Roc-Master Flange Co., Ltd. is located in Minhang heavy-industry District of Shanghai. This plant is specialized in providing sales services and technical support .we do machining, drilling, cladding and welding in Shanghai. Meanwhile Roc-Master Shanghai is considered to be our inspection and logistics service center。 We are ISO 9001:2000 accredited since 2002. We obtained API 17D license in 2007. Quality control is performed from the chemical analysis of raw-material, manufacturing to heat-treatment, to finishes process, every step of the manufacturing process. We have an air hammers for producing high performance forged bolts & nuts up to 4 inch. We have a 4-Ton electro-hydraulic hammer manipulator operating flange production, and the maximum outside diameter is up to 1600mm, maximu..