A Review of Manufacturing Process of Polyethylene Pipe and Connectors for Applying in High-Pressure Natural Gas Pipelines oleh Omid Moini Jazani, Reyhaneh Khalafi, Mohammad Khosravi, Mohammad Reza Hassanpour, Danial Dadkhah, Mehdi Mostafaeian, Mohammad Mahdi Salehi, Hossein Riazi