Tools – Wrench – screwdriver – or driver therefor – Machine
Reexamination Certificate
1998-09-01
2001-06-12
Morgan, Eileen P. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Machine
Reexamination Certificate
active
06244138
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to a torque reaction device, particularly for use with a nut runner tool.
BACKGROUND OF THE INVENTION
In industries where large valves are employed, it has been common practice to utilize pneumatic wrenches, such as a nut runner tool, to rotate valve hand wheels to reduce the physical effort required to operate the valves. The wrenches are typically applied to the nut at the center of the hand wheel. A shortcoming of the use of such wrenches occurs when the valve comes to the limit of travel. The powerful rotational torque delivered by the pneumatic wrench is suddenly transmitted to the body of the person operating the tool. Such a sudden application of force transmitted to the body has become a cause of lost time injuries to plant personnel.
Various efforts have been undertaken to overcome this problem. In one application, a massive piping substructure was constructed about a valve. A pneumatic wrench was permanently affixed to the piping substructure to operate the valve. This system was very cost prohibitive and required a dedicated pneumatic wrench for each valve location. A second concept was the use of a forked reaction arm attached to the pneumatic wrench. The arm was placed over a plate and pipe bracket welded to the decking adjacent to the valve. Unfortunately, the piping system often undergoes large cycles of thermal expansion and contraction, with resulting movement relative to the bracket mounted to the stationary deck structure. Also, the forked arm was long and when torque loads were applied to the arm it spread the slot open, necessitating the periodic replacement of the forked arm. A third system was a plate and U-shaped strap bracket bolted to the valve itself just behind the hand wheel. The U-shaped strap bracket allowed the wrench to be cradled in the U-shaped strap.
Despite these efforts, a need still exists for an apparatus and method for the control of sudden applications of force by such power wrenches.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, an apparatus is provided for use with a power wrench to open and close a valve in a valve assembly by rotating a valve stem about a first axis. The apparatus includes a frame member which is mounted on the valve assembly and defines at least one surface. An arm member is secured onto the power wrench. The arm member faces the surface on the frame member as the valve stem is rotated by the power wrench. Movement of the power wrench relative to the valve is limited by contact between the surface on the frame member and the arm member.
In accordance with another aspect of the present invention, the frame member includes a U-channel and the arm member is a blade extending parallel to and spaced from the elongate length of the power wrench. In accordance with another aspect of the present invention, at least one pin is incorporated to confine the arm member to movement within the U-channel. The frame member can have a clamp, with the frame member clamped to the valve assembly. The frame member can have a bracket, with the frame member bolted to the valve assembly at the bracket. The frame member can have a pair of clamps, with the valve assembly including a pipe section. The pair of clamps clamp the frame member to the pipe section.
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patent: 5579801 (1996-12-01), Pye et al.
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patent: 5715869 (1998-02-01), Patterson
patent: 5924442 (1999-07-01), Vorosmarti
Danganan Joni B.
Furmanite Worldwide, Inc.
Morgan Eileen P.
Sidley & Austin
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