Composite Structure with Exposed Conductive Fiber for Static Dissipation, and Method for Making Same

Abstract

Provided is a storage tank or structure with conductive fiber material (e.g. carbon fiber) for dissipating electrostatic charge. The tank comprises a tank wall made of composite material, such as polyester-fiberglass composite. On an inner tank surface, open areas are provided in which the conductive fiber is exposed. The conductive fiber material has broken fiber tips and stray fibers for collecting electrostatic charge. Outside the open areas, the conductive fiber material is covered with a layer of cured resin. The conductive fiber is exposed only in the open areas. An impermeable film may be present under the conductive fiber in the open areas. The present invention also includes a method for making the tank, in which a liquid, gel, or impermeable film mask is applied to the conductive fiber material. The mask functions to prevent infiltration of liquid resin into the conductive fiber material.

Description

RELATED APPLICATIONS[0001]The present application claims the benefit of priority of copending provisional patent application 61 / 851,028 filed on Feb. 28, 2013 and copending provisional patent application 61 / 852,780 filed on Mar. 21, 2013, which are hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to explosion prevention and electrostatic charge dissipation. More particularly, the present invention relates to a composite storage tank having an integral conductive fiber material for electrostatic charge removal, and a method of making the same.BACKGROUND OF THE INVENTION[0003]Liquid storage tanks are commonly used in petroleum production and at industrial facilities. These tanks are used to store petroleum products, contaminated wastewater, or process chemicals. These materials may contain flammable, volatile components that present an explosion hazard. If a tank contains flammable vapors and air, an electrostatic discharge can trigg...

AI Technical Summary

Benefits of technology

The solution effectively reduces the risk of electrostatic-spark triggered explosions by providing a conductive path for charge dissipation, overcoming the limitations of conventional solutions with improved durability and installation ease.

Problems solved by technology

These materials may contain flammable, volatile components that present an explosion hazard.

If a tank contains flammable vapors and air, an electrostatic discharge can trigger a dangerous and costly explosion.

The trapped electrostatic charge can trigger an explosion of the air and flammable vapor mixture.

Nonconductive tanks (e.g. made of polymers or fiberglass) are particularly problematic because they do not provide an electrically conductive path to ground potential.

Metal tanks can also present a hazard if they are coated with an electrically insulating coating of epoxy or paint.

However it has several serious disadvantages, including cost, susceptibility to corrosion, difficulty of installation (since the central twisted wire is rigid or semi-rigid), and tendency of the small wires to loosen and fall off over time.

Hence if corrosion causes one wire to dislodge, then all other wires in the same bundle will fall out as well.

Small wires or corroded metal particles that fall into the liquid will damage downstream equipment Consequently, the wire brush 12 presents a significant hazard for liquid-handling equipment such as filters, valves and pumps.

Fiberglass tanks are corrosion resistant, but because they are electrically insulating, fiberglass tanks are an explosion hazard.

A problem with this method is that all inside surfaces of the tank are electrically non-conductive due to a thin layer of non-conductive resin coating the inside surfaces.

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