Journal ArticleDOI
Failure Analysis of High Density Polyethylene Butt Weld Joint
TLDR
In this paper, a detailed failure analysis conducted on high density polyethylene which acts as the liner of composite compresses natural gas cylinder was observed after about 2000 cycles of hydrostatic pressure testing at 250 bars.Abstract:
This article discusses a detailed failure analysis conducted on high density polyethylene which acts as the liner of composite compresses natural gas cylinder. Leakage from the cylinder was observed after about 2000 cycles of hydrostatic pressure testing at 250 bars. Visual inspection revealed that the leakage occurred from the circumferential fusion joint between the cylinder and dome section. The cylinder and dome sections were produced from different techniques and joined together by using a heated tool butt welding process conducted by a local manufacturer. The joined components work as an integral part. The investigation was carried out using various techniques including mechanical, thermal and metallurgical examination. Fractography of the failed joint surface showed stepwise marks typical of a fatigue failure. Mechanical testing results showed that the strength of dome section was significantly lower than that of the cylinder section. Moreover, both the tensile and fatigue strength of joint was also almost half that of the cylinder. The fracture surface of the broken welded joint showed brittle failure. The melting points of both the cylinder and the dome sections were found almost same by differential scanning calorimeter but large difference was found between the melt point indexes of both sections. The results suggested that the failure was actually a stress cracking via a process of slow crack growth, which occurred due to use of a dome material having inferior properties and very high melt flow index. These properties inhibited proper fusion and resulted in a poor weld joint. Consequently, the weld joint of lower strength eventually failed in macroscopically brittle manner upon cyclic loading.read more
Citations
More filters
Journal ArticleDOI
Mechanical behavior analysis of buried polyethylene pipe under land subsidence
TL;DR: In this article, a finite element model was established to study the mechanical behavior of buried polyethylene pipe under land subsidence, and parameters in the constitutive model were obtained by a uniaxial tensile test, and the deformation degree of the pipeline was characterized by defining the minimum radius of curvature and relative deformation rate.
Journal ArticleDOI
Failure mechanisms of geocell walls and junctions
Yang Liu,An Deng,Mark B. Jaksa +2 more
TL;DR: In this article, an extensive testing program was undertaken to assess the geocell junctions, which included uniaxial tensile, shear, peeling and splitting strength tests.
Journal ArticleDOI
Thermal and mechanical properties of e-beam irradiated butt-fusion joint in high-density polyethylene pipes
TL;DR: In this paper, the effects of electron beam irradiation on the thermal and mechanical properties of a butt-fusion joint in high density polyethylene (HDPE) pipes were investigated.
Journal ArticleDOI
Analytical and experimental study of shape memory alloy reinforcement on the performance of butt-fusion welded joints in high-density polyethylene pipe:
TL;DR: In this article, shape memory alloy wire is employed as confinement to enhance the flexural rigidity of the butt-fusion welded joints in the high-density polyethylene pipes.
Journal ArticleDOI
On crack propagation in the welded polyolefin pipes with and without the presence of weld beads
Jakub Mikula,Pavel Hutař,Eva Nezbedova,Ralf Lach,Florian Arbeiter,Martin Ševčík,Gerald Pinter,Wolfgang Grellmann,Luboš Náhlík +8 more
TL;DR: In this article, the influence of both material inhomogeneity and weld bead geometry on crack propagation in welded polyolefin pipes was studied and the stress intensity factors were compared considering different positions of the cracks.
References
More filters
BookDOI
Physical properties of polymers handbook
TL;DR: Theoretical models and simulations of polymers have been used to study the molecular dynamics of different molecular architectures and properties of polymeric networks and gels as discussed by the authors, including the properties of different types of networks.
Journal ArticleDOI
Molecular aspects of tack
TL;DR: In this paper, the authors examined strength development at a polymer-polymer interface in terms of the dynamics and statics of random-coil chains and the interdiffusion of chain segments across the interinterfaces.
Journal ArticleDOI
Effect of strain rate on stepwise fatigue and creep slow crack growth in high density polyethylene
TL;DR: In this article, the effects of frequency and R-ratio on the kinetics of step-wise crack propagation in fatigue and creep of high density polyethylene (HDPE) was characterized.
Journal ArticleDOI
Hot plate welding of polypropylene. Part I: Crystallization kinetics
Jenn Yeu Nieh,L. James Lee +1 more
TL;DR: In this paper, a simplified, phenomenological crystallization model was developed, which can describe the crystal formation from completely melted and partially melted polypropylene polymers, and predictions obtained from the model were compared with experimental results.
Related Papers (5)
A study of structure and mechanical properties of welded joints in polyethylene pipes
K. Leskovics,M. Kollár,P. Bárczy +2 more