When two dissimilar metals are in electrical contact with each other and are exposed to a common electrolyte, a cell is formed in which galvanic corrosion occurs at the anode while the cathode metal is protected from attack.

The MG COUPLING forms such a cell in an environment containing a common electrolyte. Tests indicate (see page 8) that, under such conditions, the stainless steel bolt units are receiving a full level of cathodic protection from the couple with the cast iron clamping members (coupling body).

Since the stainless steel bolting units are lower in the galvanic series, they are cathodic to the cast iron coupling clamping halves which inevitably become anodic and protect the stainless steel bolting units.

Because the cast iron clamping member body and the stainless steel bolting units are relatively close in the galvanic series and more significantly because the cast iron clamping body is decisively large compared to the small cathodic area of the stainless steel bolting members, the current will be small causing no substantial change or damage to the anodic clamping member.