Fastener for permanently securing composite gratings to...

Joints and connections – Rigid angle

Reexamination Certificate

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Details

C052S202000, C052S507000, C052S656800, C052S664000, C052S698000, C248S224800

Reexamination Certificate

active

06390725

ABSTRACT:

SPECIFICATION
1. Field of the invention
The present invention relates to a fastening system for securing a grating to a structural support member, and more particularly, to a fastener for permanently securing fiberglass gratings to a walkway or landing in the wave zone area of an offshore platform or other similar platforms located in chemical plants, docks, refineries and elsewhere, where the gratings are subjected to wave pressures exerted by storm wave action or other hydraulic forces.
2. Background of the Invention
Grating sheets or panels are used in a variety of applications such as in walkways on offshore platforms. Due to its structural strength, a metallic grating has typically been used to form the walking surface of a walkway. Metallic gratings are typically secured to its supporting steel members by tack-welding the grating to the supporting steel members at designated intervals. These “tack-welds,” or the weld affected areas require touch-up painting and it is these ouch-up areas that generally break down first, creating a corrosion cell. However, due to this corrosion caused by deterioration of the paint system, a metallic grating is often not desirable. Although the metallic grating is typically galvanized or painted, the paint eventually wears, chips or fades or otherwise succumbs to corrosion primarily at the weld-affected areas. Fabricating the grating out of a noncorrosive metal, such as stainless steel, is expensive and impractical for a large walkway.
For providing support, a typical walkway has longitudinal structural support members, most often pipe members, extending along the edge of the walkway and transverse members extending between and reinforcing the longitudinal structural support members. The grating is placed on top of these structural support members. As previously stated, metallic gratings are typically secured to the structural support members by tack-welding the grating to the transverse supports at every 3rd or 4th support and 6 inch intervals along the longitudinal members.
Currently, the solution to the above-discussed corrosion problem typically involves replacing the metallic grating with grating formed from a fiberglass material which is resistant to corrosion and furnishes firm support for the walkway. However, the fiberglass grating introduces additional problems, as the above-described system for mounting the metallic grating does not work when fiberglass grating is used. as the fiberglass grating cannot be welded. Placing the fiberglass grating on top of the structural support pipe members and securing it in place with clips, such as described in U.S. Pat. No. 5,118,147, does not firmly secure the grating in the offshore platform environment subjected to severe wave action. The circular motion of waves that constantly wash through the grating subjects it to multidirectional forces that eventually displaces the grating from the clips and the grating washes out.
Other prior art includes the use of flexible bands to secure the fiberglass grating to the underlying crossbar support members. However, the use of flexible bands require a worker to go beneath the grating to secure the grating to the supporting structure. Working beneath the grating can be quite hazardous in an offshore platform environment. Also. this system secures the grating vertically but not laterally and with constant wave action, lateral movement of the grating occurs which produces a “saw cutting” phenomenon that continues until the flexible bands saw through the grating.
It would be desirable to have a system for securing the fiberglass gratings to the support members of the platform that would not only be corrosion resistant but would also be able to withstand the forces of the waves in the wave-zone areas of the platform The “wave-zone” is the portion of an offshore structure that, in the event of a hurricane, typhoon or any other violent storm, could be under water as a wave passes through the platform. In a typical platform in the Gulf of Mexico the elevation of this potion of the platform could be as high as 40 to 50 feet above the mean low water level. When large waves pass through the platform, they exert extremely high horizontal and vertical pressures on the platform structure and any appurtenances such as the grating system.
It would further be desirable to have a fastening system for permanently securing fiberglass gratings to the support members of the platform that would not only be corrosion resistant but would also be able to withstand the forces of the waves in the wave-zone areas of the platform.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus for permanently securing a grating sheet having parallel and transverse bars that form a pattern of openings to a structural member. The present apparatus includes an elongated generally L-shaped connector having an upper plate section generally rectangular in shape for mounting on an upper surface of the grating sheet and a downwardly extending sidewall formed integrally with the plate section and adapted to extend along a longitudinal edge of the grating sheet. The L-shaped connector also can optionally include a plurality of downwardly extending teeth formed integrally with the plate section and spaced apart from each other for insertion in between the grating bars. At least one generally right-angled brace is attached to the outer surface of the sidewall for permanently securing the L-shaped connector to the structural member. The brace has an edge configured to conform to an outer surface of the structural member, wherein the improved apparatus is formed of corrosion resistant material and is able to withstand the forces of waves in a wave-zone portion of an offshore platform.


REFERENCES:
patent: 1567446 (1925-12-01), McClure
patent: 1707533 (1929-04-01), Nagin
patent: 2075588 (1937-03-01), Meyers
patent: 2705550 (1955-04-01), Joseph
patent: 3309119 (1967-03-01), Phillips
patent: 3367078 (1968-02-01), Thompson
patent: 3742671 (1973-07-01), Ellis
patent: 4185435 (1980-01-01), Schiffers, Jr.
patent: 4221038 (1980-09-01), Singer et al.
patent: 5118147 (1992-06-01), Correll
patent: 5291714 (1994-03-01), Wright et al.
patent: 5732523 (1998-03-01), Masters et al.
patent: 5911664 (1999-06-01), Masters et al.
Admitted Prior Art , handrwritten pages from application 08/654730.

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