46 CFR 111.106-17: -17 Piping: electrical bonding.

(a) Tanks or piping systems that are separated from the hull structure by thermal isolation must be electrically bonded to the hull structure by a method under paragraph (c) of this section.

(b) A pipe joint or a hose connection fitting that has a gasket must be electrically bonded by a method under paragraph (c) of this section that bonds—

(1) Both sides of the connection to the hull structure; or

(2) Each side of the connection to the other side.

(c) An electrical bond must be made by at least one of the following methods:

(1) A metal bonding strap attached by welding or bolting;

(2) Two or more bolts that give metal-to-metal contact between the bolts and the parts to be bonded; or

(3) Other metal-to-metal contact between adjacent parts under designed operating conditions.