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    In-service recoating of a 40-incrude oil pipeline:

    the KP 0-60 section of the CPC

    pipeline in Kazakhstan

    The Evaluation and Rehabilitation of Pipelines Conference

    Marriott HotelPittsburgh, PA, USA

    October 21-22, 2009

    Organized by

    Clarion Technical Conferencesand

    Scientific Surveys Ltdand supported by

    The Professional Institute of Pipeline Engineers

    by Sidney Taylor

    Incal Pipeline Rehabilitation Inc, Houston, TX, USA

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    Proceedings of the 2009 Evaluation and Rehabi l i tat ion of Pipel ines Conference , Pi ttsburgh, PA, USA .

    Copyright 2009 by Clarion Technical Conferences , Scienti f ic Surveys Ltd an d the author (s ). All rightsreserved. This document may not be reproduced in any form without permission from the copyright owners.

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    In-service recoating of a 40-in crude oil pipeline:

    Section KP 0-60 of the CPC pipeline in Kazakhstan

    HE CPC Pipeline is owned by a consortium of Russia, Kazakhstan, Oman,

    Chevron, and a number of others. They started construction in 1998 and the

    pipeline became operational in March 2001. It was initially designed to deliver 28.2

    million tons of crude annually with planned expansions that would bring annual

    exports to 67 million tons.

    Built to Russian/Kazakh standards, the pipeline was coated with cold applied tape.

    Part of the pipeline route runs close to the Caspian Sea. In some areas the pipeline is

    below the water table and completely immersed in brackish water.

    They are experiencing severe corrosion in several areas because:

    wrong coating selected initially, poor quality materials, poor application technique (no surface preparation prior to application), soil stress damaging the coating, salt water environment was accelerating the corrosion rate.

    Areas of the pipeline are being recoated by a Russian contractor who is able to recoat

    about 150 linear meters of pipe per day with the line in service. This paper describes

    the methods being used to excavate the pipeline, remove the existing coating,

    prepare the surface of the pipe, and apply the new coating.

    Historical perspective

    The CPC crude pipeline system is the largest operating investment project with foreign

    participation on the territory of the former USSR. The cost of the first phase of construction

    amounted to $2.6 billion. The 1,510-km pipeline extends from the Tengiz oil field in

    Kazakhstan to the Novorossiisk-2 Marine Terminal on Russias Black Sea coast. The

    pipeline route is shown in Fig.1. The pipeline diameter is 1,067 mm between Kropotkin and

    the terminal and 1,016 mm for the rest of the pipeline. There are currently 5 pump stations

    in operation along the route. The throughput of the pipeline is currently rated at 28.2

    million tons of oil per year.

    There is a planned expansion of the pipeline network. The total number of pump stationswill be increased to 15, additional storage facilities will be added and a third loading buoy

    constructed at CPC's Marine terminal at Novorossiysk. After all phases of the pipeline

    have been completed, the maximum throughput of the CPC pipeline system will reach 67

    million tons of oil per year.

    CPC has a complex organizational structure. Three Governments and ten companies

    representing seven countries participate in the project. Two joint stock companies CPC-R

    (Russia) and CPC-K (Kazakhstan) - have been created to implement the project. The

    Structure of CPC Shareholder Capital is the following:

    Russia - 24%

    Kazakhstan - 19% Oman - 7% Chevron Caspian Pipeline Consortium Co. - 15%

    T

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    Lukarco B.V. - 12,5% Mobil Caspian Pipeline Co. - 7,5% Rosneft - Shell Caspian Ventures Ltd. - 7,5% Agip International (N.A.) N.V. - 2% BG Overseas Holdings Ltd. - 2% Oryx Caspian Pipeline LLC - 1,75% Kazakhstan Pipeline Ventures LLC - 1,75%.

    Corrosion problems

    The new sections of the pipeline in Kazakhstan were constructed to Russian / Kazakh

    standards. The pipe coating material selected was cold applied tape. The tape was field

    applied over a Swedish Standard ST3 Power Tool Cleaning brushed surface.

    As can be seen in Fig.1, part of the pipeline route runs close to the Caspian Sea. In some

    areas the pipeline is below the water table and the pipeline is completely immersed in

    brackish water.

    In hindsight, cold applied tape was the wrong coating for this section of the pipeline. Poor

    quality coating materials, lack of adequate surface preparation and the inherent

    deficiencies in applying cold applied tape in the field all contributed to the problem. A

    major problem was tenting of the tape over the weld seams. Soil stresses caused rippling of

    the coating and allowed water to enter the tented area next to the weld seam. The water

    could then migrate along the weld seam resulting in spiral corrosion. The salt water

    environment accelerated the corrosion rate.

    There are only three solutions at this point:

    Replace the line,

    Recoat the line, or A combination of the two.

    In January 2008 Stroytransgaz signed an agreement with the Caspian Pipeline

    Consortium-K to replace the CPC pipeline section 0 km116 km in Atyrau region in

    Kazakhstan. Stroytransgaz will build a new pipeline section with length of 130.3

    kilometres and 1020 millimetres diameter laid in a new route. Upon completion of

    construction and tie-in of newly constructed section into existing pipeline, Stroytransgaz

    will also dismantle the old, decommissioned section of the oil pipeline.

    This paper describes the efforts of a Russian Contractor, Grasco, to recoat portions of the

    KP 0-60 section of the CPC Pipeline. The project reported on here was done in the summer

    of 2006. Additional work was done in 2007 and 2008 using the same methodology. CPCplans to award additional work through 2011.

    The recoating work was done with the line in service but at a reduced operating pressure.

    Work on the line was permitted when the operating pressure of the pipeline was between

    50 and 80 percent of normal operating pressure. Work had to stop if operating pressures

    were outside of this range.

    The entire spread of equipment, shown in Fig.2, was very compact and consisted of only

    three excavators, four sidebooms and the specialized line travel equipment described below.

    There were approximately 40 people in the crew including project management and

    inspection.

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    Excavation

    Excavation was done using two excavators, one on each side of the pipeline as shown in

    Fig.3. The pipe is excavated to a depth of about 1.5 m below the bottom of the pipe on both

    sides of the pipe. All the spoils are placed on the far side of the pipeline.

    The next step in the excavation process is to remove the soil from directly under the bottom

    of the pipe. This soil is very difficult to remove as it has been compacted over the years by

    the weight of the pipeline and its contents. To accomplish this, Grasco used the under-pipe

    excavator shown in Fig.4.

    The soil is removed by two electrically driven rotating drums. The drums are about 0.7 m

    high and about 1.37 m in diameter. The drums are equipped with teeth that dig through

    the soil as the drums are rotated. The unit is about 5.5m in length and weighs about 5 tons.

    The under-pipe excavator is shown in operation in Fig.5. The unit is held in place on the

    pipe by the two clamps at the rear of the unit (directly in front of the operator) in the photo.

    The clamps are in the retracted position and the rear clamp is engaged and the front clampis disengaged. A hydraulic cylinder moves forward forcing the rotating drums into the soil.

    The under-pipe excavator is shown in the extended position in Fig.6. At this point the

    forward clamp is engaged and the rear clamp disengaged and the cylinder pulls the rear

    clamp forward and the process is repeated.

    The soil removed from under the pipe is deposited in the excavated area on each side of the

    pipe. The end result is about 0.8 m under pipe clearance from one side of the trench to the

    other. There is no chance of hitting or damaging the pipe using this equipment as the unit

    rides directly on the line.

    A sideboom is positioned directly behind the under-pipe excavation unit. The sidebooms are

    equipped with an A-frame boom. The foot of the A-frame is placed against the spoilsbank and the load line is attached to a cradle holding the pipe as shown in Fig.7.

    The sidebooms are there to hold and support the line in the same position the line was in

    prior to excavation, neither raising nor lowering the line. This minimizes the additional

    stress the line is subjected to during the recoating operation. Once the operation in front of

    the sideboom has advanced about 15 m, the sideboom operator lowers the load line, raises

    the boom, and moves forward 15 m. He then lowers the boom and raises the load line until

    he is once again supporting the line. During this operation the line is supported by the

    sideboom in front and behind the sideboom being repositioned.

    Coating removal

    The tape coating is removed by the mechanical cutting machine shown in Fig.8. The tape is

    actually being cut off the pipe by a series of cutters. In addition, other cutting tools located

    at the rear of the machine are actually milling off several millimetres of pipe wall. The

    cutting tools are shown in Fig.9.

    Pipelines designed to Russian / Kazakh standards provide for a 20% corrosion allowance

    when determining the minimum wall thickness required as opposed to a 5% corrosion

    allowance used in designing most western pipelines. This allows them to reduce the wall

    thickness by a couple of millimetres without affecting the MAOP of the pipeline. This

    process has several negative results. The milling process leaves a large amount of metal

    cuttings in the ditch as can be seen in Fig.10. The milling tools also create stress risers on

    the surface of the pipe as shown in Fig.11 and the weld cap is also milled off along with the

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    pipe surface. The cutting tools also raise fine hairs on the pipe surface making it

    necessary to apply a very thick external coating.

    Surface preparation

    The area around the spiral weld seam cannot be completely cleaned by the mechanical

    cutting machine. The cutters tend to jump over the weld leaving corrosion deposits still

    adhered to the pipe. The weld seam area is particularly vulnerable to corrosion because of

    the tenting of the tape described earlier.

    The weld seam area is cleaned up using manual air abrasive blast equipment as shown in

    Fig.12. This is done just prior to application of the primer. Figure 13 shows the blast

    operator in the ditch. Note the presence of water in the bottom of the trench. The trench is

    starting to fill with water indicating that it is below the water table at this point. This

    creates additional problems and hazards for the workers.

    Coating application

    Modified BIKAZ, a bitumastic coating system, was selected as the new coating to be

    applied. The coating is manufactured in Russia and is a very thick coating system

    consisting of a primer, a hot bitumastic inner coating, fibreglass reinforcement layer and a

    tape outerwrap. It is one of the few coatings approved for pipeline use in Russia and

    Kazakhstan.

    Primer is applied using a flood wipe system. The Primer Application Unit is shown in

    Fig.13. The primer material is stored in a tank on top of the unit. A valve at the bottom of

    the tank allows the primer material to run on to the pipe. A spinning rug wipes or smears

    the primer around the pipe. Primer application is often inconsistent when applied in thismanner as can be seen in Fig.14. When the unit stops the primer will often run on to the

    ground if the valve is not shut off immediately. A puddle of primer can be seen beneath the

    unit in Fig.14. This would certainly create an environmental problem in some jurisdictions.

    Following primer application, a side boom is used to support the pipe. The pipe is held by a

    steel wheeled cradle as shown in Fig.15. The cradle does damage the primer at the specific

    location where the pipe is picked up. However, the cradle does not roll along the pipe

    during the recoating operation so the damage is limited to just those points where the

    cradle supports the pipe. This does not create a significant problem for the coating system.

    The rest of the coating system is applied with the line travel applicator shown in Fig.16.

    This photo shows the coating applicator in operation. The cloud visible in the photograph is

    similar to that of a hot coal tar enamel application operation. As in the primer application,

    the hot bitumastic material is applied using a flood-wipe system. The hot material is

    stored in a reservoir on top of the unit. A valve is opened and the hot material is allowed to

    run over the pipe. The pipe rapidly cools the material in contact with it and allows the

    material to build up to the desired thickness. Excess material is caught in a pan

    underneath the unit where a pump returns it to the reservoir on top.

    The fibreglass inner wrap is applied after the material has been flooded on to the pipe. A

    roll of fibreglass material is on one of the two tape arms and can be seen above the top of

    the pipe in Fig.17. The tension on the fibreglass roll provided by the tape arm allows the

    material to be pulled into the hot bitumastic material, providing additional strength to the

    coating system and helps keep the material from sagging to the bottom of the pipe. The

    second tape arm holds the outer tape material. Figure 18 shows the tape being applied overthe hot bitumastic material.

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    The bitumastic material is kept at the proper application temperature in a dope kettle

    shown in Fig.19. The unit is electrically heated and temperature control is very good. The

    reservoir is refilled from the dope kettle by the operator. (See Fig.20).

    Backfilling

    Once the coating material has cooled sufficiently, a third backhoe begins backfilling

    (Fig.20). The soil is taken from the spoils bank and placed in the trench. The backhoe

    operator forces soil under the pipe using his bucket. Initially the trench is only backfilled to

    the top of the pipe. Once the coating has cooled overnight and becomes hard, the remaining

    soil is placed over the top of the pipe.

    The pipe coating is checked for adhesion periodically. A test site is shown in Fig.21. No

    attempt is made to jeep the entire surface of the pipe to check for holidays.

    Will this work on Western lines?

    There are many obvious advantages to this method of pipe recoating:

    Recoating done with the line in operation, Minimal amount of equipment required, 40-man work crew, 150 linear metres of 1020-mm diameter pipe recoated per day.

    Western companies designed their pipelines to different standards, have different methods

    of operating, and have different legal and environmental considerations. The question

    becomes what would have to be done to adapt this recoating methodology to westernpipeline recoating projects.

    Engineering considerations

    One of the key benefits of this method is being able to recoat the line while it is in-service.

    The CPC line is a relatively new line, only 16-17 years old. Construction inspection records

    exist for this section of the pipeline and the pipeline has had numerous in-line inspections.

    Consequently a great deal is known about this section of the line.

    It is necessary to perform a credible failure analysis in order for this to work on older

    western lines. The line must have undergone recent in-line inspections and if the welds are

    questionable, an ultrasonic inspection for cracks should be considered. Axial and

    circumferential stresses on the pipe must be evaluated . In the end, a safe operating

    pressure range must be determined. You have to develop methods for resolving problems

    concerning pipe operating pressure requirements and work schedules.

    Civil work

    It will be necessary to evaluate company operating procedures and governmental

    regulations affecting mechanical excavation next to an operating pipeline. Particular

    attention should be paid to the need to compact the soil under the pipeline. The lack of

    rigorous soil compaction on the CPC line will certainly result in some additional settling of

    the line over time. It must be determined how much additional settling would be

    acceptable.

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    Coating removal

    The coating removal unit used on the CPC project would not be acceptable on most western

    lines. The lines have smaller corrosion allowances, the milling machine damages the weld

    caps and leaves stress risers on the pipe. However, it is possible to remove the coatings

    using high pressure water jets at production rates that meet or exceed those of the CPCcoating removal equipment. Using water jets to remove the coating has the additional

    advantage of removing any soluble salts from the surface of the pipe.

    Inspection

    The methodology used on this project did not incorporate 100% visual and NDT inspection

    of the pipe. It will be necessary to develop an inspection program and a way to protect the

    inspectors while they are in the trench.

    Surface preparation

    Most modern coating systems require an SA 2.5 surface preparation grade before coatingapplication. Automated air abrasive blast equipment can achieve this at comparable

    production rates. Another question to consider is the containment and recovery of blast

    media. The entire spread of equipment is very compact. It will probably be necessary to

    contain and recover the blast media to prevent it from impacting the other operations going

    on at the same time.

    Repairs

    A repair procedure must be developed prior to the start of work. The procedure must

    address the following issues:

    What type of repairs are going to be made and how to do them? When do you do the repairs? Before coating application After coating application How to protect people in the trench while they make the repair? Moveable shoring? Additional excavation at the site?

    Coating application

    Many western countries no longer permit the field application of hot coal tar or bitumastic

    coatings primarily for environmental and health and safety reasons. The only liquid

    coatings that could be used are very rapid setting urethane coatings. The coating should be

    stackable in 10-20 minutes when applied at the operating pipeline temperature. Recentlycoating manufacturers have developed some Polyurethane coatings meeting these

    requirements. However these are new coatings and while laboratory tests look very

    encouraging the coatings do not have a lot of in-ground experience.

    It is also necessary to be able to start and stop the application of the coatings without

    allowing solvents to contaminate the coating applied to the pipeline.

    Conclusions

    In-situ rehabilitation of large diameter pipelines in operation is possible withproduction rates of about 450 to 500 sq meters of pipe per day.

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    The methodology used on the CPC line greatly reduces the amount of equipmentand manpower required to recoat long pipeline segments.

    Comprehensive engineering analysis of the pipeline must be done to determine thepipeline operating parameters while work is being performed.

    Other coating removal, surface preparation and coating application equipment willbe required for work on western pipelines.

    New rapid curing polyurethane coatings will have to be evaluated.

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    Fig.1. Pipeline route.

    Fig.2. Entire spread.

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    Fig.3. Excavation.

    Fig.4. Under-pipe excavator.

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    Fig.5. Under-pipe excavator in operation - retracted position.

    Fig.6. Under pipe excavator - extended position.

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    Fig.7. Sideboom A-frame.

    Fig.8. Coating removal machine.

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    Fig.9. Cutting tools.

    Fig.10. Metal cuttings left in the trench.

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    Fig.11. Cleaned pipe.

    Fig.12. Blasting weld joints.

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    Fig.13. Primer applicator.

    Fig.14. Primed pipe.

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    Fig.15. Steel cradle on primed pipe.

    Fig.16. Line travel coating applicator in operation.

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    Fig.17. Application of the fibreglass inner wrap.

    Fig.18. Tape application.

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    Fig.19. Refilling bitumastic material.

    Fig.20. Backfilling operation.

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    Fig.21. Repair.