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Specifying Composite Performance <br />The design and manufacture of composite equipment for <br />corrosion service is a highly customized process. In order <br />to produce a product that successfully meets the unique <br />needs of each customer, it is essential for fabricators <br />and material suppliers to understand the applications <br />for which composite equipment is intended. One of the <br />most common causes of equipment failure is exposure <br />of equipment to service conditions that are more severe <br />than anticipated. This issue has been addressed <br />by the American Society of Mechanical Engineers <br />(ASME) in their RTP -1 specification for corrosion -grade <br />composite tanks. RTP -1 includes a section called the <br />User's Basic Requirement Specifications (UBRS). <br />The UBRS is a standardized document provided to <br />tank manufacturers before vessels are constructed. <br />It identifies, among other factors, the function and <br />configuration of the tank, internal and external operating <br />conditions, mechanical loads on the vessel, installation <br />requirements and applicable state and federal codes <br />at the installation site. Reichhold strongly recommends <br />that the information required by the UBRS is provided to <br />composite equipment fabricators before any equipment <br />is manufactured. <br />Factors Affecting Resin Performance <br />Shelf Life Policy <br />Most polyester resins have a minimum three-month <br />shelf life from the date of shipment from Reichhold. <br />Some corrosion resistant resins have a longer shelf life, <br />notably unpromoted bisphenol epoxy vinyl ester resins, <br />unpromoted and accelerated bisphenol fumarate resins, <br />and DION® 6694 modified bisphenol fumarate resin. <br />See the individual product bulletins, available at <br />www.reichhold.com, for specific information for each <br />resin. Shelf stability minimums apply to resins stored in <br />their original, unopened containers at temperatures not <br />exceeding 75° F, away from sunlight and other sources <br />of heat or extreme cold. Resins that have exceeded <br />their shelf life should be tested before use. <br />Elevated Temperatures <br />Composites manufactured with vinyl ester or bisphenol <br />fumarate resins have been used extensively in <br />applications requiring long-term structural integrity at <br />elevated temperatures. Good physical properties are <br />generally retained at temperatures up to 200° F. The <br />selection of resin becomes crucial beyond 200° F <br />because excessive temperatures will cause resins to <br />soften and lose physical strength. Rigid resins such <br />as ultra-high crosslink density vinyl esters, bisphenol <br />fumarate polyesters, epoxy novolac vinyl esters, and <br />high-crosslink density terephthalics typically provide the <br />best high-temperature physical properties. Appropriate <br />DION® resin systems may be considered for use in <br />relatively non-aggressive gas phase environments at <br />temperatures of 350° F or higher in suitably designed <br />structures. <br />When designing composite equipment for high <br />temperature service, it is important to consider <br />how heat will be distributed throughout the unit. <br />Polymer composites have a low thermal conductivity <br />(approximately 0.15 btu -ft/ hr -sq. ft.* F) which provides <br />an insulating effect. This may allow equipment having <br />high cross-sectional thickness to sustain very high <br />operating temperatures at the surface, since the <br />structural portion of the laminate maintains a lower <br />temperature. <br />