Taylor-Wharton High Capacity GST Storage Tanks User Manual
BT-523
GST-250 PSI
VERTICAL STORAGE TANKS
1500 Gallons
Through
20,000 Gallons
9918-7523
2/23/2012
Do not attempt to use or maintain these units until you read and understand these instructions. Refer to the TaylorWharton’s Safety First booklet (TW-202) for handling cryogenic material. Do not permit untrained persons to use or
maintain this equipment. If you do not understand these instructions, contact your supplier for additional information.
TABLE OF CONTENTS
SAFETY PRECAUTIONS FOR LIQUID OXYGEN ......................................................................... 4
SAFETY PRECAUTIONS FOR LIQUID NITROGEN ..................................................................... 6
INTRODUCTION ................................................................................................................................. 7
FUNCTIONAL DESCRIPTION .......................................................................................................... 7
Tank Construction ..................................................................................................................... 7
Piping ........................................................................................................................................ 7
Fill ............................................................................................................................................. 8
Withdrawal and Economizer .................................................................................................... 8
Pressure Building ...................................................................................................................... 8
Safety Devices ........................................................................................................................... 9
Instrumentation ......................................................................................................................... 9
Vacuum System ...................................................................................................................... 10
INSTALLATION ................................................................................................................................ 11
Handling .................................................................................................................................. 11
Installation Checks .................................................................................................................. 12
Customer Installed Equipment ............................................................................................... 12
Rigging .................................................................................................................................... 14
OPERATION ...................................................................................................................................... 17
Purge Procedure ...................................................................................................................... 17
Filling a Warm Tank ............................................................................................................... 18
Filling a Cold Tank ................................................................................................................. 19
Normal Operation ................................................................................................................... 20
Taking a Tank out of Service .................................................................................................. 21
Tanks in Oxygen Service ........................................................................................................ 21
Tanks In Nitrogen/Argon Service ........................................................................................... 21
MAINTENANCE ................................................................................................................................ 22
General .................................................................................................................................... 22
Leak Testing ............................................................................................................................ 22
Hand Valves ............................................................................................................................ 22
Control Valves ........................................................................................................................ 23
Resetting Control Valves ........................................................................................................ 23
Setting PRESSURE BUILDING REGULATOR (PCV-1): .................................................. 24
Setting ECONOMIZER BACK PRESSURE REGULATOR: ............................................. 24
Inner Vessel and Piping Safety Devices ................................................................................. 24
Pressure and LIQUID LEVEL GAUGES .............................................................................. 25
CASING VACUUM MAINTENANCE ............................................................................................ 26
Checking Vacuum ................................................................................................................... 26
Vacuum PROBE Replacement ............................................................................................... 27
Analyzing Vacuum Deterioration ........................................................................................... 27
PAINTING .......................................................................................................................................... 28
Safety Precautions Pertaining To Painting Operations .......................................................... 28
TROUBLE-REMEDY GUIDE .......................................................................................................... 29
RECOMMENDED TOOLS, EQUIPMENT, AND MATERIALS .................................................. 31
REPLACEMENT PARTS .................................................................................................................. 31
WARNING
Following safety precautions are for your protection. Before performing installation,
operating, or maintenance procedures read and follow all safety precautions in this section
and in reference publications. Failure to observe all safety precautions can result in property
damage, personal injury, or possible death. It is the responsibility of the purchaser of this
equipment to adequately warn the user of the precautions and safe practices for the use of
this equipment and the cryogenic fluid stored in it.
SAFETY PRECAUTIONS FOR LIQUID OXYGEN
Oxygen is a colorless, odorless, and tasteless gas that can be condensed into a liquid at the low
temperature of 297 degrees below zero Fahrenheit (-183°C) under normal atmospheric pressure.
Approximately one-fifth of normal air is oxygen. As a liquid, oxygen is pale blue in color. Oxygen
is non-flammable but vigorously accelerates the burning of combustible materials.
Keep Combustibles Away from Oxygen and Eliminate Ignition Sources
Many substances, which do not normally burn in air, require only a slight spark or moderate heat to
set them aflame in the presence of concentrated oxygen. Other substances, which are only
moderately combustible in air, can burn violently when a high percentage of oxygen is present.
Do not permit smoking or open flame in any area where liquid oxygen is stored, handled, or used.
Keep all organic materials and other flammable substances away from possible contact with liquid
oxygen. Some of the materials that can react violently with oxygen are oil, grease, kerosene, cloth,
wood, paint, and dirt, which contains oil or grease. Under certain conditions flammable materials,
which have become permeated with liquid oxygen, are impact sensitive and can detonate if
subjected to shock.
Keep Area and Exterior Surfaces Clean to Prevent Ignition
As normal industrial soot and dirt can constitute a combustion hazard, all equipment surfaces must
be kept very clean. Do not place oxygen equipment on asphalt surfaces, or allow grease or oil
deposits to remain on benches or concrete surfaces in the vicinity of the oxygen equipment. Use
cleaning agents, which will not leave organic deposits on the cleaned surfaces. Equipment to be
used in contact with liquid oxygen should be handled only with clean gloves or hands washed clean
of oil.
Maintain Adequate Ventilation
Enclosed areas containing oxygen equipment should be ventilated to prevent accumulations of
oxygen and thereby minimize combustion hazards.
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Extreme Cold - Cover Eyes and Exposed Skin
Accidental contact of liquid oxygen or cold issuing gas with the skin or eyes may cause a freezing
injury similar to frostbite. Handle the liquid so that it won't splash or spill. Protect your eyes and
cover the skin where the possibility of contact with the liquid, cold pipes and cold equipment, or the
cold gas exists. Safety goggles or a face shield should be worn if liquid ejection or splashing may
occur or cold gas may issue forcefully from equipment. Clean, insulated gloves that can be easily
removed and long sleeves are recommended for arm protection. Cuffless trousers should be worn
outside boots or over the shoes to shed spilled liquid. If clothing should be splashed with liquid
oxygen or otherwise saturated with the gas, air out the clothing immediately, removing it if
possible. Such clothing will be highly flammable and easily ignited while the concentrated oxygen
remains, and should not be considered safe for at least 30 minutes.
Replacement Parts Must be Suitable for Oxygen Service
Many materials, especially some non-metallic gaskets and seals, constitute a combustion hazard
when in oxygen service, although they may be acceptable for use with other cryogenic liquids.
Make no substitutions for recommended spare parts. Also, be sure all replacement parts are
thoroughly "Cleaned For Oxygen Service" in accordance with Compressed Gas Association (CGA)
Pamphlet G-4.1 "Cleaning for Oxygen Service" or equivalent industrial cleaning specifications.
Observe Safety Codes When Locating Oxygen Equipment
Before locating oxygen equipment, become thoroughly familiar with National Fire Protection
Association (NFPA) Standard No. 50, "Bulk Oxygen Systems", and with all federal, state and local
safety codes. The NFPA Standard covers the general principles recommended for the installation
of bulk oxygen systems on industrial and institutional consumer premises.
CAUTION: When installing field fabricated piping, make certain a suitable safety valve is
installed in each section of piping between shut-off valves.
For more detailed information concerning safety precautions and safe practices to be observed when handling
cryogenic liquids consult CGA pamphlet P-12 "Handling Cryogenic Liquids" available from the Compressed
Gas Association, 1235 Jefferson Davis Highway, Arlington, Va. 22202.
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SAFETY PRECAUTIONS FOR LIQUID NITROGEN
Nitrogen is an inert, colorless, odorless, and tasteless gas, which makes up four-fifths of the air you
breathe. Liquid nitrogen is obtained by cooling air until it becomes a liquid and then removing the
oxygen, which makes up the other fifth of the air. Liquid nitrogen is at a temperature of 320
degrees below zero Fahrenheit (-196°C) under normal atmospheric pressure.
Extreme Cold - Cover Eyes and Exposed Skin
Accidental contact of liquid nitrogen or cold issuing gas with the skin or eyes may cause a freezing
injury similar to frostbite. Handle the liquid so that it won't splash or spill. Protect your eyes and
cover the skin where the possibility of contact with the liquid, cold pipes and cold equipment, or the
cold gas exists. Safety goggles or a face shield should be worn if liquid ejection or splashing may
occur or cold gas may issue forcefully from equipment. Clean insulated gloves that can be easily
removed and long sleeves are recommended for arm protection. Cuffless trousers should be worn
outside boots or over the shoes to shed spilled liquid.
Keep Equipment Area Well Ventilated
Although nitrogen is non-toxic and non-flammable, it can cause asphyxiation in a confined area
without adequate ventilation. Any atmosphere, which does not contain enough oxygen for
breathing, can cause dizziness, unconsciousness, or even death. Nitrogen being colorless, odorless,
and tasteless cannot be detected by the human senses and will be inhaled normally as if it were air.
Without adequate ventilation, the expanding nitrogen will displace the normal air without warning
that a non-life-supporting atmosphere is present. Store liquid containers outdoors or in other wellventilated areas.
Dispose of Waste Liquid Nitrogen Safely
Dispose of waste liquid nitrogen out-of-doors where its cold temperature cannot damage floors or
driveways and where it will evaporate rapidly. An outdoor pit filled with clean sand or gravel will
evaporate liquid nitrogen safely and quickly.
CAUTION: When installing field fabricated piping, make certain a suitable safety valve is
installed in each section of piping between shut-off valves.
For more detailed information concerning safety precautions and safe practices to be
observed when handling cryogenic liquids consult CGA pamphlet P-12 "Handling
Cryogenic Liquids" available from the Compressed Gas Association, 1235 Jefferson Davis
Highway, Arlington, VA 22202.
NOTE: Argon is an inert gas whose physical properties are very similar to those of nitrogen. For handling of
liquid argon, follow the safe practices described for the handling and use of liquid nitrogen.
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INTRODUCTION
This manual provides information for the user to operate and maintain Taylor-Wharton's GST-250
model cryogenic storage tanks which can be supplied with Taylor-Wharton Final Piping or
customer specific Final Piping Options. These tanks are suitable for the storage and delivery of
liquid oxygen, nitrogen or argon at a maximum allowable working pressure of 250 psig (17.24
bar/1724 kPa). They are also suitable for the delivery of gaseous product when combined with a
vaporizer.
Tank specifications, flow diagram and an elevation with bottom view of the tank showing controls
and piping may be found on the General Arrangement Drawings located in the back of this manual.
Additional copies of these drawings may be obtained from the factory. Please include information
on the tank model number and part number in making drawing requests. Tank Specifications,
Rigging Details and Vacuum System Components are also shown in this manual.
FUNCTIONAL DESCRIPTION
TANK CONSTRUCTION
The GST-250 tanks are vertical tanks with a maximum allowable working pressure of 250 psig
(17.24 bar/1724 kPa). The pressure vessel is suspended inside a vacuum jacket and insulated with
perlite powder under high vacuum. The liquid and gas phase lines to the pressure vessel pass
through the lower head of the vacuum jacket. All piping is designed to withstand the stresses
caused by expansion and contraction of the pressure vessel, its support system and piping itself.
The pressure vessel is designed and constructed in accordance with the ASME Boiler and Pressure
Vessel Code Section VIII, Division 1. The inner vessel is constructed of 304 stainless steel and the
piping is stainless steel. The vacuum jacket and leg supports are made of structural steel.
The insulation space between the pressure vessel and the vacuum jacket is filled with perlite
powder insulation and evacuated to a high vacuum through a VACUUM PUMPOUT VALVE that
is permanently sealed at the factory. Insulation space vacuum is measured in the field by
connecting a vacuum gauge to the VACUUM PROBE, which is located on the lower head of the
tank. The VACUUM PROBE is isolated from the vacuum jacket by a VACUUM PROBE
ISOLATION VALVE.
PIPING
The following paragraphs describe the operation of the main circuits of the GST-250 bulk tanks.
The descriptions refer to the main components of each circuit and are grouped by function. These
component and circuit descriptions are pertinent to any of the GST-250 tanks and should be read
before attempting operation.
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FILL
The tank is filled with liquid through the FILL CONNECTION, FILL LINE CHECK VALVE,
and FILL VALVES. One FILL VALVE is connected to the top of the pressure vessel and other
is connected to the bottom of the of the pressure vessel. Filling through the TOP FILL VALVE
tends to reduce tank pressure, while filling through the BOTTOM FILL VALVE tends to
increase tank pressure.
TANK BLOWDOWN VALVE can be opened for venting and throttled to maintain desired tank
pressure during filling.
FILL LINE CHECK VALVE prevents flow out of the tank through the fill connection in the event
of a misconnection or broken line.
FILL LINE DRAIN VALVE is used to vent the fill line during fill hose cool-down, and to drain
liquid product trapped between the fill connection and the fill valves after a fill is completed.
THERMAL EXPANSION RELIEF VALVE will relieve pressure in the fill line that may result
from expanding residual liquid trapped between the FILL LINE CHECK VALVE and the
BOTTOM and TOP FILL VALVES.
The TRYCOCK VALVE is used to determine fill termination.
WITHDRAWAL AND ECONOMIZER
During operation when the tank pressure is below the set point of ECONOMIZER BACK
PRESSURE REGULATOR liquid product is withdrawn through the siphon withdrawal line and
PRODUCT SUPPLY VALVE. When tank pressure exceeds the set point of ECONOMIZER
BACKPRESSURE REGULATOR, and ISOLATION VALVES are open gas will flow from the
top of the tank through PRESSURE BUILDING ISOLATION VALVE, ECONMOMIZER
ISOLATION VALVE, and ECONOMIZER REGULATOR. From BACK PRESSURE
REGULATOR the gas flows back in the annular space economizer line that connects to the
siphon withdrawal line, and finally exits through PRODUCT SUPPLY VALVE. When installed
external vaporizers are normally connected to PRODUCT SUPPLY VALVE.
AUXILIARY LIQUID WITHDRAWAL CONNECTION and AUXILIARY LIQUID LINE
provide liquid only withdrawal from the tank.
VAPOR LINE is the point where vapor product can be returned to the tank from a pump.
The THERMAL EXPANSION RELIEF VALVE will relieve pressure buildup from trapped
product between ECONOMIZER ISOLATION VALVE and ECONOMIZER BACK PRESSURE
REGULATOR.
PRESSURE BUILDING
The pressure building system provides a means of maintaining tank pressure at a preset value
during product withdrawal. This system operates when PRESSURE BUILDING ISOLATION
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VALVES are open. When tank pressure decreases to the PRESSURE BUILDING REGULATOR
setpoint, it opens and liquid flows from the bottom of the tank through PRESSURE BUILDING
COIL. This liquid product is vaporized in the coil and expanded gaseous product returns to the top
of the tank maintaining tank pressure. When tank pressure increases above the regulator’s set point
it closes and the pressure building process stops.
The THERMAL EXPANSION RELIEF VALVE will relieve pressure buildup from trapped liquid
between the pressure building regulator and the inlet valve.
SAFETY DEVICES
The tank vacuum jacket is protected from overpressure by the VACUUM JACKET LIFT PLATE.
Overpressure protection for the pressure vessel is provided by dual TANK PRESSURE RELIEF
VALVES and RUPTURE DISCS. The pressure relief valves provide primary protection for the
inner vessel; the rupture disks are secondary safety devices. A RELIEF SYSTEM DIVERTER
VALVE permits the operation of one set of protection devices while the other set is isolated. This
arrangement prevents both sets of safety devices from being isolated from the tank at the same time
and permits maintenance of the devices without the need to vent tank pressure. Either one of two
types of diverter valves may be installed on the tank.
Tanks equipped with diverter ball valves: To activate one set of devices while isolating the other
move the selector valve handle all the way to the end of its travel toward the devices to be activated.
Tanks equipped with diverter globe valve: Turn the RELIEF SYSTEM DIVERTER VALVE
handle counterclockwise (in direction of arrow on hand wheel) to the end of its travel to open port
#1 and to close port #2 for servicing the relief devices. Likewise, turn the handle clockwise to the
end of its travel to open #2 and close port #1 for servicing.
Line THERMAL EXPANSION RELIEF VALVES are installed in the tank external piping at
points where liquid or cold gas could become trapped.
INSTRUMENTATION
Tank pressure is indicated by a tank PRESSURE GAUGE. Liquid level is indicated on the
LIQUID LEVEL GAUGE. Piping with LIQUID LEVEL GAUGE ISOLATION VALVES and an
EQUALIZATION VALVE connect the gauges to the tank. The LIQUID LEVEL GAUGE is
calibrated in inches of water and a conversion chart located next to the liquid level gauge is used to
convert the gauge reading to volume of liquid.
For some customer specific Final Piping Options the liquid level and pressure indicating devices
are not supplied. VAPOR PHASE ISOLATION VALVE is connected to a pressure tap that is
attached to the top of the pressure vessel. LIQUID PHASE ISOLATION VALVE is connected to a
pressure tap attached to the bottom to the pressure vessel. These connections provide the customer
a means of connecting a differential pressure gauge to determine liquid level and a pressure gauge
to determine tank pressure. When installed the differential pressure gauge’s high-pressure port will
be connected to LIQUID PHASE ISOLATION VALVE, the low-pressure port will be connected to
9
VAPOR PHASE ISOLATION VALVE, and a bypass valve connecting the instrument lines should
be installed between the isolation valves and the device. During operation this bypass valve will
remain closed; its function being to equalize the pressure on each side of the differential pressure
gauge. The pressure gauge will be connected to VAPOR PHASE ISOLATION VALVE so that
pressure at the top of the vessel is measured.
For some customer specific Final Piping Options a LIQUID LEVEL GAUGE with electrical
switches is available for installations requiring low and high level warnings. The gauge switches
can be wired to sound an alarm or light indicator lamps on either low or high tank liquid level.
VACUUM SYSTEM
Several tank components are provided for vacuum system maintenance. The VACUUM
PUMPOUT VALVE is the port used to pump air from the tank insulation space. It is normally
blanked-off and never opened unless the tank requires a field re-evacuation after a repair. The
VACUUM PROBE is a thermocouple that is installed to allow connection of a vacuum gauge to
measure the quality of the vacuum in the insulation space. The VACUUM PROBE ISOLATION
VALVE is opened during vacuum measurement to expose the vacuum probe sensors to the tank
insulation space. This valve is normally closed to protect the integrity of the vacuum and insulation.
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