A system for indicating the wall thickness of pipe. The higher the schedule number, the thicker the wall for a certain pipe size.
A weld that does not contribute anything to the mechanical integrity of an assembly, but is made purely to seal or prevent leakage from, for instance, a threaded joint.
The part of a valve against which the closure element effects a tight shut-off.
The process by which excessive internal body cavity pressure is automatically relieved either into the upstream or downstream line - generally found in ball valves
Internal defect in castings that are internal voids, irregular in shape, caused by volume contraction during solidification. Can be caused by not maintaining a fluid channel to the riser during solidification.
Socketweld end (SW):
The end connection of a valve suitably prepared for Socket welding to a connecting pipe.
Natural gas containing significant amounts of hydrogen sulfide (H2S). Requires special material treatments to avoid valve failures from sulfide corrosion cracking.
A document that defines the requirements that a finished product must conform to - may include chemical and mechanical properties, tolerances, marking, shipping, etc.
The simplest of gears - in a gear set, the pinion and ring gear are aligned on parallel shafts. Can be added to another gear operator to further increase the mechanical advantage afforded by the gear.
Square operating nut:
A nut, usually 2" x 2", which is attached to a valve stem or the pinion shaft of a gear operator allowing use of wrenches to quickly operate the valve.
Any of a number of types of iron alloy with chrome, nickel, or other elements that does not oxidize in free air.
The rod or shaft transmitting motion from an operator (handwheel or gear operator) to the closure element of the valve.
Stem nut (yoke nut):
The threaded nut that surrounds a reciprocating valve stem and causes the stem to move when the nut is rotated.
A bolt, threaded on both ends, often used in bolting together bodies and bonnets or bodies and closures.
The annular chamber provided around a valve stem in a sealing system into which deformable packing is placed. Sometimes called packing chamber.
Swing check valve:
A check valve in which the closure element is a hinged clapper which swings or rotates about a supporting shaft.