The requirements in this subpart for piping systems apply instead of those in Section 122 of ASME B31.1 (incorporated by reference; see § 56.01-2). The following installation requirements are applicable to all systems:

(a) Where pipes and scuppers are carried through watertight or oiltight bulkheads, decks, or tank tops, or are carried through fire control bulkheads and decks, the integrity of the structure must be maintained. Lead or other heat sensitive materials must not be used in piping systems in bulkhead or deck penetrations where fire would impair the integrity of the penetration. (For nonmetallic or plastic pipe installations, see § 56.60-25(a).) Openings in structure through which pipes pass must be reinforced where necessary. Metallic materials having a melting point of 1,700 °F or less are considered heat sensitive and if used must be suitably insulated.

(b)(1) Pipes piercing the collision bulkhead must be fitted with valves operable from above the bulkhead deck and the valve must be fitted inside the forepeak tank adjacent to the collision bulkhead. The pipe penetrating the collision bulkhead must be welded to the bulkhead on both sides. The valve body must be of steel or ductile cast iron.

(2) Passenger vessels must not have the collision bulkhead pierced below the margin line by more than one pipe conveying liquids in the forepeak tank.

(c) Valves and cocks not forming part of a piping system are not permitted in watertight subdivision bulkheads. However, sluice valves or gates in oiltight bulkheads of tank vessels may be used if approved by the Marine Safety Center.

(d) Piping must generally not be run over switchboards, and must be installed as far away from other electrical equipment as practicable. When such leads are necessary, provision must be made to prevent leakage from damaging the equipment.

(e) Stuffing boxes must not be used on deep tank bulkheads, double bottoms or in any position where they cannot be easily examined. This requirement does not apply to ore carriers operating on the Great Lakes or cargo lines of oil tankers.

(f) Piping systems must be installed so that under no condition will the operation of safety or relief valves be impaired.

(g)(1) Power actuated valves may be used if approved for the system by the Marine Safety Center. All power-actuated valves must have a backup manual means of operation.

(2)(i) Remote valve controls must be fitted with nameplates describing the applicable system.

(ii) Remote valve controls must be accessible under normal service conditions.

(iii) Remote valve controls, except reach rods, must be fitted with indicators that show whether the valves they control are open or closed. Valve position indicating systems must be independent of valve control systems.

(iv) Valve reach rods must be adequately protected.

(v) Solid reach rods must be used in tanks containing liquids, except that reach rods of constructed of extra-heavy pipe may be considered acceptable by the OCMI.

(3) Air-operated remote-control valves must be provided with self-indicating lines at the control boards that indicate the desired valve positions, such as open or closed.

(h) Suitable drains must be provided at low points of piping systems.

(i) Valves and cocks must be easily accessible. Valves attached to the shell of the vessel or to sea chests located below deck plating must be operable from above the deckplates.

(j) When welded fabrication is employed, a sufficient number of detachable joints must be provided to facilitate maintenance of machinery.

(k) Piping systems used where the fluid temperature exceeds 150 °F must be suitably insulated as necessary to preclude injury to personnel.

(l) Where pipes are run through dry cargo spaces they must be protected from mechanical injury by a suitable enclosure or other means.

(a) Where pressure-reducing valves are employed, a pressure gauge must be provided on the low-pressure side of the reducing station.

(b) Fuel oil service and transfer, fire, cargo, and boiler feed pumps must be provided with a discharge pressure gage. Additional information pertaining to fire pumps is in § 34.10-5 of subchapter D, § 76.10-5 of subchapter H, § 95.10-5 of subchapter I, and § 108.417 of subchapter IA, all of this chapter.

(a) The design pressures of the steam piping connected to the boiler drum or to the superheater inlet header must not be less than the lowest pressure setting of any drum safety valve. The value of allowable stress for the material must not exceed that corresponding to the saturated steam temperature at drum pressure and must be selected as described in § 56.07-10(e).

(b) Main superheater outlet piping systems, desuperheater piping systems, and other auxiliary superheated piping systems led directly from the boiler superheater must be designed for a pressure not less than the pressure at which the superheater safety valve is set. In the case of a superheated safety valve that is drum pilot actuated, the design pressure of such piping systems must not be less than the pressure setting of the actuator valve on the drum. Valves and fittings must be selected for the above systems from the accepted standards in table 1 to 56.60-1, using the pressure-temperature rating in the standard.

(c) Steam stop valves in sizes exceeding 6 inches must be fitted with bypasses.

(d) In multiple boiler installations each boiler's main, auxiliary and desuperheater steam lines must be fitted with two valves, one a stop valve and one a stop check valve.

(e) Main and auxiliary steam stop valves must be readily accessible, operable by one person and arranged to seat against boiler pressure.

(f) The auxiliary steam piping of each vessel equipped with more than one boiler must be so arranged that steam for the whistle and vital auxiliary systems may be supplied from any power boiler.

(g) Steam and engine exhaust pipes must not be led through coal bunkers or dry cargo spaces.

(h)(1) Steam piping, with the exception of the steam heating system, must not be led through passageways, accommodation spaces, or public spaces unless the arrangement is specifically approved by the Marine Safety Center.

(2) The pressure in steam heating systems must not exceed 150 psig, and the steam pressure for accommodation and public space heating must not exceed 45 psig.

(3) Steam lines must be suitably located and shielded to minimize hazards to any personnel within the space.

(4) High temperature hot water for heating systems may not exceed 375 °F.

(i) Where the exhaust side of machinery is not designed for the full inlet pressure, the exhaust side must be protected from over pressure by one of the following means:

(1) A relief valve in the exhaust side with appropriate set pressure and sufficient capacity to prevent the exhaust side from overpressure.

(2) A sentinel valve or other warning device fitted on the exhaust side, together with a trip device, which will close the inlet valve.

(j) Shore steam connections must be fitted with a relief valve set at a pressure not exceeding the design pressure of the piping.

(k) Means must be provided for draining every steam pipe in which water hammer might occur.

(a) General. There must be no intervening stop valves between the pressure vessel or piping system being protected and its protective device or devices, except as authorized by the Marine Safety Center.

(b) Discharge lines. (Reproduces 122.6.2(d).) Discharge lines from pressure-relieving safety devices must be designed to facilitate drainage.

(c) Stop valves. Stop valves between the safety or relief valve and the point of discharge are not permitted, except as specifically approved by the Marine Safety Center.

(d) Reference. See also § 56.07-10(a) and (b) for specific requirements.

(a) Escape piping from safety valves must have an area of not less than that of the combined areas of the outlets of all valves discharging thereto and must be led as near vertically as practicable to the atmosphere.

(b) Expansion joints or flexible pipe connections must be fitted in escape piping. The piping must be adequately supported so that no stress is transmitted to the safety valve body.

(c) Safety or relief valve discharges, when permitted to terminate in the machinery space, must be led below the floorplates or to a remote position.

(d) The back pressure effect of the escape piping on the operation of the relief device must be considered.

(a) General requirements. (1) Steam vessels, and motor vessels fitted with steam driven electrical generators must have at least two separate means of supplying feed water for the boilers. All feed pumps must be fitted with the necessary connections for this purpose. The arrangement of feed pumps must be in accordance with paragraph (d) or (e) of this section.

(2) Feed pump supply to power boilers may utilize the group feed system or the unit feed system.

(3) Feed discharge piping from the pump up to, but not including the required stop and stop-check valves, must be designed for either the feed pump relief valve setting or the shutoff head of the pump if a relief valve is not fitted. (Refer to § 56.07-10(b) for specific requirements.) Feed piping from the boiler, to and including the required stop and stop-check valves (see paragraph (b) of this section), must have a design pressure which exceeds the maximum allowable working pressure of the boiler by either 25 percent or 225 psig, whichever is less. The value of allowable stress for design purposes must be selected as described in § 56.07-10(e) at a temperature not below that for saturated steam at the maximum allowable working pressure of the boiler.

(4) Feed pumps for water tube boilers must have freshwater connections only.

(b) Feed valves. (1) Stop and stop-check valves must be fitted in the main feed line and must be attached as closely as possible to drum inlets or to the economizer inlet.

(2) Auxiliary feed lines must be fitted with stop valves and stop-check valves.

(3) Boilers fitted with economizers must have a check valve fitted in the economizer discharge and located as close as possible to the drum feed inlet nozzle.

(c) Feed water regulators and heaters. (1) Where feed water regulators or feed water heaters are installed, an alternate means of operation with these devices bypassed must be provided.

(2) All feed water regulators installed in a unit feed system must be fitted with an external bypass.

(3) A feed water regulator may be interposed between the stop and stop-check valves in the feed lines.

(d) Group feed system. Group feed systems must be provided with pumps and piping as follows:

(1) Vessels having a feed pump attached to the main propulsion unit must be provided with at least one independently driven feed pump. Each of these pumps must be used exclusively for feed purposes and must be capable of supplying the operating boilers at their normal capacity. In addition, a second independently driven pump, capable of supplying such boilers at 75 percent of their normal capacity, must be provided.

(2) If two independently driven pumps are provided, each capable of supplying the boilers at their normal required operating capacity, and neither pump is used for other purposes, the third or emergency feed pump is not required.

(3) River or harbor steam vessels must have at least two means for feeding the boilers; one of which must be an independently driven pump, the other may be an attached pump, an additional independently driven pump, or an injector.

(e) Unit feed system. Unit feed systems must be provided with pumps and piping as follows:

(1) The unit feed system may be used on vessels having two or more boilers. When the unit feed system is employed, each boiler must have its own independently driven main feed pump capable of supplying the boiler at its normal operating capacity. In addition, there must be an auxiliary independent feed pump of the same capacity that can be operated in place of and in conjunction with the main feed pump. In vessels with three or more boilers, not more than two boilers may be served by any one auxiliary pump. The auxiliary pump may be so interconnected that any pump can feed any boiler.

(2) In the unit feed system, a separate feed line must be provided for each boiler from its pumps. A separate auxiliary feed line is not required. The discharge from each pump and the feed supply to each boiler must be automatically controlled by the level of the water in that boiler. In addition to the automatic control, manual control must be provided.

(f) Feedwater. The feedwater must be introduced into a boiler as required by § 52.01-105(d) of this subchapter.

Two means must be provided for discharging the condensate from the main condenser, one of which must be independent of the main propelling machinery.

(a)(1) The owner or operator of a vessel must follow the requirements for blowoff piping in this section instead of the requirements in 122.1.4 of ASME B31.1 (incorporated by reference; see § 56.01-2).

(2) Where blowoff valves are connected to a common discharge from two or more boilers, a nonreturn valve must be provided in the line from each boiler to prevent accidental blowback in the event the boiler blowoff valve is left open.

(b) Blowoff must be designed for not less than 125 percent of the maximum allowable working pressure of the boiler, or the maximum allowable working pressure of the boiler plus 225 psig, whichever is less. The value of allowable stress for design purposes must be selected as described in § 56.07-10(e) at a temperature not below that of saturated steam at the maximum allowable working pressure of the boiler.

(c) Boiler blowoff piping which discharges above the lightest loadline of a vessel must be arranged so that the discharge is deflected downward.

(d) Globe valves must not be used for blowoff service.

(a) A main circulating pump and emergency means for circulating water through the main condenser must be provided. The emergency means may consist of a connection from an independent power pump fitted between the main circulating pump and the condenser.

(b) Independent sea suctions must be provided for the main circulating and the emergency circulating pumps.

(c) A cross connection between the circulating pumps in the case of multiple units will be acceptable in lieu of an independent power pump connection.

(a)(1) The requirements of SOLAS Chapter II-1 regulation 35-1 (incorporated by reference, see § 56.01-2) for passenger and cargo ships are considered equivalent to this section.

(2) All vessels except unmanned barges must be provided with a satisfactory bilge pumping plant capable of pumping from and draining any watertight compartment except for ballast, oil, and water tanks. The bilge pumping system must be capable of operation under all practicable conditions after a casualty whether the ship is upright or listed.

(3) Arrangements must be made whereby water in the compartments will drain to the suction pipes. Where piping is led through the forepeak, see § 56.50-1(b).

(4) Where the vessel is to carry flammable liquids with a flashpoint below 23 °C (74 °F) in enclosed cargo spaces, the bilge-pumping system must be designed to ensure against inadvertent pumping of such liquids through machinery spaces.

(5) For vessels constructed on or after June 9, 1995, and on an international voyage, arrangements must meet the requirements of SOLAS Chapter II-1 regulation 35-1 to drain the enclosed cargo spaces on either the bulkhead deck of a passenger vessel or the freeboard deck of a cargo vessel.

(b) Passenger vessels must have provision made to prevent the compartment served by any bilge suction piping from being flooded in the event the pipe is severed or otherwise damaged by collision or grounding in any other compartment. Where the piping is located within one-fifth of the beam of the side of the vessel or is in a duct keel, a nonreturn valve must be fitted to the end of the pipe in the compartment, which it serves.

(c)(1) Each bilge suction must lead from a manifold unless otherwise approved by the Marine Safety Center. As far as practicable, each manifold must be in, or capable of remote operation from, the same space as the bilge pump. In either case, the manifold must be capable of being locally controlled from the floorplates. As far as practicable, each overboard-discharge valve for a bilge system must comply with the requirements governing location and accessibility for suction manifolds. Except as otherwise permitted by paragraph (c)(3) of this section for a vessel employing a common-rail bilge system, each bilge-manifold valve controlling a bilge suction from any compartment must be of the stop-check type.

(2) Each passenger vessel on an international voyage must comply with the provisions of SOLAS Chapter II-1, Regulation 35-1.

(3) A common-rail bilge system may be installed as an acceptable alternative to the system required by paragraph (c)(1) of this section, provided it satisfies all of the following criteria:

(i) The common-rail main runs inboard at least one-fifth of the beam of the vessel.

(ii) A stop-check valve or both a stop valve and a check valve are provided in each branch line and located inboard at least one-fifth of the beam of the vessel.

(iii) The stop valve or the stop-check valve is power-driven, is capable of remote operation from the space where the pump is, and is capable of manual operation.

(iv) The stop valve or the stop-check valve is accessible under all operating conditions, and the space used for access contains no expansion joint or flexible coupling that, upon failure, would cause flooding and prevent access to the valve.

(v) A port and a starboard suction serve each space protected unless, under the worst conditions of list and trim and with liquid remaining after pumping, the vessel's stability remains acceptable, in accordance with subchapter S of this chapter.

(vi) For each vessel designed for the carriage of combinations of both liquid and dry bulk cargoes, no bilge pump or piping is located in a machinery space other than in a pump room for cargo, and no liquid and other cargoes are carried simultaneously.

(vii) For each cargo vessel in Great Lakes service, each common-rail piping for the bilge and ballast system serving cargo spaces, if installed and if connected to a dedicated common-rail bilge system, must lead separately from a valved manifold located at the pump.

(d) The internal diameter of bilge suction pipes including strainers must be determined by formulas 1 and 2 to § 56.50-50(d) introductory text, except that the nearest commercial size not more than one-fourth inch under the required diameter may be used.

(1) For suctions to each main bilge pump, use formula 1 to § 56.50-50(d) introductory text. For branch suctions to cargo and machinery spaces, use formula 2 to 56.50-50(d) introductory text.

(2) The following “where” clause applies to formulas 1 and 2 to § 56.50-50(d) introductory text:

(3) For vessels of 150 gross tons and over, no main suction piping must be less than 2.5 inches internal diameter. Branch piping need not be more than 4 inches and must not be less than 2 inches in diameter except for drainage of small pockets or spaces in which case 1.5-inch diameter may be used. For vessels less than 150 gross tons no bilge suction must be less than 1.5 inches internal diameter and branch piping must not be less than 1-inch nominal pipe size.

(4) For vessels of 65 feet in length or less and not engaged on an international voyage, the bilge pipe sizes computed by formulas 1 and 2 to § 56.50-50(d) introductory text are not mandatory, but in no case must the size be less than 1-inch nominal pipe size.

(5) The number, location, and size of bilge suctions in the boiler and machinery compartments must be determined when the piping plans are submitted for approval and must be based upon the size of the compartments and the drainage arrangements.

(e) Independent bilge suction. One of the independent bilge pumps must have a suction of a diameter not less than that given by formula 2 to § 56.50-50(d) introductory text that is led directly from the engine room bilge entirely independent of the bilge main, and on passenger vessels each independent bilge pump located in the machinery spaces must have such direct suctions from these spaces, except that not more than two pumps are required to have direct suctions from any one space. A suction that is led directly from a suitably located pump manifold may be considered to be independent of the bilge main. Where two direct suctions are required in any one compartment on passenger vessels, one suction must be located on each side of the compartment. If watertight bulkheads separate the engine and boiler rooms, a direct suction or suctions must be fitted to each compartment unless the pumps available for bilge service are distributed throughout these compartments, in which case at least one pump in each such compartment must be fitted with direct suction in its compartment. In a vessel with more than one hull, there must be one bilge pump that has an independent bilge suction in each hull. In a column stabilized mobile offshore drilling unit, the independent bilge suction must be from the pumproom bilge.

(f) Emergency bilge suctions. In addition to the independent bilge suction(s) required by paragraph (e) of this section, an emergency bilge suction must be provided in the machinery space for all self-propelled vessels as described in the following subparagraphs. Emergency suctions must be provided from pumps other than those required by § 56.50-55(a). Such suctions must have nonreturn valves, and must meet the following criteria as appropriate:

(1) On passenger vessels propelled by steam and operating on an international voyage or on ocean, coastwise, or Great Lakes routes, the main circulating pump is to be fitted with a direct bilge suction for the machinery space. The diameter of such suctions must not be less than two-thirds the diameter of the main sea injection. Other independent power pumps in the machinery space may be approved by the Commandant if the main circulating pump is not suitable.

(2) On passenger vessels propelled by internal combustion engines and operating on an international voyage or on ocean, coastwise, or Great Lakes routes, the largest available pump in the engine room is to be fitted with the direct bilge suction in the machinery space. The area of the suction pipe is to be equal to the full suction inlet of the pump.

(3) Vessels over 180 feet in length which are not passenger vessels, and which operate on international voyages or in ocean, coastwise, or Great Lakes service, must be provided with a direct emergency bilge suction from any pump in the machinery space, except that a required bilge pump may not be used. The discharge capacity of the pump selected must exceed the capacity of the required main bilge pump and the area of the suction inlet is to be equal to the full suction inlet of the pump.

(4) Vessels under 180 feet in length need not provide an emergency bilge suction, except that passenger vessels must comply with the requirements of paragraphs (f)(1) and (2) of this section.

(5) Each vessel with more than one hull must have an emergency bilge suction in each hull.

(6) Each column stabilized mobile offshore drilling unit must have—

(i) An emergency bilge suction in each hull; and

(ii) A remote control for the emergency pump and associated valves that can be operated from the ballast control room.

(g) Each individual bilge suction must be fitted with a suitable strainer having an open area of not less than three times that of the suction pipe. In addition, a mud box or basket strainer must be fitted in an accessible position between the bilge suction manifold and the pump.

(h) Pipes for draining cargo holds or machinery spaces must be separate from pipes which are used for filling or emptying tanks where water or oil is carried. Bilge and ballast piping systems must be so arranged as to prevent oil or water from the sea or ballast spaces from passing into cargo holds or machinery spaces, or from passing from one compartment to another, whether from the sea, water ballast, or oil tanks, by the appropriate installation of stop and non-return valves. The bilge and ballast mains must be fitted with separate control valves at the pumps. Piping for bilge and ballast must be arranged so as to prevent, by the appropriate installation of stop and non-return valves, oil or water from the sea or ballast spaces from passing into a cargo hold or machinery space, or from passing from one compartment to another, regardless of the source. The bilge and ballast mains must be fitted with separate control valves at the pumps.

(i) Ballast piping must not be installed to any hull compartment of a wood vessel. Where the carriage of liquid ballast in such vessels is necessary, suitable ballast tanks, structurally independent of the hull, must be provided.

(j) When dry cargo is to be carried in deep tanks, arrangement must be made for blanking-off the oil and ballast lines. The bilge suctions must be blanked-off when oil or ballast is carried.

(k) Where bilge and ballast piping are led through tanks, except ballast piping in ballast tanks, means must be provided to minimize the risk of flooding of other spaces due to pipe failure. In this regard, such piping may be in a watertight pipe tunnel, or the piping may be of Schedule 80 pipe wall thickness, fitted with expansion bends, with all joints welded. Alternative designs may be approved by the Marine Safety Center. Where a pipe tunnel is installed, the watertight integrity of the bulkheads must be maintained. No valve or fitting may be located within the tunnel if the pipe tunnel is not of sufficient size to afford access.

(l) When bilge pumps are utilized for other services, the piping must be so arranged that under any condition at least one pump will be available for drainage of the vessel through an overboard discharge, while the other pump(s) are being used for a different service.

(m) All bilge pipes used in or under fuel storage tanks or in the boiler or machinery space, including spaces in which oil settling tanks or oil pumping units are located, must be of steel or other acceptable material.

(n) Oil pollution prevention requirements for bilge and ballast systems are contained in 33 CFR part 155, subpart B.

(a) Self-propelled vessels.

(1) Each self-propelled vessel must be provided with a power-driven pump, or pumps connected to the bilge main as required by table 1 to § 56.50-55(a).

(b) Nonself-propelled vessels. (1) Ocean going sailing vessels and barges must be provided with pumps connected to the bilge main as required in table 2 to § 56.50-55(b)(1).

(2) The pumps and source of power for oceangoing sailing vessels and barges must be located above the bulkhead deck or at the highest convenient accessible level.

(3) Each hull of a vessel with more than one hull, such as a catamaran, must meet table 2 to § 56.50-55(b)(1).

(c) Capacity of independent power bilge pump. (1) Each power bilge pump must develop a suction velocity of not less than 400 feet per minute and a corresponding capacity based on the size of bilge main piping required by § 56.50-50(d)(1).

(2) Alternatively, the minimum pump capacity, Q, in m 3/hr may be based on the following formula:

(3) For vessels of less than 65 feet in length not engaged on international voyages, the pump must have a minimum capacity of 25 gallons per minute and need not meet the velocity requirement of this paragraph.

(d) Priming. Suitable means must be provided for priming centrifugal pumps which are not of the self-priming type.

(e) Location. (1) For self-propelled vessels, if the engines and boilers are in two or more watertight compartments, the bilge pumps must be distributed throughout these compartments. On other self-propelled vessels and mobile offshore drilling units, the bilge pumps must be in separate compartments to the extent practicable. When the location of bilge pumps in separate watertight compartments is not practicable, alternative arrangements may be considered by the Marine Safety Center.

(2) For non-self-propelled vessels requiring two bilge pumps, these pumps, insofar as practicable, must be located in separate watertight machinery spaces. When the location of bilge pumps in separate watertight compartments is not possible, the Marine Safety Center will consider alternate arrangements.

(3) The emergency bilge pumps must not be installed in a passenger ship forward of the collision bulkhead.

(4) Each hull of a vessel with more than one hull must have at least two means for pumping the bilges in each hull.

(f) Other pumps. Sanitary, ballast, and general service pumps having the required capacity may be accepted as independent power bilge pumps if connected to the bilge system.

(a)(1) Oil-piping systems for cargo or fuel oil must be separate from other piping systems as far as practicable, and positive means must be provided to prevent interconnection in service.

(2) Fuel oil and cargo oil systems may be combined if the cargo oil systems contain only Grade E oils.

(3) Oil pumps must have no discharge connections to fire mains, boiler feed systems, or condensers.

(b) When oil needs to be heated to lower its viscosity, heating coils must be properly installed in each tank.

(1) Each drain from a heating coil as well as each drain from an oil heater must run to an inspection tank or other suitable oil detector.

(2) No part of the fuel-oil system containing heated oil under pressure exceeding 180 kPa (26 psi) may be placed in a concealed position so that defects and leakage cannot be readily observed. Each machinery space containing a part of the system must be adequately illuminated.

(c) Filling pipes may be led directly from the deck into the tanks or to a manifold in an accessible location permanently marked to indicate the tanks to which they are connected. A shutoff valve must be fitted at each filling end. Oil piping must not be led through accommodation spaces, except that fill piping not normally used at sea may pass through accommodation spaces if it is of steel construction, all welded, and not concealed.

(d) Piping subject to internal head pressure from oil in the tank must be fitted with positive shutoff valves located at the tank.

(1) Valves installed on the outside of the oil tanks must be made of steel, ductile cast iron ASTM F1155 (incorporated by reference; see § 56.01-2), or a ductile nonferrous alloy having a melting point above 1,700 °F and must be arranged with a means of manual control locally at the valve and remotely from a readily accessible and safe location outside of the compartment in which the valves are located.

(i) In the special case of a deep tank in any shaft tunnel, piping tunnel, or similar space, one or more valves must be fitted on the tank. In the event of fire, the flow of oil from the tank may be stopped by means of an additional valve on the piping outside the tunnel or similar space. Any such additional valve installed inside a machinery space must be capable of being operated from outside this space.

(ii) [Reserved]

(2) If valves are installed on the inside of the tank, they may be made of cast iron and arranged for remote control only. Additional valves for local control must be located in the space where the system exits from the tank or adjacent tanks. Valves for local control outside the tanks must meet paragraph (d)(1) of this section.

(3) Power operated valves installed to comply with the requirements of this section must meet the following requirements:

(i) Valve actuators must be capable of closing the valves under all conditions, except during physical interruption of the power system (for example, from cable breakage or tube rupture). Fluid power actuated valves, other than those opened against spring pressure, must be provided with an energy storage system which is protected, as far as practicable, from fire and mechanical damage. The energy storage system must be used for no other purpose and must have sufficient capacity to cycle all connected valves from the initial valve position to the opposite position and return. The cross connection of this system to an alternate power supply will be given special consideration by the Marine Safety Center.

(ii) The valve must have a local power actuator to both open and close the valve, unless local manual opening operation will not prevent remote closing of the valve.

(iii) The positioning of the valve by either the local or remote power actuators must not void the ability of the other actuator to close the valve.

(iv) The valve must be provided with a means of emergency manual operation to both open and close the valve regardless of the status of the power operating system. Such manual operation may interfere with the power operation, and if so, must be protected by means of covers, locking devices, or other suitable means. Instructions and warnings regarding the emergency system must be conspicuously posted at the valve.

(4) Remote operation for shutoff valves on small independent oil tanks will be specially considered in each case where the size of tanks and their location may warrant the omission of remote operation.

(e) Fuel oil tanks overhanging boilers are prohibited.

(f) Valves for drawing fuel or draining water from fuel are not permitted in fuel oil systems except that a single valve may be permitted in the case of diesel driven machinery if suitably located within the machinery space away from any potential source of ignition. Such a valve must be fitted with a cap or a plug to prevent leakage.

(g) Test cocks must not be fitted to fuel oil or cargo oil tanks.

(h) Oil piping must not run through feed or potable water tanks. Feed or potable water piping must not pass through oil tanks.

(i) Where flooding equalizing cross-connections between fuel or cargo tanks are required for stability considerations, the arrangement must be approved by the Marine Safety Center.

(j) Piping conveying oil must be run away from hot surfaces wherever possible. Where such leads are unavoidable, only welded joints are to be used, or alternatively, suitable shields are to be fitted in the way of flanged or mechanical pipe joints when welded joints are not practicable. Piping that conveys fuel oil or lubricating oil to equipment and is in the proximity of equipment or lines having an open flame or having parts operating above 500 °F must be of seamless steel. (See § 56.50-65.)

(k) Oil piping drains, strainers, and other equipment subject to normal oil leakage must be fitted with drip pans or other means to prevent oil draining into the bilge.

(l) Where oil piping passes through a non-oil tank without stop valves complying with paragraph (d) of this section installed at all tank penetrations, the piping must comply with § 56.50-50(k).

(m) Each arrangement for the storage, distribution, and use of oil in a pressure-lubrication system must—

(1) Comply with § 56.50-80; and

(2) In a machinery space, meet the applicable requirements of paragraphs (b)(2) and (d) of this section and §§ 56.50-85(a)(11), 56.50-90(c) and (d), and 58.01-55(f) of this subchapter. No arrangement need comply with § 56.50-90 (c)(1) and (3) if the sounding pipe is fitted with an effective means of closure, such as a threaded cap or plug or other means acceptable to the Officer in Charge, Marine Inspection.

(n) Each arrangement for the storage, distribution, and use of any flammable oil employed in a fluid power, control, or heating system must—

(1) Comply with subpart 58.30 of this subchapter; and

(2) Where means of ignition are present, meet the applicable requirements of §§ 56.50-85(a)(11), 56.50-90 (c) and (d), and 58.01-55(f) of this subchapter. Each pipe and its valves and fittings must be of steel or other approved material, except that the use of flexible piping or hose is permitted in accordance with §§ 56.35-10, 56.35-15, and 56.60-25(c).

(a) All discharge piping from the fuel oil service pumps to burners must be seamless steel with a thickness of at least Schedule 80. Short lengths of steel, or annealed copper nickel, nickel copper, or copper pipe and tubing may be used between the fuel oil burner front header manifold and the atomizer head to provide flexibility. All material used must meet the requirements of subpart 56.60. The use of non-metallic materials is prohibited. Flexible metallic tubing may be used when approved by the Marine Safety Center. Tubing fittings must be of the flared type except that flareless fittings of the nonbite type may be used when the tubing is steel, nickel copper or copper nickel.

(b)(1) All vessels having oil fired boilers must have at least two fuel service pumps, each of sufficient capacity to supply all the boilers at full power, and arranged so that one may be overhauled while the other is in service. If installed, fuel oil heaters must be so arranged that any heater may be overhauled while the other is in service. Suction and discharge strainers must be capable of being cleaned without interrupting the oil supply.

(2) All auxiliary boilers, except those furnishing steam for vital equipment and fire extinguishing purposes, may be equipped with a single fuel oil service pump. Such pumps need not be fitted with discharge strainers.

(3) Strainers must be located so as to preclude the possibility of spraying oil on the burner or boiler casing, or be provided with spray shields. Coamings, drip pans, etc., must be fitted under fuel oil service pumps, heaters, etc., where necessary to prevent oil drainage to the bilge.

(4) Boilers burning fuel oils of low viscosity need not be equipped with fuel oil heaters.

(c) Piping between service pumps and burners must be located so as to be readily observable, and all bolted flange joints must be provided with a spray shield to deflect spray in case of a leak. Fuel pump or heater relief valves must discharge back to the settling tank or the suction side of the pump. The return line from the burners must be so arranged that the suction piping cannot be subjected to discharge pressure.

(d) If threaded-bonnet valves are employed, they must be of the union-bonnet type capable of being packed under pressure.

(e) Unions must not be used for pipe diameters of 1 inch and above.

(f) Boiler header valves of the quick closing type must be installed in the fuel supply lines as close to the boiler front header as practicable. The location is to be accessible to the operator or remotely controlled.

(g) Bushings and street ells are not permitted in fuel oil discharge piping.

(h) Each fuel-oil service pump must be equipped with controls as required by § 58.01-25 of this subchapter.

(a) Material. (1) Fuel supply piping to the engines must be of seamless drawn annealed copper pipe or tubing, nickel copper, or copper nickel pipe or tubing meeting the requirements of subpart 56.60.

(2) Thicknesses of tubing walls must not be less than the larger of that shown in table 1 to § 56.50-70(a) or that required by § 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see § 56.01-2).

(3) Tubing fittings must be of nonferrous drawn or forged metal and of the flared type except that the flareless fittings of the nonbite type may be used when the tubing system is of nickel copper or copper nickel. Tubing must be cut square and flared by suitable tools. Tube ends must be annealed before flaring. Pipe fittings must be of nonferrous material. Pipe thread joints must be made tight with a suitable compound.

(4) Valves for fuel lines must be of nonferrous material of the union bonnet type with ground seats except that cocks may be used if they are the solid bottom type with tapered plugs and union bonnets.

(b) Installation. (1) All fuel pipes, pipe connections, and accessories must be readily accessible, protected against mechanical injury, and effectively secured against excessive movement and vibration by the use of soft nonferrous metal liners or straps. Where passing through steel decks or bulkheads, fuel lines must be protected by close fitting ferrules or stuffing boxes. Refer to § 56.30-25 for tubing joint installations.

(2) A short length of suitable metallic or nonmetallic flexible tubing or hose, or a loop of annealed copper tubing, must be installed in the fuel-supply line at or near the engine to prevent damage by vibration.

(i) If nonmetallic flexible hose is used, it must meet the requirements of § 56.60-25(b) for fuel service.

(ii) Flexible hose connections should maintain metallic contact (continuity) between the sections of the fuel-supply lines; however, if they do not, the fuel tank must be grounded.

(c) Shutoff valves. Shutoff valves of a suitable type must be installed in the fuel supply lines, one as close to the tank as practicable. Where fuel tanks are installed below the weather deck, arrangements must be provided for operating all shutoff valves at the tanks from outside the compartments in which they are located. The operating gear for the shutoff valves at the tanks must be accessible and suitably marked.

(d) Strainers. A suitable twin strainer must be fitted in the fuel supply line in the engine compartment. A drip pan must be fitted under the strainer.

(e) Outlets and drains. Outlets in fuel lines for drawing gasoline for any purpose are prohibited. However, fuel tank openings fitted with a threaded plug or cap can be used for cleaning purposes.

(f) Fuel suction connections. All fuel suction and return lines must enter the top of the fuel tanks and connections must be fitted into spuds. Such lines must extend nearly to the bottom of the tank.

(g) Filling and sounding pipes. Filling and sounding pipes must be so arranged that vapors or overflow when filling cannot escape to the inside of the vessel and will discharge overboard. Such pipes must terminate on the weather deck clear of any coamings and must be fitted with suitable shutoff valves. A corrosion-resistant flame screen of must be fitted in the throat of the filling pipe. Sounding pipes must be kept closed at all times except during sounding.

(h) Vent pipes. Each tank must be fitted with a vent, the cross-sectional area of which must not be less than that of the filling pipe. The vent pipes must terminate at least 2 feet above the weather deck and not less than 3 feet from any opening into living quarters or other below-deck space. The ends of vent pipes must terminate with U-bends and be fitted with flame screens or flame arresters. The flame screens must consist of a single screen of corrosion resistant wire of at least 30 by 30 mesh.

(i) Gasoline tanks. For requirements pertaining to independent gasoline fuel tanks see subpart 58.50 of this subchapter.

(j) Fuel pump shutdown. Each fuel pump must comply with § 58.01-25 of this subchapter.

(a) Vessels greater than 100 gross tons. (1) The diesel fuel system must comply with §§ 56.50-60, 56.50-85, and 56.50-90. The fuel supply piping to engines must be of seamless steel, annealed seamless copper or brass pipe or tubing, or of nickel copper or copper nickel alloy meeting the requirements of subpart 56.60 for materials and § 56.50-70(a)(2) for thickness. Fuel oil service pumps must comply with § 58.01-25 of this subchapter.

(2) The installation must comply with § 56.50-70(b).

(3) Tubing connections and fittings must be drawn or forged metal of the flared type except that flareless fittings of the nonbite type may be used when the tubing system is steel, nickel-copper, or copper-nickel. When making flared tube connections the tubing must be cut square and flared by suitable tools. Tube ends must be annealed before flaring.

(b) Vessels of 100 gross tons and less and tank barges—(1) Materials. Fuel supply piping must be of copper, nickel copper, copper nickel, seamless steel, or other materials having a minimum wall thickness of 0.035 inch.

(2) Tubing connections and fittings. Tubing connections must comply with the provisions of paragraph (a)(3) of this section.

(3) Installation. The installation of diesel fuel piping must comply with the requirements of § 56.50-70(b).

(4) Shutoff valves. Shutoff valves must be installed in the fuel supply lines, one as close to each tank as practicable, and one as close to each fuel pump as practicable. Valves must be accessible at all times.

(5) Outlets and drains. Valves for removing water or impurities from fuel oil systems will be permitted in the machinery space provided such valves are fitted with caps or plugs to prevent leakage.

(6) Filling pipe. Tank filling pipes must terminate on an open deck and must be fitted with suitable shutoff valves, deck plugs, or caps.

(7) Vent pipes. Each tank must be fitted with a vent pipe complying with § 56.50-85.

(8) Independent diesel fuel tanks. See subpart 58.50 of this subchapter for specific requirements.

(a) The lubricating oil system must be designed to function satisfactorily when the vessel has a permanent 15° list and a permanent 5° trim. See § 58.01-40 of this subchapter for operational requirements for propulsion and vital machinery at vessel angles of inclination.

(b) When pressure or gravity-forced lubrication is employed for the main propelling machinery, an independent auxiliary lubricating pump must be provided.

(c) Oil coolers must be provided with two separate means of circulating water through the coolers.

(d) For internal combustion engine installations, the requirements of paragraphs (b) and (c) of this section do not apply to vessels in river and harbor service, nor to any vessel below 300 gross tons. For internal combustion engines, two separate means are to be provided for circulating coolant. One of those means must be independently driven and may consist of a connection from a pump of adequate size normally used for other purposes utilizing the required coolant. Oil filters must be provided on all internal combustion engine installations. On main propulsion engines fitted with full-flow type filters, the arrangement must be such that the filters may be cleaned without interrupting the oil supply except that such an arrangement is not required on vessels having more than one main propulsion engine.

(e) The lubricating oil piping must be independent of other piping systems and must be provided with necessary coolers, heaters, filters, etc., for proper operation. Oil heaters must be fitted with bypasses.

(f) Diesel engine lubrication systems must be so arranged that vapors from the sump tank may not be discharged back into the engine crank case of engines of the dry sump type.

(g) Steam turbine driven propulsion and auxiliary generating machinery depending on forced lubrication must be arranged to shut down automatically upon failure of the lubricating system.

(h) Sight-flow glasses may be used in lubricating-oil systems provided they can withstand exposure to a flame at a temperature of 927 °C (1,700 °F) for one hour, without appreciable leakage.

(i) Steam driven propulsion machinery must be provided with an emergency supply of lubricating oil that must operate automatically upon failure of the lubricating oil system. The emergency oil supply must be adequate to provide lubrication until the equipment comes to rest during automatic shutdown.

(a) This section applies to vents for all independent, fixed, non-pressure tanks or containers or for spaces in which liquids, such as fuel, ship's stores, cargo, or ballast, are carried.

(1) The structural arrangement in double bottom and other tanks must be such as to permit the free passage of air and gases from all parts of the tanks to vent pipes.

(2) Tanks having a comparatively small surface, such as fuel oil settling tanks, need be fitted with only one vent pipe, but tanks having a comparatively large surface must be fitted with at least two vent pipes. The vents must be located so as to provide venting of the tanks under any service condition.

(3) Vent pipes for fuel oil tanks must, wherever possible, have a slope of no less than 30°.

(4) Tank vents must extend above the weather deck, except vents from freshwater tanks, bilge oily-water holding tanks, bilge slop tanks, and tanks containing Grade E combustible liquids, such as lubricating oil, may terminate in the machinery space, provided—

(i) The vents are arranged to prevent overflow on machinery, electrical equipment, and hot surfaces;

(ii) Tanks containing combustible liquids are not heated; and

(iii) The vents terminate above the deep load waterline if the tanks have boundaries in common with the hull.

(5) Vents from oil tanks must terminate not less than three feet from any opening into living quarters.

(6) Vents extending above the freeboard deck or superstructure deck from fuel oil and other tanks must be at least Schedule 40 in wall thickness. Except for barges in inland service and for Great Lakes vessels, the height from the deck to any point where water may gain access through the vent to below deck must be at least 30 inches (760mm) on the freeboard deck and 17 1/2 inches (450mm) on the superstructure deck. On Great Lakes vessels, the height from the deck to any point where water may gain access through the vent to below deck must be at least 30 inches (760mm) on the freeboard deck, 24 inches (610mm) on the raised quarterdeck, and 12 inches (305mm) on other superstructure decks. Where the height of vents may interfere with the working of the vessel, a lower height may be approved by the Marine Safety Center provided the vent cap is properly protected from mechanical damage. For barges in inland service, the vents must extend at least 6 inches above the deck.

(7) Satisfactory means, permanently attached, must be provided for closing the openings of all vents, except that barges in inland service may be exempted. Acceptable means of closure are:

(i) A ball check valve where the ball float, normally in the open position, will float up and close under the action of a submerging wave. The valve must be designed so that the effective clear discharge area through the valve with the float in the open position is not less than the inlet area of the vent pipe to which the valve is connected; or

(ii) Another suitable device acceptable to the Commanding Officer, Marine Safety Center.

(8) Vent outlets from all tanks which may emit flammable or combustible vapors, such as bilge slop tanks and contaminated drain tanks, must be fitted with a single screen of corrosion-resistant wire of at least 30 by 30 mesh, or two screens of at least 20 by 20 mesh spaced not less than one-half inch (13mm) nor more than 1 1/2 inches (38mm) apart. The clear area through the mesh must not be less than the internal unobstructed area of the required pipe.

(9) Where vents are provided with flame screens, the closure device must be situated so as not to damage these screens.

(10) The diameter of each vent pipe must not be less than 1 1/2 inches nominal pipe size for freshwater tanks, 2 inches nominal pipe size for water ballast tanks, and 2 1/2 inches nominal pipe size for fuel oil tanks.

(11) (i) If a tank may be filled by a pressure head exceeding that for which the tank is designed, the aggregate cross-sectional area of the vents in each tank must be not less than the cross-sectional area of the filling line unless the tank is protected by overflows, in which case the aggregate cross-sectional area of the overflows must be not less than the cross-sectional area of the filling line.

(ii) Provision must be made to guard against liquids rising in the venting system to a height that would exceed the design head of a cargo tank or fuel-oil tank. It may be made by high-level alarms, overflow-control systems, or other, equivalent means.

(12) Vents from freshwater or water ballast tanks must not be connected to a common header with vents from oil or oily ballast tanks.

(b) Unless permitted by the Marine Safety Center, tank vents must remain within the watertight subdivision boundaries in which the tanks they vent are located. All tank vents that penetrate watertight subdivision bulkheads must terminate above the weather deck.

(a) Each tank must be provided with a suitable means of determining liquid level. Except for a main cargo tank on a tank vessel, each integral hull tank and compartment must be fitted with a sounding pipe or other level indicating device acceptable to the Marine Safety Center.

(b) Where sounding pipes terminate below the freeboard deck on cargo vessels, they must be fitted with gate valves. On passenger vessels, where sounding pipes terminate below the bulkhead deck, they must be fitted with gate valves.

(c) Except as allowed by this paragraph, on each vessel constructed on or after June 9, 1995, no sounding pipe used in a fuel-oil tank may terminate in any space where the risk of ignition of spillage from the pipe might arise. None may terminate in a space for passengers or crew. When the Commanding Officer, Marine Safety Center, determines it impracticable to avoid terminating a pipe in a machinery space, a sounding pipe may terminate in a machinery space if all the following requirements are met:

(1) The fuel-oil tank has an oil-level gauge complying with paragraph (d) of this section.

(2) Precautions are taken such as fitting an effective screen (shield) to prevent the fuel oil, in case of spillage through the end of the pipe, from coming into contact with a source of ignition.

(3) The end of the pipe is fitted with a self-closing blanking device.

(d) Other oil-level gauges may be used instead of sounding pipes if all the following requirements are met:

(1) In a passenger vessel, no such gauge may require penetration below the top of the tank, and neither the failure of a gauge nor an overfilling of the tank may permit release of fuel into the space.

(2) In a cargo vessel, neither the failure of such a gauge nor an overfilling of the tank may permit release of fuel into the space. The use of cylindrical gauge-glasses is prohibited. The use of oil-level gauges with flat glasses and self-closing valves between the gauges and fuel tanks is acceptable.

(e) The upper ends of sounding pipes must be closed by a screw cap or plug.

(f) On mobile offshore drilling units where installation of sounding pipes may not be practicable for some tanks, alternate means of determining liquid level may be used if approved by the Commandant.

(a)(1) All inlets and discharges led through the vessel's side must be fitted with efficient and accessible valves, located as close to the hull penetrations as is practicable.

(2) The number of scuppers, sanitary discharges, tank overflows, and other similar openings in the vessel's side must be reduced to a minimum, either by making each discharge serve for as many as possible of the sanitary and other pipes, or in any other satisfactory manner.

(3) In general, when the bulkhead deck is above the freeboard deck, the requirements of this section apply relative to the bulkhead deck. For vessels not assigned load lines, such as certain inland vessels and barges, the weather deck must be taken as the freeboard deck.

(b)(1) Scuppers and discharge pipes originating at any level and penetrating the shell either more than 17.5 inches (450mm) below the freeboard deck or less than 23.5 inches (600mm) above the summer load waterline must be provided with an automatic nonreturn valve at the shell. This valve, unless required by paragraph (b)(2) of this section, may be omitted if the piping is not less than Schedule 80 in wall thickness for nominal pipe sizes through 8 inches, Schedule 60 for nominal pipe sizes above 8 inches and below 16 inches, and Schedule 40 for nominal pipe sizes 16 inches and above.

(2) Discharges led through the shell originating either from spaces below the freeboard deck, or from within enclosed superstructures and equivalent deckhouses on the freeboard deck as defined in § 42.13-15(i) of subchapter E of this chapter, must be fitted with efficient and accessible valves for preventing water from passing inboard. Normally each separate discharge must have one automatic nonreturn valve with a positive means of closing it from a position above the freeboard deck. Where, however, the vertical upward distance from the summer load line to the inboard end of the discharge pipe through which flooding can take place exceeds 0.01L, the discharge may have two automatic nonreturn valves without positive means of closing, provided that the inboard valve is always accessible for examination under service conditions. Where that vertical distance exceeds 0.02L a single automatic nonreturn valve without positive means of closing is acceptable. In an installation where the two automatic nonreturn valves are used, the inboard valve must be above the tropical load line. The means for operating the positive action valve must be readily accessible and provided with an indicator showing whether the valve is open or closed. A notice must be posted at the operating station stating that the valve must not be closed except as required in an emergency.

(3) Where scuppers and drains are installed in superstructures or deckhouses not enclosed as defined in § 42.13-15(j) of subchapter E of this chapter, they must be led overboard. Refer to paragraph (b)(1) of this section for any nonreturn valve requirement.

(c) Overflow pipes which discharge through the vessel's side must be located as far above the deepest load line as practicable and fitted with valves as required by paragraph (b) of this section. Two automatic nonreturn valves must be used unless it is impracticable to locate the inboard valve in an accessible position, in which case a nonreturn valve with a positive means of closure from a position above the freeboard deck will be acceptable. Overflows which extend at least 30 inches above the freeboard deck before discharging overboard may be fitted with a single automatic nonreturn valve at the vessel's side. Overflow pipes which serve as tank vents must not be fitted with positive means of closure without the specific approval of the Marine Safety Center. Overflow pipes may be vented to the weather.

(d)(1) Sea inlets and discharges, such as used in closed systems required for the operation of main and auxiliary machinery, as in pump connections or scoop injection heat exchanger connections, need not meet the requirements of paragraphs (b)(1) and (2) of this section but instead must be fitted with a shutoff valve located as near the shell plating as practicable, and may be locally controlled if the valve is located in a manned machinery space. These controls must be readily accessible above the floor plates. Manned machinery spaces include the main machinery space and are either attended by the crew or are automated in accordance with part 62 of this subchapter to be comparable to an attended space.

(2) In unmanned machinery spaces, all machinery inlets and discharges as described in paragraph (d)(1) of this section must be remotely operable from a position above the freeboard deck unless otherwise approved and must meet the access and marking requirements of paragraph (b)(2) of this section.

(e)(1) Pipes terminating at the shell plating must be fitted with bends or elbows between the outboard openings and the first rigid connection inboard. In no case must such pipes be fitted in a direct line between the shell opening and the first inboard connection.

(2) Seachests and other hull fittings must be as short as possible and located so as to minimize the possibility of being blocked or obstructed.

(3) The thickness of inlet and discharge connections outboard of the shutoff valves, and exclusive of seachests, must be not less than that of Schedule 80 for nominal pipe sizes through 8 inches, Schedule 60 for nominal pipe sizes above 8 inches and below 16 inches, and Schedule 40 for nominal pipe sizes 16 inches and above.

(f) Valves required by this section and piping system components outboard of such required valves must be of a steel, bronze, or ductile cast iron specification listed in table 1 to § 56.60-1. Lead or other heat sensitive materials having a melting point of 1,700 °F or less must not be used. Brittle materials such as cast iron must not be used in such service. Where nonmetallic materials are used in a piping system, and shell closures are required by this section, a positive closure metallic valve is required (see also § 56.60-25).

(g) The inboard openings of ash and rubbish-chute discharges must be fitted with efficient covers. If the inboard opening is located below the freeboard deck, the cover shall be watertight, and in addition, an automatic nonreturn valve must be fitted in the chute in any easily accessible position above the deepest load line. Means must be provided for securing both the cover and the valve when the chute is not in use. When ash-ejectors or similar expelling devices located in the boiler room have the inboard openings below the deepest load line, they must be fitted with efficient means for preventing the accidental admission of water. The thickness of pipe for ash ejector discharge must be not less than Schedule 80.

(h) Where deck drains, soil lines, and sanitary drains discharge through the shell in way of cargo tanks on tank vessels, the valves required by this section must be located outside the cargo tanks. These valves must meet the material requirements of paragraph (f) of this section. The piping led through such tanks must be fitted with expansion bends where required, and must be of steel pipe having a wall thickness of not less than Schedule 60, except that the Commandant will consider the use of suitable corrosion-resistant material of lesser thickness. All pipe joints within the tanks must be welded. Soil lines and sanitary drains which pass through cargo tanks must be provided with nonreturn valves with positive means of closing or other suitable means for preventing the entrance of gases into living quarters.

(i) Sea valves must not be held open or closed with locks.

(a) Keel cooler installations must meet the requirements of § 56.50-95(d)(1) and (2), (e)(3), and (f) except that shutoff or isolation valves will not be required for the inlet and discharge connections if:

(1) The installation is forward of the collision bulkhead; or,

(2) The installation is integral with the ship's hull such that the cooler tubes are welded directly to the hull of the vessel with the hull forming part of the tube and satisfies all of the following:

(i) The cooler structure is fabricated from material of the same thickness and quality as the hull plating to which it is attached except that in the case of half round pipe lesser thickness may be used if specifically approved by the Commandant. In any case the structure, with the exception of the hull proper, need not exceed three-eighths inch in thickness.

(ii) The flexible connections and all openings internal to the vessel, such as expansion tank vents and fills, in the installation are above the deepest load line and all piping components are Schedule 80 or thicker below the deepest load line.

(iii) Full penetration welds are employed in the fabrication of the structure and its attachment to the hull.

(iv) The forward end of the structure must be faired to the hull such that the horizontal length of the fairing is no less than four times the height of the structure, or be in a protected location such as inside a bow thruster trunk.

(b) [Reserved]

(a) Piping for instruments, control, and sampling must comply with paragraph 122.3 of ASME B31.1 (incorporated by reference; see § 56.01-2) except that:

(1) Soldered type fittings may not be used.

(2) The outside diameter of takeoff connections may not be less than 0.840 inches for service conditions up to 900 psig or 800 °F, and 1.050 inches for conditions that exceed either of these limits.

(b) [Reserved]

(a) This section applies to fixed piping installed for the distribution of oxygen and acetylene carried in cylinders as vessels stores.

(b) The distribution piping must include a means, located as close to the supply cylinders as possible, of regulating the discharge pressure from the supply cylinders.

(c) Acetylene distribution piping and pipe fittings must be seamless steel. Copper alloys containing less than 65 percent copper may be used in connection with valves, regulators, gages, and other equipment used with acetylene.

(d) Oxygen distribution piping and pipe fittings must be seamless steel or copper.

(e) When more than two cylinders are connected to a manifold, the supply pipe between each cylinder and manifold must be fitted with a non-return valve.

(f) Except for the cylinder manifolds, acetylene is not to be piped at a pressure in excess of 100 kPa (14.7 psig).

(g) Pipe joints on the low-pressure side of the regulators must be welded.

(h) Branch lines must not run through unventilated spaces or accommodation spaces.

(i) Relief valves or rupture discs must be installed as relief devices in the piping system if the maximum design pressure of the piping system can be exceeded. The relief device set pressure must not exceed the maximum design pressure of the piping system. Relief devices must discharge to a location in the weather at least 3 m (10 ft) from sources of ignition or openings to spaces or tanks.

(j) Outlet stations are to be provided with suitable protective devices which will prevent the back flow of gas into the supply lines and prevent the passage of flame into the supply lines.

(k) Shutoff valves must be fitted at each outlet.

(a) Class I-L. Piping systems designated to operate at temperatures below 0 °F and pressures above 150 psig must be of Class I-L. Exceptions to this rule may be found in the individual requirements for specific commodities in subchapters D, I, and O of this chapter. The following requirements for Class I-L piping systems must be satisfied:

(1) Materials. All materials used in low temperature piping systems must be selected from among those specifications listed in table 2 to § 56.50-105 and must satisfy all of the requirements of the specifications, except that:

(i) The minimum service temperature as defined in § 54.25-10(a)(2) of this subchapter must not be colder than that shown in table 2 to § 56.50-105; and

(ii) The material must be tested for low temperature toughness per ASTM E23 (incorporated by reference, see § 56.01-2), Figure 4. The toughness testing requirements of subpart 54.05 of this subchapter must be satisfied for each particular product form. Charpy V-notch tests must be conducted at temperatures not warmer than 10 °F below the minimum service temperature of the design, except that for service temperatures of −320 °F and below, the impact test may be conducted at the service temperature. The minimum average energy must not be less than that shown in table 2 to § 56.50-105. In the case of steels conforming to the specifications of table 1 to § 54.25-20(a) of this subchapter the minimum lateral expansion must not be less than that required in § 54.25-20 of this subchapter. The minimum energy permitted for a single specimen and the minimum subsize energies must be those obtained by multiplying the average energy shown in table 2 to § 56.50-105 by the applicable fraction shown in table 1 to § 56.50-105(a)(1)(ii).

(iii) Steels differing in chemical composition, mechanical properties, or heat treatments from those specified may be specially approved by the Marine Safety Center. Similarly, aluminum alloys and other materials not covered in table 2 to § 56.50-105 may be specifically approved by the Marine Safety Center.

(2) Piping weldments. Piping weldments must be fabricated to satisfy the requirements of § 57.03-1(b) of this subchapter in addition to subpart 56.70. Toughness testing of production weldments for low temperature piping systems and assemblies is not required.

(3) Postweld heat treatment. All piping weldments must be postweld heat treated for stress relief in accordance with the procedures of subpart 56.85.

(4) Nonacceptable joints. Single welded butt joints with backing ring left in place, socket welds, slip-on flanges, pipe joining sleeves, and threaded joints must not be used, except in small diameter instrument lines.

(5) Other requirements. All other requirements of this part for Class I piping apply to Class I-L piping. Pressure testing must comply with subpart 56.97, and nondestructive testing of circumferentially welded joints must comply with § 56.95-10. Seamless tubular products must be used except that, when the service pressure does not exceed 1724 kPa (250 psi), the Marine Safety Center, may give special consideration to appropriate grades of piping and tubing that are welded without the addition of filler metal in the root pass. Each production procedure and quality-control program for welded products must be acceptable to the Officer in Charge, Marine Inspection.

(b) Class II-L. Piping systems designed to operate at temperatures below 0 °F and pressures not higher than 150 psig must be of Class II-L. Exceptions to this rule may be found in the individual requirements for specific commodities in subchapter D and subchapter I, both of this chapter. The following requirements for Class II-L piping systems must be satisfied:

(1) Materials must be the same as those required by paragraph (a)(1) of this section except that pipe and tubing of appropriate grades welded without the addition of a filler metal may be used. The Commandant may give special consideration to tubular products welded with the addition of filler metal.

(2) Piping weldments must be fabricated to satisfy the requirements of § 57.03-1(b) of this subchapter in addition to subpart 56.70. Toughness testing of production weldments for low temperature piping systems and assemblies is not required.

(3) All piping weldments must be postweld heat treated for stress relief in accordance with the procedures of subpart 56.85.

(4) Socket welds in nominal sizes above 3 inches, slip-on flanges in nominal sizes above 4 inches, and threaded joints in sizes above 1 inch must not be used.

(5) Pressure testing must comply with subpart 56.97, and nondestructive testing of welded joints must comply with § 56.95-10.

(6) All other requirements contained in this part for Class II piping are applicable to Class II-L systems, except that § 56.70-15(b)(3)(iv) does not apply.

(a) In addition to the requirements of this part, piping for diving installations which is permanently installed on the vessel must meet the requirements of subpart B of part 197 of this chapter.

(b) Piping for diving installations not permanently installed on the vessel need not meet the requirements of this part, but must meet the requirements of subpart B of part 197 of this chapter.

(c) Piping internal to a pressure vessel for human occupancy (PVHO) need not meet the requirements of this part, but must meet the requirements of subpart B of part 197 of this chapter.