Pipefitting Glossary of Terms


Alloy Steel
     A steel which owes its distinctive properties to elements other than carbon. 

Area of a Circle
     The measurement of the surface within a circle. To find the area of a circle, multiply the product of the radius times the radius times Pi (3.142). 

Braze Weld or Brazing
     A process of joining metals using a nonferrous filler metal or alloy, the melting point of which is higher than 800 degrees F(427 degrees C) but lower than that of the metals to be joined. 

Butt Weld
     A circumferential weld in pipe fusing the abutting pipe walls completely from inside wall to outside wall. 

Carbon Steel
     A steel which owes its distinctive properties chiefly to the various percentages of carbon (as distinguished from the other elements) which it contains. 

Circumference of a Circle
     The measurement around the perimeter of a circle. To find the circumference, multiply Pi (3.142) by the diameter. 

Coefficient of Expansion
     A number indicating the degree of expansion or contraction of a substance. The coefficient of expansion is not constant and varies with changes in temperature. For linear expansion it is expressed as the change in length of one unit of length of a substance having one degree rise in temperature. 

     The gradual destruction or alteration of a metal or alloy caused by direct chemical attack or by electromechanical reaction. 

     The plastic flow of pipe within a system; the permanent set in metal caused by stresses at high temperatures. Generally associated with a time rate of deformation. 

Diameter of a Circle
     A straight line drawn through the center of a circle from one extreme edge to the other. Equal to twice the radius. 

     The property of elongation, above the elastic limit, but under the tensile strength. A measure of ductility is the percentage of elongation of the fractured piece over its original length. 

Elastic Limit
     The greatest stress which a material can withstand without a permanent deformation after release of the stress. 

     The gradual destruction of metal or other material by the abrasive action of liquids, gases, solids or mixtures thereof 



Radius of a Circle
     A straight line drawn from the center to the extreme edge of a circle. 

Socket Fitting
     A fitting used to join pipe in which the pipe is inserted into the fitting. A fillet weld is then made around the edge of the fitting and the outside wall of the pipe. 

     A method of joining metals using fusable alloys, usually tin and lead, having melting points under 700 degrees F(371 degrees C). 

     Change of shape or size of a body produced by the action of a stress. 

     The intensity of the internal, distributed forces which resist a change in the form of a body. When external forces act on a body they are resisted by reactions within the body which are termed stresses. 

Stress, Compressive
     One that resists a force tending to crush a body. 

Stress, Shearing
     One that resists a force tending to make one layer of a body slide across another layer. 

Stress, Tensile
     One that resists a force tending to pull a body apart. Stress, Torsional: One that resists forces tending to twist a body. 

Tensile Strength
     The maximum tensile stress which a material will develop. The tensile strength is usually considered to be the load in pounds per square inch at which a test specimen ruptures. 

     Any deviation from parallel flow in a pipe due to rough inner walls, obstructions or directional changes. 

     Time rate of motion in a given direction and sense, usually expressed in feet per second. 

Volume of a Pipe
     The measurement of the space within the walls of the pipe. To find the volume of a pipe, multiply the length (or height) of the pipe by the product of the inside radius times the inside radius times Pi (3.142). 

     A process of joining metals by heating until they are fused together, or by heating and applying pressure until there is a plastic joining action. Filler metal may or may not be used. 

Yield Strength
     The stress at which a material exhibits a specified inciting permanent set.  

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