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.
1AUGUST 2014
2
DRYING METHODS
AUGUST 2014
DRYING METHODS
3AUGUST 2014
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.
4AUGUST 2014
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.
5AUGUST 2014
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.
6AUGUST 2014
DRYING METHODSVACUUM DRYING METHOD (CONTI.)
7AUGUST 2014
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.
8AUGUST 2014
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)
9AUGUST 2014
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);
10AUGUST 2014
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.
11AUGUST 2014
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.
12AUGUST 2014
CLEANING PIGS
13
Brush cleaning pig
AUGUST 2014
THE GEOMETRY PIGS FOR INSPECTION
14AUGUST 2014
MAGNETIC INSPECTION TOOLS
15AUGUST 2014