Select terminology from Pressure-Vessels.net

Atmospheric Pressure - The amount of force the atmosphere exerts upon the earth's surface, measuring 14.7 psi at sea level.

Design Pressure - The maximum internal and external pressure limits that a pressure vessel can withstand, usually equivalent to 110% of vessel operating pressure.

Design Temperature - The temperature of the pressure vessel metal when the vessel is subjected to the design pressure.

Hydrostatic Test - Test in which pressure vessels are subjected to 150% of the design pressure.

ID (Inside Diameter) - Diameter of the vessel measured from the interior of the vessel surfaces. This dimension does not include the material thickness.

Lifting Lugs - Lugs attached to the outside of the vessel specifically placed to help aid lifting of the vessel.

Megapascal - Unit of measurement equal to 1,000,000 pascals, used to express tensile strength and yield strength.

National Board Inspection Code – Worldwide standard for pressure vessel inspection, alteration and repair.
   
Operating Pressure – The pressure at which a vessel operates while in use.
 
Psi (Pounds per Square Inch) – Unit that measures the amount of pressure applied to an object.
 
Relief Valve – Pressure relief mechanism that automatically releases liquids from pressure vessels when vessel pressure exceeds set pressure, and closes when the pressure level returns to normal.
 
Safety Relief Valve – Pressure relief mechanism that automatically releases liquid and vapor streams from pressure vessels when vessel pressure exceeds set pressure, and closes when the pressure level returns to normal.
 
Set Pressure – The predetermined pressure at which a pressure relief device begins to discharge fluid.
 
Strain – The change in an object’s dimensions, resulting from the application of force.
 
Stress – The force responsible for causing a change in an object’s dimensions.
                                                          
Tensile Strength – The maximum stress level exerted upon a test specimen before the specimen fractures.
 
Tensile Stress – The force applied to a test specimen to produce strain.
 
Vessel Heads – The end of a pressure vessel, including flanged and dished, ellipsoidal, flat, conical and hemispherical.
 
Vessel Shell – The pressure vessel body.