Loading (50 kb)...'
(continued)
Elev. 2 i .56-1(a), (c).........
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Urea, Ammonium nitrate solution Atmos. Amb. III 1 i Integral Gravity...... PV Restr. II G-1 NR Vent F No .56-1(b).............. I-D NA G
(containing more than 2% NH 3). 2 i
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Valeraldehyde (all isomers)........ Atmos. Amb. III 1 i Integral Gravity...... PV Restr. II G-1 Inert Vent F Yes No.................... I-C NA G
2 i i
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vanillan black liquor (free alkali Atmos. Amb. III 1 i Integral Gravity...... Open Open II G-1 NR NR No .50-73................ NA NA G
content 3% or more). 2 i .56-1(a), (c), (g)....
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vinyl acetate...................... Atmos. Amb. III 1 i Integral Gravity...... PV Open II G-1 NR Vent F Yes .50-70(a)............. I-D NA G
2 i i .50-81(a), (b)........
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vinyl chloride..................... Press. Amb. II 1NA Ind. Pressure......... SR Closed II P-2 NR Vent F Yes .50-30................ I-D NA 8
2 i i .50-34................
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vinyl chloride..................... Atmos. Low II 1NA Ind. Gravity.......... PV Closed II-L G-2 NR Vent F Yes .50-30................ I-D .40- 8
2 i i .50-34................ 1(b)(1)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vinylidene chloride................ Atmos. Amb. II 1NA Ind. Gravity.......... PV Closed II P-2 Padded Vent F Yes .55-1(f).............. I-D NA G
2 i i .50-70(a).............
.50-81(a), (b)........
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vinyltoluene....................... Atmos. Amb. III 1 i Integral Gravity...... PV Restr. II G-1 NR Vent F Yes .50-70(a)............. I-D NA G
2 i i .50-81................
.56-1(a), (b), (c),
(g).
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
For requirements see these sections ......... ...... .10-1 .13- 5 .15- 1................ .15-5 .15- 10 .20- 1 .20- 5 .25-1 .25-2 .30 ...................... 111.105 .40 .04- 5
in Part 151:. (Sub-
chapter J)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
See Table 2 of Part 153 for additional cargoes permitted to be carried by tankbarge.
Terms and symbols:
Segregation_Tank_
Line 1_Segregation of cargo from surrounding waters:
i=Skin of vessel (single skin) only required. Cargo tank wall can be vessel's hull.
i i=Double skin required. Cargo tank wall cannot be vessel's hull.
Line 2_Segregation of cargo space from machinery spaces and other spaces which have or could have a source of ignition:
i=Single bulkhead only required. Tank wall can be sole separating medium.
i i=Double bulkhead required. Cofferdam, empty tank, pumproom, tank with Grade E Liquid (if compatible with cargo) is satisfactory.
Internal tank inspection_
G_Indicates cargo is subject to general provisions of 151.04-5(b).
Specific numbers in this column are changes from the general provisions.
Abbreviations used:
Tank type: Ind=Independent.
Vent:
PV=Pressure vacuum valve.
SR=Safety relief.
Gauging device: Restr.=Restricted.
General usage:
NR=No requirement.
NA=Not applicable.
1. The provisions contained in 46 CFR Part 197, subpart C, apply to liquid cargoes containing 0.5% or more benzene by volume.
[USCG 2000–7079, 65 FR 67183, Nov. 8, 2000]
Subpart 151.10—Barge Hull Construction Requirements
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§ 151.10-1 Barge hull classifications.
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(a) Each barge constructed or converted in conformance with this subpart shall be assigned a hull type number.
(1) Effective dates for certain requirements:
(i) Barges constructed or converted between July 1, 1964, and June 1, 1970, in accordance with the construction requirements of §§32.63 and 98.03 of this chapter are considered to comply with the basic provisions of this subpart and will retain the hull type classification for the service for which they were originally approved. Changes in product endorsement will not be considered a change in service, except when a change to a product of higher specific gravity necessitates a reevaluation of the intact and damage stability requirements in subpart E of part 172 of this chapter.
(2) [Reserved]
(b) For this purpose the barge hull types shall be defined as follows:
(1) Type I barge hull. Barge hulls classed as Type I are those designed to carry products which require the maximum preventive measures to preclude the uncontrolled release of the cargo. These barges are required to meet:
(i) Standards of intact stability and a modified two compartment standard of subdivision and damage stability, as specified in subpart E of part 172 of this chapter; and
(ii) Hull structural requirements, including an assumed grounding condition.
(2) Type I-S (special) barge hulls. Type I-S (special) barge hulls are those constructed or converted for the carriage of chlorine in bulk prior to July 1, 1964, and modified to higher stability standards prior to July 1, 1968, but not meeting the requirements for full Type I classification.
(3) Type II barge hull. Barge hulls classed as Type II are those designed to carry products which require significant preventive measures to preclude the uncontrolled release of the cargo. These barges are required to meet:
(i) Standards of intact stability and a modified one compartment standard of subdivision and damage stability, as specified in subpart E of part 172 of this chapter; and
(ii) Hull structural requirements, including an assumed grounding condition.
(4) Type III barge hull. Barge hulls classed as Type III are those designed to carry products of sufficient hazard to require a moderate degree of control. These barges are required to meet:
(i) Standards of intact stability as specified in subpart E of part 172 of this chapter; and
(ii) Hull structural requirements.
[CGFR 70–10, 35 FR 3714, Feb. 25, 1970, as amended by CGD 79–023, 48 FR 51008, Nov. 4, 1983; CGD 88–100, 54 FR 40040, Sept. 29, 1989]
§ 151.10-5 Subdivision and stability.
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Each barge must meet the applicable requirements in subchapter S of this chapter.
[CGD 70–023, 48 FR 51009, Nov. 4, 1983]
§ 151.10-15 Certificate endorsement.
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(a)–(b) [Reserved]
(c) Certificate endorsement. The following information shall be submitted, and upon approval of calculations shall form part of the endorsement on the Certificate of Inspection:
(1) Limiting draft for each hull type service for which approval is requested.
(2) Maximum density (lb./gal.) and maximum cargo weight (tons) for each tank for which approval is requested. Their weights will normally reflect uniform loading except that for trim purposes the individual tank cargo weight may exceed the uniform loading tank cargo weight, corresponding to the barge fresh water deadweight at the limiting draft, by 5 percent. Where a greater degree of nonuniform loading is desired, longitudinal strength calculations shall be submitted.
[CGFR 70–10, 35 FR 3714, Feb. 25, 1970, as amended by CGD 79–023, 48 FR 51009, Nov. 4, 1983]
§ 151.10-20 Hull construction.
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(a) Construction features. (1) Each barge hull shall be constructed with a suitable bow form (length, shape, and height of headlog) to protect against diving at the maximum speed at which the barge is designed to be towed. In any integrated tow, only the lead barge need comply with this requirement.
(2) All “open hopper” type barges shall be provided with coamings around the hopper space and a 36–inch minimum height plowshare breakwater on the forward rake. The plowshare breakwater may be omitted, if it is demonstrated to the satisfaction of the Commandant that sufficient protection is achieved without it. Coamings shall have a minimum height of 36 inches forward and may be graduated to a minimum height of 24 inches at midlength and 18 inches thereafter. All hopper barges constructed with a weathertight rain shield over the hopper space are exempt from these requirements, except that they shall be provided with an 18–inch minimum coaming all around the hopper.
(3) All “open hopper” type barges modified for the carriage of chlorine in bulk shall be provided with 36–inch minimum height coamings around the hopper.
(4) All barges in ocean or coastwise service shall be provided with a structural deck and hatches in accordance with the applicable provisions of subchapter E of this chapter and the scantling requirements of the American Bureau of Shipping.
(b) Hull structural requirements. (1) All Types I, II, and III barges shall comply with the basic structural requirements of the American Bureau of Shipping for barges of the ordinary types and the applicable supplementary requirements of this section.
(2) Types I and II barges in inland service: A grounding condition shall be assumed where the forward rake bulkhead rests upon a pinnacle at the water surface. The maximum hull and tank bending moment and tank saddle reactions (if applicable) shall be determined. The hull bending stress shall not exceed the applicable limits of paragraphs (b)(2) (i), (ii), or (iii) of this section. The maximum tank bending moment and saddle reaction shall be used in the tank design calculations required by §151.15–2(b)(3).
(i) Independent tanks supported by only two saddles do not contribute to the strength and stiffness of the barge hull. In such case, the hull stress shall not exceed either 50 percent of the minimum ultimate tensile strength of the material or 70 percent of the yield strength when specified, whichever is greater.
(ii) Independent tanks supported by three or more saddles contribute to the strength and stiffness of the hull. In such case, the hull stress shall not exceed the percentage stress values prescribed in §151.10–20(b)(2)(i), multiplied by the quantity
(1.5-SWT/UTS),
where SWT is the stress calculated without including the effect of the tanks, and UTS is the minimum ultimate tensile strength of the material. The value SWT, however, shall in no case be more than 75 percent of UTS.
(iii) Integral tanks may be considered as contributing to the strength and stiffness of the barge hull. The hull stresses for integral tank barges shall not exceed the percentage stress values prescribed in paragraph (b)(2)(i), of this section.
(3) Types I and II barges in ocean service:
(i) Independent tank barges with tanks supported by three or more saddles shall be subjected to a 0.6L 0.6 trochoidal wave hogsag analysis to determine the maximum hull and tank bending moments and tank saddle reactions.
(ii) All independent tank barges, regardless of the number of saddle supports shall be subject to a still water bending analysis to determine the hull bending moment. For those barges with independent tanks supported by three or more saddles, this analysis shall consider tank-hull interaction so as to determine tank bending moments and saddle reactions.
(iii) The still water tank bending moments and saddle reactions shall be superimposed upon those obtained by simultaneous application of the following dynamic loadings:
(a) Rolling 30° each side (120° full cycle) in 10 seconds.
(b) Pitching 6° half amplitude (24° full cycle) in 7 seconds.
(c) Heaving L/80 half amplitude (L/20 full cycle) in 8 seconds.
(iv) The hull structure and saddle support system shall be analyzed, using the maximum hull bending moments and saddle reactions obtained from the foregoing. Bending stress shall not exceed 60 percent of the yield strength or 42 percent of the minimum tensile strength of the material, whichever is less. Critical buckling strength shall be at least 75 percent greater than calculated buckling stresses. The maximum tank bending moments and saddle reactions shall be used in the tank design calculations required by §151.15–3(b)(8).
Subpart 151.12—Equipment and Operating Requirements for Control of Pollution From Category D NLS Cargoes
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Source: CGD 81–101, 52 FR 7777, Mar. 12, 1987, unless otherwise noted.
§ 151.12-5 Equipment for Category D NLS.
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The Coast Guard endorses the Certificate of Inspection and for ships making foreign voyages issues the endorsed NLS Certificate required by §151.12–10 for an oceangoing non-self-propelled ship to carry as bulk cargo the following Category D NLSs if the ship meets the requirements of this part and the requirements applying to ships that carry Category D NLS cargoes in §§153.470, 153.486, and 153.490 of this chapter:
Acetic acid
Acrylic acid
Adiponitrile
Aminoethylethanolamine
Ammonium bisulfite solution
Butyl methacrylate
Caustic soda solution
Coal tar pitch
Cyclohexanone
Cyclohexanone, Cychexanol mixture
Dichloromethane
2,2-Dichloropropionic acid
Diethylenetriamine
N,N-Dimethylacetamide
Dimethylethanolamine
Dimethylformamide
1,4-Dioxane
Ethanolamine
N-Ethylcyclohexylamine
Ethylene cyanohydrin
Ethylene glycol monoalkyl ethers
Ethyl methacrylate
Formic acid
Glutaraldehyde solution
Glyoxylic acid solution (50% or less)
Hydrochloric acid
Mesityl oxide
Methyl methacrylate
Morpholine
1- or 2-Nitropropane
Phosphoric acid
Polyethylene polyamines
Polymethylene polyphenyl isocyanate
Propionic acid
iso-Propyl ether
Pyridine
Tetraethylenepentamine
Tetrahydrofuran
Triethanolamine
Triethylenetetramine
[CGD 81–101, 52 FR 7777, Mar. 12, 1989, as amended by CGD 88–100, 54 FR 40040, Sept. 29, 1989; CGD 92–100, 59 FR 17028, Apr. 11, 1994; CGD 94–900, 59 FR 45139, Aug. 31, 1994; CGD 94–902, 60 FR 34043, June 29, 1995; USCG 2000 –7079, 65 FR 67196, Nov. 8, 2000]
§ 151.12-10 Operation of oceangoing non-self-propelled ships Carrying Category D NLS.
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(a) An oceangoing non-self-propelled ship may not carry in a cargo tank a Category D NLS cargo listed under §151.12–5 unless the ship has on board a Certificate of Inspection and for ships making foreign voyages an NLS Certificate endorsed under that section to allow the cargo tank to carry the NLS cargo.
(b) The person in charge of an oceangoing non-self-propelled ship that carries a Category D NLS listed under §151.12–5 shall ensure that the ship is operated as prescribed for the operation of oceangoing ships carrying Category D NLSs in §§153.901, 153.909, 153.1100, 153.1102, 153.1104, 153.1106, 153.1124, 153.1126, 153.1128, 153.1130 and 153.1132 of this chapter.
[CGD 81–101, 52 FR 7777, Mar. 12, 1987, as amended by CGD 81–101, 53 FR 28974, Aug. 1, 1988 and 54 FR 12629, Mar. 28, 1989]
Subpart 151.13—Cargo Segregation
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§ 151.13-1 General.
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This subpart prescribes the requirements for cargo segregation for cargo tanks. These requirements are based on considerations of cargo reactivity, stability, and contamination of the surroundings and other cargoes.
[CGD 88–100. 54 FR 40029, Sept. 29, 1989, as amended by CGD 96–041, 61 FR 50731, Sept. 27, 1996]
§ 151.13-5 Cargo segregation—tanks.
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(a) The configurations listed in this paragraph refer to the separation of the cargo from its surroundings and list the various degrees of segregation required. Paragraphs and (2) of this section explain the symbols used in lines 1 and 2, in order, under the tank segregation column of Table 151.05.
(1) Segregation of cargo from surrounding waters (Line 1 of Table 151.05).
i=Skin of vessel (single skin) only required. Cargo tank wall can be vessel's hull.
ii=Double skin required. Cargo tank wall cannot be vessel's hull.
NA=Nonapplicable for this case. Independent tanks already have such segregation built in through design.
(2) Segregation of cargo space from machinery spaces and other spaces which have or could have a source of ignition (Line 2 of Table 151.05).
i=Single bulkhead only required. Tank wall can be sole separating medium.
ii=Double bulkhead, required. Cofferdam, empty tank, pumproom, tank with Grade E Liquid (if compatible with cargo) is satisfactory.
(b) [Reserved]
(c) If a cofferdam is required for segregation purposes and a secondary barrier is required for low temperature protection by §151.15–3(d)(4), the void space between the primary and secondary barriers shall not be acceptable in lieu of the required cofferdam.
[CGFR 70–10, 35 FR 3714, Feb. 25, 1970, as amended by CGD 75–59, 45 FR 70273, Oct. 23, 19805; CGD 96–041, 61 FR 50731, Sept. 27, 1996]
Subpart 151.15—Tanks
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§ 151.15-1 Tank types.
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This section lists the definitions of the various tank types required for cargo containment by Table 151.05.
(a) Integral. A cargo containment envelope which forms a part of the vessel's hull in which it is built, and may be stressed in the same manner and by the same loads which stress the contiguous hull structure. An integral tank is essential to the structural completeness of its vessel's hull.
(b) Independent. A cargo containment envelope which is not a contiguous part of the hull structure. An independent tank is built and installed so as to eliminate, wherever possible (or, in any event, to minimize) its stressing as a result of stressing or motion of the adjacent hull structure. In general, therefore, motion of parts of the tank relative to the adjacent hull structure is possible. An independent tank is not essential to the structural completeness of its carrying vessel's hull.
(c) Gravity. Tanks having a design pressure (as described in Part 54 of this chapter) not greater than 10 pounds per square inch gauge and of prismatic shape or other geometry where stress analysis is neither readily nor completely determinate. (Integral tanks are of the gravity type.)
(d) Pressure. Independent tanks whose design pressure (as described in Part 54 of this chapter) is above 10 pounds per square inch gauge and fabricated in accordance with part 54, of this chapter. Independent gravity tanks which are of normal pressure vessel configuration (i.e., bodies of revolution, in which the stresses are readily determinate) shall be classed as pressure vessel type tanks even though their maximum allowable working pressure is less than 10 pounds per square inch gauge. Pressure vessel tanks shall be of Classes I, I-L, II, II-L, or III, as defined in subchapter F of this chapter.
§ 151.15-3 Construction.
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This section lists the requirements for construction of the types of cargo tanks defined in §151.15–1.
(a) Gravity type tanks. Gravity type cargo tanks vented at a pressure of 4 pounds per square inch gauge or less shall be constructed and tested as required by standards established by the American Bureau of Shipping or other recognized classification society. Gravity type tanks vented at a pressure exceeding 4 but not exceeding 10 pounds per square inch gauge will be given special consideration by the Commandant.
(b) Pressure vessel type tanks. Pressure vessel type tanks shall be designed and tested in accordance with the requirements of Part 54 of this chapter.
(1) Uninsulated cargo tanks, where the cargo is transported, at or near ambient temperatures, shall be designed for a pressure not less than the vapor pressure of the cargo at 115 °F. The design shall also be based on the minimum internal pressure (maximum vacuum), plus the maximum external static head to which the tank may be subjected.
(2) When cargo tanks, in which the cargo is transported at or near ambient temperature, are insulated with an insulation material of a thickness to provide a thermal conductance of not more than 0.075 B.t.u. per square foot per degree Fahrenheit differential in temperature per hour, the tanks shall be designed for a pressure of not less than the vapor pressure of the cargo at 105 °F. The insulation shall also meet the requirements of paragraph (f) of this section.
(3) Cargo tanks in which the temperature is maintained below the normal atmospheric temperature by refrigeration or other acceptable means shall be designed for a pressure of not less than 110 percent of the vapor pressure corresponding to the temperature of the liquid at which the system is maintained, or the pressure corresponding to the greatest dynamic and static loads expected to be encountered in service. For mechanically stressed relieved cargo tanks, additional factors relating design pressure and maximum allowable pressure shall be as specified by the Commandant. The material of the tank shall meet the material requirements specified in part 54 of this chapter for the service temperature, and this temperature shall be permanently marked on the tank as prescribed in §54.10–20 of this chapter.
(4) The maximum allowable temperature of the cargo is defined as the boiling temperature of the liquid at a pressure equal to the setting of the relief valve.
(5) The service temperature is the minimum temperature of a product at which it may be contained, loaded and/or transported. However, the service temperature shall in no case be taken higher than given by the following formula.
tz=tw-0.25(tw-tB)
where:
tz=Service temperature.
tw=Boiling temperature of gas at normal working pressure of container but not higher than +32 °F.
tB=Boiling temperature of gas at atmospheric pressure.
Under normal circumstances, only temperatures due to refrigerated service will be considered in determining the service temperature. Refrigerated service for purposes of this paragraph is defined as service where the temperature is controlled in the process rather than being caused by atmospheric conditions.
(6) Heat transmission studies, where required, shall assume the minimum ambient temperatures of 0 °F still air and 32 °F still water, and maximum ambient temperatures of 115 °F still air and 90 °F still water.
(7) Where applicable, the design of the cargo tanks shall investigate the thermal stresses induced in the tanks at the service temperature.
(8) Calculations showing the stress level in the tanks under dynamic loading conditions for ocean service barges (see §151.10–20(b)(4)) and grounding conditions for inland service barges (see §151.10–20–(b)(2)) shall be submitted to the Commandant for approval. These calculations shall take into account the local stresses due to the interaction between the barge hull and the tanks.
(c) High density cargo. Cargoes with a specific gravity greater than that for which the scantlings of the tank are designed may be carried provided that:
(1) The maximum cargo weight (tons) in a specific tank does not exceed the maximum cargo weight (tons) endorsed on the certificate of inspection.
(2) The scantlings of the tank are sufficient to prevent rupture under a full head of the higher density cargo. Scantlings meeting ordinary bulkhead requirements for the full head will satisfy this requirement.
(d) Arrangements—(1) Collision protection. (i) Tanks containing cargoes which are required to be carried in Type I hulls by Table 151.05 shall be located a minimum of 4 feet inboard from the side shell and box end of the vessel. Tanks containing cargoes which are required to be carried in Type II hulls by Table 151.05 shall be located a minimum of 3 feet inboard from the side shell and box end of the vessel.
(ii) All independent cargo tanks installed on Type I or Type II barge hulls shall be protected with suitable collision chocks or collision straps. A longitudinal collision load of one and one half times the combined weight of the tank and the cargo shall be assumed. All other independent cargo tanks shall be provided with suitable collision chocks or collision straps assuming a longitudinal collision load equal to the combined weight of the tank and the cargo. The design bearing stress shall not exceed 2 times the yield strength or 1.5 times the minimum ultimate strength, whichever is less.
(iii) Tanks containing cargoes, which are required to be carried in Type I or Type II hulls by Table 151.05, shall be located a minimum of 25 feet from the head log at the bow. Box barges and trail barges need not comply with this requirement.
(2) Inspection clearances. The distance between tanks or between a tank and the vessel's structure shall be such as to provide adequate access for inspection and maintenance of all tank surfaces and hull structure; but shall not normally be less than 15 inches except in way of web frames or similar major structural members where the minimum clearance shall be equal to the flange or faceplate width.
(3) Access openings. Each tank shall be provided with at least a 15&inch;×18&inch; diameter manhole, fitted with a cover located above the maximum liquid level as close as possible to the top of the tank. Where access trunks are fitted to tanks, the diameter of the trunks shall be at least 30 inches.
(4) Low temperature protection. (i) When low temperature cargoes are to be carried in gravity type tanks at a temperature lower than that for which the hull steel is adequate, a secondary barrier designed to contain leaked cargo temporarily shall be provided. The design of the cargo containment system shall be such that under normal service conditions, or upon failure of the primary tank, the hull structure shall not be cooled down to a temperature which is unsafe for the materials involved. The secondary barrier and structural components of the hull which may be exposed to low temperatures shall meet the material requirements (i.e., chemistry and physical properties) specified in part 54 of this chapter for the service temperature involved. Heat transmission studies and tests may be required to demonstrate that the structural material temperatures in the hull are acceptable.
(ii) The design shall take into consideration the thermal stresses induced in the cargo tank at the service temperature during loading.
(iii) Where necessary, devices for spray loading or other methods of precooling or cooling during loading shall be included in the design.
(iv) Pressure-vessel type tanks shall be radiographed in accordance with the requirements of part 54 of this chapter. For gravity type tanks, all weld intersections or crossings in joints of primary tank shells shall be radiographed for a distance of 10 thicknesses from the intersection. All other welding in the primary tank and in the secondary barrier, shall be spot radiographed in accordance with the requirements specified in part 54 of this chapter for Class II-L pressure vessels.
(v) For nonpressure vessel type containment systems, access shall be arranged to permit inspection one side each of the primary tank and secondary barrier, under normal shipyard conditions. Containment systems which, because of their peculiar design, cannot be visually inspected to this degree, may be specially considered provided an equivalent degree of safety is attained.
(e) Installation of cargo tanks. (1) Cargo tanks shall be supported on foundations of steel or other suitable material and securely anchored in place to prevent the tanks from shifting when subjected to external forces. Each tank shall be supported so as to prevent the concentration of excessive loads on the supporting portions of the shell or head.
(2) Foundations, and stays where required, shall be designed for support and constraint of the weight of the full tank, and the dynamic loads imposed thereon. Thermal movement shall also be considered.
(3) Foundations and stays shall be suitable for the temperatures they will experience at design conditions.
(4) Cargo tanks may be installed “on deck,” “under deck,” or with the tanks protruding through the deck. All tanks shall be installed with the manhole openings located in the open above the weather deck. Provided an equivalent degree of safety is attained, the Commandant may approve cargo tanks installed with manhole openings located below the weather deck. Where a portion of the tank extends above the weather deck, provision shall be made to maintain the weathertightness of the deck, except that the weathertightness of the upper deck need not be maintained on:
(i) Vessels operating on restricted routes which are sufficiently protected; or,
(ii) Open hopper type barges of acceptable design.
(5) No welding shall be performed on tanks which require and have been stress relieved unless authorized by the Commandant.
(f) Materials. (1) Materials used in the construction of cargo tanks shall be suitable for the intended application and shall be in accordance with the applicable requirements of part 54 of this chapter. For cargoes carried at low temperatures, the tank supports and foundations, and portions of the hull which may be exposed to low temperature, shall also meet the applicable requirements of that part.
(2) When required, cargo tanks shall be lined with rubber or other material acceptable to the Commandant. The interior surfaces of the cargo tanks shall be made smooth, welds chipped or ground smooth, and the surfaces thoroughly cleaned before the lining is applied. The lining material shall be resistive to attack by the cargo, not less elastic than the metal of the tank proper, and nonporous when tested after application. It shall be of substantially uniform thickness. The lining shall be directly bonded to the tank plating, or attached by other satisfactory means acceptable to the Commandant.
(g) Insulation. (1) Insulation, when provided, shall be compatible with the cargo and the tank materials.
(2) Insulation in a location exposed to possible high temperature or source of ignition shall be one of the following:
(i) Incombustible, complying with the requirements of Subpart 164.009 of Part 164 of this chapter; or
(ii) Fire retardant, having a flame spread rating of 50 or less as determined by ASTM Specification E 84 (incorporated by reference, see §151.01–2) (Tunnel Test); or,
(iii) Nonburning or “self-extinguishing” as determined by ASTM Specification D 4986, “Horizontal Burning Characteristics of Cellular Polymeric Materials” (incorporated by reference, see §151.01–2) and covered by a steel jacket having a minimum thickness of 18 gauge (0.0428 inches) (U.S. Standard Gauge) or an equivalent means of protection acceptable to the Commandant.
(3) Insulation in a location protected against high temperature or source of ignition need satisfy no requirement for combustibility.
(4) Insulation shall be impervious to water vapor, or have a vapor-proof coating of a fire-retardant material acceptable to the Commandant. Unless the vapor barrier is inherently weather resistant, tanks exposed to the weather shall be fitted with a removable sheet metal jacket of not less than 18 gauge over the vapor-proof coating and flashed around all openings so as to be weathertight. Insulation which is not exposed to the weather when installed on tanks carrying cargoes above ambient temperatures need not be impervious to water vapor nor be covered with a vapor-proof coating.
(5) Insulation shall be adequately protected in areas of possible mechanical damage.
(h) Fire exposure protection. Tanks which are provided with fire exposure protection of one of the following categories may be allowed a reduction in the size of relief valves.
(1) Approved incombustible insulation meeting the requirements of subpart 164.007 of part 164 of this chapter which is secured to the tank with steel bands.
(2) Located in a hold or protected by a self-supporting steel jacket or cover (such as a hopper cover) of at least 10 gauge (0.1345) for insulation.
(i) Tanks not protected against fire exposure as described in this paragraph shall not be permitted a reduction in size of relief valves.
[CFGR 70–10, 35 FR 3714, Feb. 25, 1970, as amended by CGD 88–100, 54 FR 40040, Sept. 29, 1989; USCG–1999–5151, 64 FR 67183, Dec. 1, 1999; USCG–2000–7790, 65 FR 58463, Sept. 29, 2000]
§ 151.15-5 Venting.
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This section contains definitions and requirements for the various methods of venting specified in Table 151.05. In addition to the requirement that all vents must penetrate into tanks at the top of the vapor space, the following methods of venting and the applicable restrictions are listed:
(a) Open venting. A venting system which offers no restriction (except pipe losses and flame screen, where used) to the movement of liquid or vapor to or from the cargo tank (via the vent) under normal operating conditions. The total cross-sectional area of the vents shall not be less than the total cross-sectional area of the filling pipe or pipes. Ullage openings may be counted as part of the required cross-sectional area: Provided, That each cargo tank has at least one permanent vent. The minimum size of a cargo tank vent shall be not less than 2 1/2 inches. The outlet end of the vent shall terminate in a gooseneck bend and shall be located at a reasonable height above the weather deck, clear of all obstructions. No shut-off valve or frangible disk shall be fitted in the vent lines except that a float check valve may be installed so as to exclude the entry of water into the tank (i.e., to prevent downflooding). An open venting system may be fitted with a flame screen.
(b) Pressure-vacuum venting. A normally closed venting system fitted with a device to automatically limit the pressure or vacuum in the tank to design limits. Pressure-vacuum relief valves shall comply with the requirements of subpart 162.017 of this chapter. The required capacity of the venting system shall be in accordance with part 54 of this chapter.
(c) Safety relief venting. A closed venting system fitted with a device to automatically limit the pressure in the tank to below its maximum allowable working pressure. The maximum safety relief valve setting shall not exceed the maximum allowable working pressure of the tank. For cargoes carried at ambient temperatures, the minimum safety relief valve setting shall correspond to the saturated vapor pressure of the cargo at 105 °F if carried in an insulated tank, or 115 °F if carried in an uninsulated tank. For cargoes carried below ambient temperature, the safety relief valve setting shall be selected to provide a suitable margin between normal operating pressure of the tank and the opening pressure of the valve but in no case shall it exceed the maximum allowable working pressure of the tank. The safety relief valves shall be of a type approved under subparts 162.001 or 162.018 of subchapter Q of this chapter. The required capacity of the safety relief valves shall be in accordance with the requirements of part 54 of this chapter.
(d) Rupture disks. (1) When required by the nature of the cargo, rupture disks may be installed in lieu of or in addition to other pressure limiting devices in accordance with the requirements of §54.15–13 of this chapter.
(2) When a pressure-vacuum relief valve or safety relief valve normally protected by a rupture disk or breaking pin device is exposed to the cargo due to breakage of the disk, the valve shall be reinspected before being returned to service.
§ 151.15-6 Venting piping.
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(a) The back pressure in the relief valve discharge lines shall be taken into account when determining the flow capacity of the relief valve to be used. The back pressure in the discharge line shall be limited to 10 percent of the valve operating pressure or a compensating-type valve shall be used. Suitable provision shall be made for draining condensate which may accumulate in the vent piping.
(b) [Reserved]
§ 151.15-10 Cargo gauging devices.
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This section contains definitions and requirements for types of gauging devices specified in Table 151.05.
(a) Open gauging. A gauging method which uses an opening in the cargo tank and which may expose the gauge user to the cargo and its vapors. Examples of this type are gauge hatch, ullage hole.
(b) Restricted. A gauging device which penetrates the cargo tank and which, in operation, causes or permits the release to the atmosphere of small quantities of cargo vapor or liquid. The amount of cargo released is controlled by the small diameter of the tank penetration opening and by a locally operated valve or similar closure device in that opening. When not in use, this type gauging device is closed to maintain the complete integrity of cargo containment. Examples of this type are rotary tube, fixed tube, slip tube, sounding tube. (See §§151.03–49 and 151.15–10(g).)
(c) Closed. A gauging device which penetrates the cargo tank, but which is part of a closed system maintaining the complete integrity of cargo containment. This device is designed and installed so as not to release cargo liquid or vapor in any amount to the atmosphere. Examples of this type are automatic float, continuous tape (magnetic coupled), sight glass (protected), electronic probe, magnetic, differential pressure cell.
(d) Isolated or indirect. A gauging method or device which is isolated from the tank (no penetration of the tank shell) and which may employ an indirect measurement to obtain the desired quantity. Examples of this type are weighing of cargo, sonic depth gauge (without penetration of tank shell), pipe flow meter.
(e) All gauging devices and related fixtures which form a part of the cargo containment barrier shall be of suitable material and shall be designed for the pressure and temperature of the cargo in accordance with the requirements of Subchapter F of this chapter.
(f) Use of restricted gauging devices. (1) When required in Table 151.05, cargoes carried under pressure shall have restricted gauging devices designed so that the maximum bleed valve opening is not larger than 0.055;inch; diameter, unless provided with an excess flow valve. Sounding tubes are prohibited for use with cargoes having a vapor pressure in excess of 14.7 p.s.i.a. at 115 °F, if carried in an uninsulated tank, or at 105 °F, if carried in an insulated tank.
(2) When utilizing a sounding tube, the cargo tank vent system shall be designed to prevent the discharge of cargo through the sounding tube due to pressure build up in the cargo tank vapor space. (See §151.03–43) When cargoes carried at atmospheric pressure are required to have a restricted gauging device, open gauges may be provided in addition to restricted gauges for this type of cargo. However, open gauges may not be used while cargo transfer operations are actually being performed.
(g) Fixed tube gauges are not acceptable as primary means of gauging. They may be used as a check on the calibration of other gauging devices.
(h) For pressure-vessel type tanks, each automatic float, continuous reading tape or similar type gauge not mounted directly on the tank or dome shall be fitted with a shutoff device located as close to the tank as practicable. When an automatic float gauging device, which gauges the entire height of the tank, is used, a fixed tube gauge set in the range of 85 percent to 90 percent of the water capacity of the tank shall be provided in addition as a means of checking the accuracy of the automatic float gauge, or other alternate means acceptable to the Commandant may be used.
(i) Gauge glasses of the columnar type are prohibited.
(j) Flat sight glasses may be used in the design of automatic float continuous reading tape gauges. However such glasses shall be made of high strength material, suitable for the operating temperatures, of not less than one-half inch in thickness and adequately protected by a metal cover.
[CGFR 70–10, 35 FR 3714, Feb. 25, 1970, as amended by USCG–2005–22329, 70 FR 57183, Sept. 30, 2005]
Subpart 151.20—Cargo Transfer
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§ 151.20-1 Piping—general.
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(a) Cargo piping systems shall be arranged and fabricated in accordance with this section and Subchapter F. The class of piping system required for a specific cargo shall be as listed in Table 151.05 as a minimum; however, a higher class may be required when the actual service temperature or pressure so dictates. See Table 56.04–2 of this chapter.
(b) Piping system components shall be suitable for use with the cargoes for which the barge is certificated, and shall be of materials listed in Subchapter F of this chapter, or such other material as the Commandant may specifically approve. All piping materials shall be tested in accordance with the requirements of Subchapter F of this chapter. The valve seat material, packing, gaskets, and all other material which comes into contact with the cargo shall be resistant to the chemical action of the cargoes for which the barge is certificated.
(c) Cargo piping systems, when subject to corrosive attack of the cargo, and when serving cargo tanks which are required by this subchapter to be lined or coated, shall be constructed of, lined or coated with corrosion-resistant material. Vent systems shall be similarly constructed, lined, or coated up to and including the vent control device.
(d) All piping systems components shall have a pressure rating at operating temperature (according to the applicable American National Standards Institute, Inc., pressure/temperature relations) not less than the maximum pressure to which the system may be subjected. Piping which is not protected by a relief valve, or which can be isolated from its relief valve, shall be designed for the greatest of:
(1) The cargo vapor pressure at 115 °F.
(2) The maximum allowable working pressure of the cargo tank.
(3) The pressure of the associated pump or compressor relief valve.
(4) The total discharge head of the associated pump or compressor where a discharge relief valve is not used.
The escape from cargo piping system relief valves shall be run to venting system or to a suitable recovery system. Provisions shall be made for pressure relief of all piping, valves, fittings, etc., in which excessive pressure build-up may occur because of an increase in product temperature.
(e) Provisions shall be made by the use of offsets, loops, bends, expansion joints, etc., to protect the piping and tank from excessive stress due to thermal movement and/or movements of the tank and hull structure. Expansion joints shall be held to a minimum and where used shall be subject to individual approval by the Commandant.
(f) Low temperature piping shall be isolated from the hull structure. Where necessary, arrangements to provide for the protection of the hull structure from leaks in low temperature systems in way of pumps, flanges, etc., shall be provided.
(g) Connections to tanks shall be protected against mechanical damage and tampering. Underdeck cargo piping shall not be installed between the outboard side of cargo containment spaces and the skin of the barge, unless provision is made to maintain the minimum inspection and collision protection clearances (where required) between the piping and the skin. Cargo piping which is external to tanks, and is installed below the weather deck shall be joined by welding, except for flanged connections to shutoff valves and expansion joints.
(h) Piping shall enter independent cargo tanks above the weatherdeck, either through or as close to the tank dome as possible.
(i) Horizontal runs of cargo piping on integral tank barges may be run above or below the weatherdeck. When run below the weatherdeck, the following are applicable:
(1) Horizontal runs located entirely within integral cargo tanks shall be fitted with a stop valve, located inside the tank that is being serviced and operable from the weatherdeck. There shall be cargo compatibility in the event of a piping failure.
(2) Horizontal runs of cargo piping installed in pipe tunnels may penetrate gravity type tanks below the weatherdeck: Provided, That each penetration is fitted with a stop valve operable from the weatherdeck. If the tunnel is directly accessible from the weatherdeck without penetrating the cargo tank, the stop valve shall be located on the tunnel side. If the tunnel is not accessible from the weatherdeck, the valve shall be located on the tank side of the penetration.
(3) The tunnel shall comply with all tank requirements for construction, location, ventilation, and electrical hazard. There shall be cargo compatibility in the event of a piping failure.
(4) The tunnel shall have no other openings except to the weatherdeck or a cargo pumproom.
§ 151.20-5 Cargo system valving requirements.
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For the purpose of adequately controlling the cargo, both under normal operating and casualty conditions, every cargo piping system shall be provided with one of the following sets of control valves and meet the requirements listed below. Cargo tanks, whether gravity or pressure vessel type, for cargoes having a saturated vapor pressure of 10 pounds per square inch gauge or less at 115 °F (105 °F if the tank is insulated) shall be provided with a valving system designated as Gravity–1. Cargo tanks, whether gravity or pressure vessel type, for cargoes which are carried below ambient temperature and whose vapor pressure is maintained at 10 pounds per square inch gauge or below shall be provided with a valving system designated as Gravity–2. Cargo tanks for cargoes which have vapor pressures above 10 p.s.i.g. at 115 °F (105 °F if tank is insulated) shall be provided with a valving system designated as Pressure–1. Cargo tanks for cargoes which have vapor pressures above 10 pounds per square inch gauge at 115 °F (105 °F if tank is insulated) and which require greater protection due to their hazardous characteristics shall be provided with a valving system designated as Pressure–2. The requirements of paragraphs (a) through (d) of this section for stop valves or excess flow valves to be fitted at tank penetrations are not applicable to nozzles at which pressure vacuum or safety relief valves are fitted. (continued)