46 CFR §111.106-17

1. (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.
2. (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. (1)Both sides of the connection to the hull structure; or
   2. (2)Each side of the connection to the other side.
3. (c)An electrical bond must be made by at least one of the following methods:
   1. (1)A metal bonding strap attached by welding or bolting;
   2. (2)Two or more bolts that give metal-to-metal contact between the bolts and the parts to be bonded; or
   3. (3)Other metal-to-metal contact between adjacent parts under designed operating conditions.