OCTG (Oil Country Tubular Goods)
Label applied to the pipe products used by petroleum exploration customers. Includes casing, drill pipe and oil well tubing, which, depending on their use, may be formed through welded or seamless processes.

Outside Diameter (of coil or pipe)

Oil Hardening
A process of hardening a ferrous alloy of suitable composition by heating within or above the transformation range and quenching in oil.

Oil-Hardening Steel
Steel adaptable to hardening by heat treatment and quenching in oil.

Oiled Sheet
Sheet product that is processed with the final step being the application of oil to the surface. Usually, the oil is intended to provide protection from rusting during shipment and storage. These oils are called rust-preventative oils. The oil may also serve to assist in the subsequent fabrication process, but this is not usually the main purpose. Oils used to enhance formability are often called pre-lubricants or "prelubes".

Oil Stain Aluminum
Stain produced by the incomplete burning of the lubricants on the surface of the sheet. Rolling subsequent to staining will change color from darker browns to lighter browns down to white.

Olsen (DUCTILITY) Test
A method of measuring the ductility and drawing properties of strip or sheet metal which involves determination of the width and depth of impression. The test simulating a deep drawing operation is made by a standard steel ball under pressure, continuing until the cup formed from the metal sample fractures. Readings are in thousandths of an inch. This test is sometimes used to detect stretcher straining and indicates the surface finish after drawing, similar to the Erichsen ductility test.

Open arc welding
Arc welding in which the arc is visible.

Open circuit voltage
In a welding plant ready for welding, the voltage between two output terminals which are carrying no current

Open Hearth Furnace
A broad, shallow hearth to refine pig iron and scrap into steel. Heat is supplied from a large, luminous flame over the surface, and the refining takes seven to nine hours. Open Hearths, at one time the most abundant steelmaking furnaces among integrated companies, have been replaced by the basic oxygen furnace.

Open-Hearth Process
Process of making steel by heating the metal in the hearth of a regenerative furnace. In the basic open-hearth steel process, the lining of the hearth is basic, usually magnetite; whereas in the acid open-hearth steel process, an acid material, silica, is used as the furnace lining and pig iron, extremely low in phosphorous (less than 0.04%), is the raw material charged in.

Open Surface
Rough surface on black plate, sheet or strip, resulting from imperfection in the original steel bars from which the plate was rolled.

Open Welds
A weld that shows an area that is not fused.

Orange Peel
(Effect) - A surface roughening (defect) encountered in forming products from metal stock that has a coarse grain size. It is due to uneven flow or to the appearance of the overly large grains usually the result of annealing at too high a temperature. Also referred to as “pebbles” and “alligator skin.”

A mineral from which metal is (or may be) extracted.

(Crystal) - Arrangement of certain crystal axes or crystal planes in a polycrystalline aggregate with respect to a given direction or plane. If there is any tendency for one arrangement to predominate, it is known as the preferred orientation. In the absence of any such preference, random orientation exists.

Oscillated Wound or Scroll Wound
A method of even winding metal strip or wire on to a reel or mandrel wherein the strands are uniformly overlapped. Sometimes termed “stagger wound” or “vibrated wound.” The opposite of ribbon wound.

A method of winding narrow strip steel over a much wider roll. Customers want to have as much steel on a coil as will fit in their machines, so they can spend less time moving the material and more time using it. By coiling the strip like fishing line (or thread) over a spool, a much longer strip can fit onto a coil of proper diameter. Oscillate-wound coils allow the customer to enjoy longer processing runs.

Aging under conditions of time and temperature greater than those required to obtain maximum change in a certain property, so that the property is altered in the direction of the initial value.

Heating a metal or alloy to such a high temperature that its properties are impaired. When the original properties cannot be restored by further heat treating, by mechanical working, or by combination of working and heat treating, the overheating is known as burning.

An imperfection at a toe or a root of a weld caused by metal flowing on to the surface of the parent metal without fusing it.

The addition of oxygen to a compound. Exposure to atmosphere sometimes results in oxidation of the exposed surface, hence a staining or discoloration. This effect is increased with temperature increase.

  • A reaction in which there is an increase in valence resulting from a loss of electrons.

  • Chemical combination with oxygen to form an oxide.

Compound of oxygen with another element.

Oxygen-arc cutting
Thermal cutting in which the ignition temperature is produced by an electric arc, and cutting oxygen is conveyed through the centre of an electrode, which is consumed in the process.

Oxygen Lance
A length of pipe used to convey oxygen onto a bath of molten metal.
A steel tube, consumed during cutting, through which cutting oxygen passes, for the cutting or boring of holes.

Oxygen lancing
Thermal cutting in which an oxygen lance is used.