Mumtaz Bulging & blistering noted in rubber lining could be due to the following possibilities: 1. Due to poor rubber lining quality ( i.e., rubber lining with inadequate hardness and strength and with porous nature) 2. Poor adhesion strength over a period of time (in some years of usage) between the steel base and rubber lining 3. Due to reaction between Triact Amine dosing and rubber lining due to concentration variation or temperature increase in tank (i.e., with tank in semi filled condition and with rubber lining seeing higher than design temperature in non-wetted parts) 4. Temperature variation in the tank - due to tank shell getting heated during summer months thus dis-bonding and losing adhesion strength if poor quality adhesion had been used during original lining and original improper cured rubber lining) at the time of construction of tank 5. Pin hole development at joints or over-lapped portions of rubber lining from reaction of dosing injection or reaction of tank liquid over a period of years. 6. Regular inspection not being done by user : to detect pin hole or cracks to assess rubber lining condition for a rubber lined tank ( periodicity of at least 6 - 12 months and regular spark test and hardness test both at liquid ( wetted zone) and vapor zones ( non-wetted zones) If the tank is originally designed for rubber lined use, with proper specification / purchasing needs + construction quality inspection had been done with proper care and tests to meet rubber lining testing, a change to FRP may not be needed (this is my preliminary view from the posting made by you). You have to assess the quality of rubber now to determine and evaluate if any of the following had contributed: i.e., Is it due to: Due to poor quality supply or Due to poor quality work-manship during the construction of evaluating proper bonding between steel and rubber lining the inspection needed for rubber lining at the time of construction, or is it due to poor quality inspection - if periodicity of regular inspection of rubber lining condition assessment had not been done by user, a mere change of material to FRP is not the solution. Before considering simply a replacement lining material like FRP, assess carefully the present condition and do the diagnostic evaluation carefully. Most probably improper curing and improper inspection could have contributed to bulging and blistering noted by you. Periodic assessment of rubber lining condition is a "must" in an operating plant involving dosing injection. Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Nov 4, 2008 E-mail: nishi@vsnl.com >Hello All, > >We are facing problem of rubberlining bulging in a TRIACT >AMINE DOSING Tank for boiler .The rubber lining has a number >of blisters and bulging. The outlet nozzle gets choked with >the rubber material due to bulging inside the outlet nozzle. >Can any body pl. explain why the bugling and blistering is >happening and can we upgrade to some different material for >the tank like FRP , etc. > >BEST regards, > >Mumtaz Abbas

Mumtaz It could be workmanship or other causes. Please evaluate from all possibilities before concluding that it was workmanship that had contributed to this failure hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Nov 4 E-mail: nishi@vsnl.com >Dear Srinivasan, > >Thanks for a detailed reply. The mentioned tank is in >operation since July 2006, in approx. 2 and half years, the >development of blisters and bulging in tank rubber lining is >indicating lack of quality of workman ship. What is your >opinion.? > >Best regards, > >Mumtaz