Bronze Vs Brass Fittings

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.

So what should you do?

You should continue with what has always been sound marine practice: use bronze fittings for the thru-hull mushrooms, seacocks, strainer bodies and valves. If one of the pipes must be turned through an angle, use a bronze Street Ell, either 90° or 45°. Once the bronze fittings are in place and aligned, thread a bronze hose barb into each, and join them with sturdy hoses and stainless steel clamps.

Don’tconfuse bronze hose-to-pipe fittings like those made by Groco and Perko with small brass hose-to-pipe adapters. Bronze fittings used for seacocks are fine for use in saltwater.

But what if the application absolutely demands other fittings? Try fittings of some other, nonmetal material such as nylon or marelon, both of which we carry. These galvanically inert materials present no problems when used in conjunction with any marine metals in underwater applications.