Tham khảo tài liệu 'guide to ship repair estimates episode 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Current density of material in mA m2 Information from manufacturer between 10 and 30 say 20 Design Life Number of years between dry dockings . 3 K Number of hours in 1 year 8760 Capacity of material amp hours kg Information from manufacturer 781 is common Using the above formula it is a simple matter to create a spreadsheet to determine the weight of zinc anodes. Input the data into the table and use the formula to determine the weight of zinc anodes for the period required. Drydocking works 21 Sea chests Table Sea chests and strainers Opening up of sea chests by removing ship side strainers cleaning and painting with owner s paints as per hull treatment specification. Assuming single grid per chest. Surface Area m2 Man-hours Below 12 20 Above 1 30 Additional charge per extra grid 5 Docking plugs Allowance made of 1 man-hour for removing and later refitting of each tank drain plug using ship s spanner assuming no locking devices fitted and excluding all removals for access and repairs to threads. 22 Guide to Ship Repair Estimates in Man-hours Valves Table Sea valves Opening up hand-operated globe and gate valve for in situ overhaul by disconnecting and removing cover spindle and gland cleaning all exposed parts hand grinding of globe valve light hand scraping of gate valve testing bedding painting internal exposed areas and reassembling with new cover joint and repacking gland with conventional soft packing. a Butterfly valve remove clean check testing bedding of seals paint internal exposed areas and refit excluding operating gear. b Checking and cleaning large butterfly valves through the sea chest. Valve bore mm Globe valve Gate valve a Butterfly valve b Butterfly valve 50 4 6 100 6 7 150 8 9 200 10 11 14 250 13 14 18 300 16 17 22 350 20 21 26 13 400 23 24 29 14 450 26 28 33 500 30 31 37 15 550 34 35 42 16 600 37 39 46 650 41 43 51 17 700 44 47 56 18 750 47 49 60 19 800 50 53 66 20 900 57 60 81 22 1000 65 68 100 24 .
