Start up and Commissioning of the Pipeline

- B. B. Prasad

Objective of the commissioning

To bring the constructed / installed system to deliver the desired function.

The Pipeline commissioning means introducing crude/ product/Gas in the pipeline from originating station, filling the entire length and then start delivering to receipt system.

What we need prior to commissioning?

The pipeline and associated facilities are completed in allrespect

All Fire and Safety equipments / facilities are tested andcommissioned

Availability of dedicated communication

Statutory Clearances obtained

What we need prior to commissioning?

Availability of Product (HSD)/ Crude oil – Not less thanline-fill

Required Manpower is placed at all locations

Availability of water and its disposal plan

Availability of a dedicated commissioning team

What will be the procedures to commission a Water Pipeline?

Critical issues in commissioning a Petroleum Pipeline

Movement of hydrocarbon in empty pipeline can generatestatic current.

Hydrocarbon Vapor mixed with oxygen may lead to explosion.

There may be formation of Air / Vapor pocket that may getcompressed leading to rise in pressure.

Air / vapor pocket may explode in receiving tank leading todamage of the tank roof seal.

Leakage of any hydrocarbon may lead to fire or damage to environment .

Flash Point:The flash point of a volatile liquid is the lowest temperature at which it can vaporize to form an ignitable mixture in air.

Vapor Pressure:The vapor pressure of a liquid is the pressure exerted by its vapor when the liquid and vapor are in dynamic equilibrium.

At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.

Properties of Hydrocarbons

Properties of Petroleum Products

Products RVP at 37.8 deg C Flash Point 

MS 375‐412 mm Hg. ‐ 43 0C

SKO <0.1 mm Hg > 38 0C

HSD 2.12 to 26 mm Hg. > 42 0C

ATF <0.1 mm Hg > 42 0C

NAPHTHA 450‐472mm Hg. ‐22 0C

CRUDE OIL 230 – 300 mm Hg 37‐620 C

LPG > 1000 mm Hg at 250C ‐600C to ‐1040C

Preferred Liquid for Commissioning

Pipeline Pumping Liquid Preferred Liquid

Multi products

MS, SKO, HSD, ATF, LDO, NPHTHA

HSD

ATF  ATF SKO

LPG LPG LPG 

NAPHTHA Naphtha Naphtha

CRUDE OIL Crude Oil Crude Oil

What is PIG ?

A device that moves through the inside of 

a pipeline for the purpose of cleaning, dimensioning, sealing and inspect.

Objective of PiggingNew Pipeline 

• Remove debris

• Verify ovality, dent etc• Water filling & dewatering after hydro‐testing• Sealing of product or water during commissioning 

In Service Pipeline• Maintain line efficiency• Corrosion control• Check dents, buckles and any other internal abnormality• To minimize interface generation between two dissimilar 

products• To avoid cross‐contamination• To evacuate the pipeline

Conventional / Utility Pigs – Different types

• Various components are fitted on mandrel.

• It can be uni‐directional or bi‐directional

Sealing DiscGuide Disc

Intelligent Pig

• To record bends, dents, ovality, bend radius & angle.

PIG Launching / Receiving Barrel

Commissioning of a Multi-products Pipeline

Ensure the pipeline is ready in all respects for the commissioning.

Ensure adequate product (HSD) is available for the commissioning (At least more than line-fill of a Pipeline section).

The pipeline or a section of the pipeline is pressurized with air (2 to 3 Kg/Sq-cm)

Pump a water column of about 500 kL to 1000 kL

Launch a Bi-Di Pig followed by 1000 kL to 2000 kL water

Water (1000 to 2000 kL)

Air (2/3 Kg/cm2)Water (500 to 1000 kL)BI-DI PIG

Commissioning of a Multi-products Pipeline

Launch second Bi-Di- Pig behind 1000 KL to 2000 KL water

Pump HSD at minimum flow

Track the movement of Pig

Vent the air at receiving end and maintain back pressure 3 to 4Kg/Sq-cm

Monitor receipt of water at Receiving end – it may be disposeddirectly in to a protected pit or in a designated tank.

Water (1000 to 2000 kL)

Air (2/3 Kg/cm2)

Water (500 to 1000 kL)BI-DI PIGBI-DI PIGHSD

Commissioning of a Multi Products Pipeline

Receive Ist Bi-Di Pig

Monitor the quantity and quality of water at receiving end

Receive second Bi-Di Pig

Once diesel or diesel mixed with water arrives, switch over todesignated HSD Tank.

Observe flow and pressure, once these become stable, the operation may be made normal and the pipeline may be declaredas commissioned and handed over to Operation.

Commissioning of an ATF Pipeline

The procedure is similar to multi-products pipeline except the following

• Commissioning liquid is used SKO instead of HSD

• ATF is not used because it is likely to get contaminated withwater and dirt particles.

Water (1000 to 2000 kL)

Air (2/3 Kg/cm2)

Water (500 to 1000 kL)BI-DI PIGBI-DI PIGSKO

Commissioning of an ATF Pipeline

The procedure is similar to multi-products pipeline except the following

• Commissioning liquid is used SKO instead of HSD

• ATF is not used because it is likely to get contaminated withwater and dirt particles.

Water (1000 to 2000 kL)

Air (2/3 Kg/cm2)

Water (500 to 1000 kL)BI-DI PIGBI-DI PIGSKO

Commissioning of Naphtha Pipeline

The procedure is similar to multi-products pipeline except the following

• Air from entire Pipeline is displaced with Nitrogen column using a Bi-Di Pig

•Commissioning liquid is used Naphtha instead of HSD

Nitrogen (10.0 KM)

Air (2/3 Kg/cm2)

Nitrogen (500 to 1000 kL)BI-DI PIGBI-DI PIGNaphtha

Commissioning of LPG Pipeline

The procedure is similar to multi-products pipeline except the following

• Air from entire Pipeline is displaced with Nitrogen column using a Bi-Di Pig

•Commissioning liquid is used LPG instead of HSD

Nitrogen (10.0 KM)Nitrogen BI-DI PIGBI-DI PIGLPG

Commissioning of a Gas Pipeline

A gas pipeline is treated as Tank.

However, before taking gas in the Pipeline, it is to be made moisture and oxygen free.

Commissioning of a Gas Pipeline

Commissioning Steps:

Drying – Purging of super dry airCompressed Super dry air is purged using air compressors with accessories viz. Moisture Separator, Oil Separator and Dryer. The air shall be supplied in the pipeline at (-) 20 deg. C dew point.

Super dry air with dew point (-) 20 deg. C will have sufficient capacity to absorb water vapour to the extent of 30 % of the desired capacity.

Commissioning of a Gas Pipeline

Commissioning Steps:

Drying – Purging of super dry airCompressed Super dry air is purged using air compressors with accessories viz. Moisture Separator, Oil Separator and Dryer. The air shall be supplied in the pipeline at (-) 20 deg. C dew point.

Super dry air with dew point (-) 20 deg. C will have sufficient capacity to absorb water vapour to the extent of 30 % of the desired capacity.

Commissioning of a Gas PipelineCommissioning Steps:

Vacuum Drying The process utilizes high capacity vacuum to reduce pressure within the Pipeline to a level from 760 Torr to 40 Torr. At this pressure (40 Torr), any water within the pipeline will start boiling and vaporizing.

Air left inside the Pipeline is subjected to a vacuum of 40 Torr, the water vapor will expand approx. 18.8 times, which will be displaced using high capacity vacuum booster pumps (rated capacity 5000 CuM/Hr)

When the vacuum of 7.6-10 Torr is achieved, it is confirmed that whole pipeline system has been dried to required level.

Commissioning of a Gas PipelineCommissioning Steps:

Nitrogen PurgingAt vacuum level 7.6 Torr and dew point (-) 20 deg.C, the oxygen content inside the Pipeline is 0.20%.

To further dilute the oxygen content, nitrogen purging is done almost 13 times more than pipeline volume. This will reduce oxygen content to 0.015%, which is considered negligible.

Now the Pipeline system is ready to receive Gas.