Graphitization (Graphitic corrosion)

Corrosion of gray cast iron in which the metallic constituents are converted to corrosion products, leaving the graphite flakes intact. Graphitization is also used in a metallurgical sense to mean the decomposition of iron carbide to form iron and graphite.

Gravel

Per ASTM D653, rounded or semirounded particles of rock that will pass a 3-in. (76.2-mm) sieve and be retained on a #4 (4.75-mm) US standard sieve.

Gravity Sewer

A sewer that is designed to operate under open channel conditions (below pipe full capacity) up to a maximum design flow at which point it will become surcharged.

GRC

Glass fiber Reinforced Concrete; a rehabilitation lining.

Grease Trap

Mechanism in a lateral that collects grease before it can reach a main line.