Pipe joints or couplings – With assembly means or feature – Guide and support
Reexamination Certificate
1999-04-13
2002-04-09
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
With assembly means or feature
Guide and support
C285S920000, C285S420000, C285S081000, C285S411000
Reexamination Certificate
active
06367843
ABSTRACT:
FIELD OF INVENTION
This invention relates to a fastener to securely fasten joints, preferably in pressure vessels, pipes, and other structures, intended to isolate internal volumes from the external environment, or in structural joints. The invention may be used to secure a pressure seal in vessel applications, join structural units or tubular members having internal passages. The invention may be used in any application currently utilizing standard bolted flanges or to aid in sealing vessels, pipes, or other structural joints.
In an embodiment of the invention, the fastener is used in a clamp-type connector that can join flange members together in an abutting engagement, creating a pressure seal in order to isolate the joint's internal environment from its external environment. This embodiment is unique in its controlled contact with the flange members wherein uniform seal integrity is secured and contact surface wear is dispelled.
An embodiment of the invention is especially useful in Delayed Cokers, wherein extremely high temperature and relatively low pressures are generated. It effectively handles the deleterious effects of coke exposure or other “dirty” operations. This embodiment is especially useful in quickly and simply retrofitting existing Delayed Cokers. It can be adapted to the existing flange member disposed on Delayed Cokers without having to use a spool-piece adapter.
An embodiment of the invention is also especially adapted to quickly flange up and safely secure extreme pressure vessels while supplying uniform seal integrity under extreme pressure and to quickly open such secured vessels. Therefore, the invention is advantageous in making high-pressure batch-type operations highly efficient and cost effective. A typical application is high-pressure food processing wherein, under extremely high-pressure, pathogens rupture, leaving food less perishable.
BACKGROUND OF THE INVENTION
The limitations of the prior art compromised safety to provide quick acting joint connecting devices. The prior art discloses single point failure mechanisms, wherein the failure of only one fastener element can catastrophically rend the joint. There is a need in industry to be able to remote open and close a joint with advantages of a safely articulated fastening mechanism and to do so while providing uniform seal integrity. The prior art is laden with quick acting joint connecting devices that fail to provide significant safety. Failure of these mechanisms prompted the American Society of Mechanical Engineers (ASME) to develop rules in their Boiler and Pressure Vessel Codes that give specific rules for adding safety to “Quick Acting” devices. Single acting fastening mechanisms and single point failure devices need secondary back-up retaining elements that assure joint integrity upon failure of the single acting fastening means or single point failure devices. Such retaining elements complicate automated operation, however.
In some installations, pressure vessels, pipes, and structural joints are opened and closed manually under conditions that are hazardous to the people performing the operation. Most prior installations utilize joint connectors comprised of bolted flanges that demand significant manual activity. The basic closing nature of bolted flanges is illustrated in the American Society of Mechanical Engineers' (ASME) Publication B16.5. Other manually operated prior art for connecting joints comprise threaded, clamped, and breach-lock mechanisms. These labor-intensive designs are not well suited in hazardous environments, however.
Most coke drums have manually-bolted joint connectors to join vessel closures and other structural units to the coke drum, thus closing and sealing the internal environment of coke drum. Coke drums may also have manually bolted connections connecting upstream and downstream pipes to the coke drum. Historically, manually operating these connections to dispose them open or closed has proven to be harmful to workmen and inefficient to production.
Although the prior art provides attempts at simplicity, it does not provide sufficient safety. In analyzing paths of failure, the prior art contains unsafe, single component failure paths that cause the catastrophic opening of the connected joint upon failure. A need exists to create a safe connection by incorporating safe articulation in the fasteners and eliminate all single point failure locations in a connector's articulation.
The inclusion of safe articulation in a remote operable connector entails additional expense and difficulty. Those skilled in the art can appreciate the benefit of a simple, remote operable fastener that can provide safely articulated connections. The system should be manually operable as well as provide for alternative operation in the event of an interruption of the remote operation. In short, when compared to other remote operable connectors, a need exists for a simpler connection.
This simplicity directly relates to lower operating and maintenance costs and shortened down time for maintenance. In some processes, one day of down time can result in an economic loss far surpassing the initial cost of the remote operable connector. Simplicity in design is highly valued by end users of this technology. The prior art discloses remote operable joint connectors providing multiple fasteners by incorporating overly complex mechanisms. In the process of providing multiple fasteners, the prior art sacrifices simplicity, reliability, and economy.
U.S. Pat. Nos. 5,336,375; 4,820,384; 5,221,019; 5,294,157; 5,228,825; 5,048,876, 5,471,739 and 4,726,76 are clamp-type mechanisms designed to remote assist or perform connecting and disconnecting of joints in pressure vessels. Those skilled in the art recognize that these devices have many limitations and are inherently unreliable, and expensive to manufacture.
Pressure and temperature of the working fluid, mechanical loads, and mechanical properties of the sealing gaskets dictate the magnitude of the gasket crushing clamping force. Gaskets that are suitable for moderate to high temperatures and pressures are not generally self-energized elastomers. A self-energized gasket will attempt to provide its own sealing force such as a rubber or asbestos gasket. Of course such gaskets cannot provide sufficient sealing force in many applications. Self-energized or low seating stress gaskets are generally used with connectors that produce no gasket crushing force or have some limitation or weakness in providing sufficient force to seat crush-type gaskets that are appropriate in high temperature service and many other application. Self-energized gaskets are also used when a connector is unable to provide substantial uniform seal integrity.
Prior clamp-type connectors have significant weakness in such areas. In a clamp-type connector, clamp segments deflect under load of fasteners. If such deflection is not accounted for, seal integrity is questionable because such prior clamp segments apply more clamping force near the fasteners and are therefore susceptible to leaks away from the fasteners. If this deflection is not accounted for, clamp segments and mating flange members are susceptible to contact interface damage in cyclic service. Therefore, a need exists in the industry for a safely articulated fastener incorporated into a remote operable clamp-type connector that effectively seals a joint even if a high seating stress, crush-type gasket is warranted or beneficial.
The mechanism disclosed in U.S. Pat. No. 4,483,458 (“the '458 patent”) cannot supply axial joint closing force because this device allows the clamp halves, the closing elements, and the pressure vessel housing to move axially relative to one another. Another result stemming from this relative movement is fatigue damage. The '458 patent device will encounter unacceptable fatigue damage in cyclic operation, requiring frequent testing, repair, or replacement. The '458 mechanism also requires external guide frames and anchor locations for automatic actuators and supports
Automated Connectors Holdings, L.B.
Locke Liddell & Sapp LLP
Nicholson Eric K.
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