We have pipelines in chiller unit (Ammonia).Due to ice formation ,CUI is very high in those pipelines.Lines are having cold insulation with moisture barrier coating?Is there any better insulation practice to avoid CUI in cold lines?What about using factory pre-coated pipelines? regards

Krish CUI for ammonia pipeline - sub zero temp- is a common mode to keep icing to the minimum and also to avoid vapor loss. PUF (Poly Urethene Foam - with pre cut to suit line dia, length ) with moisture barrier coat is an alternative . This is more or less the industry standard today instead of mineral wool insulation of earlier years. Pre cut molded cold insulation is also followed by industry users. Pre-coated pipelines, without conventional molded or PUF insulation, may not serve any purpose for sub zero temperature ammonia line. Preventing vapor loss (i.e., excess of vapor load on compressor and pumps) and also energy saving is the norm today. Trust this is is of help to your question. C.V.Srinivasan Nishi Engineers Pvt Ltd India Feb 22,2006 E-mail:nishi@vsnl.com >We have pipelines in chiller unit (Ammonia).Due to ice >formation ,CUI is very high in those pipelines.Lines are >having cold insulation with moisture barrier coating?Is >there any better insulation practice to avoid CUI in cold >lines?What about using factory pre-coated pipelines? > >regards

Recently it has been heard that instead of using Pre-Cast PUF if we can use in-situ poured PUF it can have much much better effect. Otherwise you can also pre-paint the line by High Solid Polysiloxane type Paint before making applying Pre-Cast PUF. Icing due to leak path needs to subjected to prevenative maintenance to control energy losses. regards DM