Galling: A situation where two moving parts that are in close contact, seize and are bonded together.
Galvanic corrosion: Corrosion due to electrolysis of the anodic metal when two metals in the galvanic series are connected with electrolyte. For example, different stainless steel composites will undergo galvanic corrosion if used to manufacture different components in a pump.
Galvanic series: A way to order metals such that those at the beginning of the series will attack any metal further down the list. The further apart the two metals are in the series, the faster the attack will occur.
Garter spring: A long coiled spring with its ends fused together. It exerts radial force (can be either inward or outward) and is used in shaft seals.
Gasket: A seal between static components in mechanics. Made of deformable material.
Gauge pressure: The pressure exhibited on a dial gauge or on a digital read out from a pressure gauge. This reading indicates the pressure above atmospheric pressure and is usually measured in PSIG (pounds per square inch gauge).
Gland: A component of a mechanical seal that attaches to the stuffing box.
Gland follower: In a mechanical seal, it is a part of the stuffing box that is forced against the packing rings to increase radial sealing force
Gland plate (or gland): The plate that connects the mechanical seal to the seal chamber / stuffing box.
Grease seal: A bearing seal that is spring loaded and made of an elastomer, also known as a lip seal. Face seals or labyrinth seals are better choices for pumps.