【正文】 e is under pressure or in service. A special procedure is required to make an opening in the pipe without leaking any of the line contents.Hot tearsA defect occurring in castings caused where partially solidified or weak, newly solidified sections are subjected to a pull resulting from the contraction of thinner parts that have solidified earlier. A hot tear is an intergranular failure.Huey testA corrosion resistance test for stainless steel, most useful for predicting resistance to intergranular corrosion. Hydrostatic testA pressure test in which a valve is tested with water to detect leaks may be a shell test or a seat closure test.IBBMIron body, bronze mounted mon term for valves with cast iron body and bonnet and bronze trim (seating surfaces, stem, bushings).IDThe measurement of the inside diameter of a circular part.ISRSInside screw, rising stem mon term for any valve design in which the stem threads are exposed to the fluid below the packing and the stem rises up through the packing when the valve is opened.LeverAn operating device for quarterturn valves.Liquid penetrant inspectionA nondestructive method of detecting the presence of surface cracks and imperfections through use of a special red dye. Abbreviated as LPI or PT.Locking deviceAny valve attachment whose purpose is to prevent the operation of the valve by unauthorized persons.Magnetic particle inspectionA nondestructive method of detecting the presence of surface cracks and imperfections through use of fine iron particles in an electrical field. Abbreviated as MPI or MT.Material Test ReportsCertificates provided by the steel manufacturer indicating the chemical analysis and mechanical properties of a specific batch of steel traced by sequentially assigned heat numbers or codes.MoldA hollow cavity, frequently in packed sand, for giving a desired shape to a material in a molten or plastic shape.NPSNominal pipe size dimensionless number used to indicate sizes of pressure pipe and valves used interchangeably with valve size in inches.NPTNational Pipe Thread standard tapered thread for pressure pipe and ponents. Requirements defined in ASME .NRSNonrising stem A gate valve having its stem threaded into the gate. As the stem turns the gate moves but the stem does not rise. Stem threads are exposed to the line fluid.ODThe measurement of the outside diameter of a circular part.OringAn elastomeric or synthetic seal ring of circular cross section.OSamp。 F.Austenitic stainless steelThe mon stainless steel, where the primary microstructure is austenite and the position primarily iron but also includes both chromium and nickel. The steels are designated as 300 series such as 304, 316, CF8M, etc.Bevel gear operatorDevice facilitating operation of a gate or globe valve by means of a set of bevel gears having the axis of the pinion gear at right angles to that of the larger ring gear. The reduction ratio of this gear set determines the multiplication of torque achieved.Back seatA shoulder on the stem of a gate or globe valve which seals against a mating surface inside the bonnet to prevent leakage of media through the bonnet stuffing box when the valve is fully opened.BallThe closure element of a ball valve.Ball valveA valve using a spherical closure element which is rotated through 90176。 F to +100176。ActuatorDevice used to operate a valve using electric, pneumatic or hydraulic means. Often used for remote control or sequencing of valve operations.Alloy steelA steel consisting primarily of iron with some percentage of one or more other elements such as chromium, nickel, manganese, or vanadium deliberately added to enhance its properties.Ambient temperatureThe prevailing temperature of the environment immediately surrounding an object generally considered to be 20176。 Yoke A valve design in which the stem threads are above the packing gland or outside the valve body and there is a yoke to support the top or outer end of the stem. PackingThe deformable sealing material inserted into a valve stuffing box which when pressed by the gland provides a tight seal about the stem.PatternA duplicate made of wood or metal of a part to be cast. Used to form the mold into which the molten metal is poured.PinholeNumerous small gas holes at the surface or just below the surface of castings, generally occurring in the thicker pa