them to break. The effects are discoloration, embrittlement and eventual cracking. Elevated temperatures and oxygen tend to accelerate the deterioration. Tanks listed as suitable for outdoor service are protected from UV attack by: coloring or pigmenting and/or adding internal stabilizers which preferentially absorb or dissipate the UV energy. Shading tanks from the sun will also prevent deterioration. Tanks must be free to expand or contract, avoid excessive tension on the tank. For assistance in selecting the appropriate tank for a specific application, see the Tank Resin Selector Guides with reputable resin manufacturers. Resources being published by siting additional references to AVENGENERAL ISOLINES OF GLOBAL RADIATION AND THERE EFFECTS ON POLYMERS Years = 70 x UV Rating (Your Location's Isoline) (from Figure 3) Example: Natural Part, Molded Properly, Using UV-8 Additive Package For Use in Florida i.e.Florida= 140 Kcal/cm@2/yr. (from Figure 3) Thus Years “Expected”= 70/140 x 8 = 4 Years (until 50% of original break elongation properties left. Think of protecting your fiberglass investments from UV, much the same way you would protect your children with sun screen; gelcoats are sunscreens for your tanks, vessels and other fiberglass constructs. Design standards Fiberglass Tanks fall under regulation of several groups. Bs4994-87 is the British Standards Standard for FRP Tanks and Vessels superseded by EN 13121. EN 13121 ASME RTP-1 (Reinforced Thermoset Plastic Corrosion Resistant Equipment) is the standard for FRP tanks and vessels held within the United States under 15 psig and located partially or fully above ground. Typical design parameters and specifications will require either compliance with ASME RTP-1 or accreditation from ASME. ASTM 3299 which is only a product specification, governs the filament winding process for tanks. It is not a design standard. SS245:1995 Singapore Standard for Sectional GRP Water Storage Tanks. Bs4994 It is to avoid the uncertainty associated with specifying the thickness alone, that BS4994 introduced the concept of "unit properties". It is property per unit width, per unit mass of reinforcement. For example, UNIT STRENGTH is defined as load in Newton per millimeter (of laminate width) for a layer consisting of 1 kg of glass per square meter. i.e. the unit is N/mm per Kg/m2 glass ASME RTP-1 In RTP-1 specifications, the primary concerns relate stress and strain, such as hoop stress, axial stress, and breaking stress to the physical properties of the material, such as Young's modulus (which may require an anisotropic analysis due to