Bronze vs Brass Fittings in the Marine World
The
difference between bronze and brass in the world of plumbing fittings
concerns their relative potentials for galvanic corrosion. Dissimilar
metals in contact can set up an electric current in an electrically
conductive fluid (an electrolyte, such as saltwater). One of the metals
will be “eaten away” or “sacrificed” in the process. Sacrificial anodes
are made of zinc because it is one of the least “noble” (i.e., highly
active) metals and is thus sacrificed to protect your engine, rudder,
propeller shaft, refrigeration condenser, etc. from damage due to
galvanic corrosion. However, with thru-hulls, seacocks, etc. dissolving
fittings are not an option. You want all the fittings to remain intact.
To
avoid this potentially hazardous situation, make sure you are not
setting up the conditions for galvanic corrosion by connecting
dissimilar brass fittings to bronze fittings. Generally, you can tell
them apart just by looking at them. Bronze fittings have an outer
surface that is rough in feel and appearance, almost like it’s covered
with sand. That’s because bronze fittings are sand cast, and then
machined.