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The Lease Pumpers Handbook

Chapter 10

The Tank Battery

Section E

CRUDE OIL LINE SYSTEMS AND EQUIPMENT

Figure 1. The crude oil lines in this diagram of a tank battery are labeled with an O.

E-1. Lines from the Separator.

Crude oil lines from the separator should

lead directly to the stock tank. A divertermanifold is assembled in the line to provide

line openings for connections to lead to and

from specialized vessels, such as a

heater/treater or a gun barrel. The crude oil

then continues on toward the stock tank. The

specialized vessel can then be utilized or

bypassed according to need. When water

and paraffin are also produced with

medium- to low-gravity oil, the second

vessel in the system will probably be a

heater/treater.

E-2. Lines from the Separator to the

Heater/Treater.

For fire safety the heater/treater is located

a minimum of 100 feet from the nearest

hatch that contains gas. Although the

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outside air supporting the flame in the

heater/treater must travel through a flame

arrester (for fire safety), this distance is

always maintained.

The lines to and from a conventional styleheater/treater (Figure 2) are obvious. The

highest side line on the right is the inlet. The

second line down as seen from this angle is

the oil outlet, and the water comes out the

lower left opening. The gas comes off the

top. On the vessel in the background of the

photograph, the right line is the inlet, the

second line to the left is the oil outlet, the

third line is the gas line, and the fourth (the

one on the left) is the water disposal line.

Figure 2. The lines on these

heater/treaters are color-coded to identify

the fluids they contain.

For the lease pumper, understanding the

use of each line does not create any problem,

even if the lines are buried because each one

serves a different purpose. Even a casual

examination of the line and the connections

that make up that line will allow the lease

pumper to easily identify the purpose of each

line. However, during installation of thevessel, it may be necessary to remove a

round manway plate and examine the inside

using a spark-proof flashlight to verify the

purpose of each outlet. The manufacturer

will also be able to provide this information.

When the crude oil enters the vertical

heater/treater, it travels down to contact a

spreader baffle in the lower section of the

vessel. A plate welded in the vessel just

below the inlet channels the incoming oil

down a tube, allowing the water to drop to

the bottom of the vessel and out. The oil

migrates up through the water section,

contacts the heated tube, and moves upward

through the wash section. There, the baffle

plates remove most of the remaining water.

Water continues to drop out of the oil until

the time that it enters the sales line.

The horizontal heater/treater, which uses

electricity to separate water and oil,

dramatically increases the efficiency of the

operation. This type of heater/treater is

described in Chapter 13, Testing, Treating,

and Selling Crude Oil.

E-3. Lines from the Heater/Treater to the

Gun Barrel.

If a gun barrel is the next vessel in the

system, the oil outlet line from the

heater/treater drops to ground level and

travels to the gun barrel. The line enters thegun barrel down through a central flume or

through an external boot arrangement

(Figure 3). In this system, the crude oil inlet

line comes in from the back side, travels up

through the 2-inch line, and enters the gas

boot from the left side. The flash separator

(the large container on top) allows the gas to

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break out of the liquid and travel upward

and into the low-pressure gas system.

Figure 3. The gun barrel crude oil inlet

boot (center).

The oil then travels down through the inlet

boot, enters the vessel at about the 12-inch

level, and travels across the spreader. The

spreader is a long horizontal pipe crossing

the bottom of the gun barrel with many

small holes in it to distribute crude oil all the

way across the vessel. The oil comes out of

the holes and works its way up through the

water in droplet form. Free water remains in

the lower part of the gun barrel and travels

through the water leg to the disposal system.As shown in Figure 3, additional support

is often provided to the boot by braces, such

as the V-shaped brace attached to the top

edge of the tank to stabilize the boot. A

second stabilizer is welded to the boot

down-comer and the side of the tank for

additional support.

The line system from the separator should

always provide a means of producing

directly to the stock tanks without going

through the heater/treater or the gun barrel.

E-4. Lines from the Gun Barrel to the

Stock Tanks.

The oil outlet line from the upper side of

the gun barrel to the stock tank is normally

installed directly to the top of the stock

tanks. This line may come off the gun barrel

at a 45o angle, so the distance is usually only

a few feet away to the first stock tank.

Figure 4 illustrates how the line is installed

to allow the oil to flow by gravity feed to the

stock tank. A shutoff valve is normally

installed just above the stock tank as shown.

The line must be of sufficient size to avoid

restrictions and to accommodate production.

Figure 4. The oil line from the gun barrel

(left) to the stock tank. Note that the

handle of the valve is perpendicular to the

flow of the line, meaning that the valve is

closed.

E-5. The Equalizer Line from Stock

Tank to Stock Tank.

The equalizer line is a line located near the

top edge of the tank at an angle of 45o

to the

side and approximately 10 inches down.

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This line connects the two stock tanks. This

equalizer line allows the lease pumper to top

out a tank (fill it almost full) during any

time of the day or during the hours that the

lease pumper is off so that the tank is full ofoil when the lines are switched. This saves

the pumper much time, and the tank is

always full when the oil is sold.

There are two ways of installing an

equalizer line. Figures 5 and 6 show both

systems. In the system in Figure 5, the oil

must go to the next tank, while in the system

shown in Figure 6, the oil can go to any

selected tank. Most walkways, however, fit

snugly to the tank so that the second

approach is not always available. The pipe

would occupy part of the walkway space,

and this would be a safety hazard.

When the crude oil is sold through a

pipeline, several valves will have to be

closed, a seal inserted, and the valve handle

locked in a closed position. There are two

common styles of seals. One is a flat strap

that locks together, and the second is a wire

and lead seal.

The gauger will probably seal both the

drain line and the oil inlet. The seal on the

sales line will then have to be broken to

remove the valve handle. These seals will

have the name of the pipeline company and

a serial number stamped on them in raised

letters for identification. After the oil has

been sold, the valve is closed and a new seal

is put in place to make sure that this valve

remains closed when oil is not being

purchased. All seal numbers are accounted

for, and occasionally the company willrequire that the used seals accompany the

sales ticket when it is turned in to the office.

Figure 5. An equalizer system in which

equalizing can be done only to the next

tank.

Figure 6. An equalizer system in which

any of several tanks can be selected for

filling next.