Primary Application: Insulation Jacketing Moisture Barrier Typical Use: petrochemical, chemical plants, refineries, offshore platforms, LNG facilities) where long-term performance and maximum protection against CUI and other corrosion forms are crucial. Often specified for critical piping and equipment. Polykraft Moisture Barrier (PKMB or Kraft Paper): Aluminum Coils (with Polysurlyn/Polykraft): Lighter weight, easier to fabricate, generally lower cost. Most common jacketing material. Good corrosion resistance in many environments, but susceptible to certain chemicals and galvanic corrosion if not protected (hence the barrier). Stainless Steel Coils (with Polysurlyn/Polykraft): Offers superior corrosion resistance (especially in coastal, chemical, or food processing environments), higher mechanical strength, and better fire resistance. It is heavier and more expensive than aluminum. The moisture barrier is still applied primarily to protect the underlying insulation and prevent CUI on the insulated pipe/vessel (which might be carbon steel). While SS is corrosion-resistant, the barrier still adds a layer of protection, especially against crevice corrosion possibilities and protecting the insulation itself. In summary, Polysurlyn and Polykraft coatings are applied to aluminum and stainless steel coils destined for use as insulation jacketing, serving as crucial interior-side moisture barriers to protect the insulation's thermal performance and prevent various forms of corrosion. Polysurlyn offers higher performance, while Polykraft is a more economical option.   Jitendra M Porwal 9890999222 jitendra@albraco.com, albraco@gmail.com