Hilliard
Emission Controls,
Inc.
3100 Edloe Street Suite 350
Houston, TX 77027
888-621-3132
|
Hilliard
Emission Controls,
Inc.
3100 Edloe Street Suite 350
Houston, TX 77027
888-621-3132
|
. |
Subj.: SAFETY STANDARDS FOR THE DESIGN AND OPERATION OF A MARINE VAPOR CONTROL SYSTEM (VCS) AT TANK BARGE CLEANING FACILITIES
l. Purpose. The purpose of this Circular is to provide
recommended
safety standards for the design and operation of a marine VCS at tank
barge
cleaning facilities.
2. Background.
a. Tank barge cleaning facilities are utilized by the
barge industry to gas-free and clean cargo tanks on tank barges prior
to
a change of cargo or conducting repair/retrofit work. The vapor space
in
the cargo tanks of barges entering these facilities contains cargo
vapors
from the last cargo carried and sometimes from cargoes previous to the
last cargo. These vapors may contain high levels of Volatile Organic
Compounds
(VOCs) and/or Hazardous Air Pollutants (HAPs). Existing work practices
for gas freeing and cleaning of cargo tanks result in the release of
these
VOCs and HAPs to the atmosphere, causing a degradation of air quality.
b. In 1990, Congress amended the Federal Clean Air Act.
One section of the Amendments requires states to achieve and maintain a
15 percent (%) reduction in their VOC emissions level below the 1990
base
year level by 1996 in non attainment areas within individual states.
This
amendment has required states to review their State Implementation
Plans
(SIPs) in order to determine potential sources of emissions reductions.
The tank barge cleaning industry has been identified in several states
as a viable source of emissions reductions, and two states have
subsequently
passed regulations requiring the control of emissions from tank barge
cleaning
facilities. Controlling vapor emissions at tank barge cleaning
facilities
will require the installation and use of a marine VCS.
c. In June 1990, the Coast Guard promulgated safety
regulations
for the design and operation of marine vapor control systems for
facilities
contained in Title 33, Code of Federal Regulations (CFR) Part 154,
Subpart
E and vessels contained in Title 46 CFR Part 39. These regulations were
developed from recommendations submitted to the Coast Guard by the
Chemical
Transportation Advisory Committee (CTAC) and apply to the control of
emissions
from vapors collected during vessel lightering operations and from
vapors
collected by a marine transfer facility during cargo loading
operations.
During the CTAC study and subsequent development of the regulations by
the Coast Guard, it was not anticipated that tank barge cleaning
facilities
would employ a VCS in their operations. Consequently, tank barge
cleaning
facility operations were not included as part of the CTAC study, and
the
current VCS regulations are not applicable to these facilities.
d. The Coast Guard recognized a need to conduct a detailed
review of cleaning facility operations to determine the technical
feasibility
of utilizing a VCS during gas freeing and tank cleaning operations, to
identify pertinent safety issues, and to develop standards for the safe
design and operation of a VCS. In April 1994, the CTAC Subcommittee on
Marine Vapor Control Systems, at the request of the Coast Guard,
convened
to commence work on evaluating the technical and safety aspects of the
application of a VCS during tank barge cleaning operations, and to
develop
recommended safety standards for implementation by the Coast Guard. The
Subcommittee was comprised of members representing the tank barge
industry,
cleaning facility operators, marine chemists, third party VCS
certifying
entities, and cargo shippers. The Subcommittee completed its work in
June
1995 and forwarded its recommendations to CTAC. These recommendations
were
approved by the CTAC membership and forwarded to the Coast Guard in
January
1996. These recommendations have been utilized by the Coast Guard to
form
the basis for the enclosed safety standards.
3. Discussion.
a. The enclosed safety standards for the design and
operation
of a VCS have been developed for use by tank barge cleaning facilities
during gas freeing and tank cleaning operations on tank barges, and
represent
the minimum acceptable level of system safety. The Coast Guard
recognizes
that the design and installation of a VCS represents a major capital
investment
on the part of cleaning facilities and barge operators, and has
attempted
to provide as much flexibility as possible in the design options for
both
cleaning facilities and tank barges.
b. The Coast Guard does not have, nor does it seek, the
statutory authority to require cleaning facilities to control emissions
of VOCs and HAPs during gas freeing and tank cleaning operations.
Accordingly,
the Coast Guard does not require the use of a VCS at cleaning
facilities.
Rather, the Coast Guard's role is to promote safety within the maritime
industry and to protect the marine environment. This can be
accomplished
through the development and implementation of uniform national safety
standards.
4. Implementation. Captains of the Port and Officers in Charge,
Marine Inspection are encouraged to bring this Circular to the
attention
of appropriate individuals in the maritime industry within their zones.
The Coast Guard fully intends to further publish these recommended
safety
standards as statutory regulations. Therefore, adherence to these
safety
standards is strongly recommended for tank barge cleaning facilities.
Encl.: (1) Safety Standards for the Design and Operation of A Marine VCS at Tank Barge Cleaning Facilities
Non-Standard Distribution:
B:a G-MOS-3(5), G-MOS-2(2), G-MCO-2(2), G-MCO-3(2).
B:z MSC-3 (5).
C:e New Orleans, Houston, Galveston (30), All other offices (5).
C:m New York (10).
E:n Baton Rouge (5).
Section One - Applicability
A Except as specified by paragraph C. of this section, these
standards apply to each facility which collects vapors emitted from
tank
barge cargo tanks during or in preparation for tank cleaning.
These
standards do not apply to the collection of vapors emitted during tank
barge cargo loading or lightering operations.
B These standards do not apply to the collection of vapors of
liquefied flammable gases as defined in 46 CFR 30.10-39.
C When a facility VCS which receives vapor during a barge
cleaning
operation is connected to a facility VCS that serves tank storage areas
and other facility processes, these standards apply between the barge
vapor
connection and the point where the VCS connects to the facility's main
VCS.
Section Two - Definitions
The following definitions apply to terms used in this part:
Barge vapor connection means the point in a barge's piping
system
where it connects to a vapor collection hose or arm. This may be
the same as the barge's cargo connection.
Certifying entity means an individual or organization accepted
by Commandant (G-MOS) to review plans and calculations for VCS designs,
and to conduct initial inspections and witness tests of VCS
installations.
Cleaning facility means a facility used or capable of being
used to conduct cleaning operations on a tank barge.
Cleaning operation means any stripping, gas freeing, or tank
washing operation of a barge's cargo tanks conducted at a cleaning
facility.
Combustible liquid means a liquid as defined in 46 CFR 30.10-15.
Elevated temperature means the temperature that exceeds 70%
of the auto-ignition temperature of the vapors being collected.
Facility means an onshore or mobile facility which includes,
but is not limited to structures, equipment, and appurtenances thereto,
used or capable of being used to transfer and control vapors.
Facility vapor connection means the point in a facility's fixed
vapor collection system where it connects to a vapor collection hose or
the base of a vapor collection arm.
Fixed stripping line means a pipe extending to the low point
of each cargo tank, which is welded through the deck and terminates
above
the deck with a valve, plugged at the open end.
Flammable liquid means a liquid as defined in 46 CFR 30.10-22.
Flame arrester means a device which is designed, built, and
tested in accordance with Appendix B to 33 CFR 154 for use in
end-of-line
applications for arresting flames.
Fluid displacement system means a system that removes vapors
from a barge's cargo tanks during gas freeing through the addition of
an
inert gas or other medium into the cargo tank.
Fluid injection connection means the point in a fluid
displacement
system at which the fixed piping or hose that supplies the inert gas or
other medium connects to a barge's cargo tanks or fixed piping system.
Gas freeing means the removal of vapors from a tank barge.
High flash point cargoes means Grade E cargoes and cargoes
having
a closed cup flash point greater than 60o C, carried at a temperature
no
higher than 5o C below their flash points.
Inerted means the oxygen content of the vapor space in a barge's
cargo tank is reduced to 8% or less by volume in accordance with the
inert
gas requirements of 46 CFR 32.53.
Liquid knockout vessel means a device designed to separate
liquids
from vapors.
Maximum allowable gas freeing rate means the maximum volumetric
rate at which a barge may be gas freed during cleaning operations.
Maximum allowable stripping rate means the maximum volumetric
rate at which a barge may be stripped during cleaning operations prior
to the opening of any hatch and/or fitting in the cargo tank being
stripped.
Multiple facility vapor collection system connection means the
point in the vapor collection system where two or more branch lines
originating
from separate facility vapor connections are connected.
Stripping means the removal, to the maximum extent practicable,
of cargo residue remaining in the barge's cargo tanks and associated
fixed
piping system after cargo transfer or during cleaning operations.
Vacuum displacement system means a system that removes vapors
from a barge's cargo tanks during gas freeing by sweeping air through
the
cargo tank hatch openings.
Vapor collection system means an arrangement of piping and hoses
used to collect vapor emitted from a barge's cargo tanks and transport
the vapor to a vapor processing unit.
Vapor control system (VCS) means an arrangement of piping and
equipment used to control vapor emissions collected from a barge, and
includes
the vapor collection system and the vapor processing unit.
Vapor destruction unit means a vapor processing unit that
destroys
cargo vapor by a means such as incineration.
Vapor dispersion unit means a vapor processing unit which
releases
cargo vapor to the atmosphere through a venting system not located on
the
barge undergoing cleaning operations.
Vapor processing unit means the components of a VCS that
recovers,
destroys, or disperses vapor collected from a barge.
Vapor recovery unit means a vapor processing unit that recovers
cargo vapor by a non-destructive means such as lean oil absorption,
carbon
bed adsorption, or refrigeration.
Section Three - Review, Certification and Initial Inspection
A. A VCS installed at a cleaning facility must be certified
by a certifying entity, acceptable to the Coast Guard in accordance
with
33 CFR 154.806, as meeting the requirements of these standards prior to
operation.
B. Plans and information submitted to the certifying entity
must include a qualitative failure analysis. The analysis must
demonstrate
the following:
l. The VCS is designed to permit the system to
continuously
operate safely during cleaning operations of tank barges;
2. The VCS is provided with the proper alarms and
automatic
control systems to prevent unsafe operation;
3. The VCS is equipped with sufficient automatic or
passive
devices to minimize damage to personnel, property, and the environment
if an accident were to occur; and
4. If a quantitative failure analysis is conducted in
lieu of a qualitative failure analysis, the level of safety attained is
at least one order of magnitude greater than that calculated for
operating
without a VCS.
Note: The American Institute of Chemical Engineers
publications,
Guidelines for Hazard Evaluation Procedures and Chemical Process
Quantitative
Risk Assessment, may be used as guidance when preparing a qualitative
or
quantitative failure analysis, respectively.
C. The certifying entity must conduct all initial inspections
and witness all tests required to demonstrate that the facility:
l. Conforms to certified plans and specifications;
2. Meets the safety requirements of this part; and
3. Is operating properly.
D. Upon receipt of written certification from the certifying
entity that a facility's VCS complies with these safety standards, the
Captain of the Port shall endorse the facility operations manual, as
described
in Section Sixteen of this part, to indicate that the facility is
acceptable
for collecting vapors during cleaning operations.
E. Any design or configuration alteration involving a certified
VCS must be reviewed by a certifying entity. After conducting any
inspections and witnessing tests necessary to verify that the modified
VCS meets the standards of this part, the certifying entity must
recertify
the installation.
F. Certifications issued in accordance with this section, as
well as a copy of all plans, calculations and specifications for the
VCS
must be maintained at the facility.
G. A certifying entity, accepted under 33 CFR 154.806, may not
certify a cleaning facility VCS if the certifying entity was involved
in
the design or installation of the system.
Section Four - Vapor Control System (VCS), General
A. A VCS design and installation must eliminate potential over
pressure and vacuum hazards, and sources of ignition to the maximum
extent
practical. Each remaining hazard source which is not eliminated
must
be specifically addressed in the protection system design and
operational
requirements.
B. Vapor collection system piping and fittings must be in
accordance
with the American National Standards Institute (ANSI) standard B31.3
and
designed for a maximum allowable working pressure of at least 150
pounds
per square inch gauge (psig). Valves and flanges must be in accordance
with ANSI 816.5 or B16.24, 150 pound class.
C. All electrical equipment used in a VCS must comply with the
National Fire Protection Association (NFPA) standard 70, National
Electric
Code, 1987.
D. Any pressure, flow, or concentration indication listed in
these standards must provide a remote indicator at the cleaning
facility
where the VCS is controlled.
E. Any alarm condition specified in this part must activate
an audible and visible alarm at the cleaning facility where the VCS is
controlled.
F. The VCS must be separated or insulated from external heat
sources to limit VCS piping surface temperature to not more than 70% of
the auto-ignition temperature in degrees Celsius of the vapors being
gas
freed during normal operation.
G. A means must be provided to eliminate any liquids from the
vapor collection system.
H. A liquid knockout vessel must be installed between the
facility
vapor connection and any vapor moving device in systems that have the
potential
for two phase (vapor/liquid) flow from the barge or has the potential
for
liquid condensate forming as a result of the enrichment process.
The liquid knockout vessel must have:
l. A means to indicate the level of liquid in the device;
2. A high liquid level sensor that activates an alarm;
and
3. A high high liquid level sensor that closes the
remotely
operated cargo vapor shutoff valve described in Section Five, paragraph
A. and shuts down any vapor moving device prior to liquid carrying over
to the vapor moving device. The high high liquid level sensor
must
be independent of the high liquid level sensor listed in H.2. of this
section.
I. Vapor collection piping must be electrically grounded and
electrically continuous.
J. If the facility handles inerted vapors of cargoes containing
sulfur, provisions must be made to control heating from pyrophoric iron
sulfide deposits in the vapor collection line.
K. Each cleaning facility that utilizes a vapor collection
system
must maintain a list of cargoes for which the system is approved.
This list must be made part of the facility operations manual and be
approved
by the certifying entity during the initial system review. If a
facility
wishes to add more cargoes to this list, a certifying entity must be
contacted
to complete a recertification of the facility.
Section Five - Vapor Line Connections
A. A remotely operated cargo vapor shutoff valve must be
installed
in the vapor collection line between the facility vapor connection and
nearest point where any inerting, enriching, or diluting gas is
introduced
into the vapor collection line or where a detonation arrester is
fitted.
The valve must:
1. Close within thirty (30) seconds after detection of
a shutdown condition by components listed in this part;
2. Close automatically if the control signal is lost;
3. Activate an alarm when a signal to shutdown is
received;
4. Be capable of manual operation or manual activation;
5. Have a local valve position indicator or be designed
so that the valve position can be readily determined from the valve
handle
or valve stem position; and
6. If the valve seat is fitted with resilient material,
not allow appreciable leakage when the resilient material is damaged or
destroyed. The definition of "appreciable" may be found in 46 CFR
56.20-15(c)(1).
B. A fluid displacement system must have a remotely operated
shutoff valve installed in the fluid injection supply line between the
point where the inert gas or other medium is generated and the fluid
injection
connection. The valve must:
1. Close within thirty (30) seconds after detection of
a shutdown condition by components listed in this part;
2. Close automatically if the control signal is lost;
3. Activate an alarm when a signal to shutdown is
received;
4. Be capable of manual operation or manual activation;
5. Have a local valve position indicator or be designed
so that the valve position can be readily determined from the valve
handle
or valve stem position; and
6. If the valve seat is fitted with resilient material,
not allow appreciable leakage when the resilient material is damaged or
destroyed. The definition of "appreciable" may be found in 46 CFR
56.20-15(c)(1).
C. Each hose used for transferring vapors must:
l. Have a design burst pressure of at least 25 psig;
2. Have a maximum allowable working pressure of et least
5 psig;
3. Be capable of withstanding at least the maximum vacuum
rating of the vapor moving device without collapsing or constricting
when
subject to a vacuum;
4. Be electrically continuous with a maximum resistance
of ten thousand (10,000) ohms;
5. Have flanges with a bolt hole arrangement complying
with the requirements for ANSI B16.5 150 pound class flanges; and
6. Be abrasion resistant, resistant to kinking, and
compatible
with the vapors being transferred.
D. Vapor hose handling equipment must be provided with
hose saddles which provide adequate support to prevent kinking or
collapse
of hoses.
E. Fixed vapor collection arms must meet the standards
of paragraph C. of this section.
F. The facility vapor connection must be electrically
insulated from the barge vapor connection in accordance with section
6.10
of the Oil Companies International Marine Forum (OCIMF) publication
International
Safety Guide for Oil Tankers and Terminals.
Section Six - Facility Requirements For Barge Vapor Over pressure
And Vacuum Protection
A. A facility's vapor collection system must have a
capacity
for collecting cleaning facility vapors at a rate of not less than l.l
times the facility's maximum allowable gas freeing rate, plus any
inerting,
diluting, or enriching gas which may be added to the system.
B. A facility vapor collection system must maintain the
pressure in the barge's cargo tanks between 80% of the highest setting
of any of the barge's vacuum relief valves and 80% of the lowest
setting
of any of the barge's pressure relief valves. The system must be
capable of maintaining the pressure in the barge's cargo tanks within
this
range at any gas freeing rate less than or equal to the maximum gas
freeing
rate determined by the requirements in Section Seven, paragraph C. in
Part
B of these standards.
C. A fluid displacement system must provide a pressure
sensing device which activates an alarm when the pressure at the fluid
injection connection exceeds either the pressure corresponding to the
upper
pressure determined in paragraph H. of this section or a lower pressure
agreed upon by the facility and barge persons in charge. The
pressure
sensing device must be located in the fluid displacement system's
piping
down stream of any devices that could potentially isolate the barge
from
the pressure sensing device. The pressure measured by the sensing
device must be corrected for pressure drops across any barge piping,
hoses,
or arms used to inject the fluid.
D. A fluid displacement system must provide a pressure
sensing device, independent of the device required by paragraph C. of
this
section, which activates the fluid displacement system emergency
shutdown
and closes the remotely operated cargo vapor shutoff valve of Section
Five,
paragraph A. and the remotely operated shutoff valve of Section Five,
paragraph
B. when the pressure at the fluid injection connection reaches 90% of
the
lowest setting of any pressure relief valve on the barge. The
pressure
sensing device must be located in the fluid displacement system's
piping
downstream of any device that could potentially isolate the barge from
the pressure sensing device. The pressure measured by the sensing
device must be corrected for pressure drops across any barge piping,
hoses
or arms used to inject the fluid.
E. If a compressor, blower, eductor or other vapor moving
device capable of drawing more than 0.5 psig vacuum is used to draw
vapor,
air, inert gas or other medium from the barge, a vacuum relief valve
must
be installed on the facility's fixed vapor collection system piping
between
the facility vapor connection and the vapor moving device. The
vacuum
relief valve must meet the following standards:
l. Relieves at a pressure not to exceed 0.5 psig vacuum;
2. Has a relieving capacity equal to or greater than the
maximum capacity of the vapor moving device;
3. Has a flame screen or flame arrester fitted at the
relief opening;
4. Has been tested for relieving capacity in accordance
with paragraph 1.5.1.3. of American Petroleum Institute (API) standard
2000 with a flame screen or flame arrester fitted; and
5. Has materials of construction compatible with
the vapors being gas freed.
F. The vacuum relief valve standard of paragraph E. of this
section may include a valve to isolate it from the facility vapor
collection
piping, provided the following criteria are met:
1. The isolation valve must be interlocked with
any blower, vacuum pump, or other vapor moving device such that
start-up
of the vapor mover cannot occur unless the isolation valve is in the
full
open position (i.e., the vacuum relief valve is not isolated); and
2. The isolation valve can only be closed after
the facility person in charge has acknowledged that the hatch opening
required
by Section Thirteen, paragraph I. of this part is open and secured.
G. If a compressor, blower, eductor, or other vapor moving
device capable of drawing more than 0.5 psig vacuum is used to draw
vapor,
air, inert gas, or other medium from the barge, the facility must
install
portable, intrinsically safe pressure sensing devices on any cargo tank
at the connection required by Section Five, paragraph B. in Part B of
these
standards before any cleaning operation begins on the tank. A
pressure
sensing device must be provided which activates:
l. An alarm when the pressure in the cargo tank
being cleaned falls below 80% of the highest setting of any of the
barge's
vacuum relief valves, or a higher pressure agreed upon by the facility
and barge persons in charge; and
2. The emergency shutdown system for the vapor
moving
device and closes the remotely operated cargo vapor shutoff valve
described
in Section Five, paragraph A. of this part when the pressure in the
cargo
tank being cleaned falls below 90% of the highest setting of any of the
barge's vacuum relief valves, or a higher pressure agreed upon by the
facility
and barge persons in charge. This pressure sensing device must be
independent of the device used to activate the alarm required by
paragraph
G.l of this section.
H. The pressure sensing devices required by paragraph
G. of this section must meet the following criteria:
1. Have suitable means, such as approved intrinsic
safety barriers able to accept passive devices, to ensure that the
underpressure
alarm circuits of the barge side of the underpressure control system,
including
cabling, normally closed switches, and pin and sleeve connectors, are
intrinsically
safe;
2. Are connected to the underpressure alarm system
by a 4 wire, 16 amp shielded flexible cable; and
3. The cable shielding must be grounded to the
underpressure
alarm system.
I. A pressure indicating device must be provided within 6 meters
(19.7 feet) of the facility vapor connection which indicates the
pressure
in the vapor collection line.
J. A fluid displacement system must include a pressure
indicating
device within 6 meters (19.7 feet) of the fluid injection connection
which
indicates the pressure in the fluid displacement system injection line.
K. If a fluid displacement system used to inject inert gas or
other medium into the cargo tank of a barge being gas freed is capable
of producing a pressure greater than 2.0 psig, a pressure relief valve
must be installed in the fluid displacement system injection line
between
the fluid injection source and the fluid injection connection which:
1. Relieves at a pressure such that the pressure
in the fluid displacement system at the fluid injection connection does
not exceed 1.5 psig;
2. Has a relieving capacity equal to or greater
than the maximum volumetric flow capacity of the fluid displacement
system;
3. Has a flame screen or flame arrester fitted at
the relief opening; and
4. Has been tested for relieving capacity in
accordance
with paragraph 1.5.1.3. of API 2000 with a flame screen or flame
arrester
fitted.
L. When using the fluid displacement system, if the pressure
in the facility's fixed vapor collection system can exceed 2.0 psig due
to a malfunction in an inerting, enriching, or diluting system a
pressure
relief valve must:
l. Be installed between the point where inerting,
enriching, or diluting gas is introduced into the facility's fixed
vapor
collection system piping and the facility vapor connection;
2. Relieve at a pressure such that the pressure
in the vapor collection system at the facility vapor connection does
not
exceed 1.5 psig;
3. Have a relieving capacity equal to or greater
than the maximum capacity of the facility inerting, enriching, or
diluting
gas source;
4. Has a flame screen or flame arrester fitted at
the relief opening; and
5. Has been tested for relieving capacity in
accordance
with paragraph 1.5.1.3. of API 2000 with a flame screen or flame
arrester
fitted;
6. Has materials of construction compatible with
the vapors being gas freed.
M. For fluid displacement systems, the fluid injection
connection
must be electrically insulated from the fluid injection source in
accordance
with section 6.10 of the Oil Companies International Marine Forum
(OCIMF)
publication International Safety Guide for Oil Tankers and Terminals.
N. The relieving capacity test required by paragraphs K.4. and
L.5. of this section must be carried out with a flame screen or flame
arrester
fitted at the discharge opening if the pressure relief valve is not
designed
to ensure a minimum vapor discharge velocity of 30 meters (98.4 feet)
per
second.
O. A pressure indicating device must be provided by the facility
for installation on the connection required by Section Five, paragraph
B. in Part B of these standards.
Section Seven - Fire Explosion,, And Detonation Protection
A. A VCS with a single facility vapor connection that
processes vapor other than high flash point cargoes with a vapor
recovery
unit must:
1. Have a detonation arrester located within 6
meters
(19.7 feet) of the facility vapor connection; or
2. Have an inerting, enriching, or diluting system
that meets the standards contained in Section Nine of this part.
B. A VCS with a single facility vapor connection that
processes vapor other than high flash point cargoes with a vapor
destruction
unit must:
1. Have a detonation arrester located within 6
meters
(19.7 feet) of the facility vapor connection; and
2. Have an inerting, enriching, or diluting system
that meets the standards contained in Section Nine of this part.
C. A VCS with multiple facility vapor connections that
processes vapor other than high flash point cargoes with a vapor
recovery
unit must have a detonation arrester located within 6 meters (19.7
feet)
of each facility vapor connection.
D. A VCS with multiple facility vapor connections that
processes vapor other than high flash point cargoes with a vapor
destruction
unit must:
l. Have a detonation arrester located within 6
meters
(19.7 feet) of the facility vapor connection; and
2. Have an inerting, enriching, or diluting system
that meets the standards contained in Section Nine of this part.
E. Except for a discharge vent from a vapor destruction
unit, each outlet of a VCS that vents to atmosphere and is not isolated
with a pressure-vacuum relief valve (fitted with a flame screen at
valve
outlet) must have a flame arrester located at the outlet.
Section Eight - Detonation Arresters Flame Arresters And Flame
Screens
A. Each detonation arrester required by the standards
in this part must:
l. Be capable of arresting a detonation from either
side of the device; and
2. Be acceptable to Commandant (G-MOS). A
detonation arrester designed, built, and tested in accordance with
Appendix
A to 33 CFR 154 will be acceptable to Commandant (G-MOS).
B. Each flame arrester required by the standards in this
part must be acceptable to Commandant (G-MOS). A flame arrester
designed,
built, and tested in accordance with Appendix B to 33 CFR 154 will be
acceptable
to Commandant (G-MOS).
C. Each flame screen required by the standards of this
part must be either a single screen of corrosion resistant wire of at
least
30 by 30 mesh, or two screens, both of corrosion resistant wire, of at
least 20 by 20 mesh, spaced not less than 12.5 millimeters (0.5 inch)
or
more than 37.5 millimeters (1.5 inches) apart.
Section Nine - Inerting Enriching And Diluting Systems
A. A VCS which uses an inerting, enriching, or diluting
system must be equipped with a gas injection and mixing arrangement
located
as close as practicable but not more than 10 meters (32.8 feet) from
the
facility vapor connection that ensures complete mixing of the gases
within
20 pipe diameters of the injection point.
B. A VCS that uses an inerting or enriching system may
not be operated at a vacuum after the injection point unless:
l. There are no sleeve type 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.
C. A VCS that uses analyzers to control the amount of
inerting, enriching, or diluting gas injected into the vapor collection
piping must be equipped with at least two analyzers. The
analyzers
must be connected so that:
l. When two 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
paragraphs
G., I., or J.2. of this section. When more than two analyzers are
used, the majority pair controls the inerting or enriching system and
activates
the alarm and automatic shutdown system required by paragraphs G., I.,
or J.2. of this section;
2. When two hydrocarbon analyzers are used, the
lower hydrocarbon concentration reading controls the inerting or
enriching
system and activates the alarm and automatiC shutdown system required
by
paragraph H. of this section. When more than two analyzers are
used,
the majority pair controls the inerting or enriching system and
activates
the alarm and automatic shutdown system required by paragraph H. of
this
section;
3. When two hydrocarbon analyzers are used, the
higher h hydrocarbon concentration reading controls the diluting system
and activates the alarm and automatic shutdown system required by
paragraph
K. of this section. When more than two analyzers are used, the
majority
pair controls the diluting system and activates the alarm and automatic
shutdown system required by paragraph K. of this section.
D. A VCS that uses volumetric measurements to control
the amount of inerting, enriching or diluting gas injected into the
vapor
collection piping must be equipped with at least one analyzer to
activate
the alarms and automatic shutdown systems required by this section.
E. Each oxygen or hydrocarbon analyzer required by this
section must:
l. 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.
F. Oxygen analyzers which operate at elevated temperatures
(i.e., zirconia oxide or thermomagnetic) must not be used.
G. An inerting system must:
1. Supply sufficient inert gas to the vapor stream
to ensure that the oxygen concentration down stream of the injection
point
is maintained below 60% of the minimum oxygen concentration by volume
necessary
for combustion for the specific combination of cargo vapors and
inerting
gas being processed;
2. Activate an alarm when the oxygen concentration
in the vapor collection piping exceeds 60% of the minimum oxygen
concentration
by volume necessary for combustion for the specific combination of
cargo
vapors and inerting gas being processed;
3. Close the remotely operated cargo vapor shutoff
valve required by Section Five, paragraph A. of this part and shutdown
any vapor moving device when the oxygen concentration in the vapor
collection
piping exceeds 70% of the minimum oxygen concentration by volume
necessary
for combustion for the specific combination of cargo vapors and
inerting
gas;
4. The alarm value in paragraph 2. of this section
must be at least 1% less than the shutdown value in paragraph 3. of
this
section. If the oxygen analyzer used to measure oxygen
concentrations
cannot accurately differentiate between the alarm value and the
shutdown
value, the alarm value must be lowered until the analyzer becomes
operable;
5. If a combustion device is used to
produce the inert gas, a detonation arrester and a means to
prevent the backflow of flammable vapors must be installed
between the combustion device and the inert gas injection point.
H. An enriching system must:
1. Supply sufficient compatible hydrocarbon vapor
to the vapor stream to ensure that the hydrocarbon concentration after
the injection point is maintained above 170% by volume of the upper
flammable
limit;
2. Activate an alarm when the hydrocarbon
concentration
in the vapor collection piping falls below 170% by volume of the upper
flammable limit;
3. Close the remotely operated cargo vapor shutoff
valve required by Section Five, paragraph A. of this part and shutdown
any vapor moving device when the hydrocarbon concentration in the vapor
collection piping falls below 150% by volume of the upper flammable
limit;
and
4. For those cargoes with an upper flammable limit
too high to operate under the 170% and 150% by volume constraints in
this
section, the hydrocarbon analyzer must activate an alarm at no less
than
the upper flammable limit + 10% and shutdown at no less than the upper
flammable limit + 7.5%. The upper flammable limit is either the
cargo's
upper flammable limit or the enriching gas upper flammable limit,
whichever
is higher.
I. Oxygen analyzers may be used in lieu of hydrocarbon
analyzers in an enriching system at a facility that receives cargo
vapor
only from a barge with non-inerted cargo tanks, provided that the
analyzers:
l. Activate an alarm when the oxygen concentration
in the vapor collection piping exceeds a level corresponding to a
hydrocarbon
concentration of 170% of the upper flammable limit;
2. Close the remotely operated cargo vapor shutoff
valve required by Section Five, paragraph A. of this part and shutdown
any vapor moving device when the oxygen concentration in the vapor
collection
piping exceeds a level corresponding to a hydrocarbon concentration of
150% of the upper flammable limit;
3. For those cargoes with an upper flammable limit
too high to operate under the 170% and 150% by volume constraints, the
oxygen analyzers must activate an alarm and shutdown when the oxygen
concentration
exceeds a level corresponding to the upper flammable limit + 10%, and
the
upper flammable limit + 7.5%, respectively. For this purpose, the
upper flammable limit is either the cargo's upper flammable limit or
the
enriching gas upper flammable limit, whichever is higher; and
4. The alarm value in paragraph H.l. of this section
must be at least 1% less than the shutdown value in paragraph H.2. of
this
section. If the oxygen analyzer used to measure oxygen
concentrations
cannot accurately differentiate between the alarm value and the
shutdown
value, the alarm value must be lowered until the analyzer becomes
operable.
J. An enriching system may be used in a vapor collection
system that collects vapors from a barge with inerted cargo tanks if:
l. Hydrocarbon analyzers are used to comply with
paragraphs G.2. through G.4. of this section; or
2. If oxygen analyzers are used, the analyzers must
activate an alarm when the oxygen concentration in the vapor collection
piping exceeds 60% by volume of the minimum oxygen concentration for
the
specific combination of cargo vapors and inerting gas. The analyzers
shall
also close the remotely operated cargo vapor shutoff valve required by
Section Five, paragraph A. of this part and shutdown any vapor moving
device
when the oxygen concentration exceeds 70% by volume of the minimum
oxygen
concentration necessary for combustion for the specific combination of
cargo vapors and inerting gas.
K. An air dilution system must:
l. Supply sufficient additional air to the vapor
stream to ensure that the hydrocarbon concentration throughout the
vapor
collection system is maintained below 30% by volume of the lower
flammable
limit;
2. Activate an alarm when the hydrocarbon
concentration
in the vapor collection piping exceeds 30% by volume of the lower
flammable
limit; and
3. Close the remotely operated cargo vapor shutoff
valve required by Section Five, paragraph A. of this part and shutdown
any vapor moving device when the hydrocarbon concentration in the vapor
collection piping exceeds 50% by volume of the lower flammable limit.
Section Ten - Compressors, Blowers, And Other Vapor Moving Devices
A. Each inlet and outlet to a compressor, blower, or other
vapor moving device which handles vapor other than high flash point
cargo
that has not been inerted, enriched, or diluted prior to the inlet of
the
vapor moving device in accordance with the standards contained in
Section
Nine of this part must be fitted with a detonation arrester. The
detonation arrester must be located within 6 meters (19.7 feet) of the
inlet and outlet of the vapor moving device.
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:
l. Excessive discharge gas temperature at each
compressor
chamber or cylinder;
2. Excessive cooling water temperature;
3. Excessive vibration;
4. Low lube oil level;
5. Low lube oil pressure; and
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:
l. Low level of liquid sealing medium;
2. Lack of flow of liquid sealing medium; and
3. Excessive temperature of the liquid sealing
medium.
D. If a centrifugal compressor, fan, or lobe blower
handles vapor other than high flash point cargoes 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.
E. Before initial use of a blower, compressor, or other vapor
moving device in a cleaning operation, the maximum flow capacity of the
device must be determined for the installed piping configuration.
This shall be done by installing a temporary flow measuring device at
the
point where the vapor collection hose would attach to the facility
vapor
connection. For the test, no hose or barge should be connected to
the system. The vapor moving device should then be allowed to run
at its maximum capacity, and the actual flow of air into the system
determined.
Section Eleven - Vapor Recovery And Vapor Destruction Units
A. The inlet to a vapor recovery unit which receives vapor
other than from high flash point cargo that has not been inerted,
enriched,
or diluted in accordance with the standards contained in Section Nine
of
this part must be fitted with a detonation arrester. The
detonation
arrester must be located within 6 meters (19.7 feet) of the inlet to
the
vapor recovery unit.
B. The inlet to a vapor destruction unit that processes
vapors other than high flash point cargo must:
l. Have a liquid seal, or other acceptable means
to prevent backflow of vapors provided that the manufacturer of the
vapor
destruction unit certifies the unit to be as safe from a flameback
occurrence
as a vapor destruction unit with a liquid seal; and
2. Have installed two quick closing stop valves
in the vapor collection piping. At least one of these valves must
be located immediately upstream of the detonation arrester required by
paragraph C. of this section.
C. The manufacturer's certification allowed under
paragraph
B. of this section must be submitted in writing to the certifying
entity
prior to a review of the qualitative failure analysis required in
Section
Three of this part. Commandant (G-MOS) may be consulted for
assistance.
D. A vapor destruction unit processing vapors other than
high flash point cargoes must:
l. Not be within 30 meters (98.8 feet) of any tank
barge berth or mooring at the facility;
2. Have a detonation arrester fitted in the vapor
collection piping. This detonation arrester must be located
within
6 meters (19.7 feet) of the inlet to the vapor destruction unit;
3. Alarm and shutdown when a flame is detected on
the detonation arrester; and
4. Have an inerting, enriching, or diluting system
meeting the standards contained in Section Nine of this part installed
in the vapor collection piping so that any vapors entering the
combustion
device have been rendered noncombustible in the piping system.
E. A vapor destruction unit processing vapors of only
high flash point cargoes must:
l. Not be within 30 meters (98.8 feet) of any tank
barge berth or mooring at the facility;
2. Have a detonation arrester fitted in the vapor
collection piping. This detonation arrester must be located
within
6 meters (19.7 feet) of the inlet to the vapor destruction unit;
3. Alarm and shutdown when a flame is detected on
the detonation arrester.
F. When a vapor destruction unit shuts down or has a
flame-out
condition, the vapor destruction unit control system must:
l. Close the quick closing stop valves required
by paragraph B. of this section;
2. Close the remotely operated cargo vapor shutoff
valve required by Section Five, paragraph A. of this part;
3. Automatically shutdown any compressors, blowers,
or other vapor moving devices installed in the vapor collection system;
and
4. For fluid displacement systems, close the
remotely
operated shutoff valve required by Section Five, paragraph B. of this
part.
Section Twelve - Personnel Training
A. A facility person in charge of a cleaning operation
utilizing a VCS must have completed a training program covering the
particular
system installed at the facility and on the barge. Training must
include
drills or demonstrations using the installed VCS covering normal
operations
and emergency procedures.
B. The training program required by paragraph A. of this
section must cover the following subjects:
l. Purpose of a stripping, gas freeing and VCS;
2. Principles of the stripping, gas freeing and
VCS;
3. Components of the stripping, gas freeing and
VCS;
4. Hazards associated with the stripping, gas
freeing
and VCS;
5. Special hazards associated with the accumulation
and discharge of static electricity;
6. Coast Guard standards in this part; and
7. Operating procedures, including:
(a) Testing and inspection requirements;
(b) Pre-cleaning procedures;
(c) Chemicals approved for collection;
(d) Material safety data sheet review;
(e) Connection sequence;
(f) Start-up procedures;
(g) Safeguards to prevent static electricity
discharge;
(h) Normal operations; and
(i) Emergency procedures.
Section Thirteen - Operational Requirements
A. A facility can receive vapors only from a barge which
meets the standards contained in Part B.
B. The following test and checks must be performed by
the facility person in charge not more than 24 hours prior to each
cleaning
operation:
l. Pressure alarms and automatic shutdown systems
required by this part must be tested. Each test must include a
realistic
application of pressure and vacuum necessary to provide an operating
test;
2. The analyzers required by Section Nine, paragraph
E. of this part must be checked for calibration according to the
manufacturer's
recommendations; and
3. The vacuum relief valve required by Section Six,
paragraph E. of this part and the pressure relief valves required by
Section
Six, paragraphs K. and L. of this part must be checked to make sure
they
are operating freely and flame screens or flame arresters are not
damaged.
C. The position of all valves in the vapor line between
the barge's cargo tanks and the facility vapor collection system must
be
verified prior to the start of the cleaning operation.
D. The gas freeing rate must not exceed the maximum
allowable
gas freeing rate as determined by the lesser of the following:
l. A gas freeing rate corresponding to the maximum
vapor processing rate for the cleaning facility VCS, as specified in
the
facility operations manual; or
2. The barge's maximum gas freeing rate determined
in accordance with Section Seven, paragraph C. in Part B of these
standards.
E. Mixing of incompatible vapors is prohibited.
The vapor collection system piping, equipment, hoses, valves, and
arresters
must be purged between gas freeing operations that involve incompatible
chemical vapors. The purge must be inert gas, air or enriching
gas,
and must be adequate to reduce the level of residual vapor to a level
where
reaction with the subsequent vapor cannot occur. The required
duration
of purge time must be determined by calculation and approved by the
certifying
entity during the initial review. Chemical compatibility must be
determined by using the procedures contained in 46 CFR 150
Compatibility
of Cargoes.
F. If one or more analyzers required by Section Nine,
paragraph C. become inoperable during gas freeing operations, the
operation
may continue provided that at least one analyzer remains
operational.
However, no further gas freeing operations may be started until all
inoperable
analyzers are repaired or replaced.
G. Whenever a condition results in a shutdown of the VCS,
the facility person in charge shall immediately terminate cleaning
operations.
The operation may not be restarted until the cause of the shutdown has
been investigated and corrective action taken.
H. If it is suspected that a flare in the VCS has had
a flashback, or if a flame is detected on the detonation arrester
required
by Section Eleven, paragraph D.2. or paragraph E.2. of this part, the
cleaning
operation must be stopped and may not be restarted until the detonation
arrester has been inspected and found to be in satisfactory condition.
I. If a vacuum displacement system is used for gas
freeing,
the following items must be verified by the facility person in charge
of
the cleaning operation:
l. The minimum amount of open area for air flow
on the barge has been determined so that the pressure in the cargo tank
cannot be less than 0.2 psig vacuum, which is equivalent to 14.5 pounds
per square inch absolute (psia), at the maximum flow capacity of the
vapor
moving device;
2. The hatch and/or fitting providing the minimum
open area has been secured open so that accidental closure is not
possible;
3. The hatch and/or fitting must be opened before
the pressure in the cargo tank falls below 10% of the highest setting
of
any of the barge's vacuum relief valves.
J. All alarms, shutdowns and other operating systems
should
be tested at least once a year in accordance with the standards
contained
in 33 CFR 156.170(g). This test must be witnessed by a
representative
of the local Coast Guard Captain of the Port. The test procedure
must be approved by the certifying entity during the initial
certification
of the system and incorporated into the facility operations manual.
K. Prior to commencing any cleaning operation, the
freezing
point of the cargo must be determined and adequate precautions taken to
prevent the cargo vapor from condensing and freezing if there is a
possibility
that the ambient air temperature during cleaning operations will be at
or below the freezing point of the cargo vapor.
L. Prior to commencing any cleaning operation, the cargo
vapor must be evaluated for the potential to polymerize and adequate
precautions
taken to prevent and detect polymerization of the cargo vapors.
M. The maximum allowable stripping rate must be determined
prior to commencing stripping operations. The maximum allowable
stripping
rate cannot exceed the volumetric capacity of the barge's vacuum relief
valve at the valve's set point for the cargo tank being stripped.
N. When required by Section Six, paragraph G. of this
part, the pressure sensing devices must be installed and tested in
accordance
with paragraph B. of this section prior to commencement of cleaning
operations.
Section Fourteen - Special Requirements
A. A vapor collection system that collects vapors with
the potential to polymerize must meet the following:
1. The VCS must be designed to prevent condensation
of monomer vapor. Methods such as heat tracing and insulation are
permitted if they will not result in an increased risk of
polymerization;
2. The facility vapor collection system must be
designed so that polymerization can be detected. Any points
suspected
of being sites for potential polymerization buildup should be equipped
with inspection openings meeting the requirements of Section Four,
paragraph
B.; and
3. The facility vapor collection system must include
devices to measure the pressure drop across detonation arresters due to
polymerization. Any device used for this purpose, including
differential
pressure monitors, must not be capable of transmitting a detonation
across
the detonation arrester.
B. A vapor collection system that collects vapors with
the potential to freeze at normal ambient conditions must be designed
to
prevent condensation of the cargo vapors, or to remove the condensation
before it can accumulate.
Section Fifteen - Equipment Tests And Inspections
A. The following must be verified by the facility person
in charge prior to commencing cleaning operations:
l. Each manual valve in the vapor collection system
is correctly positioned to allow the collection of vapors;
2. A vapor collection hose or arm is connected to
the barge's vapor collection
system
; ;
3. The electrical insulating devices required by
Section Five, paragraph F. and Section Six, paragraph M. of this part
are
installed;
4. The maximum allowable gas freeing rate is
determined;
5. The maximum allowable stripping rate is
determined;
6. The maximum and minimum operating pressures of
the barge are determined;
7. Each vapor collection hose has no unrepaired
loose covers, kinks, bulges, soft spots, or any other defect which
would
permit the discharge of vapor through the hose material, and no
external
gouges, cuts, or slashes that penetrate the first layer of hose
reinforcement.
B. A vapor collection system must not be used unless the
following tests and inspections are satisfactorily completed:
1. Each vapor collection hose, vapor collection
arm pressure or vacuum relief valves, and pressure sensors are tested
and
inspected in accordance with 33 CFR 156.170(b), (c) and (f);
2. Each remote operating or indicating device is
tested for proper operation in accordance with 33 CFR 156.170(f); and
3. Each detonation arrester has been inspected
internally
within the last year, or more frequently if operational experience has
shown that frequent clogging or rapid deterioration is likely.
Section Sixteen - Facility Operations Manual
A. In addition to the requirements contained in 33 CFR
154.310, the facility operations manual shall include the following
information:
1. A physical description of the cleaning facility
including a plan of the facility showing mooring areas, locations where
cleaning operations are conducted, control stations, and locations of
safety
equipment;
2. The sizes, types, and number of barges the
facility
can conduct cleaning operations from simultaneously; and
3. The minimum number of persons required to be
on duty during cleaning operations and their duties.
B. Cleaning operations using a VCS may not be conducted
unless the facility operator has a valid endorsement for the facility
operations
manual from the Coast Guard Captain of the Port.
Section Seventeen - Facility Person In Charge: Designation And
Qualifications
A. In addition to the requirements contained in 33 CFR
154.710, the designation and qualifications for the facility person in
charge shall include the following:
1. No person may serve, and the facility operator
may not use the services of a facility person in charge of a cleaning
operation
unless the person has been properly trained and certified by the
facility
with a minimum of at least 60 hours of experience in cleaning
operations.
Section One - Applicability
A. These standards apply to each tank barge which collects
vapors emitted from a barge's cargo tanks through a VCS during gas
freeing
or cleaning operations at a cleaning facility. These standards do
not apply to the collection of vapors emitted during tank barge cargo
loading
or lightering operations.
B. These standards do not apply to the collection of
vapors
of liquefied flammable gases as defined in 46 CFR 30.10-39.
Section Two - Definitions
The following definitions apply to terms used in this part:
Barge vapor connection means the point in a barge's piping
system
where it connects to a vapor collection hose or arm. This may be
the same as the barge's cargo connection.
Cargo tank venting system means the venting system required
by 46 CFR 32.55.
Cleaning facility means a facility used or capable of being used to
conduct cleaning operations on a tank barge.
Cleaning operation means any stripping, gas freeing, or tank
washing operation of a barge's cargo tanks conducted at a cleaning
facility.
Combustible liquid means a liquid as defined in 46 CFR 30.10-15.
Gas freeing means the removal of vapors from a tank barge.
Facility means an onshore or mobile facility which includes,
but is not limited to structures, equipment, and appurtenances thereto,
used or capable of being used to transfer and control vapors.
Facility vapor connection means the point in a facility's fixed
vapor collection system where it connects to a vapor collection hose or
the base of a vapor collection arm.
Fixed stripping line means a pipe extending to the low point
of each cargo tank, which is welded through the deck and terminates
above
deck with a valve, plugged at the open end.
Flammable liquid means a liquid as defined in 46 CFR 30.10-22.
Flame arrester means a device which is designed, built, and
tested in accordance with Appendix B to 33 CFR 154 for use in
end-of-line
applications for arresting flames.
Fluid displacement system means a system that removes vapors
from a barge's cargo tanks during gas freeing through the addition of
an
inert gas or other medium into the cargo tank.
Fluid injection connection means the point in a fluid
displacement
system at which the fixed piping or hose that supplies the inert gas or
other medium connects to a barge's cargo tanks or fixed piping system.
High flash point cargoes means Grade E cargoes and cargoes
having
a closed cup flash point greater than 60o C, carried at a temperature
no
higher than 5o C below their flash points.
Inerted means the oxygen content of the vapor space in a barge's
cargo tank is reduced to 8% or less by volume in accordance with the
inert
gas requirements of 46 CFR 32.53.
Maximum allowable gas freeing rate means the maximum volumetric
rate at which a barge may be gas freed during cleaning operations.
Maximum allowable stripping rate means the maximum volumetric
rate at which a barge may be stripped during cleaning operations prior
to the opening of any hatch and/or fitting on the cargo tank being
stripped.
Stripping means the removal, to the maximum extent practicable,
of cargo residue remaining in the barge's cargo tanks and associated
fixed
piping system after cargo transfer or during cleaning operations.
Vacuum displacement system means a system that removes vapors
from a barge's cargo tanks during gas freeing by sweeping air through
the
cargo tank hatch openings.
Vapor collection system means an arrangement of piping and hoses
used to collect vapor emitted from a barge's cargo tanks and transport
the vapor to a vapor processing unit.
Vapor control system (VCS) means an arrangement of piping and
equipment used to control vapor emissions collected from a barge, and
includes
the vapor collection system and the vapor processing unit.
Vapor processing unit means the components of a VCS that
recovers,
destroys, or disperses vapor collected from a barge.
Section Three - Submission Of Vapor Control System (VCS) Designs
A. Plans, calculations, and specifications for a tank
barge's vapor collection and stripping systems must be submitted to the
Marine Safety Center for approval prior to utilization in cleaning
operations.
B. Upon satisfactory completion of plan review and
inspection
of the vapor collection system, the Officer in Charge, Marine
Inspection
shall endorse the Certificate of Inspection that the barge is
acceptable
for collecting vapor during a cleaning operation.
Section Four - Design And Equipment Of Vapor Collection And
Stripping
Systems
A. Each barge engaged in cleaning operations at an
approved
cleaning facility must have a conductive fixed stripping line installed
in each cargo tank. The line must extend to the low point of each
cargo tank, extend through and be welded to the top of the cargo tank,
and terminate above deck with a full port valve plugged at the open
end.
B. An existing fixed stripping system may be used in lieu
of the stripping line required in paragraph A. of this section.
C. Each stripping line must be labeled with the words
"Stripping Line Tank # XXX" in an on-deck location.
D. Vapors may be collected from the barge's cargo tanks
through a common fixed vapor header, through the fixed liquid cargo
header,
or through flanged flexible hoses located at the top of each cargo
tank.
E. The vapor collection system must not interfere with
the proper operation of the cargo tank venting system.
F. A barge being gas freed by a fluid displacement system
must meet the following:
l. If the fluid medium is a compressible fluid,
such as inert gas, it may be injected into the barge's cargo tanks
through
a common fixed vapor header, through the fixed liquid cargo header, or
through flanged flexible hoses located at the top of each cargo tank;
2. If the fluid medium is a non compressible fluid,
such as water, it must be injected into the barge's cargo tanks through
the fixed liquid cargo header only;
3. If the fluid medium is a non compressible fluid,
such as water, the barge must be equipped with and meet the
requirements
for tank barge liquid overfill protection contained in 46 CFR 39.20-9.
G. The barge vapor connection must be electrically
insulated
from the facility vapor connection and the fluid injection connection
must
be electrically insulated from the fluid injection source, if fitted,
in
accordance with section 6.10 of the OCIMF publication International
Safety
Guide for Oil Tankers and Terminals.
H. Vapor collection piping must be electrically bonded
to the barge hull and must be electrically continuous.
I. All equipment used on the barge during cleaning
operations
must be electrically bonded to the barge and tested to ensure
electrical
continuity prior to each use.
J. Each hose used for the transfer of vapors during
cleaning
operations must:
l. Have a design burst pressure of at least 25 psig;
2. Have a maximum allowable working pressure of
at least 5 psig;
3. Be capable of withstanding at least the maximum
vacuum rating of the cleaning facility's vapor moving device without
collapsing
or constricting when subject to a vacuum;
4. Be electrically continuous with a maximum
resistance
of ten thousand (10,000) ohms; and
5. Have flanges with a bolt hole arrangement
complying
with the requirements for ANSI B16.5 150 pound class flanges; and
6. Be abrasion resistant, resistant to kinking,
and compatible with the vapors being transferred.
K. Each hose used for the transfer of liquids during
cleaning
operations must:
1. Have a design burst pressure of at least 600
psig;
2. Have a maximum allowable working pressure of
at least 150 psig;
3. Be capable of withstanding at least the maximum
vacuum rating of the cleaning facility's vapor moving device without
collapsing
or constricting;
4. Be electrically continuous with a maximum
resistance
of ten thousand (10,000) ohms; and
5. Have flanges with a bolt hole arrangement
complying
with the requirements for ANSI B16.5 150 pound class flanges; and
6. Be abrasion resistant, resistant to kinking,
and compatible with the liquids being transferred.
L. If hose is used to transfer either vapor or liquid
from the barge during cleaning operations, hose handling equipment must
be provided with hose saddles which provide adequate support to prevent
kinking or the collapse of hoses.
Section Five - Underpressure Protection During Stripping
Gas
freeing Operations
A. The cargo tank venting system required by 46 CFR 32.55
must:
1. Not exceed the maximum design working pressure
for the cargo tank; and
2. Not exceed the maximum design vacuum for the
cargo tank.
B. Each barge must be fitted with a means for
connecting
the pressure sensors and pressure indicating devices required by
Section
Six, paragraphs G. and O. of Part A on each cargo tank top. The
valved
connection point must be labeled "Pressure Sensor Connection".
C. For stripping operations with closed cargo tanks, the
maximum stripping rate must not exceed the volumetric flow capacity of
the vacuum relief valve protecting the cargo tank to be stripped.
Section Six - Inspection Prior To Conducting Gas freeing
Operations
A. The following inspections must be conducted by the
barge person in charge prior to commencing gas freeing operations:
l. Each part of the barge's vapor collection system
is aligned to allow vapor to flow to a cleaning facility VCS;
2. If a fluid displacement system is used to conduct
gas freeing operations:
(a) The fluid supply line is connected to the fluid
injection connection; and
(b) The maximum fluid injection rate is determined
in accordance with Section Seven, paragraph C.2. of this part;
3. The maximum stripping or gas freeing rate is
determined in accordance with Section Five, paragraph C. of this part
or
Section Seven, paragraph C. of this part, respectively, and adequate
openings
required by Section Seven, paragraph C.l. of this part are available
and
identified;
4. The pressure sensors and pressure indicators
required by Section Six, paragraphs G. and M. of Part A are connected
as
required by Section Five, paragraph B. of this part;
5. The maximum and minimum operating pressures
of the barge being cleaned are determined;
6. Each vapor recovery hose has no unrepaired loose
covers, kinks, bulges, soft spots, or any other defect which would
permit
the discharge of vapors through the hose material, and no gouges, cuts,
or slashes that penetrate the first layer of hose reinforcement;
7. The facility vapor connection must be
electrically
insulated from the barge vapor connection and the fluid injection
connection
must be electrically insulated from the fluid injection source, if
fitted,
in accordance with section 6.10 of the OCIMF publication International
Safety Guide for Oil Tankers and Terminals; and
8. All equipment is bonded in accordance with
Section
Four, paragraph H. of this part.
Section Seven - Operational Requirements
A. Vapors from a tank barge may not be transferred during
cleaning operations to a cleaning facility which does not have its
facility
operations manual endorsed by the Captain of the Port as meeting the
standards
contained in Part A.
B. Prior to commencing stripping operations, the maximum
allowable stripping rate must be determined. The maximum
allowable
stripping rate must not exceed the volumetric flow capacity of the
vacuum
relief valve protecting the cargo tank to be protected.
C. The gas freeing rate must not exceed the maximum
allowable
gas freeing rate as determined by the following:
1. For a vacuum displacement system:
(a) The maximum allowable gas freeing rate is a
function of the area open to the atmosphere for the cargo tank being
gas
freed. The area open to the atmosphere must be large enough to
prevent
the pressure in the cargo tank being gas freed from becoming no less
than
0.2 psi vacuum (14.5 psia). The maximum allowable gas freeing
rate
shall be calculated from Table One (attached) using the area open to
the
atmosphere for the cargo tank being gas freed as the entering argument.
2. For a fluid displacement system, the maximum
allowable gas freeing rate is determined by the lesser of the
following:
(a) Eighty (80%) percent of the total venting
capacity
of the pressure relief valve in the cargo venting system when relieving
at its set pressure;
(b) Eighty (80%) percent of the total vacuum
relieving
capacity of the vacuum relief valve in the cargo tank venting system
when
relieving at its set pressure; or
(c) The rate based on pressure drop calculations
at which, for a given pressure at the facility vapor connection, the
pressure
in the cargo tank being gas freed exceeds 80% of the setting of any
pressure
relief valve in the cargo tank venting system.
D. Any hatch and/or fitting used to calculate the minimum
area required to be open to the atmosphere must be opened and secured
in
such a manner as to prevent accidental closure during
gas freeing. All flame screens for the hatch and/or fitting
opened
shall be removed in order to allow for maximum air flow. The
hatch
and/or fitting must be secured open before the pressure in the cargo
tank
falls below 10% of the highest setting of any of the barge's vacuum
relief
valves.
E. "Do Not Close Hatch/Fitting" signs are conspicuously
posted near the hatch and/or fitting opened during gas freeing
operations.
F. In order to minimize the dangers of static electricity,
all equipment used on the barge during gas freeing and cleaning
operations
must be electrically bonded to the barge and tested to ensure
electrical
continuity before each use.
G. If the barge is equipped with an inert gas system, the inert
gas main isolation valve must remain closed during cleaning operations.
H. Vapors from incompatible cargoes that are collected
simultaneously
must be kept separated throughout the barge's entire vapor collection
system.
Chemical compatibility must be determined in accordance with the
procedures
contained in 46 CFR 150, Part A.
Section Eight - Barge Person In Charge: Designation and
Qualifications
A. The designation and qualification requirements contained
in 33 CFR 155.700 and 33 CFR 155.710(a)(2) apply to the barge person in
charge.
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Disclaimer: A reasonable attempt was made to create an accurate
reproduction
of NVIC 1-96 (presented above). You should confirm information in this
doccument with the USCG in the case that the regulation has changed, or
a typographical error or omission in this presentation would cause
financial
loss or a safety hazard.
Return to the shipyard files page.
Return back to the PURGIT page.