The report describes the knowledge and experience gained during a 28-week internship at YASREF, a refining company under construction. It focuses on several construction activities observed, including pressure testing of pipes, post-weld heat treatment of welding joints, tightening flange bolts, pump alignment, and belt splicing. Each activity is described in detail with photos and references to standards. The report also includes three case studies, the first being a designed base case and the others involving problems encountered during construction.