46 CFR §128.420

1. (a)Except as provided by this section, each keel cooler installation must comply with § 56.50-96 of this chapter.
2. (b)Approved metallic flexible connections may be located below the deepest-load waterline if the system is a closed loop below the waterline and if its vent is located above the waterline.
3. (c)Fillet welds may be used in the attachment of channels and half-round pipe sections to the bottom of the vessel.
4. (d)Short lengths of approved non-metallic flexible hose fixed by metallic or non-metallic hose-clamps may be used at machinery connections if—
   1. (1)The clamps are of a corrosion-resistant material;
   2. (2)The clamps do not depend on spring tension for their holding power; and
   3. (3)Two of the clamps are used on each end of the hose, except that one clamp may be used on an end expanded or beaded to provide a positive stop against hose slippage.
   4. (4)The clamps are resistant to vibration, high temperature, and brittleness.