OCTG
See Oil Country Tubular Goods.

OD
Outside diameter (of a coil).

Off Gauge
A defect referring to a variation of offset of the thickness of the plate from the designated aim gauge thickness and tolerance.

Offsetting
A coating defect consisting of a transference of smearing of ink or coating or other substance from the surface of one sheet of coated substrate to the back of the next sheet in a stack.

Oil Country Tubular Goods (OCTG)
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.

Oiled
A product to which oil has been applied to retard rusting.

Oil Film Weight
Measure of the amount of oil applied to a flat rolled steel product; for Tin Mill Products, the measure is grams/base box; for Sheet Products, the measure is oz./sq.ft. (or gm./sq.m.).

Oiling
The application of a surface layer of lubricant intended to retard rusting on sheet products and lubrication on Tin Mill products.

Olsen Cup Test
A test used to obtain an indication of the drawing properties of the base metal as well as the adherence of the coating. In this test, the male and female dies are used to deform the steel into a cup shape. The force draws the metal into the die slowly so the coated sheet stretches to conform to the shape of the die. The depth of the cup is measured when the steel fractures, and the coating is then examined.

Open Coil Annealing (Unitised Annealing)
Annealing of a sheet coil in the form of a loosely wound coil with or without a metal spacer between successive laps of the coil, thus providing gap for the atmosphere to circulate around each lap of the coil. This form of annealing is generally used for decarburisation annealing and / or nitriding, that is, annealing simultaneously with decarburisation and denitriding to produce extra low carbon and low nitrogen steels. Generally it is carried out in Bell type furnaces, but when carried out in Bogie Hearth Furnaces, the process is usually termed as ‘unitised annealing’.

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 Open Hearths, at one time the most abundant steel making furnaces among integrated companies, have been replaced by the basic oxygen furnace.

Open Line
Usually a steel-making defect, an open line refers to a line down the length of the strip caused by unknown conditions.

Open Steel
Steel partially killed prior to casting.

Open Weld
A weld that shows an area which is not fused.

Operating Rates
The ratio of raw steel production to the mill's stated capacity.

Orange Peel
Characteristic roughing over the surface of cold-rolled or cold-deformed sheet or strip due to coarse grain size. Also known as pebbles and alligator skin

Order Rate
The ratio of new orders recorded to the mill's capacity to produce the steel to fill the orders. Many analysts view trends in the order rate as harbingers of future production levels.

Ore
An iron bearing material used primarily in the blast furnace.

Organosol
Organosols contain poly-vinyl chloride (PVC) dispersed in solvents. At temperatures of 325-350o F (165-175o C) the vinyl particles coalesce and dissolve in the plasticizers to form homogeneous films with good hardness, toughness and adhesion.

Oscillating
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.

Overaging
Aging under conditions of time and temperature greater than those required to obtain maximum change in a certain property. See also aging.

Overheating
Heating to such a high temperature that an undesirably coarse grained structure is produced. Severe overheating may result in the properties being permanently impaired.

Overpickling
Results from line delays which permit sections of the steel to remain in the acid too long. Causes pronounced chemical attack, resulting in pitting and roughness on the surface.

Overwidth
Product whose width is above the customer’s finished width tolerance.

Oxidation
Rust, corrosion. See Red Rust and White Rust.

Oxygen Enrichment (of Blast)
Enrichment of blast air with oxygen to increase hot metal production in the blast furnace. For every percent of oxygen above the normal air blast (21%), the production rate can be increased about 2 to 4%.

Oxygen Lance
Pure oxygen is injected into the molten steel during top-blown oxygen steel-making process through a tubular, water-cooled, copper-tipped retractable lance kept perpendicular above the center of the bath. At the top of the lance, armored rubber hoses are connected to a pressure-regulated oxygen source and top a supply of re-circulated cooling water. The tip of the lance contains from three to five converging-diverging nozzles to impart a supersonic velocity (mach 1.7 to 2.3) to the gas jets exiting normally under a pressure between 140 to 180 psi.