Essef Corporation

Gerald S Boyce

James C Murphy

Erik Coeckelbergs

A process, and the product thereof, for making a composite vessel having at least one closed end, the process including the steps of: fabricating a thermoplastic liner for the vessel; overlaying onto the liner a layer of commingled fiber and thermoplastic material to obtain a composite intermediate structure; pressing and heating the composite intermediate structure to effect at least partial consolidation in apparatus which includes upper and lower silicon rubber bags, the bags having dimensions such that, during operation, their facing peripheral regions abut to encompass the composite intermediate structure; then placing the composite intermediate structure in a mold; heating the composite intermediate structure in the mold while applying a force, such as internal gas pressure, tending to urge the composite intermediate structure against and into the shape of the interior walls of the mold until the thermoplastic liner and the overlaid layer fully consolidate; cooling the mold and composite vessel until the composite vessel is solidified; and removing the formed composite vessel from the mold. The commingled fiber and thermoplastic material may either be wound onto the liner or laid on the liner in the form of fabric woven from the fiber and threads of the thermoplastic material.

Method for fabricating composite pressure vessels and products fabricated by the method

A process of making a composite vessel with superior mechanical and aesthetic characteristics includes the steps of: A) preforming a composite thermoplastic shell (e.g., by winding a commingled roving of fiberglass and a thermoplastic material onto a thermoplastic liner) having an opening for access to the interior; B) placing the shell (which may optionally be preheated) into a mold (which itself may optionally be preheated); C) introducing an inflatable bag containing a heater into the shell through the opening; D) heating the inflatable bag to a temperature which is sufficient to render the shell fluid while pressurizing the interior of the inflatable bag; E) continuing step D) until the shell forms against the interior walls of the mold; F) allowing the formed composite vessel to cool; G) removing the inflatable bag; and H) removing the formed composite vessel from the mold. Prior to step C), an insert having an opening may be juxtaposed in alignment with the opening in the shell such that, during step C), the inflatable bag is inserted through the opening in the insert. If desired for the intended purpose of the composite vessel, a portion of the exterior surface of the insert may be threaded such that threads are formed in the opening of the shell whereby the insert can be unscrewed leaving a threaded port into the vessel.

Method for making thermoplastic composite pressure vessels

A process for fabricating a composite vessel includes the steps of: A) preforming (e.g., by winding fiber and at least one thermoplastic substance onto a thermoplastic liner) a thermoplastic shell which has at least one opening for access to the interior; B) extruding a circular cross section of a fluid parison of thermoplastic material (which preferably is chosen to have a melting point lower than that of the thermoplastic shell) into the interior of the thermoplastic shell through the opening; C) in a mold, applying at least one force (such as gas under pressure) which tends to urge the fluid parison toward the interior walls of the thermoplastic shell (which may be preheated prior to introduction into the mold) such that the fluid parison imparts heat to the thermoplastic shell; D) continuing step C) until the thermoplastic shell and the fluid parison consolidate to form a composite vessel; E) cooling the vessel until it is solidified; and F) removing the vessel from the mold. For some composite vessels, prior to step C), an insert may be introduced into the interior of the parison and positioned in alignment with the opening in the thermoplastic shell such that the insert is rendered integral with the composite vessel during step D). Suitable thermoplastic materials include polyethylene, polypropylene, polybutylene terephthalate and polyethylene terephthalate. The resulting composite vessel exhibits superior mechanical and aesthetic properties.

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Nottingham, United Kingdom

Gerald S Boyce