Preliminary study of graphene- based infill material in repairing corroded oil and gas pipelines

PRELIMINARY STUDY OF GRAPHENE- BASED INFILL MATERIAL IN REPAIRING CORRODED OIL AND GAS PIPELINES

Nordin Yahaya

Faculty of Civil Engineering, Universiti Teknologi Malaysia, UTM Skudai,

Johor 81310, Malaysia,

nordiny[AT]utm.my

Lim Kar Sing

Faculty of Civil Engineering, Universiti Teknologi Malaysia, UTM Skudai, Johor 81310,

Faculty of Civil Engineering and Earth Resources, Universiti Malaysia Pahang, Lebuhraya Tun

Razak, Gambang, Kuantan, Pahang 26300, Malaysia, limkarsing[AT]ump.edu.my

Siti Nur Afifah Azraai

Faculty of Civil Engineering, Universiti Teknologi Malaysia, UTM Skudai,

Johor 81310,

snafifah2[AT]live.utm.my

Norhazilan Md Noor

Faculty of Civil Engineering, Universiti Teknologi Malaysia, UTM Skudai,

Johor 81310,

norhazilan[AT]utm.my Introduction

Polymeric composites are being increasingly used as infill material in civil engineering applications for repairing critical infrastructures such as beam, column, pressure vessel, piping and pipelines. Pipelines are subjected to deterioration due to several factors, including third party damage, material and construction defects, natural forces and corrosion [1,2]. The deterioration of the steel pipelines is a common and serious problem, involving considerable cost and inconvenience to industry and to the public. Recently, an explosion of underground pipeline in Kaohsiung, Taiwan has killed at least 27 people and injured 286. Initial investigation showed that the cause of this incident was likely triggered by a leaky underground pipeline owned by a local chemical producer that operates a 4-inch propene pipeline [3]. It is a fact that corrosion and metal loss can cause failures in pipelines and their repair techniques is one of the prime interests of the researchers all over the world [4, 5].

In repairing damaged pipes, combination of composite wrapping layer and infill material is a preferable technique used in oil and gas industry [6, 7]. Recently, there is tendency in reducing the usage of composite wrapping layer due to several reasons. These reasons include composite wrapping layer is more expensive as compared to infill material. Besides, some damaged pipes are located in congested area such as piping on offshore platform, piping of boiler tank and underground pipelines that has limited working area for the wrapping process. This makes the replacement of the damaged pipes as the only possible solution to maintain its service life. Therefore, researchers are looking for the potential infill material to gradually reduce the usage of composite wrapping layer, hence the thickness. Ultimately, its hope that one day the repair can be done without composite wrapping. One of the possible ways in achieving this goal is by increasing the contribution and performance of infill material as part of the repair system. High performance infill material may increase the repair efficiency and serves as second protection layer if failure of composite layer occurs. Hence, this paper has taken initial step to investigate the mechanical properties (compressive and tensile) of graphene-based epoxy grout to be used as infill material in composite repair system of pipeline.

Material and Methods

The epoxy grout used in this study is a commercial three-part silica filler reinforced epoxy grout which consists of modified epoxy resin, hardener and fine silica sand. To achieve the research aim, 2% of graphene nanoplatelet by weight ratio was used as filler to enhance the performance of epoxy grout. The preparation of epoxy grouts was carried out as per manufacturer’s guideline. First, epoxy resin, hardener and silica filler were weighed based on ratio as recommended in manufacturer’s datasheet. An electrical mixer was used to thoroughly mix the graphene nanoplatelet with hardener in high speed to disperse the graphene particle in hardener. It was then followed by adding epoxy resin and continues the mixing process until a smooth consistency paste can be obtained. Lastly, silica filler was added and all parts were mixed until a homogeneous grout can be produced. Specially designed steel moulds were used in casting the compressive and tensile test samples. The samples were cured in room temperature for 24-hours prior to the testing. All the tests were carried out using INSTRON 25KN universal testing machine. Table 1 summarizes the detail of tests conducted on the prepared specimens.

Table 1

Summary of mechanical testing detail

Results and Discussion

The results of compression and tensile test for graphene-based and standard grout are summarized in Table 2. The values are the average of maximum strength prior to failure of the samples. The compressive strength of this grout is nearly 90MPa which comparable to ultra-high strength concrete ( 80MPa) while the tensile of the tested grout was found to be 15MPa. Moreover, it can be seen from the table that the compressive and tensile modulus of the grout are 14GPa and 17GPa respectively.

Table 2

Summary of mechanical properties of graphene-based grout

Figure 1 shows the failure mechanism of compression and tensile sample under uniaxial loading testing. During compression test, the sample exhibits noticeable deformation prior to failure. Initial cracks were observed at top and bottom part of the sample where the maximum stress occurred. It was then followed by gradual reduction in stress prior to failure. On the other hand, the failure of tensile sample occurred without any noticeable deformation. The samples split into two parts as shown in Figure 1. It exhibits brittle behavior when comparing to steel material. By comparing graphene-based and standard grout, there is no significant increase of strength. Nevertheless, the addition of graphene has produced a more consistent results according to a smaller standard deviation of strength (refer Table 2). This shows that the performance of graphene-based grout is reliably predictable. This is important since repair design of damaged pipeline is of deterministic nature. The standard grout also exhibits sudden rapture as compared to graphene-based grout.

Compression sample

Tensile sample

Figure 1. Failure pattern of compression and tensile sample

Previous study done by Mendis [8] suggested the typical properties of epoxy grouts used for repair and rehabilitate damaged structures. Compressive and tensile strength greater than 40MPa and 14MPa was reported suitable for repairing concrete crack. The author also suggests that for structural rehabilitation, compressive and tensile strength is suggested to be more than 80MPa and 28MPa, respectively. In composite repair of externally corroded pipeline, the infill material serves as medium to transfer the stresses on internal surface of pipeline generated by internal pressure (without sharing the load) requires high compressive strength. Therefore, the tested can serve in high compressive condition and has the potential in reducing the wrapping thickness.

References

Noor, M. N. Yahaya, N., and Othman, S.R. The Effect of Extreme Corrosion Defect on Pipeline

Remaining Life-time. Malaysian Journal of Civil Engineering, 2008. 20 (1), 47-577.

Shamsuddoha, M., Islam, M.M., Aravinthan, T., Manalo, A., and Lau, K.T. Characterization of mechanical and thermal properties of epoxy grouts for composite repair of steel pipelines. Material and Design, 2013a. 52,315-327.

Hsu, J. W., and Liu, F. Taiwan Gas Blasts Likely Caused By Faulty Pipe. The Wall Street Journal, 2014. Accessed on 11 September 2014, online.wsj.com/articles/taiwan-gas-blasts-likely-caused-by-faulty- pipe-1406964902.

Shamsuddoha, M., Islam, M.M., Aravinthan, T., Manalo, A., and Lau, K.T. Effectiveness of Using Fibre- Reinforced Polymer Composites for Underwater Steel Pipeline Repairs. Composite Structure, 2013b. 100, 40-54.

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