Chemical Engineering Department, Urmia University of Technology, P.O. Box 57155-419, Urmia, I.R. IRAN
West Azarbayjan Gas Company, P.O. Box 57155-334, Urmia, I.R. IRAN
In this research, a novel generation of stoppers for in-service natural gas distribution and transportation pipelines was prepared on the basis of nanocomposite hydrogels for preventing the gas leakage during the welding operation. The nanocomposite hydrogel stoppers were prepared on the basis of polyvinyl alcohol as the matrix phase and montmorillonite nanoclay as the reinforcing phase. Some structural, physical and mechanical properties of the prepared stoppers were experimentally investigated and their dehydration kinetics and the stopping performances were also evaluated. The results showed that the nanocomposite hydrogel stoppers possibly had an exfoliated morphology and the presence of montmorillonite in their structures increases the crosslinking and improves the mechanical properties (up to 280% increase in the elastic modulus and a 43% decrease in the elongation at break). The results obtained from the dehydration tests demonstrated that the weights of prepared stoppers are reduced to 60-70 % of their initial weights during the first hour of the dehydration process. The results obtained from the stopping performance showed that the prepared nanocomposite hydrogel stoppers could undergo the gas pressure up to 9 psi. It was observed that the stopping ability and the maximum endurable pressure of the prepared nanocomposite hydrogel stoppers are increased by increasing the diameter and length of the stopper. The accomplished experiments for investigating the stopping ability of the nanocomposite hydrogel stoppers proved their unique performances in perfect sealing and preventing gas leakage in natural gas pipelines. In general, it can be expressed that the prepared nanocomposite hydrogels are suitable candidates to be used as novel stoppers during the welding operation in the natural gas distribution and transportation pipelines.