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ANNEALING - A process involving heating and cooling, usually applied to induce softening. The term also refers to treatments intended to alter mechanical or physical properties, produce a definite microstructure.
BEND TESTS - Tests used to determine the ductility and/or other characteristics of pipe and tubing. The number of tests, radius and degree of bend are generally outlined in the applicable specification.
CHARPY IMPACT TEST - A standard V-notched test specimen bar at a predetermined temperature, supported as a cantilever beam is broken by means of a load applied suddenly by a single blow from a calibrated pendulum to determine the notch toughness of the materials at a specific temperature. The notch toughness is indicated by the energy absorbed in breaking the bar.
COLD DRAWN - Refers to tubing drawn in the cold state through hardened steel or tungsten carbide dies, either with or without a mandrel on the inside of the tubing.
COLD EXPANDING - A method of cold working pipe wherein the diameter of the pipe is increased either by mechanical or fluid pressure exerted from within.
COLD WORK - Plastic deformation at such temperatures and rates that substantial increases occur in the strength and hardness of the metal.
COLLAPSING PRESSURE - The pressure which, when applied to the outside of a tube, causes it to cave in, or to fail by bending or buckling inward.
CONCENTRICITY - A tube is concentric when the centre line of the inside diameter is consistent with the centre line of the outside diameter.
DESCALING - The process of removing scale from the surface of steel. Scale forms most readily when the steel is hot by union of the oxygen in the air with the iron in the hot steel.
DUCTILITY - The property that permits permanent deformation or stretch before fracture by stress or tension.
ELECTRIC RESISTANCE WELD (ERW) PIPE - Cold finished pipe made by a series of operations in which the flat rolled material is cold-shaped into tubular form and welded at the seam by the application of pressure and heat. The heat is generated at the seam by the resistance to the flow of an electric current applied through electrical contacts or an induction coil.
ELECTRIC RESISTANCE WELD HOT STRETCH REDUCTION - Made by cold-forming flat-rolled steel, welding the longitudinal butt-joint by the electric resistance weld process, and subsequently reducing the diameter while the material is hot throughout its cross-section.
EDDY CURRENT TESTING - A non-destructive testing method, using an electromagnetic instrument that induces eddy currents in the pipe or tube under test and detects variations caused by discontinuities.
(ELASTIC LIMIT) YIELD POINT - The maximum stress that a material is capable of sustaining without any measurable permanent extension remaining after complete release of the applied force.
ELONGATION - The amount of permanent extension in the vicinity of the fracture in the tension test. Usually expressed as a percentage of the original gauge length, such as 25% in 2".
FLARE TEST - A destructive test to check the weld quality and ductility of pipe by a tapered expansion over the apex of a cone of specified dimensions, usually 60o.
FLASH - When hot metal surfaces are joined by fusion under pressure, as in electric resistance welding, metal displaced out of the weld, usually as a thin fin, is called a flash.
FLATTENING TEST - A destructive test where a ring cut from a length of pipe is cold-flattened to establish if the ductility, soundness and weld quality meet the specified requirements.
GALVANIZING - The process of applying a coating of zinc to the finished tube to provide corrosion protection. The coating can be applied by hot-dipping or electrolytic deposition.
HOT WORKING - Plastic deformation of metal at elevated temperature. The end effect is to produce a more ductile product.
HYDROSTATIC TEST - A test where water pressure is applied (internally) to the full length of pipe to be sure it is free from leaks and capable of withstanding a specific pressure.
KILLED STEEL - Has sufficient deoxidizing agent added to remove all free oxygen. Internal gas voids are thus avoided.
LADLE ANALYSIS - The term applied to the chemical analysis representative of a heat or blow of steel as it is being poured. This is the analysis reported to the purchaser by the steel supplier.
LAMINATIONS - Defects resulting from the presence of non-metallics aligned parallel to the worked surface of a metal.
LINE PIPE - This term describes welded and seamless pipe used principally for conveying gas, oil, solids in a water slurry, liquefied petroleum products and water, usually over relatively large distances. Cross-country transmission pipe lines for oil and gas are usually laid underground with compressor or pumping stations located at regular intervals along the pipe-line to maintain proper operating pressures and product flow rates.
LONGITUDINAL TENSILE TESTS - For small-diameter sizes full-size tubular sections are tested. For the larger sizes, longitudinal test specimens are obtained from strips cut from the tube. For welded pipe, specimens are located approximately 90o from the weld.
MAGNETIC PARTICLE INSPECTION (WELD ZONE) - A magnetic field transverse to the weld is produced. Magnetic powder is applied which is attracted to regions where the magnetic field is increased by discontinuities at or near the surface.
MECHANICAL PROPERTIES - Those properties of a material that reveal the elastic and inelastic reaction when force is applied, or that involve the relationship between stress and strain — for example, the modulus of elasticity, tensile strength and fatigue limit. These properties are often referred to as "physical properties."
MECHANICAL TUBING - Tubing used for a variety of mechanical and structural purposes and not necessarily designed for the carrying of fluids or gases under pressure.
NORMALIZING - The heating of steel to a temperature exceeding its upper critical temperature, followed by cooling freely in still air so that moderately rapid cooling occurs and a fine-grained structure is obtained.
OVALITY - The difference between the maximum and minimum diameters of any one section of tubing.
PARENT METAL - As applied to a welded product, refers to that portion of the metal that was not affected by the heat from the welding operation.
PIPE - Pipe is distinguished from tubing by the fact that it is produced in relatively fewer sizes and in comparatively large quantities of each size. Diameters less than 14" have a nominal or named size, which is not the actual inside or outside diameter. For example, standard pipe with the nominal size of 2 has an outer diameter of 2.375" and inner diameter of 2.067" plus or minus the permissible specification tolerances. Size 14" and larger pipes are designated by the actual outside diameter of the pipe.
PIT - A sharp depression in the surface of metal.
PLASTIC DEFORMATION - Permanent distortion of materials under the action of applied stresses (bending).
PRESSURE PIPE - This term describes a large list of seamless or welded, carbon or alloy pipe, used for conveying fluids at low, normal, or elevated temperatures or pressures, or both, but not subjected to the application of external heat. Pressure pipe is generally confined to industrial applications, for use in plant steam and hydraulic piping systems.
SKELP - Steel plate or strip from which pipe or tubing is made by rolling the skelp into shape longitudinally and welding the edges together.
SPECIFICATION AND GRADE - In general, it can be said that the end use of the piping material and the conditions of pressure, temperature, atmosphere and fluid conveyed would dictate the specification to which it must be manufactured. Grades, of course, represent differences in steel characteristics within a given specification. It is the function of design engineers to determine the specification and grade that will be applied to a given end-use.
STANDARD PIPE - The term "standard pipe" refers to welded or seamless pipe in three classes of wall thickness, designated standard weight, extra strong, or double extra strong. This term is also used to describe welded or seamless pipe intended for general applications. Standard pipe is intended for general use in plumbing and heating, water supply systems, fire prevention systems, irrigation systems, refrigeration, snow-melting and other general purposes.
STRESS RELIEVING - A process of reducing residual stresses in materials by heating the metal to suitable temperature, holding for a sufficient time, and cooling at room temperature. Such stresses may be induced by cold-working or welding.
TENSILE STRENGTH - Breaking strength divided by the cross-sectional area. Also called ultimate strength.
TENSILE TEST - A mechanical test to determine yield strength, ultimate strength and elongation by applying tension to a specified specimen.
TRANSVERSE TENSILE TEST - The specimen shall be located 90o to the axis of the pipe. Not applicable for sizes smaller than 8 5/8" (219.1 mm) outer diameter
TRANSVERSE WELD TESTS - Specimen is taken 90o to the weld with the weld at the center. Not applicable for sizes smaller than 8 5/8” (219.1 mm) outer diameter.
ULTRASONIC TESTING - A non-destructive testing method that transmits a beam of high frequency sound into the tube and listens for echoes returned by discontinuities.
WELD JOINT FACTOR - Factor used in the establishment of the maximum allowable stress permitted for materials, taking into consideration the efficiency of the weld joint produced by the manufacturing process.
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