Elsevier

Composites Part B: Engineering

Volume 152, 1 November 2018, Pages 231-240
Composites Part B: Engineering

Mechanical properties of offshoring polymer composite pipes at various temperatures

https://doi.org/10.1016/j.compositesb.2018.07.014Get rights and content

Abstract

Polymer composite pipes can be exposed to the thermomechanical loading due to hot and cold fluid flow, which results in the degradation of their properties. In this paper, effect on mechanical properties of composite pipes under different temperatures ranging from −40 to 80 °C is studied experimentally. The composite pipes consist of glass/epoxy tubes having 86 mm internal diameter and 6.2 mm of thickness with ±55° glass filament winding, intended for offshoring applications. TEMA TTC machine and split disk are used for uniaxial tensile tests and the thermal aging is considered with the help of SERVONTAN climatic chamber. Thermal aging is carried out on these specimens in climatic chamber for 8 h at different temperatures and then uniaxial test is performed. Experimental results have shown degradation in the mechanical properties of polymer pipes with an increase in the temperature. For pipes at colder temperature, the rigidity of composite increases progressively with the temperature and results in drastic decrease in the displacement at break. Also there is a decrease in the yield stress and an increase in yield strain with an increase in the temperature.

Introduction

Recent research advancement has been focused on elucidating the environmental degradation of polymeric composites, such as pipes used in offshore and marine applications. The degradation of polymer composites is provoked by exposure to various environmental factors as variation in temperature, heat, chemical attacks, corrosion and microbes, which results in cracks and embrittlement [[1], [2], [3], [4]]. Polymer composite pipes have been widely used for petroleum and gas transportation because of their low cost of installation & maintenance and excellent chemical, physical & mechanical properties and subjected to different hot and cold temperature [5,6]. Therefore, the mechanical characterization of polymer composite pipes and the understanding of the degradation of their properties with respect to temperature change are essential to develop their potential application in offshore and marine applications.

Several investigations have been conducted in order to determine the mechanical properties of pipes. The ASTM D 2290 and ISO 8521 standard test describe the experimental methodologies to characterize the pipe and allow the use of the classical test techniques developed for flat samples. Ellyin et al. [7] presented an experimental investigation to determine the effect of moisture absorption and exposure to elevated temperature on the mechanical properties of glass fiber reinforced epoxy composite tubes. The tube specimen was a 40.6 mm outer diameter with an inner diameter of 38.1 mm and the fiber volume fraction of 70.8%. The authors observed that for mechanical test, strength and stiffness of the specimens decreased with increasing temperature. Wong et al. [3] studied the mechanical and thermal behaviors of low density polyethylene pipe with variation in thermal exposure. Composite specimens were degraded using thermal ageing at 100 °C for 720, 2400, 6000 and 7200 h and the tensile properties were evaluated with dog-bone shaped specimen. Experimental results imply the existence of transition point from ductile to brittle fracture with a proportional decrease in elongation at break in terms of the thermal exposure time. Soroush et al. [8] studied the elastic behavior of wood–plastic composites at cold temperatures. The authors provide novel methods in material characterization and, in the future, to apply this method to investigate the elastic, hyper-elastic, and viscoelastic mechanical behavior of wood–plastic composites. These composites were used for potential applications in several industries.

Recently, an experimental investigation of temperature dependent mechanical properties of Poly-methyl methacrylate polymer composites was performed by Abdel-Wahab et al. [9] at a range of temperatures 20, 40, 60 and 80 °C below its glass transition point under uniaxial tension and three-point bending tests. The variation of the temperature significantly affected mechanical properties, with brittle fracture at laboratory temperature and plastic behavior at 80 °C. The authors have shown that the temperature rise significantly affected the Young's modulus, yield stress, ultimate tensile stress and strain at fracture of polymers. Sorrentino et al. [10] studied the effect of temperature on static and dynamic properties of Polyethylene resin reinforced with four different high performing woven fabrics Carbon, Twaron, Vectran and basalt fibers. The mechanical response was determined at temperatures 20, 60 and 100 °C by means of static flexural and low velocity impact tests. Experimental results showed that at 60 and 100 °C the mechanical properties of all laminates decreased, but the Basalt/polymer showed the lowest strength reduction and less effect on the flexural behavior by the temperature variation. Effect of the temperature, ranging from −30 to 25 °C, on the mechanical properties of reinforced polypropylene and polyethylene under tension and compression was investigated by Johnsen et al. [11]. The mechanical behavior of composites was affected by the temperature change including the stress-strain curves; for example the young's modulus increases with decreasing the temperature.

To the author's best knowledge, currently a little information is available in the open literature on the degradation of mechanical properties of polymer composites pipes under different operational temperatures. This paper will consider the effects of the hot and cold temperature ranges i.e. from −40 to 80 °C, on the mechanical properties of filament winded glass fiber reinforced epoxy composite pipes. Composite pipes consist of ±55° filament winded glass/epoxy tubes that are used in the extraction domains of gas and oil. Split disk test method was used in this study to characterize the mechanical properties of filament wound composite pipes.

Section snippets

Materials, pipe dimension and preparation

All samples used in this investigation were prepared from glass fiber reinforcement epoxy polymer (GFRP) fabricated by Future Pipe Industry company using helicoidal filamentary winding technique at ±55°. The samples had an internal diameter of 86.0 ± 0.2 mm, height of 20.0 ± 0.1 mm and thicknesses of 6.2 ± 0.1 mm with 24 layers as shown in Fig. 1. For each temperature the test was repeated 3 times in order to ensure the reproducibility of experimental results. 27 samples were tested and the

Results and discussion

The mechanical properties of polymer composites pipe under tensile test were studied at different temperatures. The effect of temperature on maximum load, stiffness and displacement at break was discussed.

Conclusions

The mechanical properties of glass fiber reinforced epoxy composites were experimentally investigated under Split-disk test for different temperatures using pipe specimens. The objective of this study was the quantification of the effect of the environmental temperature in these composite structures. For that purpose, several parameters reflecting the mechanical behavior of polymer pipes were determined including maximum load, the material stiffness and the displacement at maximum load.

References (22)

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