Drum (container) - 55-gallon Drum

55-gallon Drum

A 55-gallon drum (known as a 44-gallon drum in the United Kingdom, Canada, Ireland, Australia, New Zealand, South Africa and other former British dependencies, even though all those countries now officially use the metric system and the drums are filled to 200 litres) is a cylindrical container drum with a nominal capacity of 55 US gallons (46 imp gal; 208 L). The exact capacity varies with wall thickness and other factors. Standard drums are 22.5 inches (572 mm) in diameter and 33.5 inches (851 mm) high (these dimensions yield a total volume of ~218 L). Exact dimensions are specified in ANSI MH2.

The drums are typically made of steel with a welded top and ribbed outer wall to improve rigidity and durability. They are commonly used for transporting oils and fuels, but can be used for storing various chemicals as well. The construction and performance of drums used for shipment of dangerous goods or hazardous materials are strictly governed by UN, country, and carrier regulations.

The 55-gallon drum will fit handily four to a standard wooden shipping pallet, and so ease handling by a fork truck and shipping. The drum's size, shape, and weight distribution lends itself to being moved about readily on the loading dock or factory floor with a two-wheeled hand truck. They can also be moved by hand short distances on firm surfaces by tilting and then rolling along the base, or by using a drum handler, which is designed especially for that purpose.

Today's 55-gallon drum resulted from military shipping requirements in World War II, the first war in which trucks, cold rolled steel, stamp or pattern forging machinery and welding were widely available. The drums helped win the Battle of Guadalcanal in the first U.S. offensive in the South Pacific Theater. The U.S. Navy could not maintain control of the seas long enough to offload aviation fuel for U.S. aircraft ashore, so the drums were often transported to the island on fast ships such as destroyers and shoved over the sides (or, time permitting, lowered in cargo nets). Aviation fuel is lighter than seawater, so the drums floated, and Navy Seabees in small craft corralled the drums.

Closed-head steel barrels and drums used for shipment of chemicals and petroleum products have a standardised bunghole arrangement, with one 2-inch (50.8 mm) NPT and one 3⁄₄-inch (19 mm) NPT threaded bunghole on opposite sides of the top head. This arrangement is echoed in many plastic drums in the same size. Various components can be mounted to the drum, such as drum pumps and bung mixers.

In the past, hazardous waste was often placed in drums of this size and stored in open fields or buried. Over time, some drums would corrode and leak. As a result, these drums have become iconic of pollution problems, even though they have numerous uses and are ubiquitous in commerce. Drums are often re-conditioned and then later used for storing different liquids. Shipping in reconditioned drums is one of the safest ways to remove hazardous waste.

Until the 1990s many state highway departments reused 55-gallon drums as barricades to protect construction workers from oncoming traffic. Once empty, the drums were painted orange and white and placed along roadways where construction and repairs were occurring. Today, construction crews more likely use plastic drums that resemble their steel predecessors in both size and shape. Also alongside the highways now are groups of specially engineered plastic drum-like containers arrayed in front of vulnerable locations such as large sign supports or bridge abutments, to protect errant motorists who otherwise might collide with these rigid structures. These "Fitch Barriers" often contain sand-filled compartments that break apart on impact, absorbing some of the energy of the collision, often saving lives.

Although oil is sometimes shipped in 55 US gallon drums, the measurement of oil in barrels is based on the 42 US gallon wooden barrels of the 1870s; which is about 35 imperial gallons.