Advanced Coatings & Insulation Technology
During the mid 1990's, DPA Specialist Consulting Engineers developed a technically advanced coatings and insulation system primarily for use on cold storage vessels. The system was designed on the basis that technological improvement with respect to the available materials should have a positive effect on the cost effectiveness of coatings and insulation systems based on long term life cycle costing. The specialist coatings and insulation system comprises anti-corrosion coatings relevant to the particular application, a flexible synthetic insulation foam and a tough liquid applied reinforced flexible vapour barrier system overcoated with a flexible protective coating. The various materials comprising the system were considered on the basis of compatibility, function and durability in relation to conventional cold insulation materials previously used.
The anti-corrosion coatings specification allows for effective corrosion protection of the steel substrate under dry or wet conditions. Due to the fact that un-insulated cold storage vessels are subject to a large degree of surface condensation during operation, a specification was developed in accordance with advanced coatings technology to provide for corrosion protection remedials to be carried out during on-line conditions. Although the specification developed for dry conditions is preferable from a technical and application point of view, commercial constraints often dictate that cold storage vessels cannot be taken off-line for periods of any significant duration. In addition, various adhesives required for the application of the insulation material are available and have also been designed for application under condensing conditions.
The flexible synthetic insulation foam has a number of advantages over previously commonly used materials such as rigid polyisocyanurate and polystyrene foam. These include the following:
- A significantly higher vapour diffusion resistance, resulting in a significant reduction in the long term transmission of water vapour through the fabric of the foam,
- Significant elastic properties, providing a higher level of resistance to rapid impact loading and puncturing with rapid recovery after indentation,
- Superior tensile strength characteristics, preventing puncturing,
- Higher durability and wear resistance.
Various tests including ISO Standard tests are carried out on the insulation product, including tensile strength, elongation, tear strength, compression deflection, compression set, water absorption and burn rate.
A fire resistant version of the synthetic foam is available and has been used extensively by DPA in hydrocarbon plants.
The vapour barrier is a laminated system comprising a liquid applied flexible resin membrane with an embedded reinforcing scrim. These materials provide for a vapour barrier that is durable and tough and able to withstand harsh local conditions.
Rigid vapour barrier resins that were previously used fail as a result of thermal movement and mechanical damage, thereby allowing the ingress of water to occur with the subsequent rapid degradation of the entire insulation and coating systems.
The new technology systems maintenance requirements are minimal with only the application of a new protective paint coating being required approximately every 5 to 10 years, depending on local conditions.
Projects completed with DPA's advanced coatings and insulation system include the coating and insulation of Bright Beer Vessels at South African Breweries, Alrode and more recently, the remedial coating and insulation of DOW Chemicals' and Island View Storage Cold Storage Spheres at Richards Bay Bulk Storage.
DPA Specialist Consulting Engineers have also developed technically advanced methods of coating and re-insulating hot process plant components. Although this is a common operation in many industrial plants worldwide, DPA's innovative and technically superior solutions are challenging conventional systems that have not yet provided an acceptable answer to corrosion related issues. A sound understanding of material properties and related performance has resulted in the development of systems able to cope with severe demands in highly corrosive environments. Vapour barrier quality control Protective coating application Re-blasting (Quality control) Abrasive Blast cleaning.