India's Longest Gas Pipeline

The East-West pipeline being built by Reliance Industries Limited is designed to transport natural gas from the Krishna Godavari Basin in Andhra Pradesh, traversing the southern Indian states of Andhra Pradesh, Karnataka, Maharashtra, before terminating at the world's largest refinery, Reliance's Jamnagar Refinery in Gujarat. The total length of this 48-inch pipeline, makes it India's longest gas pipeline.

Punj Lloyd, a global EPC services provider in the energy, petrochemical and infrastructure sectors, has been associated with success on tough terrain projects of LOT C of the Baku — Tbilisi — Ceyhan pipeline in Turkey and the island hopping pipeline in Indonesia through the rocky seabed and shallow waters of the Panaran and Pemping Islands.

With experience working in all sorts of terrain, it was not surprising when the toughest sections of the East-West pipeline were awarded to Punj Lloyd for laying of the 48-inch pipeline and associated facilities, with eight MLV stations, five compressor stations, two tap-off stations and seven river crossings. The work was divided into spreads across the states of Gujarat (spreads 7A and 8A) and Maharashtra (spread 7B, spread 6A, spread 6B).

Peru In October 2008, the Peruvian government announced that Kuntur Transportadora de Gas had been awarded a 30-year concession contract to build and operate a 675-mile natural gas pipeline that will extend from the Camisea gas field, located in the Amazon jungle, to the port of Ilo, on the south Pacific coast of Peru. The proposed pipeline will deliver gas to many cities in southern Peru and will enable: The development of petrochemical facilities; The installation of electric power plants that will allow small to large industrial and mining facilities, as well as residential customers to switch to a more efficient energy source; and The distribution of compressed natural gas (CNG) in the southern region of Peru. Kuntur Transportadora de Gas is a Peruvian company entirely owned by Latin Power Ill, which is one of the private equity funds managed by Conduit Capital Partners, LLC based in New York. The word "Kuntur" is in the Quechua tongue, which is a native language of South America (it was the language of the Inca Empire), and means Condor. The Andean Condor inhabits the Andes mountains. Development and construction costs for the pipeline, known as "Gasoducto Andino del Sur" (South Andean Gas Pipeline), have been estimated in the range of US$1.4 billion, considerably higher than the US$850 million alternative presented by Suez Energy Peru to run the pipeline down the Pacific coast to the southern city of Ilo. Peruvian government officials chose, however, the former proposal, which they declared would favor a much larger population, mainly in cities located in the Andes. Kuntur Transportadora de Gas' proposed route for the pipeline was based on preliminary technical and environmental studies. However, now that they have been awarded the concession, they are expected to begin the full development of the project, including the signing of firm off-take contracts, environmental and social impact studies, detailed engineering, financial structuring and the incorporation of additional equity participants. Construction is expected to begin in 2010 and the pipeline should be operational by the end of 2012. Peru's topography is extremely variable, from flat areas in the lower rainforest and coast, to deep canyons and valleys with steep slopes of 50 or even 60 degrees in the Andes and higher jungle. Access can be very difficult, making the use of helicopters necessary in some regions of the Andes and rainforest. The Andes highlands can easily reach 4,800 meters above sea level, and are the origin of a great number of steep gradients and short rivers draining toward the Pacific Ocean, as well as long and large-flow rivers draining toward the Amazon. Multiple river crossings will most certainly be unavoidable during the construction of the pipeline. Some crossings may require the use of horizontal directional drilling (HDD), while others may need to be aerial. The need of tunnels to penetrate mountain areas with rough topography and geological risks cannot be discarded. Adequate pre-construction planning for pipeline erosion control will also be required, as has been learned, unfortunately, from several leaks in the Camisea natural gas liquids (NGL) pipeline, which runs parallel to the natural gas pipeline already in operation. Six leaks have been reported in the first three years of operation in the section of the NGL pipeline that runs from the rainforest and ascends into the Andes. Most of the failures were attributed to excessive forces exerted on the pipeline due to lateral earth movements. Interestingly enough, the natural gas pipeline that runs parallel, has not suffered any rupture to date. However, it has been determined that it is the larger size and wall thickness of the natural gas pipeline which has allowed it to withstand the additional loads without failing. The NG pipeline is 32 inches by 0.625 inches vs. the NGL pipeline of 14 inches by 0.219-inches. The geological and geotechnical conditions and risks (landslides, mudslides, erosion, river crossings, superficial failures, etc.) of the new South Andean Gas Pipeline will therefore have to be sufficiently assessed and mitigated. The shortest route between two points will not always be possible. Both engineering and logistic feasibility, as well as environmental and social integrity have to be considered. Lack of adequate infrastructure and the need for building new roads and bridges or repairing existing ones will have to be taken into consideration in defining the final route. Last, but not least, the Peruvian territory is well-known to be a seismically active area, typically prone to earthquakes. Therefore, associated risks have to be assessed and the design and construction will have to be able to withstand this phenomenon. Peruvian legislation requires an Environmental and Social Impact Assessment (ESIA) to be developed for the project. Soil erosion and subsequent sedimentation of waterways near the right-of-way (ROW) are the key potential environmental impacts of the pipeline construction. The likelihood of archaeological artifacts along the ROW, landowner grievance management and effects of neighboring communities are the key potential social impacts. Peru's great cultural legacy is evidenced by the large number of archaeological sites found throughout the country. There is little doubt that numerous archaeological sites will be encountered along the path of the new pipeline. In many cases, the size and importance of the archaeological remains will make it necessary to shift the planned route. To understand the magnitude of this challenge, we only have to look back at the 456 miles of the Camisea natural gas pipeline built in 2002-2004 by TGP (Transportadora de Gas del Peru). TGP had to form a team of dozens of archaeologists to record all findings along the path of the pipeline. In total, more than a thousand archaeological sites were found in rain forest, Andes highlands and coastal areas. The project also has the potential to affect indigenous people who live in voluntary isolation along sections of the planned pipeline route in all three regions: Amazon jungle, Andes Mountains and coastal area. Therefore, the final route decision will have to provide geotechnical stability, safety and reliability of the pipeline system, and at the same time minimize the social, cultural and environmental impacts. Building transmission pipelines in a rough topography brings with it a higher risk of failures due to natural hazards (mainly landslides). Twenty-five years ago, pipeline rupture rates of 2.8/1,000 km/year in the Andes Mountains were the standard. That rate has improved. In the last 15 years pipelines built in the western side of the South American continent (Andes Mountains) — using best geological engineering practices — can show rupture rates of approximately 0.33/1,000 km/year. Although it is a great improvement, the figure is still three times higher than the 2007 European Gas Pipeline rupture frequency of 0.11/1,000 km/year. The construction of the South Andean Gas Pipeline will present several challenges to its builders, mainly due to the extremely variable topography of the regions it will traverse, and the geological and geotechnical conditions and associated risks. A thorough assessment and mitigation planning will be necessary. The lack of adequate infrastructure will require planning and investments for the construction of roads and bridges in order to transport materials and access the right of way. hi addition to the geographical challenges, the project will face potential environmental and social impacts which will affect the planned route. The success of the project will be based on achieving geotechnical stability, safety and reliability of the pipeline system, and — at the same time — minimizing the social, cultural and environmental impacts. P&GJ

Punj Lloyd accepted the challenges of the project which were: Laying of pipeline in Bhivpuri Ghat with slopes of 70°; Narmada River Crossing by HDD — the second-longest river crossing of 48-inch diameter ever done in India; Laying of pipeline in the highly sensitive and volatile atmosphere in the state of Maharashtra; Tapi River Crossing by Float and Sink technique; Laying of pipeline in the protected area of the Great Indian Bird Sanctuary in Maharashtra. Permission was received almost at the end of the contract tenure after the approval by a high-powered committee constituted by the Supreme Court of India due to the sensitivity of this restricted area.

The Western Ghats are hill ranges running parallel to the south-west coast of India. Bhivpuri Ghat in Maharashtra receives heavy rainfall, has lush tropical vegetation and dense hardwood forests. The challenge was not in terms of distance but in its very steep hilly terrain, with slopes up to 70°. The transportation of pipe, equipment, and numerous other construction tools and tackle were a logistical challenge. To overcome this, the Skyline system, a special technique of pipelaying by an eco-efficient cable-crane system, was adopted, dividing the construction activities into two sections - namely upper and lower slopes.

The route survey was a very critical activity as it involved traversing dense forest land. One of the world's biodiversity hotspots, the Right of Use was hence restricted to protect this sensitive ecosystem. Five crane towers were erected on location with the help of excavators after being pre-assembled in small sections at a workshop. Towers were supported by cable, ropes and anchored by a deadman anchor.

The towers at inaccessible areas on the slope section were erected by joining each tower element in-situ. This involved shifting each tower element to the site manually. Being a tough and risky job, joining each element on steep inclines required careful planning of safety measures to ensure that the installation work was carried out successfully with utmost safety.

As a risk-control measure, all employees were required to use the full body harness with the lifeline. This ensured elimination of accidents. Nets were provided on the slope at strategic locations to arrest possible rolling of stones or small landslides. Workers on the towers were provided retractable fall arrestors, enabling them to work freely in relative terms, eliminating the hazard of falling during ascending or descending the towers.

The steep gradients of the Bhivpuri Ghat varied from 30° to 70° broken by a plateau. Excavation on the steep slope was carried out by special Menzi Muck excavators. These excavators have an adjustable chassis to suit the terrain on which they are to work; a powerful all-wheel drive and a walking function that makes the equipment resemble a giant tarantula. Gradients in excess of 100% pose no problems. As a result, four of these excavators were put to work on the uphill and downhill gradients. They also feature a bucket attachment and a drilling attachment for drilling and blasting holes wherever rock was present.

The sheath rock was so hard that it required three to four rounds of controlled blasting to remove it. It was important to perform controlled blasting to prevent damaging towers and cables and to minimize impact on micro-climatic conditions. Excavation in the flat section was done by two 20-ton excavators transported to the location using the cable-crane system. To facilitate their transportation, the excavators were first dismantled, shipped part by part and then re-assembled, as the maximum load-bearing capacity of the cable-crane system was 12 tons.

For the welding process, the Skyline system proved to be a boon for fit up on the steep slopes. In addition to the Skyline support system, platforms were fabricated and fitted onto the pipe to facilitate welding. Owing to the varying trench profile, a surveyor accompanied the welding crew so that the required bends were calculated in advance, four to five pipes ahead, to ensure continuous welding.

For trench protection, slope breakers were transported from a central location to designated intervals along the pipeline route and manually stacked at these locations. For pre-padding, post-padding and backfilling, large capacity carriages were specially fabricated and fitted into the Skyline system to ensure speedy completion.

Cleaning, gauging and hydrotesting was completed successfully in a single attempt. It was a significant accomplishment to carry out the hydrotesting at a height difference of 580 meters. Precautionary measures and round-the-clock surveillance ensured a stable pressure head was maintained throughout the pressurization and depressurization activities.

Due to the exceptional biological diversity and richness of the Ghat region, a new concept for slope protection was introduced in India, using a combination of Gabions and Reno mattresses. These are boxes made of flexible twisted hexagonal wire mesh coated with zinc/PVC into which stones of various sizes are filled.

In keeping with the performance standards of International Financial Corporation, endemic conditions were created by spreading soil and organic material with native seeds over these boxes. Coir mattresses were laid over the Gabions to keep them in place. This system controls soil erosion during the monsoon season and ensures the growth of locally prevalent species for restoration of the endemic vegetation along the pipeline route to its original form.

The Tapi River was one of the critical crossings for the East-West Pipeline project. Initially this crossing was planned to be executed by a horizontal directional drill (HDD) as part of the mainline contract. However, due to resistance from local villagers concerned about a temple along the original pipeline route, the alignment of Tapi River crossing was shifted.

Fresh soil investigation for the crossing was carried out and it was discovered that despite the short distance, the soil strata had changed completely. At the new location, the river bed had huge boulders, rock and high density gravel. Punj Lloyd offered a plan to execute the crossing by a float and sink method where the concrete-coated pipe could be laid across the Tapi River.

After the client had approved the methodology, the contract for the river crossing was awarded to Punj Lloyd. It involved design, engineering with anti-buoyancy calculations, design float spacing from setup to removal of the floats once the pipe is pulled into the water.

This was a challenging river crossing. The 48-inch diameter pipe string, with more than 6 inches of concrete coating weighed 1,200 tons. Nearby, a road crossing away from the north bank had to be negotiated by thrust boring, as it was a busy city road. A 66-inch RCC casing across the road was installed and the 60-inch diameter concrete-coated pipe string was fabricated in a continuous string and bored through.

Meanwhile, on the river front, the design calculations were carried out for anti-buoyancy and to determine the size and number of floats required to pull the pipe into the river. Also, an `A' frame was fabricated on a pontoon to support the cold field sag and bends were welded to the string, so that no tie-in was required once the pipe was pulled into the water and the end of the bend was on the river bank after the pullback was completed.

Our 400-ton HDD rig was mobilized and rigged up on the south bank of the river to pull the string from the north bank. Six 100-ton sidebooms were deployed to keep the string in place on the rollers during the pullback. Once on the rollers, the floats were clamped onto the concrete-coated pipe.

As the trench was being readied, the string was being prepared for pullback. The drill pipe string was shifted to the other bank by a pontoon and hooked up to the 'A' frame while the bend was supported by the 'A' frame on the pontoon. The pullback started in the morning and took two consecutive days. The operation was so smooth and well-designed that the pull force was very minimal.

Once the string was pulled across, the 'A' frame was disconnected and the cold field sag and over bend were welded to the tail end of the pipe and pulled further into the river. Once the string was across the river, the floats were removed and the pipe was allowed to sink into the trench. The pipeline was later backfilled with the help of the excavators on pontoons.

V.N. Prasad. The Impossible Made Possible On The East-West Gas Pipeline. Pipeline & Gas Journal. August 2008. Antonio A. Montes. South America Pipeline Project. Pipeline & Gas Journal. May 2009.

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