Fluid handling – Processes – Cleaning – repairing – or assembling
Patent
1997-08-06
1999-08-24
Walton, George L.
Fluid handling
Processes
Cleaning, repairing, or assembling
292131, 137315, 251305, 251306, 25131514, 25131516, 251316, 251317, 251357, 251360, 251363, F16K 4300, F16K 506
Patent
active
059412666
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to valves, specifically to industrial and commercial ball and butterfly valves used to isolate and control flow in equipment and piping.
BACKGROUND ART
In industrial plants, valves are repaired frequently. Valves which are welded into the pipe are usually repaired in place due to the expense related to removal and reinstallation. Linear acting valves of the gate and globe style have a bonnet, which when removed, gives access to the internal parts of the valve. Valves which have flanged or clamped pipe connections can be either repaired in place or removed to a shop for repair. Shop repair is preferred, when feasible, due to the ability to shop test valves after the seat and sealing members have been restored. Also, a shop is a more ideal working environment compared to an insitu job and repair quality is generally better.
A problem arises with split body or side entry ball and butterfly (rotary) valves when repairs are necessary and the valves are welded in line, or flanged (or clamped) but not feasible to remove due to space restrictions, or a limited available repair time. Valves of this type do not have a bonnet which can be removed to access the valve internals.
If a split body valve is welded into the line, the line must be cut so that the body bolts can be removed to access the internal valve member. Cutting a pipeline is very costly. After lines greater than 21/2" are cut the pipe ends and the valve ends have to be machined to achieve the beveled butt weld end dimension in accordance with American National Standard Institute B16.25. Then after the valve has been repaired it must be rewelded back into the flowline. Finally, depending on the nature of the valve installation, non-destructive testing, ranging from dye checking to full penetration x-ray is done. Removal and reinstallation costs often are the most expensive step in the repair of a welded in split body or end entry valve.
Some manufacturers of split body valves will suggest removing the body bolts and pulling the valve apart. The problems with this method are many. The piping to which the valve is attached, cannot be sprung apart without placing undesirable stresses in the piping. These stresses can become the root cause of future pipe rupture, which can be catastrophic in high pressure or hazardous medium situations. Furthermore, even after using the heavy duty slings and come-alongs to spread the valve apart, there is usually not enough space between the two sections of the split body to properly remove and reinstall the internals, and, misaligned trim (internals) is often the result. Lastly, but not least, this method can also be very dangerous as there is a risk of the sprung pipe letting go or moving. If this were to happen while repair personnel were working in the valve, that part of the mechanic's body (head, hands, arms, etc.) which is between the two valve body sections could be crushed.
Two of the three primary types of industrial service rotary valves have inline repairable (bonneted) designs. They are top entry (spherical plug) ball valves and plug (tapered and straight cylinder) valves. The other rotary valve widely used in the industrial/commercial environment is the butterfly valve. Butterfly valves are made in a side entry design, and therefore are not inline repairable. To repair a butterfly valve at least one valve pipe connection must be opened. It suffers from the same problems that a split body or side entry ball valve does when it comes to insitu repair. Tapered plug valves, due to their requirement to have linear seating force (gravity and/or often some mechanical assist) are generally always top or bottom entry. While the technology described in this patent is presently indicative of that found in the spherical, near spherical or partially spherical plug (ball) and the butterfly valve, it is not intended to exclude its application to plug valve art.
Several types of top entry, inline repairable ball valves have been proposed--for example, in the U.S. Pat. Nos. 2,998,223 to
REFERENCES:
patent: 3474818 (1969-10-01), Hartman
patent: 3697043 (1972-10-01), Baker
patent: 3949965 (1976-04-01), Sharples et al.
patent: 4027698 (1977-06-01), Weinhold
patent: 4273152 (1981-06-01), Freeman
patent: 4307747 (1981-12-01), Carpentier
patent: 4508139 (1985-04-01), Teumer
Lipton, Esq. Robert S.
Newport Technologies Holdings, Inc.
Walton George L.
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