46 CFR § 111.106-17 - 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.