A flow line, used on a drilling rig, is a large diameter pipe (typically a section of casing) that is connected to the bell nipple

Bell nipple

A ' is a section of large diameter pipe fitted to the top of the blowout preventers that the flow line attaches to via a side outlet, to allow the drilling fluid to flow back over the shale shakers to the mud tanks.See Drilling rig for a diagram....

 (under the drill floor

Drill floor

The Drill Floor is the heart of any drilling rig and is also known as the pad. This is the area where the drill string begins its trip into the earth. It is traditionally where joints of pipe are assembled, as well as the BHA , drilling bit, and various other tools. This is the primary work...

) and extends to the possum belly

Possum belly

A Possum belly, on a drilling rig, is a metal container at the head of the shale shaker that receives the flow of drilling fluid and is directly connected to and at the end of the flow line.A possum belly may also be referred to as a distribution box or flowline trap.The purpose of the possum belly...

 (on the mud tank

Mud tank

A mud tank is an open-top container, typically made of steel, to store drilling fluid on a drilling rig. They are also called mud pits, because they used to be nothing more than pits dug out of the earth....

s) and acts as a return line, (for the drilling fluid

Drilling fluid

In geotechnical engineering, drilling fluid is a fluid used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells. Liquid drilling fluid...

 as it comes out of the hole), to the mud tank

Mud tank

A mud tank is an open-top container, typically made of steel, to store drilling fluid on a drilling rig. They are also called mud pits, because they used to be nothing more than pits dug out of the earth....

s.

Flow Line Components

The flow line will typically have equipment attached to it, such as a flow show

Flow show

A Flow show is a device on a drilling rig that is attached to the flow line and has a paddle that swings out as the flow of drilling fluid passes by it...

, possum belly

Possum belly

A Possum belly, on a drilling rig, is a metal container at the head of the shale shaker that receives the flow of drilling fluid and is directly connected to and at the end of the flow line.A possum belly may also be referred to as a distribution box or flowline trap.The purpose of the possum belly...

 and the sample box

Flow Show

The flow show

Flow show

A Flow show is a device on a drilling rig that is attached to the flow line and has a paddle that swings out as the flow of drilling fluid passes by it...

 shows whether drilling fluid

Drilling fluid

In geotechnical engineering, drilling fluid is a fluid used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells. Liquid drilling fluid...

 is flowing down the flow line or not and any changes in that flow. High-pressure jets are typically attached along its length to dislodge any obstructions (such as drill cuttings

Drill cuttings

Drill cuttings are the broken bits of solid material removed from a borehole drilled by rotary, percussion, or auger methods. Boreholes drilled in this way include oil or gas wells, water wells, and holes drilled for geotechnical investigations or mineral exploration.The drill cuttings are commonly...

 collecting in one spot) that may occur.

Possum Belly

The possum belly

Possum belly

A Possum belly, on a drilling rig, is a metal container at the head of the shale shaker that receives the flow of drilling fluid and is directly connected to and at the end of the flow line.A possum belly may also be referred to as a distribution box or flowline trap.The purpose of the possum belly...

 is used to slow the flow of returning drilling fluid

Drilling fluid

In geotechnical engineering, drilling fluid is a fluid used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells. Liquid drilling fluid...

 before it hits the shale shakers

Shale shakers

Shale shakers are devices that remove drill cuttings from the drilling fluid that is used for boring holes into the earth. Controlling the solids in drilling fluid is an important component of the cost of drilling, so research into improved shaker design is ongoing.-Shale shaker design:Shale...

. This enables the shale shaker to clean the cuttings out of the drilling fluid before it is returned to the pits for circulation.

Sample Box

Another common add on is the sample box. This is a heavy duty rubber hose that is inserted at the end of the flow line and at the other end emplaced into the sample box itself. The sample box is used to capture samples of drill cuttings for geological logging. The box is typically equipped with a raising door that allows the water and cuttings to escape after a sample is collected.

Stinger Line

A stinger line is similar to a flow line, but unlike a flow line is not used to maintain circulation. The stinger line is attached to the blowout preventer

Blowout preventer

A blowout preventer is a large, specialized valve used to seal, control and monitor oil and gas wells. Blowout preventers were developed to cope with extreme erratic pressures and uncontrolled flow emanating from a well reservoir during drilling. Kicks can lead to a potentially catastrophic...

 to allow for the pressure from a blowout

Blowout

-Science and technology:*Blowout , a sudden release of oil and gas from a well*Blowout , a sandy depression caused by the removal of sediment by wind*Blowout grass is a grass that can be found on sand dunes...

to be released. The stinger line usually will run parallel to the flow line.