Abstract
Offshore oil and gas pipelines are susceptible to corrosion and need rehabilitation to keep them operating in-service conditions. Fibre composite filled with epoxy-based grout is emerging as an effective repair and rehabilitation system for offshore pipelines performing underwater. In such applications, the infill grout is often subjected to moisture and elevated temperature along with compressive, tensile and localised stresses at the defect. Current standards and practices for composite repairs suggest detailed investigation of the fibre reinforced sleeve, while the characterisation of the infill material is yet to be conducted for performance evaluation. The present work investigates the mechanical and thermal properties of three epoxy grouts as candidates for infill in a grouted sleeve repair for underwater pipeline. An understanding on the effect of hygrothermal ageing on the grout properties for defining the period of 1000 hours as “long-term” according to ISO/TS 24817, in comparison to their unconditioned state, is also presented. The compressive and tensile strength of the unconditioned grouts ranges from 100–120 MPa, and 19–32 MPa, respectively, which indicates that these grouts are suitable for structural rehabilitation of the pipelines. Moreover, the glass transition temperatures, Tg and Tt of the unconditioned grouts are found to be within the ranges of 50–60 °C, and 80–90 °C, respectively, which are reduced by about 20°C after conditioning.
Highlights
Global energy demand is expected to grow in the decades and fossil fuels will continue to act as the dominant source of energy all over the world [1,2]
The compressive and tensile strength of the unconditioned grouts ranges from 100–120 MPa, and 19–32 MPa, respectively, which indicates that these grouts are suitable for structural rehabilitation of the pipelines
While epoxy grouts are often recommended due to superior properties and ease of application [8,9], limited information are available on the long-term properties of epoxies especially when exposed to harsh environmental conditions including elevated temperature, which are taken into consideration while designing the pipelines [10]
Summary
Global energy demand is expected to grow in the decades and fossil fuels will continue to act as the dominant source of energy all over the world [1,2]. Infilled polymer composite is considered as a suitable option for rehabilitating metallic structures with metal loss, where annulus between the pipe and the encircling sleeve is filled with a suitable filler material [3,4]. The properties of an infill are critical for the performance of this type of repair, where a filler is necessary for providing smooth surface for effective load bearing [5,6]. Grouts are used as infill in this type of rehabilitation system. Structural grouts derived from epoxy thermoset resins, hardeners and fillers serve as protective layer and effectively transfer load in a repair system. The effect of this extreme condition on the properties of epoxy grouts has received very little attention and needs investigation prior to being selected for structural rehabilitation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
