What are types of tanker cargo pipelines?

There are three basic types of pipeline systems:

1. Direct system
2. Ring main system
3. Free flow system.

Direct line system

Advantage:

• Quick loading & discharging.
• Short pipe line.
• Less bend.
• Less loss of pressure due to pipe line friction.
• Direct line to provide better suction.
• Time of washing the line is short.
• System is cheaper than the other system.
• Leak is minimized.
• Easy to operate so less training is required.
• It is easy to separate each cargo.

Disadvantage:

• In case of leaking the control of leakage is difficult.
• This system is very inflexible.

Fig : Direct line system

Ring main system

Advantage:

• In this system any tank can be discharged by any pump. Thus different grade of the cargo can be loaded.

Disadvantage:

• It is expensive to build due to the extra length of the piping required.
• Extra bend is required. Thus decreasing in rate.
• Risk of leakage from radius of bend exists.

Fig : Ring  main  system

Free flow system

Advantage:

• Main pipe line is not used for discharge.
• Less pipe line.
• Less bend.
• Less friction & more pressure cause very high discharge.

Disadvantage:

• Is not flexible.
• One grade is dischargeable if more risk of contamination exists.
• Risk of overflow exists if level of all tank doses not carefully monitoring.

Fig: Free flow system

Points to Pounder for all types of Pipe lines

THE FREE FLOW SYSTEM	THE DIRECT LINE SYSTEM	THE RING MAIN SYSTEM
Used on large crude	Used on VLCC	Used on Product
Carriers		Carriers
Carry only one garde	Carry two or three grade	Carry several
Of cargo	Of cargo	Different products
Large gate valve built in	Simple lines leading in the
The bulkhead	Tanks
Stern trim cause the oil	Due to straight length of	Due to the number of
To flow to the	Pipeline, there is better	Bends, joints and valve
Aftermost tank	Suction & less loss of	It take longer time
	Pressure
Suction main cargo pump	Fewer valve & bends	Due to the number of
Situated in aft	Means less erosion & leak	Bends, joints and valve
		Means more erosion &
		Leaks
	Less maintenance	More maintenance
	Required	Required
	Thorough washing of line is	Thorough washing of
	Not possible unless the	Line is possible without
	Washing are flushed into	Flushing into the tank
	The tank & discharged
	From there
	Due to fewer valves leaks
	Are difficult to control
	Valve    segregation not	Required two valve
	Provided	Segregation
		Between products
	The initial cost of fitting	The initial cost of
	Is less than ring main	Fitting is higher
	System