Figure 1 . Field welding and installation of 24 ” DSS line pipe .
Oman ’ s largest duplex pipeline : best practices & fabrication experience
A large gas production pipeline project in the Sultanate of Oman utilised duplex stainless steel for its superior corrosion resistance and mechanical strength . This article discusses procurement and construction challenges and the best practices developed to overcome these challenges .
By Dr JR Saithala , M Ghafri , P Manivannan , H Barve , I Tobi , & A Kharusi , Petroleum Development Oman
Duplex stainless steel ( DSS ) UNS S31803 grade material was selected for this gas production pipeline project due to its high corrosion resistance and mechanical strength , which are crucial for operations at high temperatures (> 100 ° C ) and pressures (> 100 bar ). The project involved the installation of 120km of DSS line pipe in various sizes , including 8-inch , 16-inch , and 24-inch lines , with wall thicknesses ranging from 5.4mm to 15.5mm . The 16-inch ( 30 km ) and 8-inch ( 51km ) lines were commonly used for gas production flowlines and manifolds , with wall thicknesses of 10.5mm and 5.6mm , respectively . The project ’ s main 24- inch pipeline , which is 34 km in length , marked the first time in Petroleum Development Oman ’ s history that a DSS pipeline of this size , in terms of outside diameter ( OD ) and wall thickness ( WT ), was designed , procured , constructed , and installed . The 24-inch line pipe is coated and buried to ensure its external corrosion protection .
The thickness of the line pipes was driven by hoop stress , which is the stress caused by the internal pressure acting on the pipe walls . On the other hand , the pipeline size was based on hydraulics and flow rates , which determined the necessary diameter to transport the required volume of gas . Best practices in line pipe manufacturing and site construction were implemented to ensure the successful fabrication of DSS materials in the oil and gas industry . In this article , we will talk about the
14 Stainless Steel World April 2023 www . stainless-steel-world . net