Mechanical behaviour of adhesively bonded polyethylene tapping tees

Abstract

11The mechanical properties of adhesively bonded MDPE joints were studied. The lap-12 shear joints were prepared using PE80 polyethylene gas pipe and four adhesive

Low temperature tensile lap-shear testing of adhesively bonded polyethylene pipe

“…MPa can be sufficient to successfully joint MDPE pipeline [19]. Therefore the results in Fig 10 for samples cured at +5 and +20°C are within this range but those cured at lower temperatures of 0, -5 and -10°C are not.…”

“…Conversely the proportion of adhesive and cohesive failure reported in Fig 11, both increased with increasing curing temperature and the ratio of cohesive to adhesive failure increased from 1:10 at -10˚C to 1:3 at +20˚C. Although this ratio of apparent adhesive bond to cohesive strength is still quite low, it is typical when trying to bond PE to PE due to its inherent low surface energy [19][20]. Although some promising lap-shear strength results have been achieved for MDPE samples bonded and tested at room temperature, which are in line with previous work [19], the reduction in strength with curing and test temperature poses a significant barrier to the development of adhesive bonding as a realistic replacement for electrofusion welded polyethylene gas pipelines.…”

“…Although this ratio of apparent adhesive bond to cohesive strength is still quite low, it is typical when trying to bond PE to PE due to its inherent low surface energy [19][20]. Although some promising lap-shear strength results have been achieved for MDPE samples bonded and tested at room temperature, which are in line with previous work [19], the reduction in strength with curing and test temperature poses a significant barrier to the development of adhesive bonding as a realistic replacement for electrofusion welded polyethylene gas pipelines. To try and tackle this problem, future work will focus on reducing the percentage of uncured adhesive present at low curing temperatures by increasing or accelerating the curing cycle time before the joint is exposed to sudden reductions in temperature, as well as considering modification of the adhesive composition to improve its low temperature performance.…”

“…Previous work by the authors has highlighted the potential of using acrylic adhesives to successfully bond MDPE pipeline and tapping tees [19]. This work focussed on testing the shear strength and impact resistance of the adhesively bonded MDPE joints at room temperature and therefore did not account for variations in soil temperature which occur throughout the UK's seasonal climate.…”

A Numerical and Experimental Study of Adhesively-Bonded Polyethylene Pipelines

“…Although adhesive bonding of PE has often been overlooked due to its low surface free energy, recent technological advancements in adhesive science and surface pre-treatments mean that it may now be a realistic alternative to fusion joining. Previous studies by the authors have highlighted this potential through successful bonding of PE using structural acrylic adhesives both at room [10] and low temperatures [11]. Pressure-tight joints with adequate mechanical strength were achieved for medium density polyethylene (MDPE) tapping tees bonded to MDPE gas pipelines.…”