33 CFR § 157.11 - Pumping, piping and discharge arrangements.
(a) Each tank vessel must have a fixed piping system for transferring oily mixtures from cargo tanks to slop tanks and for discharging oily mixtures to the sea and to reception facilities. On a vessel that has two or more independent piping arrangements, the arrangements collectively form the fixed piping system required by this paragraph.
(b) Each fixed piping system required by paragraph (a) of this section must have:
(2) Except as provided in paragraph (c) of this section, at least one discharge point that:
(i) Is used for discharges to the sea;
(ii) Is on a port or starboard weather deck or on the vessel's side above the waterline of its deepest ballast condition; and
(c) An above waterline discharge point is not required on an existing vessel if its fixed piping system meets paragraphs 3 and 4 of appendix E of this part.
(3) An oil piping line that meets paragraph (f) of this section and is connected to the cargo discharge piping on the outboard side of the manifold valves for the draining of oil residue from cargo pumps and other oil piping lines to a receptacle on the shore.
(4) An oil piping line that meets paragraph (f) of this section and is connected to the cargo discharge piping on the outboard side of the manifold valves for the draining of oil residue from cargo pumps and other oil piping lines to a receptacle on the shore.
(f) Each oil piping line under paragraph (d)(3) or (e)(4) of this section must have a cross-sectional area of 10 percent or less of the cross-sectional area of the main cargo discharge piping line, except if the oil piping line under paragraph (d)(3) of this section is installed before January 1, 1980, that piping line may have a cross-sectional area of 25 percent or less of the cross-sectional area of the main cargo discharge piping line.
(1) Except for short lengths of completely welded (or equivalent) piping,
(i) Ballast piping and other piping to ballast tanks, such as sounding and vent piping, do not pass through cargo tanks, and
(2) Suction wells in cargo tanks that protrude into the double bottom are as small as practicable and extend no closer to the bottom shell plating than 0.5h, as specified in § 157.10d(c)(2) or § 157.10d(d)(2), as applicable; and
(3) On a vessel that is constructed and certificated for service exclusively on inland, Great Lakes, or limited short protected coastwise routes, any oil piping that is located within double hull spaces must be placed as far from the outer shell as is practicable and must be fitted with valves at the point of connection to the tank served, to prevent oil outflow in the event of damage to the piping. Such valves must be closed whenever the vessel is underway with any oil in tanks served by the associated piping, except as necessary during transfer operations.
(h) Every oil tanker of 150 gross tons or more delivered on or after January 1, 2010, as defined in § 157.08(o), that has installed a sea chest that is permanently connected to the cargo pipeline system, must be equipped with both a sea chest valve and an inboard isolation valve. The sea chest must be able to be isolated from the cargo piping system by use of a positive means while the tanker is loading, transporting, or discharging cargo. This positive means must be is installed in the pipeline in such a way as to prevent, under all circumstances, the section of pipe between the sea chest valve and the inboard valve from being filled with cargo.
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