Pipeline problem solving in

Ian Taylor and Donald Chapman, IMG Composites,

UK, discuss the use of high performance composite materials

on an unusual pipeline repair in Iraq.

Engineered composite pipe repairs are widely used in the oil and gas industry; however, they are not always straightforward. Sometimes the specialist expertise of an established composite repair company can prove valuable.

When IMG Composites was commissioned to solve a pipeline problem in Iraq, using CompoSol® materials, the repair was doubly challenging as it not only required operations in a region with an unstable security situation, but was also an unusual example of severe impact damage to a gas pipeline that required a fully engineered, live-applied repair.

BackgroundIraq has plentiful reserves of oil and gas, having the 5th largest proven crude oil reserves in the world at an estimated 141 billion bbls of oil (American Energy Institute). In 2010, Iraq was the 4th largest natural gas flaring country in the world, however, with a proven 111 trillion ft3 of natural gas reserves efforts have since been made to better utilise natural gas production for domestic power generation. The security situation in Iraq is challenging, especially after an increase in the number of terrorist attacks across the country in 2013. According to the advice of the UK Foreign and Commonwealth Office, travel is strongly discouraged, with some variation in severity across the regions of Iraq.

IMG Composites was contacted by an operating company in Iraq who are responsible for a wide network of natural gas pipelines, including supplies to a number of electricity generating plants. One of the buried 24 in. gas pipelines operating in a regional network suffered mechanical damage in a military engagement, resulting in a severe dent. The pipeline was operating in excess of 800 psig (55 barg) and the nominal wall thickness of the pipe was 17.5 mm; however, onsite inspection, including NDT tests, indicated some thinning in the pipe wall material in the defect area.

To facilitate continued operation, a CompoSol® wrap repair was requested by the operator in order to provide mechanical integrity to the dented area. IMG Composites, through its strategic partnership with Cape East, has a long history of repairing oil and gas infrastructure in the Middle East, making it ideally placed to provide a solution in this instance. Utilising its bespoke, high-performance CompoSol materials, fibre reinforced polymer (FRP) pipe repairs have become commonplace on Middle Eastern and UK/Norwegian North Sea assets.

The CompoSol range of products provides a means to restore structural integrity to worn, corroded and damaged pipelines, as well as piping systems, tanks, vessels, structural members and flat surfaces. The required strength is provided by a fibre matrix, usually glass, Kevlar or carbon, depending on the properties necessary to ensure the correct standard of integrity for the pipe service. Fibres are embedded in top quality, solvent free CompoSol resins, which provide an extremely high level of adhesion and thereby an effective load transfer to the surrounding, undamaged pipe wall. The heightened adhesion and toughness of CompoSol resins mean that FRP solutions are particularly effective when sealing through-wall defects.

Designing a pipeline repairDelivering engineered composite repairs to ISO24817 is not easily achieved. Beyond the qualification of the repair system, and the development of a system of high enough performance to be useful in the majority of pipe repair scenarios, there is an onerous level of engineering, chemical and operational expertise required to meet an operator’s expectations. In the case of the above natural gas pipeline case study there was a further complication, that of defect assessment. The ISO24817 standard provides comprehensive guidelines on how to design a composite repair system for a range of standard defects; however, it does not explain how to quantify the effect of a dent on the pressure retention of a pipe.

IMG Composites engineers utilised major pipe codes that contain defect assessment procedures (such as ASME, API and DNV codes), enabling them to ascertain the effect of the dents. It was concluded that the damage in this case resulted in an equivalent loss in strength of > 80%. Using this calculation, a repair was designed in line with ISO24817 and ASME PCC2 Article 4.1, according to the available pipeline parameters. These parameters included pipe diameter, nominal and remaining wall thickness, operating and design pressures, environmental and fluid service temperatures and the defect area. The assessment procedure involves assumptions regarding the elastic behaviour of the substrate. Consequently, the process is further validated by carrying out an in-house finite element analysis to ensure that the stresses in the substrate and the composite are at satisfactory levels. Defect assessment is often the most misunderstood element of a composite repair by those suppliers lacking experience or capability and therefore should be

Figure 1. Composite repairs to buried pipelines are common in the Middle East.

Figure 2. IMG Composites’ Engineering Manager, Donald Chapman MEng, offering a presentation on composite engineering to an audience of operators in Aberdeen.

MARCH 2014 / Reprinted from World Pipelines

considered thoroughly by the client to ensure the design is always suitable.

Application: ‘on the ground’Following on from the technical assessment, the material specification and design were passed on to Cape East to implement the repair. IMG Composites works closely in the Middle East with its strategic partner Cape East (in the Kingdom of Saudi Arabia, Cape RB Hilton) to fulfil client operators’ requirements for the restoration of integrity using composite repairs designed to ISO24817 and ASME PCC2. One of the stipulations of these standards is that trained and experienced personnel must carry out the application of such repairs – application being a crucial element to any FRP solution. Supervisors are required to have at least two years of experience with FRP pipe repair applications, while applicators have to undergo extensive training, as well as demonstrate continued competency. The Cape companies in the Middle East provide oil and gas operators with an extensive range of services, including scaffolding, thermal and acoustic insulation materials, refractory linings and inspection services. The provision and installation of this wide range of services means that Cape have in excess of 8000 personnel operating in the Gulf Co-operation Council states and wider Middle East. With over 30 years of experience operating

in the region, even in the most sensitive environments, Cape are well placed to support the application of CompoSol repair and refurbishment composite systems.

Cape organise the requisite logistical resources in the region, with stocks of CompoSol materials in UAE, Qatar and KSA, and have a pool of fully trained supervisors and applicators, certified to ISO24817. IMG Composites specialist personnel offer expert training and support to Cape employees. The Cape Group has more than a decade of experience in repair and refurbishment using CompoSol REP (Kevlar reinforced filler paste) and CompoSol CRC (fibre reinforced resin laminate).

During this period of partnership, Cape and IMG Composites have carried out piping system and pipeline projects for all the major operators in the region (both offshore and onshore) in Abu Dhabi, Dubai, Sharjah, Kuwait, Qatar, Oman, KSA and Iraq. Repairs have been implemented on a wide range of assets, including above ground and buried pipelines, gas transmission and main oil lines, produced water lines, production headers and storage tanks. All types of geometries, straight sections, bends, tees and reducers have been refurbished using specifically designed CompoSol products.

When the Cape team arrived onsite in Iraq, the dent was assessed to ensure it met the details specified in the design. The substrate was then prepared by hand with wire brushes to achieve an St.2 standard of surface cleanliness. In this instance, any mechanical or blasting methods of preparation were considered to be too dangerous due to the gas contents of the line.

Following preparation the dent was filled with high strength CompoSol REP filler, with additional supporting layers of CompoSol CRC laminate. Sufficient curvature was established to enable compression to be applied over the complete filled area. A fully circumferential wrap of CompoSol laminate was then applied over the whole damaged area, extending over a length of 1200 mm. Both the thickness of the applied laminate and its axial extent were dictated by the engineered design. The next day quality assurance and control checks were carried out using IMG Composites methodology, to ensure completeness of cure.

Five trained applicators and a supervisor carried out the full repair, in accordance with the engineered design, over a period of six days at a very economical cost.

ConclusionThis repair highlights some of the key benefits of high performance FRP composite repairs, applied in conjunction with a skilled and responsive contractor, to pipelines in sensitive and difficult areas. A short lead-time and quick response put the clients mind at ease. Application requires no heavy or complicated equipment and materials are lightweight and low volume, making logistics straightforward. Finally, composite solutions can restore structures to design capacity with a guaranteed lifetime of up to 20 years. As assets continue to age, composite repairs will become more ubiquitous, with applications on a global stage.

It is important to understand that although composite repairs look simple once applied, in order to correctly deliver an engineered repair the composite repair company will require not only specialised expertise at the design stage, but also trained and competent personnel on the ground in the location the repair is to be effected. The temptation by some companies is to see composites repairs as easy, but the responsibility of all, both vendors and operators, is to appreciate the demanding standards required from a composite repair that carries the name of an engineered repair.

Figure 4. CompoSol CRC laminate is carefully applied.

Figure 3. IMG Composites’ Operations Manager (centre) training a cape applications team.

Reprinted from World Pipelines / MARCH 2014