From Cargo Work: For Maritime Operations, Seventh Edition

Tanker pipelines

There are three basic types of pipeline systems:

  1. Direct system

  2. Ring main system

  3. Free flow system.

Each system has their uses and is designed to fulfil a need in a particular type of vessel.

The direct system

This is the simplest type of pipeline system which uses fewer valves than the others. It takes oil directly from the tank to the pump and so reduces friction. This has an affect of increasing the rate of discharge, at the same time improving the tank suction. It is cheaper to install and maintain than the ring main system because there is less pipeline length and with fewer valves less likelihood of malfunction. However, the layout is not as versatile as a ring main system and problems in the event of faulty valves or leaking pipelines could prove more difficult to circumvent. Also, the washing is more difficult since there is no circular system and the washings must be flushed into the tanks Figure 5.6.

Figure 5.6: Direct line system. Used mainly on crude and black oil tankers where separation of oil grades is not so important.

The advantages are that:

  1. it is easy to operate and less training of personnel is required

  2. as there are fewer valves it takes less time to set up the valve system before commencing a cargo operation

  3. contamination is unlikely, as it is easy to isolate each section.

The disadvantages are that:

  1. it is a very inflexible system which makes it difficult to plan for...

Products & Services
Insertion and Tapping Valves
Insertion and tapping valves are used to isolate media within the existing line while an additional connection is made.
Butterfly Valves
Butterfly valves control flow through a circular disc or vane by turning the valve's pivot axis at right angles to the direction of flow in the pipe. They are normally used as throttling valves to control flow.
Hot Tapping Machines
Hot tapping machines are used to safely drill into pressurized pipe to add main or service lines without interrupting the service.
Plug Valves
Quarter-turn plug valves use a cylindrical or tapered plug with a hole in the center to control straight through flow when in the open position.
Control Valves
Control valves or proportional valves are power-operated devices used to modify fluid flow or pressure rate in a process system.

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