This book is compiled based on practical experience learned working around 30 years with GAIL especially in Operation & Maintenance (O&M) of natural gas compression & processing, supply of gas to consumers, LPG recovery, C2-C3 recovery plants, petrochemical plant and stabilization of various grades of polymers; improvements; increasing productivity & Project Development (PD) of natural gas cross country pipeline (onshore/ offshore), international natural gas pipelines (on shore / offshore), and LPG pipelines, City Gas Projects including Pre-feasibility or Detailed Feasibility Study, Project Appraisal, Financial Appraisal, Natural Gas Pipeline Design, Simulation, Hydraulics Study, Bidding, Costing, Petrochemical Industry, Due Diligence study etc. This book will provide an understanding about the intricacies in development of natural gas pipeline project such as natural gas constituents, natural gas processing, class location, demand-supply scenarios, gas availability, growth, the available natural gas pipeline network, the regulatory framework and its role, applicable regulations and so on. India is a fast-growing economy, and natural gas is established as a green fuel and being used in the automotive, commercial, industrial, and domestic sectors. It is realized that practical experience is required to be shared for beneficial of the students, new entrants, professionals for their learning and understanding.