Ship Side Valves

Ship-side valves refer to the valves that are connected to the hull without having anything in between is called Ship-side valve.

Copyright of Shipdiggers.

During dry dock the valves are overhauled by the dry dock workshop personals, where-as the job of the marine engineers is to overhaul internal valves.

why ship-side valves are important ?
In ship everything that has been installed have some purpose, moreover Ship-side valves are inspected and check by Classification society.

• Dry Dock Workshop after repairing or installing new valve, generally give 5 years guarantee for these valves.   
• However if the valves that get damaged within the guarantee period, the expense of delay in time and diver* cost is given by the dry dock workshop. 

Ship side valve must be non-return type. Screw done non--return valves are used as ship side valves because it help in preventing the flooding of the vessel in-case of fracture or break  with discharge submerged, they also allow isolation to prevent so.

Listed below are few Ship-side valves that is seen on vessels. (Name of the valve, Side, type, specification)

Under Copyright of Shipdiggers. Table credit: Arpit Singh

      Name of the Valve                                Side                          Type                        Specification

1  Sea water suction for low sea chest                   Starboard      Butterfly valve           10K 550A
2  Sea water suction for high sea chest                  Port               Butterfly valve           10K 550A        
3  Sea water suction F.W.G sea chest                     Starboard      Butterfly valve           10K 125A        
4  Main cooling S.W discharge overboard             Port               Butterfly valve           10K 300A              
5  O.W.S discharge overboard                                Port              SDNR                         10K 40A         
6  Fire & G.S pump discharge overboard               Starboard     SDNR                         10K 200A            
   (fire and ballast pump)                                                             (Screw Down Non-Return valve)
7  Steam blow valve to high sea chest                    Port              SDNR                         16K 40A           
7a Air vent for high sea chest                                 Port              Ordinary Globe valve(SDGV)   10K 40A                        
8  Steam blow valve to low sea chest                     Starboard     SDNR                         16K 40A          
8a Air vent for low sea chest                                  Starboard     SDGV                         10K 40A             
9  Steam blow valve F.W.G sea chest                     Starboard     SDNR                         16K 40A     
9a Air vent for F.W.G sea chest                              Starboard     SDGV                         10K 40A                    
10 F.W.G discharge overboard                                Port             Butterfly valve            10K 125A                        
11 Boiler blow down direct overboard                    Port            SDNR                          16K 40A              
12 Soil/waste water discharge overboard                Starboard   Storm valve                  10K 100A                        
13 Stop valve for waste water overboard                Port            Storm valve                  10K 100A                 
14 Gally/provision refer drain overboard                Starboard   Storm valve                  10K 100A                      
15 I.G system scrubber cooling tower                     Starboard   Butterfly valve             10K 200A                            
   discharge overboard
16 Draught gauge overboard valve                          Starboard   SDGV                         10K 50A                     
17 Weather deck scupper overboard                        Port                                                125A 
18 Weather deck scupper overboard                        Starboard                                       125A 
19 Main water ballast pump discharge overboard   Port            Butterfly valve            10K 550A            
20 ODME discharge overboard                               Starboard   Butterfly valve            10K 350A     


What does K and A stand for in specifications?
 K : is the pressure.
 A : is the Nominal diameter of the pipeline.  
  
 Example:   20K 50A
     This means 20 kg/cm² is the pressure that can be easily handled by the valve.
     where as 50 is the Nominal Diameter of the pipeline that can be fixed with the valve.


  
                                     

Inert Gas Marine notes (Overview)

• Inert Gas (IG) is the backbone of the tanker.

• Inert is something which does not support combustion.

• Since tankers (Gas Ships) carry payload which is highly flammable (and toxic) in nature, and to support combustion oxygen is essential, Inert Gas is use to lower the oxygen percent from the tank so as to eliminate the risk of explosion hazard.

1. Less than 11% oxygen is safe, theoretically, no gas-air mixture burn at this percentage.
2. But for practical purpose and to allow safety margin, 8% is taken as the level of oxygen at which no air-hydrocarbon mixture can burn by any means.
3. But on tankers, IG is maintained at 5% oxygen and it is ensure Oxygen does not exceed 8%.

There are mainly 3 ways to generate Inert Gas on board the Vessel.
1) Boiler
2) Inert Gas Generator (IGG)
3) Carbon Molecular Sieve

• Every pump in IG system has duplicate Pump(stand-by pump) except the Scrubber pump.

• Most of the IG equipment are located at very high point, normally nobody goes there, a visit and inspection is taken during survey.

• There is a counter which count for how much time a machinery is being running.

Few terms worth noting:

1. Flue Gas : left over of the combustion process in the boiler which come out as the exhaust. 
2. Taint : Tainting means change of color when IG is produce by boiler combustion which was not proper(indicated by black smoke at the outlet funnel) therefore Soot goes into the cargo tank and react with cargo and changes it color. The customer may refuse to take-in the cargo which has been tainted, for example the Aviation Oil is the lightest and most refined oil, and even a slightest soot goes into the cargo tank carrying A.O it will taint the oil which maybe unfit for usage.
3. Toxicity : when gas reaches it's threshold value without lowing its oxygen(21%) content which do harm.
4. Soot : a deep black powdery or flaky substance consisting largely of amorphous carbon, produced by the incomplete burning.