Custom Bid for Services- PART A Providing Annual Rate Contract for Maintenance of HVAC System including Electrical and Mechanical Maint of System Low Side for 3 years at GAIL Bhawan Navi Mumbai, Custom Bid for Services- PART B Providing Annual Rate Contract for Maintenance of HVAC System including Electrical and Mechanical Maint of System Low Side for 3 years at GAIL Bhawan Navi Mumbai