Fabricating RP Tank

An example is a tank 0.9 m (3 ft) in diameter and 1.8 m (6 ft) long with semi-spherical ends. Such a tank s stress calculations (excluding the weight of both the product contained in it, and the support for the tank) are represented by the formulas  

Tensile stresses are critical in tank design. The designer can assume the pressure in this application will not exceed 100 psi (700 Pa) and selects a safety factor of 5. The stress must be known so that the thickness can be determined. The stress or the strength of the final laminate is derived from the makeup and proportions of the resin, mat, and continuous fibers in the RP composite material. 

Representative panels must be made and tested, with the developed tensile stress values then used in the formula. Thus, the calculated tank thickness and method of lay-up or construction can be determined based on  

Another alternative would be to select a special fabric whose weave is 2 to 1, wrap to fill, and circumferentially wrap the cylindrical sections to the proper thickness, thus getting the required hoop and axial strengths with no extra, unnecessary strength in the axial (longitudinal) direction, as would inevitably be the case with a homogeneous metal tank. 

As can be seen from the above, the design of RP products, while essentially similar to conventional design, does differ in that the materials are combined when the product is manufactured. The RP designer must consider how the load-bearing fibers are placed and ensure that they stay in the proper position during fabrication. 

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Bag Molding Hinterspritzen Contact Molding Filament Winding Fabricating RP Tank... 

Extensive use is made in using commercial and engineering plastics to fabricate all tank sizes and shapes used in the transportation industry as well as many other industries (agriculture, chemical storage, filtration, etc.). The processes in other chapters review fabricating tanks and containers using different types of URPs and RPS (Chapter 5). 

As reviewed throughout this book part of the wide acceptance of plastics is from their relative compatibility to chemicals, particularly to moisture, as compared to that of other materials. Because plastics are largely immune to the electrochemical corrosion to which metals are susceptible, they can frequently be used in transportation and other markets successfully to contain water and corrosive chemicals that would attack metals. RP fabricators also have a major market for tanks as well as pipes, grating, and a variety of other structures used to withstand corrosive working environments that serve industrial customers. 

Minimum practical total RP thickness is established as 4.8 mm ( A6 in.) for the combined spray-up liquid seal and filament wound structural layers and 6.4 mm (V4 in.) for an all-chopped fiber spray-up laminate with sand filler. The choice for any construction is made on the basis of comparative design thickness, weight, and fabrication costs. The all-chopped fiber reinforced construction using somewhat greater wall thickness than the composite filament wound-chopped fiber wall is determined to provide the lowest tank cost filament winding provides lower weight. 

Very small to large filament wound cases have been fabricated for use on rockets and missiles. As an example, a racetrack filament winding RP fabricating technique was used to fabricate a very large tank (rocket motor case) for NASA. See Chapter 5 Filament Windings, Racetrack and Other Winders. 

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