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(continued) all switching is done from outside the space.
(c) All cargo tanks, piping, valves, etc., shall be effectively grounded to the vessel's hull. Tanks with an insulated inner shell (primary barrier) shall have an effective grounding bond to the outer shell (secondary barrier) or to the vessel's hull.
(d) Electric submerged motor cargo pumps may be used, when in compliance with the following requirements and subject to approval by the Commandant.
(1) Design details of the submerged motor pump, with an evaluation of the cooling efficiency of the product being pumped, shall be submitted.
(2) Provisions shall be made to exclude air from the tanks containing cargo in either vapor or liquid phase. The pump motor shall be deenergized when this condition is not satisfied.
(3) A liquid level sensing device shall automatically shut down the motor and sound an alarm at a predetermined low liquid level. The alarm location may be the station from which cargo handling is controlled or such other location outside the cargo area as is acceptable to the Commandant.
(4) Details of the power cable, tank penetrations and pump connections shall be submitted.
(5) An auxiliary means of emptying the cargo tanks shall be provided in accordance with §38.10–10(d).
(6) Means for positively disconnecting the power supply between the switchboard and the pump power panel shall be provided, i.e., disconnect links, lockable breakers, etc.
(7) All materials used in the fabrication of the submerged motor cargo pumps shall be suitable for use with the liquid cargo at the design pressures and temperatures.
§ 38.15-20 Remote shutdowns—TB/ALL.
(a) All machinery associated with cargo loading, unloading, or cooling shall be capable of being shut down from a remote location. This location may be the station from which the cargo handling is controlled or such other location outside the cargo area as is acceptable to the Commandant.
Subpart 38.20—Venting and Ventilation
§ 38.20-1 Venting—T/ALL.
(a) Each safety relief valve installed on a cargo tank shall be connected to a branch vent of a venting system which shall be constructed so that the discharge of gas will be directed vertically upward to a point which shall extend to a height above the weather deck equal to at least one-third the beam of the vessel and to a minimum of at least 10 feet, and shall terminate at a comparable distance from any other living or working space, ventilator inlet, or source of vapor ignition. When special conditions will prevent the vent line header outlets being permanently installed at a height above the deck of one-third the beam of the vessel, then an adjustable system shall be provided which, when extended vertically, shall be capable of reaching a height of one-third the beam of the vessel.
(b) The capacity of branch vents or vent headers shall depend upon the number of cargo tanks connected to such branch or header as provided for in the Table 38.20–1(b), and upon the total safety relief valve discharge capacity.
Table 38.20-1(b)_Capacity of Branch Vents or Vent Headers
Number of cargo tanks valve
1 or 2....................................................... 100
6 or more.................................................... 60
(c) In addition to the requirements specified in paragraphs (a) and (b) of this section, the size of the branch vents or vent headers, shall be such that the back pressure in the relief valve discharge lines shall not be more than 10 percent of the safety relief valve setting. In nonpressure vessel vent systems, however, where the maximum back pressure of 10 percent of the relief valve setting is insufficient to move the gases through any but an extremely large diameter vent pipe, the back pressure may exceed 10 percent provided:
(1) The pressure in the tank during venting does not exceed 120 percent of the tank maximum allowable pressure; and,
(2) The safety relief valve is sized to discharge the required capacity with the tank pressure and vent back pressure actually used.
(d) Return bends and restrictive pipe fittings are not permitted.
(e) Vents and headers shall be so installed as to prevent excessive stresses on safety relief valve mountings.
(f) The vent discharge riser shall be so located as to provide protection against mechanical injury and such discharge pipes shall be fitted with loose raincaps or other suitable means to prevent entrance of rain or snow.
(g) No valve of any type shall be fitted in the vent pipe between the safety relief valve and the vent outlets.
(h) Provisions shall be made to drain condensate from the vent header piping. Special precautions shall insure that condensate does not accumulate at or near the relief valves.
(i) Relief valves discharging liquid cargo shall not be connected to the branch vent or vent header lines from the cargo tanks. They may, however, be connected to an accumulator, the vapor space of which, may in turn, be connected to the vent header system. Relief valves in the cargo piping system may discharge back to the cargo tanks.
(j) Vapor discharged to the atmosphere in accordance with §38.05–25(b) shall utilize valves separate from the safety relief valves.
§ 38.20-5 Venting—T/ALL.
(a) Safety relief valves on cargo tanks in barges may be connected to individual or common risers which shall extend to a reasonable height above the deck. An alternate arrangement consisting of a branch vent header system as required by §38.20–1 may be installed. In any case, the provisions of §38.20–1 (d) through (j) shall apply.
(b) Arrangements providing for venting cargo tanks at sea on unmanned barges will be considered by the Commandant upon presentation of plans.
§ 38.20-10 Ventilation—T/ALL.
(a) A power ventilation system shall be provided for compartments containing pumps, compressors, pipes, control spaces, etc. connected with the cargo handling facilities. These compartments shall be ventilated in such a way as to remove vapors from points near the floor level or bilges, or other areas where vapor concentrations may be expected. The compartments shall be equipped with power ventilation of the exhaust type having capacity sufficient to effect a complete change of air in not more than 3 minutes equal to the volume of the compartment and associated trunks.
(b) The power ventilation units shall not produce a source of vapor ignition in either the compartment or the ventilation system associated with the compartment. Inlets to exhaust ducts shall be provided and located at points where concentrations of vapors may be expected. Ventilation from the weather deck shall be provided. Ventilation outlets shall terminate away from any openings to the interior part of the vessel a lateral distance at least equal to that specified in §38.20–1(a). These outlets shall be so located as to minimize the possibility of recirculating contaminated air through the compartment.
(c) Means shall be provided for purging the following spaces of cargo vapors:
(1) The space surrounding nonpressure vessel type tanks, i.e., within the secondary barrier.
(2) The space surrounding pressure-vessel type tanks whose piping connections are below the weather deck in accordance with §38.10–1(h).
(3) The space surrounding tanks whose manhole openings are below the weather deck in accordance with §38.05–10(f).
(d) Power ventilation shall be provided for each auxiliary machinery or working space located on and accessible from the cargo handling deck. Such ventilation systems shall be designed to preclude the entry of cargo vapors into the space via the open access or the ventilation system itself.
[CGFR 66–33, 31 FR 15269, Dec. 6, 1966, as amended by CGFR 68–65, 33 FR 19985, Dec. 28, 1968]
Subpart 38.25—Periodic Tests and Inspections
§ 38.25-1 Tests and inspections—TB/ALL.
(a) Each tank shall be subjected to the tests and inspections described in this section in the presence of a marine inspector, except as otherwise provided in this part.
(1) An internal inspection of the tank is conducted within—
(i) Ten years after the last internal inspection if the tank is a pressure vessel type cargo tank on an unmanned barge carrying cargo at temperatures of -67 °F (-55 °C) or warmer; or
(ii) Eight years after the last internal inspection if the tank is of a type other than that described in paragraph (a)(1)(i) of this section.
(2) An external examination of unlagged tanks and the visible parts of lagged tanks shall be made at each inspection for certification and at such other times as considered necessary.
(3) The owner shall ensure that the amount of insulation deemed necessary by the marine inspector is removed from insulated tanks during each internal inspection to allow spot external examination of the tanks and insulation, or the thickness of the tanks may be gauged by a nondestructive means accepted by the marine inspector without the removal of insulation.
(4) If required by the Officer in Charge, Marine Inspection, the owner shall conduct nondestructive testing of each tank in accordance with §38.25–3.
(5) If the tank is a pressure vessel type cargo tank with an internal inspection interval of 10 years, is 30 years old or older, determined from the date it was built, the owner shall conduct nondestructive testing of that tank, in accordance with §38.25–3, during each internal inspection.
(b) If the marine inspector considers a hydrostatic test necessary to determine the condition of the tank, the owner shall perform the test at a pressure of 1 1/2 times the tanks's—
(1) Maximum allowable pressure, as determined by the safety relief valve setting; or
(2) Design pressure, when cargo tanks operate at maximum allowable pressures reduced below the design pressure in order to satisfy special mechanical stress relief requirements.
Note: See the ASME Code, Section VIII, Appendix 3 for information on design pressure.
(c) For pressure vessels designed and/or supported such that they cannot safely be filled with water, the Commandant will consider a pneumatic test in lieu of the hydrostatic test. A leak test shall be performed in conjunction with the pneumatic test. Pneumatic testing shall be in accordance with subchapter F (Marine Engineering) of this chapter.
(d) Nonpressure vessel type tanks shall be tested to a pressure equal to the pressure on the bottom of the tank under the design conditions listed in §38.05–4(e).
(e) In the application of the requirements for testing of the cargo tanks, the test shall in no case be less severe than the worst anticipated service condition of the cargo loading.
(f) In the design and testing of the independent cargo tanks, consideration shall be given to the possibility of the independent tanks being subjected to external loads.
[CGFR 66–33, 31 FR 15269, Dec. 6, 1966, as amended by CGD 85–061, 54 FR 50962, Dec. 11, 1989]
§ 38.25-3 Nondestructive testing—TB/ALL.
(a) Before nondestructive testing may be conducted to meet §38.25–1 (a)(4) and (a)(5), the owner shall submit a proposal to the Officer in Charge, Marine Inspection for acceptance that includes—
(1) The test methods and procedures to be used, all of which must meet section V of the ASME Boiler and Pressure Vessel Code (1986);
(2) Each location on the tank to be tested; and
(3) The test method and procedure to be conducted at each location on the tank.
(b) If the Officer in Charge, Marine Inspection rejects the proposal, the Officer in Charge, Marine Inspection informs the owner of the reasons why the proposal is rejected.
(c) If the Officer in Charge, Marine Inspection accepts the proposal, then the owner shall ensure that—
(1) The proposal is followed; and
(2) Nondestructive testing is performed by personnel meeting ASNT “Recommended Practice No. SNT-TC-1A (1988), Personnel Qualification and Certification in Nondestructive Testing.”
(d) Within 30 days after completing the nondestructive test, the owner shall submit a written report of the results to the Officer in Charge, Marine Inspection.
[CGD 85–061, 54 FR 50963, Dec. 11, 1989]
§ 38.25-5 Removal of defective tanks—TB/ALL.
If a tank fails to pass the tests prescribed in this subpart, it shall be removed from service unless otherwise authorized by the Commandant.
§ 38.25-10 Safety relief valves—TB/ALL.
(a) The cargo tank safety relief valves shall be inspected at least once in every 2 years.
(b) The safety relief valve discs must be lifted from their seats in the presence of a marine inspector by either liquid, gas, or vapor pressure at least once every 5 years to determine the accuracy of adjustment and, if necessary, must be reset.
[CGFR 66–33, 31 FR 15269, Dec. 6, 1966, as amended by CGD 95–027, 61 FR 26000, May 23, 1996]