TERMINOLOGY

Alloy – a metal made by combining two or more metallic elements, especially to give greater strength or resistance to corrosion
Annealing – a general term referring to the thermal treatment process involving heating and cooling, usually applied to change mechanical or physical properties, to produce a desired microstructure.
Austenitic – non-magnetic stainless steels that contain high levels of chromium and nickel and low levels of carbon. Known for their formability and resistance to corrosion, austenitic steels are the most widely used grade of stainless steel.
AW – stands for “Average Wall.” This is the wall size with a permitted over and under tolerance.
Bright Annealing – a process of annealing carried out in a controlled furnace atmosphere so that surface oxidation is reduced to a minimum and the surface remains relatively bright
Burst Pressure – the internal pressure at which a tube or pipe will rupture or “burst”
Carbon Steel – a metal that owes it properties primarily to various percentages of carbon without substantial amounts of other alloying elements
Chloride Stress Corrosion Cracking – material cracking due to the combination of tensile stress and corrosion in the presence of chlorides
Coil – a long length of tubing that has been rolled into a circular coil to facilitate easy transport, storage, and installation
Cold Drawing – the process of pulling a tube through a die and over a mandrel to reduce its diameter and wall thickness to a specific size. This typically has reduction rates of 15-35%.
Corrosion – chemical or electrochemical deterioration of a metal
Deburring – removing the rough edge left on metals when cutting
Drawn – also known as “as drawn”, this is the temper of a tube when it has been drawn but not annealed. Also see “Full Hard” and “Half Hard”
Ductility – a measure of a material’s ability to undergo significant plastic deformation before rupture. Often expressed as a percent elongation (see “Elongation”)
Duplex – steels exhibiting both austenitic and ferritic phases and characteristics
Eddy Current Testing – a nondestructive test that uses a magnetic field to check for defects such as holes, cracks, etc.
Electropolishing – a method of electrochemical polishing where the metal is placed in an electrolytic bath and a current is applied which causes the surface metal to be removed and provide a smooth surface
Elongation – a measurement of ductility expressed in terms of the stretch that occurs over a given length on a standard tensile specimen up to the time of fracture
Extrusion – shaping metal into a chosen form by forcing it through a die
Ferritic – a magnetic grade of stainless steel having a microstructure consisting of ferrite, including some of the 200 and 400 series stainless steels. As the only major alloying element is chromium (10% to 30% depending on specific grade), these steels are relatively inexpensive to produce and are common in automotive exhaust and ornamental applications.
Flare Testing – a destructive test used to verify the formability of tubes by expanding on a mandrel
Flattening Tested – a destructive test where the tube is flattened and observed for internal and external cracking
Full Hard – a temper of steel achieved by cold working the material. The material is substantially harder than annealed material and often has a tensile strength of more than double the annealed condition.
Fully Annealed – another common term used for annealing. This simply means the material is supplied in the annealed condition as opposed to one of the hardened tempers.
Grain – individual crystals in metals
Half Hard – a temper of steel achieved by cold working the material. The material is substantially harder than annealed material and often has a tensile strength of double the annealed condition.
Hardness – the resistance of metal to plastic deformation. There are a variety of tests and scales including Rockwell, Brinell, Vickers, etc.
Heat – refers to the batch of metal produced in one melt furnace. Heat numbers are used for full traceability of material all the way back to original melt.
Heat Treatment – altering the properties of metal through temperature change. Annealing is a form of heat treatment.
Hollow – the starting product used in tube production. This is essentially a larger tube that is then reduced to smaller tube sizes.
Hot Forming – heating a metal to allow for easier shape change
Hydrogen Stress Cracking – material cracking due to the combination of tensile stress and corrosion in the presence of chlorides
Hydrostatic Testing – pressurizing a tube to a pressure typically not exceeding the material yield strength. Used to check for material strength, holes, cracks, etc.
ID – stands for “Inside Diameter”. This is the internal dimension of the tube.
Impact Test – a destructive test used to determine the energy necessary to cause fracture of the material
Intergranular Corrosion – a type of electrochemical corrosion that progresses preferentially along the grain boundaries of an alloy, usually because the grain boundary regions contain material anodic to the central regions of the grain.
Martensitic – can be high or low carbon steels built around the Type 410 composition of iron, 12% chromium, and up to 1.2% carbon.
Mechanical Properties – material properties such as yield strength, tensile strength, hardness, and elongation. Also known as “Physical Properties”
MTR – Material Test Report. Also known as MTC (Mill Test Certificate). This is the document certified by the product manufacturer that provides chemical and mechanical properties.
MW – stands for “Minimum Wall”. So as opposed to average wall, the stated wall thickness is the minimum allowed and the tolerance is over only, not under.
Nickel Alloy – alloy metals produced with large percentages of nickel. This includes Alloy C276, Alloy 625 and others.
NPS – stands for “Nominal Pipe Size”. This does not define the actual dimension. For example, 2” NPS is 2.375” OD. Refer to our Pipe Schedule Chart for a full list of sizes and dimensions.
OD – stands for “Outside Diameter”. This is the outside dimension of the tube.
Open Air Annealing – a process of annealing carried out in a furnace without a controlled atmosphere, so there is surface oxidation which is usually then removed using acid pickling
Orbital Weld – a fusion butt weld used to join two ends of tubing together. This is commonly used to create long length coil tubing, but can also be used for shorter length tubing for a variety of applications.
Oxidation – rust or corrosion due to exposure to oxygen
Oxygen Cleaned – special cleaning process to remove all grease, dirt, etc. that can be an ignition source for oxygen rich environments
Passivation – the process of creating the protective passive layer on the exterior of metal surfaces. Stainless steels passivate naturally, but chemical passivation can be used to optimize the passive layer.
Pickling – the process of remove rust and scale using acids. This is a common operation after open air annealing. It leaves the surface dull gray/white.
Pilgering – a method of cold working tubing that has a much greater reduction than cold drawing. It consists of two ring dies and a tapered mandrel to reduce the cross section of the tube by up to 90%.
Pitting – localizing corrosion on a metal surface in the form of pits
PMI – stands for “Positive Material Identification.” This is the analysis of a metallic alloy to establish composition by reading the quantities by percentage of its elements.
Polishing – a mechanical method for improving surface appearance. It is accomplished by grinding the tubing with finer and finer abrasive grits to achieve the desired finish or surface roughness
PSI – stands for “pounds per square inch.” This is a common term to define the strength of a material or the pressure of a fluid.
Quenching – the rapid cooling of metal after annealing. Water, air, or gas are used for cooling.
RA – stands for “roughness average.” It is the arithmetic average of a set of individual measurements of a surface’s peaks and valleys.
RMS – stands for “root mean square.” It is the root mean square average of the set of individual measurements of a surface’s peaks and valleys.
Seam – the zone where two ends of the material are welded together to create welded tubing
Seamless – tubular products produced using tube hollows formed by hot extrusion, so there is no weld seam
Solution Annealed – a form of annealing where the metal is heated to a temperature to ensure the solution of constituents and then cooled rapidly to hold these constituents in solution.
Stainless Steel – a steel alloy containing 10.5% or more chromium and possessing high corrosion resistance
Stenciling – also known as line marking and ink marking, this is the process of applying ink to the surface of a tube to give identifying information
Stress Corrosion Cracking – the growth of a crack formation in a corrosive environment
Stress Relieving – a method of heat treatment used to remove internal residual stresses generated by the manufacturing process
Temper – used to describe metal conditions such as annealed, half hard, full hard, etc.
Tensile Strength – the measurement of stress required to pull apart a material
Thermocouple Cleaned – defined as being free of all drawing compounds, carbon, dirt, dust, visible surface oxides, scale, and other contaminants.
Tolerance – the allowable amount of variation in dimensions or quantity
Ultrasonic Testing – a non-destructive test based on the propagation of ultrasonic waves in the object or material tested
Welded – forming tube from coiled steel by welded along a longitudinal seam
Yield Strength – the measurement of stress a material can withstand without permanent deformation