with fusible plugs?
Yes, replacing standard steel plugs with fusible plugs is considered a change in closure. This requires recertification and testing requirements apply when closures are modified.
What is the difference between pressure or vacuum relief in a drum plug?
Vacuum relief plugs (vent-in) allow air to enter the container while the contents is pumped or drained out, preventing the container from collapsing due to vacuum. Pressure relief plugs (vent-out) prevent the buildup of pressure inside the drum during storage. Drums containing flammable liquids require an approved flash-arresting vent-out plug.
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The flange is the female-threaded fitting in the top or cover that accepts the plug.
- A round head plug fits an octagonal base flange.
- A hex head plug fits a circular base flange.
- Drum material: Plastic or steel
- Bung size: 2" or ¾" (most common sizes)
- Thread type: Buttress, NPS, or NPT
- Flange type: Octagonal (round-head plug) or circular (hex-head plug)
Hex-head plugs are used on drums with a flat circular flange.
- Round Head Steel Plugs
Have a very thin gasket and a stamped metal clip welded into the center for the wrench to go.
- Hex Head Steel Plugs
Have a six-sided shape and often a center, heavy stamped bar welded in the center for the wrench.
- Straight threads
- Used in steel drum plugs
- Requires a gasket to create a seal
- 11-1/2 threads per inch in 2" size
- Tapered male threads (commonly on faucets)
- Seals as threads tighten and "jam"
- Pipe sealing tape is recommended, especially for thin liquids
- Coarse, sawtooth-shaped thread design
- Common on polyethylene drum plugs
- Thicker and spaced farther apart
- 2" NPS opening: Accepts standard plugs such as the PPA57GK plug or the G2CPP plug.
- 2" Buttress thread opening: Features large, coarse threads and does not fit standard faucets or pumps. Buttress threads are a holdover from the early days of plastic drums. At that time, molding precise pipe threads directly into the drum was difficult, causing NPS plugs to leak, cross-thread, or strip during tightening. The stronger buttress thread solved these problems. Today, plastic drum manufacturing has improved significantly, and NPS plugs perform just as reliably as buttress plugs.
A buttress adapter converts buttress threads on a plastic drum to 2" NPT threads. This allows you to install:
- 2" faucets
- Pumps
- Funnels
If you need help identifying the correct plug, thread type, or closure configuration, contact our BASCO Customer Service Experts. We Contain It All.