Steel Drum

Steel Drum

A steel drum is a cylindrical container used for shipping bulk goods. Drums can be made of steel, dense paperboard or plastics, and are generally used for the transportation of certain dangerous materials or modest quantities of bulk goods. For caustic and acid materials, plastics, usually thermoplastics like Polyethylene, Nylon, Polystyrene, Polyvinyl chlorides (PVCs) or possibly Polycarbonates are the preferred shipping container; for flammable substances like most petroleum distillates, and alcohol, etc., metal containers are the standard. Which type is used for shipping non-corrosive industrial chemicals would depend on the chemicals or materials, but the general rule would be to use the container type that is inert or non-reactive with the material being shipped.

Background

It is common to hear a drum referred to as a barrel in the United States, and some would argue that barrels hold liquids while drums are open-topped, but in everyday USA style English usage, the two terms are used nearly interchangeably in the vernacular. Drums such as these have a standard nominal volume of 55 US gallons or 44 Imperial gallons and nominally measure just under 34-1/2" tall with a diameter just under 24" and differ by holding about thirteen gallons more than a Barrel of Crude Oil one hears about (the quoted price thereof) in the daily financial news reports. In the US, 25-gallon drums are also in common use and have the same height specification. This sameness allows easy stacking of mixed pallets. Taking account the materials making up the drum, in the vernacular, these three main varieties are known as plastic drums or barrels, cardboard drums or barrels and steel drums or barrels.

The two common sub-types of drums are the open top and the welded top (with 2" NPS bung holes). The latter are almost universally called 'barrels' in preference to drums in the US. They cannot efficaciously either dispense or be filled with powdered goods, though they might store them very well, so are not used for such goods, being reserved for liquids transport and storage. Plastic drums are manufactured using injection blow moulding technology and have either a separate lid (similar to those on fiber drums) or a welded type top with the bung holes molded in. Metal drums are manufactured with steel hot-rolled into long pipe-like sections then forged on a stamping press while still red-hot into drum bodies. A welded rolled seam is then made for the drum bottom, or bottom and top both.

Standard drums have corrugations or reinforcing rings of thickened metal or plastic at four places: top, bottom, and one each a third of the way from each end ring. This sufficiently strengthens them so that they can readily be turned on their sides and rolled when filled with heavy materials, like liquids. Over short to medium distances, drums are generally tipped and rolled on the bottom rim while being held at an angle, balanced, and rotated with a two-handed top grip that also supplies the torque (rotational or rolling force).

The open-top sub-type is sealed by a mechanical ring clamp (concave inwards) that exerts sufficient pressure to hold many non-volatile liquids and make an airtight seal against a gasket, as it exerts force inward and downward when tightened by a normal three-quarter inch wrench or rachet wrench. Tops exist with bung holes as above, and these hybrid drums with lid can be used to ship many non-volatile liquids as well as industrial powders. Many drums are used to ship and store powdered products as well as liquids, such as plastic beads for injection moulding, extrusion, and purified industrial grade powders like cleansers (e.g., fertilizers, and powdered aluminum). If used to transport dangerous goods across international boundaries, they may need to have UN certification. In general, drum usage is limited to wholesale distribution of bulk products, which are then further processed or sub-divided in a factory.

These metal drums have two openings with flanges (2" NPS and 3/4" NPS). Once the drums are filled, the plugs (bungs) are screwed in the flanges. Now to secure the contents of the drums for shipment, cap-seals made of metal and other types like metal+plastic are used. These cap-seals sit on top of the flanges and are 'crimped' using drum crimping tools (also called drum cap sealers). Once cap-seals are crimped, the plugs can be unscrewed only by breaking these cap-seals and thereby securing the content of drums from adulteration and theft. Pneumatic and hand-operated cap-seal crimping tools are available. Pneumatic ones are used in production lines for high production.