Oil and gas pipelines are subjected to various types of deterioration and damage over long service years. These damaged pipes often experience loss of strength and structural integrity. Repair mechanisms have been developed in restoring the loading capacity of damaged pipelines, and composite repair systems have become popular over the past few years. The mechanical properties of the putty/grout are critical to their potential application as infill materials in structural repair. In this paper, the compression, tensile, and flexural behavior of four epoxy grouts was investigated through laboratory tests. The stiffness of the grouts for compression, tensile, and flexural was found to be 6 GPa to 18 GPa, 4 GPa to 15 GPa, and 4 GPa to 12 GPa, respectively. The ultimate strength for all grouts was found from 62 MPa to 87 MPa, 18 MPa to 38 MPa, and 34 MPa to 62 MPa under compression, tensile, and flexural tests, respectively. The behavior of all the tested grouts is discussed. A finite element (FE) model simulating a composite-repaired pipe was developed and compared with past studies. The FE results show a good correlation with experimental test with margin of error less than 10%. By replacing the infill properties in FE model to mimic the used of different infill material for the repair, it was found that about 4–8% increment in burst pressure can be achieved. This signifies that the role of infill material is not only limited to transferring the load, but it also has the potential to increase overall performance of composite-repaired pipe.
Polymeric composites are increasingly being used as infill material in civil engineering applications for repairing damaged structures, including corroded pipelines. In repairing damaged pipelines, combination of composite layer and infill materials is a preferable technique used in oil and gas industry. It is desirable for a repair work to be completed in a short period of time. More importantly, as the repair work is done, the structure is expected to back in service soonest possible to minimize the financial loss due to production interference. This paper investigates the development of tensile and compressive strength of two epoxy grouts over 28 days. This research program aims to improve fundamental understanding of this material and its potential application in repairing damaged pipeline. A total of 80 samples with different curing times were prepared based on manufacturer’s guideline. The samples were then cured in room temperature for 1, 7, 21 and 28 days before tested using universal testing machine. The trend of strength development over time was studied to identify the time at which the grout can be considered capable of serving in service condition. It was found that the compressive and tensile strength of both grouts greater than 70MPa and 14MPa at 1-days curing time, respectively. The strength is about 80% developed for 1-day curing time. When comparing the properties of the tested grouts with previous studies, both grouts were found to have the potential to be used as infill material for repairing damaged pipeline. In addition, for application of compressive strength and tensile strength less than 70MPa and 14MPa, both grouts can be considered as capable to serve its repair purpose after the grout cured for 1 day.
Oil and gas pipes are vulnerable to failure initiated by corrosion because of their operating pressure under adverse conditions. A composite repair assembled around the pipe with a small gap that is then infilled with epoxy grout is considered a suitable option for repairing corroded pipelines. This article presents an investigation into the mechanical properties (compressive, tensile, and flexural) of epoxy grout, with and without inclusion of silica sand as a filler. The mechanical tests were carried out in accordance with American Society for Testing and Materials standards. Experimental results on mechanical properties indicate that the strength in tensile and flexural mode for the grout decreases with the inclusion of filler because of a weak interface between the matrix and filler. However, the addition of filler in grout showed an increase in compressive, tensile, and flexural modulus. Based on suggested properties in a previous study, both grouts have the potential to be used on structural rehabilitation, especially for repairing damaged pipeline.
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