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(c) A vapor control system that uses an inerting or enriching system may not be operated at a vacuum after the injection point unless:
(1) There are no sleeve-type pipe couplings, vacuum relief valves, or other devices which could allow air into the vapor collection system downstream of the injection point; or
(2) An additional analyzer is used to monitor the downstream vapor concentration and a means is provided to inject additional inerting or enriching gas.
(d) A vapor control system that uses analyzers to control the amount of inerting, enriching, or diluting gas injected into the vapor collection line must be equipped with at least 2 analyzers. The analyzers must be connected so that:
(1) When oxygen analyzers are used, the higher oxygen concentration reading controls the inerting or enriching system and activates the alarm and automatic shutdown system required by paragraph (h), (j) or (k)(2) of this section;
(2) When hydrocarbon analyzers are used, the lower hydrocarbon concentration reading controls the enriching system and activates the alarm and automatic shutdown system required by paragraph (i) or (k)(1) of this section; and
(3) When hydrocarbon analyzers are used, the higher hydrocarbon concentration reading controls the diluting system and activates the alarm and automatic shutdown system required by paragraph (1) of this section.
(e) A vapor control system that uses volumetric measurements to control the amount of inerting, enriching, or diluting gas injected into the vapor collection line must be equipped with at least one analyzer to activate the alarms and automatic shutdown systems required by this section.
(f) Each oxygen or hydrocarbon analyzer required by this section must:
(1) Be installed in accordance with API Recommended Practice 550;
(2) Have a response time of not more than 30 seconds from the time the vapor is sampled; and
(3) Sample the vapor concentration continuously not more than 30 pipe diameters from the gas injection point.
(g) Oxygen analyzers which operate at elevated temperatures (i.e. zirconia oxide or thermomagnetic) must not be used.
(h) An inerting system must:
(1) Supply sufficient inert gas to the vapor stream to ensure that the oxygen concentration throughout the vapor collection system is maintained below 8.0 percent by volume;
(2) Activate an alarm when the oxygen concentration in the vapor collection line exceeds 8.0 percent by volume;
(3) Close the remotely operated cargo vapor shutoff valve required by § 154.810(a) of this part when the oxygen concentration in the vapor collection line exceeds 9.0 percent by volume; and
(4) If a combustion device is used to produce the inert gas, have a hydraulic seal and non-return valve between the combustion device and the vapor collection line.
(i) An enriching system must:
(1) Supply sufficient compatible hydrocarbon vapor to the vapor stream to ensure that the hydrocarbon concentration throughout the vapor collection system is maintained above 170 percent by volume of the upper flammable limit;
(2) Activate an alarm when the hy. drocarbon concentration in the vapor collection line falls below 170 percent by volume of the upper flammable limit; and
(3) Close the remotely operated cargo vapor shutoff valve required by $ 154.810(a) of this subpart when the hydrocarbon concentration in the vapor collection line falls below 150 percent by volume of the upper flammable limit.
(j) Oxygen analyzers may be used in lieu of hydrocarbon analyzers in an enriching system at a facility that receives cargo vapor only from a vessel with non-inerted cargo tanks, provided that the analyzers:
(1) Activate an alarm when the oxygen concentration in the vapor col. lection line exceeds 15.5 percent by volume; and
(2) Close the remotely operated cargo vapor shutoff valve required by § 154.810(a) of this subpart when the oxygen concentration in the vapor col. lection line exceeds 16.5 percent by volume.
(k) An enriching system may be used in a vapor collection system that receives cargo vapor from a vessel with inerted cargo tanks if:
(1) Hydrocarbon analyzers are used to comply with paragraph (i)(2) and (i)(3) of this section; or
(2) If oxygen analyzers are used, the analyzers activate an alarm when the oxygen concentration in the vapor collection line exceeds 8 percent by volume, and close the remotely operated cargo vapor shutoff valve required by $ 154.810(a) of this subpart when the oxygen concentration exceeds 9 percent by volume.
(1) An air dilution system must:
(1) Supply sufficient additional air to the vapor stream to ensure that the hydrocarbon concentration throughout the vapor collection system is maintained below 30 percent by volume of the lower flammable limit;
(2) Activate an alarm when the hydrocarbon concentration in the vapor collection line exceeds 30 percent by volume of the lower flammable limit; and
(3) Close the remotely operated cargo vapor shutoff valve required by
154.810(a) of this subpart when the hydrocarbon concentration in the vapor collection line exceeds 50 percent by volume of the lower flammable limit.
(2) Excessive cooling water temperature;
(3) Excessive vibration;
(6) Excessive shaft bearing temperatures.
(c) If a liquid ring-type compressor handles vapor in the vapor collection system, it must be provided with indicators and audible and visible alarms to warn against the following conditions:
(1) Low level of liquid sealing medium;
(2) Lack of flow of liquid sealing medium;
(3) Excessive temperature of the liquid sealing medium;
(4) Low lube oil level;
(5) Low lube oil pressure, if pressurized lubricating system; and
(6) Excessive shaft bearing temperature.
(d) If a centrifugal compressor, fan, or lobe blower handles vapor in the vapor collection system, construction of the blades and/or housing must meet one of the following:
(1) Blades or housing of nonmetallic construction;
(2) Blades and housing of nonferrous material;
(3) Blades and housing of corrosion resistant steel;
(4) Ferrous blades and housing with one-half inch or more design tip clearance; or
(5) Blades of aluminum or magnesium alloy and a ferrous housing with a nonferrous insert sleeve at the periphery of the impeller. § 154.828 Vapor recovery and vapor de
struction units. (a) The inlet to a vapor recovery unit which receives cargo vapor that has not been inerted, enriched, or diluted in accordance with $ 154.824 of this subpart must be fitted with one of the following:
(1) A detonation arrester;
(3) An explosion suppression system acceptable to the Commandant (GMTH).
(b) The inlet to a vapor destruction unit must:
8 154.826 Vapor compressors and blowers.
(a) Each inlet and outlet to a compressor or blower which handles vapor that has not been inerted, enriched, or diluted in accordance with 154.824 of this subpart must be fitted with:
(1) A detonation arrester; (2) A flame arrester; or
(3) An explosion suppression system acceptable to the Commandant (GMTH).
(b) If a reciprocating or screw-type compressor handles vapor in the vapor collection system, it must be provided with indicators and audible and visible alarms to warn against the following conditions:
(1) Excessive discharge gas temperature at each compressor chamber or cylinder;
(1) Have a liquid seal; and
(2) Have two quick-closing stop valves installed in the vapor line.
(c) A vapor destruction unit must:
(1) Not be within 30 meters (98.8 ft.) of any tank vessel berth or mooring at the facility;
(2) Have a flame arrester or detonation arrester fitted in the vapor line; and
(3) Alarm and shut down when a flame is detected on the flame arrester or detonation arrester.
(d) When a vapor destruction unit shuts down or has a flame-out condition the vapor destruction unit control system must:
(1) Close the quick-closing stop valves required by paragraph (b)(2) of this section; and
(2) Close the remotely operated cargo vapor shutoff valve required by § 154.810(a) of this subpart. § 154.840 Personnel training.
(a) A person in charge of a transfer operation utilizing a vapor control system must have completed a training program covering the particular system installed at the facility. Training must include drills or demonstrations using the installed vapor control system covering normal operations and emergency procedures.
(b) The training program required by paragraph (a) of this section must cover the following subjects:
(1) Purpose of vapor control system;
(2) Principles of the vapor control system;
(3) Components of the vapor control system;
(4) Hazards associated with the vapor control system;
(5) Coast Guard regulations in this subpart;
(6) Operating procedures, including:
(i) Testing and inspection requirements,
(ii) Pre-transfer procedures,
icate of inspection or certificate of compliance endorsed in accordance with 46 CFR 39.10-13(e).
(b) The following must be performed not more than 24 hours prior to each transfer operation:
(1) All alarms and automatic shutdown systems required by this part must be tested; and (2)
The analyzers required by $ 154.820(a), § 154.824 (d) and (e) of this subpart must be checked for calibration by use of a span gas.
(c) The position of all valves in the vapor line between the vessel's tanks and the facility vapor collection system must be verified prior to the start of the transfer operation.
(d) A tank barge overfill control system that meets the requirements of 46 CFR 39.20-9(b) must not be connected to an overfill sensor circuit that exceeds the system's rated cable length, inductance, and capacitance.
(e) When vapor is being received from a vessel with inerted cargo tanks, the remotely operated cargo vapor shutoff valve required by $ 154.810(a) of this subpart must not be opened until the pressure at the facility vapor connection exceeds the pressure on the downstream side of the remotely operated cargo vapor shutoff valve.
(f) The initial cargo transfer rate must not exceed the rate agreed upon at the pre-transfer conference quired by $ 156.120(w) of this chapter and 46 CFR 39.30-1(h).
(g) The cargo transfer rate must not exceed the maximum allowable transfer rate as determined by the lesser of the following:
(1) A transfer rate corresponding to the maximum vapor processing rate for the vapor control system, as speci. fied in the facility operations manual required by $ 154.300 of this chapter; or
(2) The vessel's maximum transfer rate determined in accordance with 46 CFR 39.30-1(d).
(h) While transferring cargo to a vessel connected to a vapor control system, compressed air or gas may be used to clear cargo hoses and loading arms, but must not be used to clear cargo lines.
(i) If one of the two analyzers required by $ 154.824(d) of this subpart
8 154.850 Operational requirements.
(a) A facility must receive vapors only from a vessel which has its certif
becomes inoperable during a transfer operation, the operation may continue provided the remaining analyzer remains operational; however, no further transfer operations may be started until the inoperable analyzer is replaced or repaired.
(j) Whenever a condition results in a shutdown of the vapor control system, the person in charge shall immediately terminate cargo loading.
(k) If it is suspected that a flare in the vapor control system has had a flare-back, or if a flame is detected on the flame arrester required by $ 154.828(c)(2) of this subpart, the transfer operation must be stopped and not be restarted until the flame arrester has been inspected and found to be in satisfactory condition.
APPENDIX A TO PART 154-GUIDELINES
FOR DETONATION FLAME ARRESTERS
This appendix contains the draft ASTM standard for detonation flame arresters. Devices meeting this standard will be accepted by the Commandant (G-MTH).
1.1 This standard provides the minimum requirements for design, construction, performance and testing of detonation flame arresters.
2.1 This standard is intended for detonation flame arresters protecting systems containing vapors of flammable or combustible liquids where vapor temperatures do not exceed 60 °C. For all tests, the test media defined in 14.1.1 can be used except where detonation flame arresters protect systems handling vapors with a maximum experimental safe gap (MESG) below 0.9 millimeters. Detonation flame arresters protecting such systems must be tested with appropriate media (the same vapor or a media having a MESG no greater than the vapor). Various gases and their respective MESG are listed in attachment 1.
2.2 The tests in this standard are intend. ed to qualify detonation flame arresters for all in-line applications independent of piping configuration provided the operating pressure is equal to or less than the maximum operating pressure limit specified in the manufacturer's certification and the diameter of the piping system in which the detonation arrester is to be installed is equal to or less than the piping diameter used in the testing.
NOTE: Detonation flame arresters meeting this standard as Type I devices, which are certified to be effective below 0 °C and
which can sustain three stable detonations without being damaged or permanently deformed, also comply with the minimum requirements of the International Maritime Organization, Maritime Safety Committee Circular No. 373 (MSC/Circ. 373/Rev.1).
3. Applicable Documents 3.1 ASTM Standards (1) A395 Ferritic Ductile Iron Pressure-Re
taining Castings For Use At Elevated
Temperatures. F722 Welded Joints for Shipboard Piping
Systems F1155 Standard Practice for Selection and
Application of Piping System Materials 3.2 ANSI Standards (2) B16.5 Pipe Flanges and Flanged Fittings. 3.3 Other Documents
3.3.1 ASME Boiler and Pressure Vessel Code (2)
Section VIII, Division 1, Pressure Vessels Section IX, Welding and Brazing Qualifi
cations. 3.3.2 International Maritime Organization, Maritime Safety Committee (3) MSC/Circ. 373/Rev. 1-Revised Standards
for the Design, Testing and Locating of Devices to Prevent the Passage of Flame
into Cargo Tanks in Tankers. 3.3.3 International Electrotechnical Commission (4) Publication 79-1-Electrical Apparatus for
Explosive Gas Atmospheres. 4. Terminology
4.1 AP/P.-The dimensionless ratio, for any deflagration and detonation test of 14.3, of the maximum pressure increase (the maximum pressure minus the initial pressure), as measured in the piping system on the side of the arrester where ignition begins by the device described in paragraph 14.3.3, to the initial absolute pressure in the piping system. The initial pressure should be greater than or equal to the maximum operating pressure specified in paragraph 11.1.7.
4.2 Deflagration-A combustion wave that propagates subsonically (as measured at the pressure and temperature of the flame front) by the transfer of heat and active chemical species to the unburned gas ahead of the flame front.
4.3 Detonation-A reaction in a combustion wave propagating at sonic or supersonic (as measured at the pressure and temperature of the flame front) velocity. A detonation is stable when it has a velocity equal to the speed of sound in the burnt gas or may
Footnotes appear at the end of this article.
be unstable (overdriven) with a higher velocity and pressure.
4.4 Detonation flame arrester-A device which prevents the transmission of a detonation and a deflagration.
4.5 Flame speed—The speed at which a flame propagates along a pipe or other system.
4.6 Flame Passage-The transmission of a flame through a device.
4.7 Gasoline Vapors-A non-leaded petroleum distillate consisting essentially of aliphatic hydrocarbon compounds with a boiling range approximating 65 °C/75 °C.
5.1 The two types of detonation flame arresters covered in this specification are classified as follows:
5.1.1 Type I-Detonation flame arresters acceptable for applications where stationary flames may rest on the device.
5.1.2 Type II—Detonation flame arresters acceptable for applications where stationary flames are unlikely to rest on the device, and further methods are provided to prevent flame passage when a stationary flame occurs. One example of “further methods” is a temperature monitor and an automatic shutoff valve.
6. Ordering Information
6.1 Orders for detonation flame arresters under this specification shall include the following information as applicable:
6.1.1 Type (I or II). 6.1.2 Nominal pipe size.
6 1.3 Each gas or vapor in the system and the corresponding MESG.
6.1.4 Inspection and tests other than specified by this standard.
6.1.5 Anticipated ambient air temperature range.
6.1.6 Purchaser's inspection requirements (see section 10.1).
6.1.7 Description of installation.
6.1.8 Materials of construction (see section 7).
6.1.9 Maximum flow rate and the maximum design pressure drop for that maximum flow rate.
6.1.10 Maximum operating pressure. 7. Materials
7.1 The detonation flame arrester housing, and other parts or bolting used for pressure retention, shall be constructed of materials listed in ASTM F1155, or section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code. Cast and malleable iron shall not be used; however, ductile cast iron in accordance with ASTM A395 may be used.
7.1.1 Arresters, elements, gaskets, and seals must be made of materials resistant to attack by seawater and the liquids and vapors contained in the system being protected (see section 6.1.3).
7.2 Nonmetallic materials, other than gaskets and seals, shall not be used in the
construction of pressure retaining components of the detonation flame arrester.
7.2.1 Nonmetallic gaskets and seals shall be non-combustible and suitable for the service intended.
7.3 Bolting materials, other than that of section 7.1, shall be at least equal to those listed in Table 1 of ANSI B16.5.
7.4 The possibility of galvanic corrosion shall be considered in the selection of materials.
7.5 All other parts shall be constructed of materials suitable for the service intended.
8. Other Requirements
8.1 Detonation flame arrester housings shall be gas tight to prevent the escape of vapors.
8.2 Detonation flame arrester elements shall fit in the housing in a manner that will insure tightness of metal-to-metal contacts in such a way that flame cannot pass between the element and the housing.
8.2.1 The net free area through detonation flame arrester elements shall be at least 1.5 times the cross-sectional area of the arrester inlet.
8.3 Housings, elements, and seal gasket materials shall be capable of withstanding the maximum and minimum pressures and temperatures to which the device may be exposed under both normal and the speci. fied fire test conditions in section 14, and shall be capable of withstanding the hydrostatic pressure test of section 9.2.3.
8.4 Threaded or flanged pipe connections shall comply with the applicable B16 standards in ASTM F1155. Welded joints shall comply with ASTM F722.
8.5 All flat joints of the housing shall be machined true and shall provide for a joint having adequate metal-to-metal contact.
8.6 Where welded construction is used for pressure retaining components, welded joint design details, welding and non-destructive testing shall be in accordance with Section VIII, Division 1, of the ASME Code and ASTM F722. Welders and weld procedures shall be qualified in accordance with section IX of the ASME Code.
8.7 The design of detonation flame arresters shall allow for ease of inspection and removal of internal elements for replacement, cleaning or repair without removal of the entire device from the system.
8.8 Detonation flame arresters shall allow for efficient drainage of condensate without impairing their efficiency to prevent the passage of flame. The housing may be fitted with one or more drain plugs for this purpose. The design of a drain plug should be such so that by cursory visual in. spection it is obvious whether the drain has been left open.
8.9 All fastenings shall be protected against loosening.