DRYING METHODS

3. Operational drying (applicable to gas pipelines)

By carefully controlling the pressure, nitrogen gas is introduced

into the pipeline along with the product.

This continues until the dew point falls to an acceptable level.

Once this is reached, the pipeline pressure is then raised up to the

required operational level.

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2

DRYING METHODS

AUGUST 2014

DRYING METHODS

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DRYING METHODS

4. VACUUM DRYING METHOD

The vacuum drying method was applied after the dewatering with pigs.

The considerable volume of 102.000 m3 was evacuated down to 0,3

mbar(a) [29,905 in Hg (V)], which corresponds to the Dew Point of -

32° C [-25.6° F] in 6 days only.

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DRYING METHODS

4. VACUUM DRYING METHOD (CONTI.)

Vacuum drying Involves reducing the pressure in the pipeline until

the remaining water begins to boil off. This pressure is known as

vapor pressure.

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DRYING METHODSVACUUM DRYING METHOD (CONTI.)

Vacuum drying consists of three phases:

Evacuation: The pressure is reduced to a level causing the water to

evaporate at the ambient temperature.

Evaporation: Once this pressure is reached, it is maintained to

ensure that all the free water is evaporated.

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DRYING METHODSVACUUM DRYING METHOD (CONTI.)

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DRYING METHODS

Final drying: The final process is to remove all water vapor from

the pipeline. This is achieved by further reducing the pressure

using vacuum equipment, drawing the remaining vapor out of

the pipeline.

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PIPELINE PIGGING

Pipeline pigs are devices that are inserted into and travel

throughout the length of a pipeline driven by a product flow.

Pipeline pigging is done for the following reasons

1. Pigging process remove any debris left in the line from new

construction.

2. To periodically remove wax, dirt and water from the pipeline

(scraper pigs and brush pigs);

3. To sweep liquids from gas pipelines (spheres)

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PIPELINE PIGGING

4. To separate products to reduce the amount of mixing between

different types of crude oil or refined products;

5. To control liquids in a pipeline, including two-phase pipelines

(spheres and foam pigs);

6. To inspect pipelines for defects such as dents, buckles or corrosion

(“intelligent-pigs).

7. To fill lines for hydrostatic testing, dewatering following hydrostatic

testing, and drying and purging operations (spheres and foam pigs);

 

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TYPES OF PIGS

Pigs can be divided into three general categories;

1. The conventional or utility pig for "on stream" or routine

pigging,

2. The geometry pigs for inspection, and

3. The ILI (In Line Inspection) tools for metal loss and corrosion.

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TYPES OF PIGS

1. The conventional or utility pigs can be divided into three

categories:

A. Cleaning,

B. Sealing pigs, and

C. Batching pigs

A. Cleaning pigs

Are used to remove accumulated solids and debris from the walls

of the pipeline.

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CLEANING PIGS

13

Brush cleaning pig

AUGUST 2014

THE GEOMETRY PIGS FOR INSPECTION

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MAGNETIC INSPECTION TOOLS

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