Krish Debasis suggestion for in-situ PUF injection pouring is OK. To implement this suggestion and to have in-situ PUF insulation, the line should be completely free from ammonia. You would be fully aware that in wet or iced condition in-situ PUF casting will be difficult and will not be fully effective from insulation and from good adhesion free of porous air trap conditions even with high pressure gun use for injecting or pouring of PUF. Considering today's concept of cutting down energy losses, pre-cast at room temp after removing all ammonia from chiller unit or in-situ PUF would serve for a long time. Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd India March 08, 2006 E-mail: nishi@vsnl.com >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

I presume that the ammonia piping is of CS A333 gr.6. To avoid CUI the follwoing system has been proven to give satisfactory results: 1) Grit blast the surface to Sa3 2) Apply Epoxy or Phenolic epoxy primer 25-200 DFT 3) Apply intermediate coat of Epoxy or Phenolic Epoxy 25-200 DFT 4) total DFT 250-400 microns 5) Use Foam glass or Cellular Glass T4 preformed insulation confirming to ASTM C552/C795 with anti abrasion lining of hydrocal B11. 6) Ensure that insulation is dry during application and workmanship is good with no possible passage for water ingress; adequate vapour and weather barrier. 7) Use aluminized steel cold rolled ASTM A463 Type 1as jacketing material Foam Glass or Cellular Glass is an excellent insulation material that offers zero water absorption and reasonable installation cost. Care is to be taken during installation to avoid damage to the closed cells of the insulation. Though it seems that PUF is popular in india, the disadvantages are: vulnerability to damage, utter dependency on the vapour barrier because of its high level of water absorbency, corosivity of water because of hydrolysis of halogenated flame retardants used to make the insulation safe in the plant, sensitivity to humidity during application. Hope the above information helps.

Krish, Please read painting thk as 125-250 and not 25-250. typo error is regretted. Rgds,