City Gas Distribution Challenges: Challenges Faced by CGD, IGL — A Case Study With Solutions Adopted

There are some issues and concerns that need urgent attention. Chief among these are delays in securing multiple clearances, lack of well-defined market potential, entry barriers, deficient pipeline connectivity and uncertainty regarding domestic gas supply. The challenges during the reward of license revolve around issues affecting project Internal Rate of Return (IRR), project investment rate of return, market exclusivity, gas allocation, gas availability issues, logistic and manpower issues. With the formation of PNGRB, the safety practices and guidelines were looked into and framed. But once allocation process is over and operation is in progress, there are still several challenges that are being faced as: • Safety Management • Space Constraint for CNG station facilities • Queue Management • GIS for CGD network • Third party damages • Coordination with other utility Companies • Compliance of emission norms • Equipment Availability • Customer satisfaction (Services, Metering, billing) • Threat of alternate energy solutions • Embrace digital technology in conjunction with analytics intervention. • Compliance of stringent targets by the ministry. For IGL, being into the operation at the capital of the nation the major concern with CGD is safety, customer friendly operation and on-time solutions. This paper will discuss in detail the work adopted by IGL to cater the problem of space constraint, queue management and external threats. Apart from this, it also covers the various technologies and automation strategies adopted towards safety system, metering, billing, equipment availability etc. CGD companies must embrace digital technology in conjunction with analytics intervention to enjoy technology renaissance. It will help in achieving improvements and address issues in PNG, CNG and management of assets, among others. Emphasis will be given to provide a few such initiatives in detail, mentioned above, such as the pilot project going for HCNG plant, SCADA system for online monitoring of equipment, GIS system for pipeline integrity, automation of safety system and customer satisfaction.

New Materials for Protection of City Gas Distribution Networks

Polyethylene pipes and Steel pipes with 3LPE coatings are integral part of a citygas distribution network. These are being used in India since late 80’s. Standard MDPE and HDPE materials are Butene copolymers of Ethylene, where Butene (C4) is added as comonomer to form the side branches of linear Polyethylene (C2) chains. The research on PE materials have improved various attributes of the polymer, providing them with higher durability, pressure resistance and service life. One such development is use of Hexene (C6) as a copolymer replacing Butene (C4) to make an Ethylene Hexene copolymer providing superior resistance to mechanical damages and slow crack growth during installation and service. For PE100 Orange pipe materials for low / medium pressure distribution system, the new hexene PE copolymer, offers much superior resistance to slow crack growth. Hence it is ideal for Trenchless installations like HDD or pipe bursting, where pulling the pipe through the bore in the ground may substantially notch and scratch the pipe or coating. Using a Hexene PE service life of the pipe is not affected despite the demanding installation techniques due to higher entanglement of polymer chains. These types of PE materials are already being used by Indian CGD Industry for past 2–3 years. For 3LPE coated steel pipes for high pressure gas mains as well as trunk lines, Hexene based Black PE top coat has been adopted by several Gas companies. This is mainly due to two advantages. They offer a higher upper design temperature limit of +90 C (compared to +80 C as per international specification (ISO21809-1). They also offer material savings as 10% lower thickness compared to standard PE top coat is able to meet and exceed all system requirements. The paper deals with the mechanism of these new polymers that helps to offer these superior properties.

Fitness for Service Assessment of Cross Country Oil Pipelines Based on API 579 (Application of API 579 on ASME B 31.4)

Pipelines are one of the safest forms of transportation for oil and gas. However, Pipelines may experience defects, such as corrosion, cracks during service period. Therefore, evaluation of these defects is very important in terms of assessment and for continued safe operation. Corrosion defects at the external surface of pipelines are often the result of fabrication faults, coating or cathodic protection issues, residual stress, cyclic loading, temperature or local environment (soil chemistry). In general, corrosion may occur in most pipes due to coating failure, and a pipe without any protective coating will experience external corrosion after some years. However, corrosion can occur on the internal surface of the pipeline due to contaminants in the products such as small sand particles. At present, there are different assessment methods for different types of defects in pipelines. The most popular codes for defect assessment in oil and gas pipelines are RSTRENG, Modified B31G, BS 7910 and API 579. Besides these codes and methods, there are numerical programs, such as CorLAS, which have been used successfully for assessing crack flaws in Pipelines. RSTRENG and B 31G methods are very simple when compared with API 579. API 579 is very complex method of assessing defects but very useful for remaining life assessment of Pipelines. In this paper corrosion defects like general metal loss, localized metal loss, pitting corrosion, other defects like dents, gouges, cracks, their remediation methods assessed based on API 579 method and our experience in Oil Pipelines. Since API 579 doesn’t cover cross country pipelines explicitly, we have made a research applying API 579 to ASME B31.4. Even though, we have done research on all types of defects (Level 1 and Level 2 assessment), in this paper we have covered only General metal loss assessment.

Pipeline Coating Failures and Preventions

The coating and cathodic protection protect pipeline against the corrosion. The failure of these two defense systems leads to corrosion failure of pipelines. Any changes in chemical, physical or electrochemical properties of coating which affect their properties to isolate tFhe pipes from the corrosive atmosphere is considered as failure of coating. The failure mechanism and the gap analysis need to be continuously done for improvements in specifications and its executions. Majority of the global oil and gas pipelines are being protected externally with either 3-Layer Polyolefin coating system or fusion bonded coatings. Some of the gas pipelines are provided with a flow improvement internal coatings considering nil corrosive challenges on internal surfaces. The failures in the external coating appear in the form of edge disbondment from cutbacks and near holidays, complete loss of adhesion of coating, loss of cohesion within coating, cracking in the coating, swelling & blistering around holidays, distortions in the coating, electro osmosis, electrophoresis and highly alkaline atmosphere near holidays, continual increase in CP currents and corrosion of the substrate. The internal surfaces of pipes are suffering corrosion mainly due to presence of corrosive gases viz. carbon dioxide, oxygen, condensates and other corrosive substances even in traces. The common methods like Dehydration, Inhibitors, Buffering, Biocide and Cleaning pigs are not adequate to protect the pipelines to from the corrosion. A very thin internal flow coat can hardly resist any corrosion and gets failed. This paper presents the in-depth analysis of the major causes of coating failures and the improvements required in the external and internal coating selections, specifications, coating applications, testing and its maintenance.

Development of API 5L X70 Grade Steel Through Thin Slab Casting and Rolling Process

API 5L grade steel is mainly used for oil and gas transportation. The economy of gas transportation via pipeline demands for high operating pressures and large pipe diameters in order to improve transportation capacity which requires heavy thickness and/or high grade of the steel. This pushed the steelmakers to develop high strength steels (HSS) with superior metallurgical and mechanical (strength, toughness and ductility) properties in order to allow exploitation in hostile environments. The technology of production of API 5L grade through conventional thick slab process is matured enough as it gives flexibility of using higher %C, lower casting speed, high slab thickness (200–250 mm), higher reheating temperature and time, high reduction etc. However due to slower cooling rate during liquid to γ transformation, possibilities of centerline segregation defect increases. Thin slab technology (TSCR), on the other side allows a reduction in energy consumption (because of lower slab thickness and elimination of reheating process), with consequent benefits in terms of production costs and pollution reductions. But producing API X65 and above though TSCR route with subzero impact and DWTT is a challenge because of the difficulties in achieving a refined and homogeneous microstructure due to lower reduction ratio from slab to finish sheet thickness. This paper aims to give an overview of recent developments of high strength pipe steel grades as API 5L X70 through TSCR route. Information regarding the metallurgy and processing, such as chemical composition, microstructural design, thermo-mechanical controlled process (TMCP) and accelerated cooling process (AcC), to achieve the target strength, ductility and toughness properties are discussed. Mechanical properties are well above the requirement of X70 at HR stage as well as after pipe formation. Excellent Impact and DWTT is achieved up to −40° C.

Conceptual Design of Dahej-Nagothane Ethane Pipeline in India

Reliance Industries Limited (RIL) planned to import liquid Ethane from North American market for use as feedstock in Gas Crackers at Dahej Manufacturing Division (DMD), Hazira Manufacturing Division (HMD) in the state of Gujarat and Nagothane Manufacturing Division (NMD) in the state of Maharashtra. Liquid Ethane was planned to be unloaded at GCPTCL (Gujarat Chemical Port Terminal Company Limited) Jetty and stored in cryogenic tank in DMD. For use in NMD and HMD, it was proposed to transport Ethane via a dedicated pipeline traversing through the states of Gujarat and Maharashtra and deliver at respective gas crackers of HMD and NMD in a direct usage mode as no storage facilities for Ethane were envisaged at delivery locations. Reliance Gas Pipelines Limited (RGPL), a wholly owned subsidiary of RIL implemented the Asia’s 1st liquid Ethane Pipeline project as “Dahej - Nagothane Ethane Pipeline Project” (DNEPL) and successfully commissioned the pipeline in September, 2018. This paper presents the Conceptual Design of the project including selection of phase of transportation, pipeline configuration in terms of pipeline size, no. of pump stations, spacing of main line valves (MLV’s), operating conditions, material of construction and emergency evacuation requirements of Ethane during long haul transportation.

Manufacturing of Extremely Low D/t LSAW Welded Pipe

Critical offshore pipelines require extremely low D/t (Outer diameter to wall thickness ratio) pipes, that pose a manufacturing challenge using conventional practices and operational toolings. Such pipes are most often manufactured through the seamless route, due to the D/t ratio. But seamless pipe are more expensive as compared to welded pipes, along with having higher lead times due to fewer manufacturers. There is also a concern with the uniformity of wall thickness throughout the pipe body due to the manufacturing process, but with an advantage of better properties citing homogenous composition due to absence of a weld seam. Though in the last couple of decades, owing to advances in the welding technology, the weld seam of a welded pipe has proved to be superior to the base metal plates/coils in terms of its strength integrity. To manufacture such pipes through the LSAW (Longitudinal Submerged Arc Welded) process requires major overhauling and process modifications at practically all the stages of the process flow. The low diameter and high wall thickness become very demanding when it comes to bending the plate and then welding (SAW) from the inside due to space constraints. This paper describes in detail the challenges faced and overcoming of the difficulties in manufacturing an 18″ diameter, 35 mm wall thickness LSAW pipe (D/t ratio of 13) for a major oil & gas player, by development of new designed toolings for various equipment like plate crimping, pipe forming and mechanical expander; new lubrication oil; and optimizing the process parameters, as the major factors contributing to success. The tooling design modifications were done in-house, along with the development of a new lubrication oil and its treatment in plant. This enabled Welspun Corp to surpass the equipment capacities prescribed by the OEMs, and set a new benchmark in the industry for the production of extremely low D/t welded pipes, with excellent mechanical properties along with impeccable pipe dimensions.

Geo-Spatial Information System (GIS) Mapping of Pipeline Network in India Using Modern Route Survey Techniques and Practices

SECON developed GIS Database and Web based Pipeline Information Management System (PIMS Application) covering all the pipelines and facilities across the country for which work has been awarded to SECON Pvt. Ltd., Bangalore. This database comprises of different map layers and associated tables pertaining to pipeline alignment, stations and facilities, dwellings and structures along the pipeline alignment, pipeline depth of cover, points of interest along the route etc.

A Case Study: Failure Analysis of Crude Oil Pipeline Rupture

More than 80% of crude oil requirement in India is met through imports. Imported crude oil is delivered to the shore tanks through Single Point Mooring (SPM) system. Generally, SPM systems are installed in the sea where water depth is around 30m and more. Crude oil tankers discharge their cargo through these SPMs and off-shore pipelines to storage tanks located in the shore. Therefore, off-shore crude unloading pipelines are a vital link to in the energy supply chain in India. Management of these off-shore pipelines is a challenging task. This paper discusses a case of mechanical damage to an Indian off-shore pipeline and how the damage is being evaluated to ensure reliability and safety of this vital link to ensure sustained and safe operation of the line. The mechanical damage discussed in this paper is in a 48″ off-shore pipeline at a depth of nearly 30m and 24km away from the shore. Owners believe that the damage was caused due to anchor hit from a ship that was buffeted away from safe anchor zone to no anchor zone during a cyclonic storm. Owner had to face considerable challenge in locating and measuring the extent of damage and evaluating its severity and probable impact on the integrity of the pipeline. Owner had done multiple geometry inspection of the pipeline to measure the length of the damage and restriction introduced in the bore due to local reduction in diameter. Possibility of presence of a crack and its likelihood of growth in the near and distant future is also evaluated. The paper also discusses the possible remedial measures to ensure long term integrity of the pipeline.

Is Small Bore Tubing Systems an Achilles’ Heel of Asset Integrity? An In-Depth Analysis Through Case Studies

Small bore connecting (SBC) systems, including small bore piping (SBP), Small bore tubing (SBT) and Flexible Hose Assemblies (FHA) with size below DN 2″, are significant contributor to the incidences of Loss of Primary Containment (LOPC) and are a major source of failures in piping systems. Modern hydrocarbon installations feature large numbers of control and monitoring instruments, which require a considerable application of SBT assemblies, along with enormous number of threaded fittings and joints. However, the basic expectations from these SBTs will remain to provide the integrity over the entire life cycle of the installation. One of the estimates from standard database (Courtesy: Energy Institute Guidelines, year 2013) indicate that 20.4 % of all hydrocarbon leaks recorded in the Hydrocarbon Release (HCR) data were related to SBTs. Of these events, over half were classified as major or significant HCRs events (notionally an amount greater than 1 kg) linked to SBT assemblies. With complexity and extensive applications, SBT assemblies are vulnerable to failure due to incorrect design, selection, installation, operation, modification, inspection & maintenance and could result into events of LOPC and Major Accident Hazards (MAH). Despite availability of guidelines for design and installation, failures in SBT assemblies continue to occur in operational phase. Lack of formal procedures, inconsistent controls to manage the biggest contributors to HCR on assets, signifies the requirement of a structured approach to achieve Asset Integrity. Then there arise a question “is small bore connection systems an Achilles heel of Asset integrity? This paper covers, an in-depth analysis of few LOPC events, of geographically different installations, related to SBTs with an aim to achieve overall Asset Integrity through a. Verification of availability of sufficient barriers, between safe operation & incident. b. Effective management of threaded connections in existing SBT assemblies with respect to relevant ASME standards. c. Practical guidelines for providing preventive and recovery controls barriers for an effective management of SBTs.