Pipe joints or couplings – Elbow
Reexamination Certificate
1997-12-15
2001-08-28
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
Elbow
C285S031000, C285S363000, C285S181000
Reexamination Certificate
active
06279964
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to high pressure flow lines and more particularly to removable connections or closures having multiple pieces which can be assembled in series between substantially immovable high pressure pipes and form a sealed flow path therebetween.
BACKGROUND
Pipe systems for routing fluids may have virtually any configuration. Large systems are normally made of several separate sections which are connected together during construction. These pipe systems generally have a number of bends or angled pipe sections, many of which are found at the point at which the connections are made between pipe sections.
The two most common means for joining sections of pipe are welding and bolting the sections together. For welded connections, the pipes are prepared by cleaning the surfaces of the tapered ends. The ends of sections which are to be welded together do not mate or overlap, but are instead placed face-to-face prior to welding. A section which is to be welded may therefore simply be inserted laterally (parallel to the faces of the pipe openings) between two adjacent sections and welded into place.
In bolted connections, the pipe ends have flanges through which bolts are inserted and then tightened so that the flange faces are held together. Bolted connections typically require gaskets or other types of seals between the flange faces to prevent fluids from leaking out of the pipes at the point of connection. Bolted connections also commonly utilize flanges with mating faces to provide a seal which can withstand greater fluid pressures in the pipe. The mating flange faces have surfaces which are complementary to each other and are usually designed to accommodate seals therebetween.
Pipe sections which have mating flanges must be axially aligned, or nearly aligned, and then moved toward each other to bring the mating surfaces into engagement. Even flat-surfaced flanges used in bolted connections cannot simply be moved laterally into position and bolted because the gasket between the surfaces must be compressed by the surfaces in order to provide the friction fit necessary to seal the connection and prevent movement of the gasket out from between the surfaces. In low pressure systems, this does not normally present a problem because a pipe section which must be inserted between two others can often be installed by flexing the already-installed pipes away from the inserted section. Then, when the pipes are allowed to return to their normal positions, the flange faces of the previously-installed sections spring back toward the flange faces of the new section. The flanges are then bolted together, compressing the seals and securing the connections.
Pipes used in high pressure fluid handling are required to have extremely thick walls (on the order of 50% to 100% of the pipes' inner diameter) in order to withstand the forces exerted by the fluid. As a result, high pressure piping is very rigid and cannot be flexed in the same manner as piping for low pressure applications. Consequently, connection flanges on high pressure piping often cannot be moved enough to allow a single-piece angled joint or elbow with mating surfaces to be inserted or removed. In addition to the fact that thick, high pressure pipe usually cannot be flexed, it is very heavy (because of its increased thickness) and it may require additional support compared to low pressure pipe. The additional support can be provided by stationary mounting brackets which prevent movement of the pipe regardless of how much it can be flexed. Because high pressure pipe usually cannot be moved, angle joints in high pressure pipe systems are formed in the prior art by placing an elbow in position between two pipes and welding the elbow to the pipes.
In normal use, many pipe systems need to be inspected for corrosion or they may contain strainers which must be periodically cleaned. They may also contain valves which occasionally require maintenance which must be performed from the interior of the pipes. It is necessary in these situations to gain access to the interior of the pipe system to allow the cleaning or other service to be performed.
In prior art systems in which the joints to be removed are welded into place in the system, access to the pipe interior can only be obtained by cutting a joint out of the system and then re-welding the joint into place after the adjacent pipes are inspected or the appropriate maintenance is performed. If, on the other hand, the connections are made with a removable means such as bolted flanges, pipe access requires only loosening and removal of the bolts and reinstallation of the bolts after the pipes are serviced.
The removal and replacement of welded joints is very time-consuming and costly in comparison to the removal and replacement of bolted joints. Clearly, it takes less time to loosen the bolts of a flange than to completely cut through the thick walls of high pressure pipes and it is equally apparent that the level of skill required to loosen the bolts is less than that required to safely operate a cutting torch. The same is true of tightening the bolts in comparison to making numerous welding passes around the joint. It is somewhat less obvious, though equally significant, that welded connections must be inspected using x-ray equipment to ensure the integrity of the weld. Also, every time a welded joint is cut out of a pipe system, the section which is removed is actually shortened so that it must either be built up to its original length or replaced with a new joint.
Because a welded joint requires extra time to remove, replace and inspect, and because it may require extra materials, it is typically much more costly than a bolted joint. Unfortunately, as noted above, there are systems in which prior art bolted connections could not be used because the pipe sections simply could not be properly positioned between substantially immovable pipes.
It is therefore an object of the invention to provide an easily removable pipe section which can be used to make a connection between pipes which cannot be moved with respect to each other.
It is another object of the invention to provide a means for removably connecting two non-movable, non-parallel pipes, the connecting means utilizing mating faces to produce a seal capable of withstanding increased internal pressures.
It is yet another object of the invention to provide a means for making angled connections between stationary high pressure pipes which is quick, inexpensive and easy to assemble and disassemble so that the pipe interior is easily accessed.
SUMMARY OF THE INVENTION
As noted above, angle joints in the prior art are welded into place because the ends of the high pressure pipes to which the angle joint must be connected are essentially immovable so that a one-piece angle joint having mating connecting surfaces cannot be moved into position between the pipes. The invention solves this problem by utilizing a two-piece angle joint to make the connection. The preferred embodiment of the invention has an elbow which forms, for example, a 90 degree bend and has a male mating surface on one end and a female mating surface on the other end. The second piece of the joint is an adapter ring which has female mating surfaces on both sides.
The ends of the elbow and adapter which connect to the pipe ends (the “connection ends”) are placed against the pipe ends and the bodies of the elbow and adapter are rotated slightly away from each other. In this position, the connection ends of the elbow and adapter touch their respective pipe ends only on the side opposite the other pipe. The elbow and adapter are then slowly rotated toward each other while maintaining contact with the respective pipe ends. As they are rotated, the elbow and adapter gradually near alignment with the pipes and their connection ends make more contact with the pipe ends.
The mating surfaces of the elbow and adapter make contact with each other before the elbow and adapter are completely aligned with the pipes. When the elbow and
Gray Cary Ware & Freidenrich LLP
Nicholson Eric K.
Specialty Piping Components, Inc.
LandOfFree
Multiple-piece elbow assembly does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multiple-piece elbow assembly, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multiple-piece elbow assembly will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2461587