Friday, June 12, 2020

Hull repair

Cracked weld :
  • Inform Class surveyor & seek his opinion.
  • Trace the length ok crack by DPT.
  • One inch from both sides  drill crack arresting holes.
  • Gas free the tank from inside
  • Guaging of Crack to be carried out by guaging electrode till bottom of the crack is reached
  • Welding electrode, welder & procedure to be class approved. Low Hydrogen Electrodes are used.
  • The affected portion to be heated to 200 deg C by flame torch & temp to be noted by IR sensor.
  • Carry out welding from either side
  • The weld is again to be heated by flame to rleive stress & covered with insulation tapes to reduce cooling rate.
  • Weld to be inspected & arrest holes to be welded
  • Radiography to be carried out.
  • Hose test to be carried out.
  • Primer & paint to be applied

Severe indentation in way of frame  :
  • It cannot be tolerated so has to be cropped off alongwith bend frame & renewed.
  • Put 2 small size plates & weld it to frame (tag) with actual size plate.
  • Heating & stress rereleiving to be carried out.
  • Radiograpgy & Hose test of the weld to be carried out.

Surfaces suffering from general Corrosion  :
  • Guaging to be carried out & if 20 % is eaten away plate needs to be renewed.(decided by class survyr)
  • Only thing to be done is clean the surface, coat with primer, anti fouling & anti corrosive paints.
  • Add Zinc Anodes.
Bilge Keel Fractured :
  • Crop the damaged part & renew.    

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