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Purchasing a railroad tank car for any application can be a major challenge
for most people. Educating you to make a better purchase is our primary
goal. We want you to become familiar with what options are available and
which options you may or may not want. We have been in the railroad tank
car industry for many years and are always willing to share our experiences with
you.
GP Tank
- "General Purpose" GP tanks are the most common type of tank. By
looking to see if a tank has a bottom fitting (or bottom outlet valve) one can
determine if it's a GP tank or not as only GP tanks have bottom fittings.
GP tanks haul just about everything except for LPG and ammonia (which are
hauled by High Pressure Tanks). GP tanks come in a large variety of
sizes, generally from 17,000 to the biggest 30,000 GP tank. There are
smaller tanks out there but they are not very common.
- Some GP tanks will be completely coil free.
- The following information is written for GP tanks:
Interior heater coils:
- Description: The 2 inch diameter pipe sections that generally run
the length of the tank and which are mounted to brackets inside of the tank.
Pipes have an inlet and an outlet nipple at the bottom center of the car.
Steam is ran through the pipes in order to heat the product up and allow for
product flow.
- Advantages: Great for products that need to be heated up.
- Disadvantages: Tank is harder to clean. If the pipes ever
brake or crack you could have product contaminate the coils and possibly
have product leak out of the pipe nipples (can be corrected by the
application of heater coil nipple pipe caps).
- Notes: Typically, the price for a railroad tank car with or
without interior heater coils is the same. If you don't
need the heater coils you just don't use them. Tanks with interior
heater coils generally do not have tank jackets.
Exterior heater coils:
- Description: These are oblong shaped coils that are welded
directly to the exterior of the tank. Pipes have an inlet and an
outlet nipple at the bottom center of the car. Steam is ran through
the pipes in order to heat the product up and allow for product flow.
- Advantages: Great for products that need to be heated up and tank
cleaning is easier. Generally, all tanks that have exterior heater
coils will also have a 4" think blanket of fiberglass insulation which is
covered by a 1/8" think steel jacket which provides for better
thermal protection.
- Disadvantages: None.
- Notes: These tanks are ideal for above ground application as using
these tanks as either a cistern or culvert will require that the tank
jacket be removed.
Tank jacket:
- Description: A thin outer shell over a tank used to contain
insulating material.
- Advantages: Better thermal protection.
- Disadvantages: If jacket is not removed and tank is buried there
could be an accumulation of moisture which will lead to the premature
failure of tank by rusting.
- Notes: Jackets can be removed by us at select locations otherwise
customer is responsible for removing tank jacket. Generally, all GP
tanks with a jacket will have a 4" think insulation behind it and
exterior heater coils. Tanks with interior heater coils
will not have a tank jacket.
Fiberglass insulation:
- Description: Similar to what is used in residential application.
Generally 4" think.
- Advantages: Better thermal protection.
- Disadvantages: None.
- Notes: Other types of insulation that are not as common but still
in circulation are Fiberfrax, wool blanket & foam.
Top fittings:
- Description: Generally comprised of the following items:
- Loading/Unloading valve: Either a 2 or 3" valve, generally ball
type, attached to a 3" pipe that runs to the bottom of the tank leaving a
few inch gap. Used to load or unload commodity.
- Air inlet valve: Either a 1" or 2" valve, generally ball type,
attached to a 1 or 2" pipe that is only a few inches long. Used to
pressurize the tank or to let air out of the tank.
- Vacuum relief valve: Used to relive negative pressure inside
tank. Not as common as loading/unloading valves & air inlet valves
but still generally available.
- Gauging device: Used to check commodities levels. Less
common than vacuum relief valves but still available on some tanks.
- Safety valve: Either a 35 lb or 75 lb safety valve. Used
to allow excessive pressure to escape without damaging the tank.
- Advantages: Allow for many different configurations and can easily
be modified or removed.
- Disadvantages: None.
- Notes: Ideal for both above ground and below ground applications.
All of these fittings can be removed if converting tank into a culvert.
Bottom fittings:
- Description: Generally a 4" valve located at the center bottom
used to drain commodity. Most of these valves have a handle located on
the bottom (exterior of tank) while some have a shaft running to the top of
the tank, near the top fittings, to allow for operation on top of the tank.
- Advantages: Gravity fed can eliminate need to pressurize tank.
- Disadvantages: None.
- Notes: Top operated valves are ideal for cisterns.
Pressurizing tanks:
- Generally tanks are tested to 100 lbs per Federal Rules and Regulations.
Manway:
- Either an 18" or 20" manway with a hinged lid is standard on GP tanks.
There are 6 to 8 eyebolts that secure the manway closed when not in use and
can be locked to prevent unauthorized tank entry.
High Pressure Tank
- These tanks are similar to GP tanks but still extremely different.
They are primarily designed to haul LPG (also called Liquid Petroleum Gas,
Butane, and Iso-Butane) and Anhydrous Ammonia. They do not vary in size
very much as they are typically 34,000 gallons. Most have a tank jacket
with insulation while the ones that do not have a jacket & insulation will
have a really think rubber like exterior paint. None of these tanks have
heater coils.
- The following information is for High Pressure Tanks only:
Interior heater coils:
- Not available in High Pressure Tanks. See GP tank info.
Exterior heater coils:
- Not available in High Pressure Tanks. See GP tank info.
Tank jacket:
- Description: A thin outer shell over a tank used to contain
insulating material.
- Advantages: Better thermal protection.
- Disadvantages: If jacket is not removed and tank is buried there
could be an accumulation of moisture which will lead to the premature
failure of tank by rusting.
- Notes: Jackets can be removed by us at select locations otherwise
customer is responsible for removing tank jacket. Generally, all tanks
with a jacket will have a 4" think insulation behind.
Fiberglass insulation:
- Description: Similar to what is used in residential application.
Generally 4" think.
- Advantages: Better thermal protection.
- Disadvantages: None.
- Notes: Other types of insulation that are not as common but still
in circulation are Fiberfrax, wool blanket & foam.
Top fittings (Pressure Plate):
- Description: All the valves are housed in one central area called
the pressure plate. This pressure plate assembly weighs about
500 to 800 lbs and is only intended to be removed for cleaning or repairs.
All of the following are common place:
- Loading/Unloading valves: There are two of these valves that are
either 2" or 3" and are either ball or plug type. These valves are
mounted on a check valve which is mounted to a 3" pipe that runs to the
bottom of the tank. These valves are designed to load or unload
product into the tank.
- Vapor valve: Looks identical to the load/unloading valves.
Is mounted in the same way to a check valve then to a 3" pipe but the pipe
is only a few inches long. This valve is intended to release vapors
out of tank.
- Gauging device: There are a few different types of gauging
devices out there. Both essentially do the same thing...let you know
when the tank is almost full.
- Sample valve: This 1/4" needle valve is mounted to a pipe that
runs to the bottom of the tank which allows you to take a sample of the
commodity.
- Safety valve: Usually rated at 280 lbs. Allows excessive
tank pressure to release and not damage the tank.
- Check valve: These ball type or plunger type check valves are
mounted under both loading/unloading valves and the vapor valve.
These valves prevent too much product from being released at once.
Some gauging devices are also equipped with check valves.
- Advantages: Allows for many different configurations.
- Disadvantages: Difficult to gain access to tank if being used as a
cistern.
- Notes: All of these valves & fittings are designed specifically
for LPG and ammonia. If you are not working with either commodity you
might want to consider a GP tank.
Bottom fittings:
- Not available in High Pressure Tanks. See GP tank info.
Pressurizing tanks:
- Generally tanks are tested to 340 lbs per Federal Rules and Regulations.
Manway:
- The pressure plate covers the manway opening. Gaining access to
the tank requires the removal of the pressure plate. Not designed for
easy access.
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