[Code of Federal Regulations]
[Title 33, Volume 2]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 33CFR154.824]

[Page 318-320]
 
                TITLE 33--NAVIGATION AND NAVIGABLE WATERS
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 154--FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK--Table 
of Contents
 
                    Subpart E--Vapor Control Systems
 
Sec. 154.824  Inerting, enriching, and diluting systems.

    (a) A vapor control system which uses inerting, enriching, or 
diluting gas must be capable of inerting, enriching, or diluting the 
vapor collection line prior to receiving cargo vapor.
    (b) Except as permitted by Sec. 154.820(a) of this subpart, a vapor 
control system which uses an inerting, enriching, or diluting system 
must be equipped with a gas injection and mixing arrangement located as 
close as practical but

[[Page 319]]

not more than 10 meters (32.8 ft.) from the facility vapor connection 
that ensures complete mixing of the gases within 20 pipe diameters of 
the injection point;
    (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 (l) 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 Sec. 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 hydrocarbon 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 Sec. 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 
collection line exceeds 15.5 percent by volume; and

[[Page 320]]

    (2) Close the remotely operated cargo vapor shutoff valve required 
by Sec. 154.810(a) of this subpart when the oxygen concentration in the 
vapor collection 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 Sec. 154.810(a) of this subpart when the oxygen 
concentration exceeds 9 percent by volume.
    (l) 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 Sec. 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.

[CGD 88-102, 55 FR 25429, June 21, 1990; 55 FR 39270, Sept. 26, 1990]