The by – pass fitted on Main Engines fuel flow meters will be of open type and are to be kept closed with blind flanges. The relevant ten (10) intercepting valves will be delivered to the crew as spare parts. Two spool pieces (one (1) DN 65 and one (1) DN 80) will be supplied to be mounted by crew to restore the by-pass pipes continuity. The spool pieces, one for each Engine Room, can be selected among the ones used by the Shipyard for pipes pressure tests. One (1) pneumatic FO shut off valve to be installed at each engine fuel oil inlet and outlet for a total of ten (10) valves. Inlet and outlet valves are to be interlocked each other and are to be manually activated (closing) through push buttons located in ECR and engine room.