The present invention relates to flexible couplings in general, especially to flexible pipe couplings, and more particularly to improvements in flexible couplings wherein an elastic component (e.g., a rubber hose, also known as compensator) is connected to and extends between two flanges serving to secure the flexible coupling to sections of a pipe line or the like.
It is known to utilize in a flexible coupling a rubber hose whose ends are connected with metallic hubs or flanges. The hose is relatively thin so that it can readily expand lengthwise in order to compensate for increasing distance between two sections of a pipe line which flank the coupling. If the pipe line conveys a highly pressurized fluid, the fluid acts against the internal surface of the hose and tends to move the adjacent sections of the pipe line nearer to each other. If the hose has a bulge, pressurized fluid acts against the internal surfaces which flank the bulge and tends to move the adjacent sections of the pipe line away from each other. Such movements of the sections are prevented by resorting to elastic and/or rigid fastening means which secure the sections to the ground, floor, ceiling or a rigid frame member. The provision of such fastening means contributes significantly to the initial and maintenance cost of the pipe line.
It was further proposed to use the just described conventional flexible pipe coupling in conjunction with devices which engage the ends of nearest pipe line sections adjacent to the respective ends of the compensator and oppose axial stretching of the compensator. Such devices operate satisfactorily if the transmission of sound between the sections which flank the flexible coupling is of no consequence. However, the just mentioned devices are overly complex and expensive if they must be designed with a view to prevent or reduce the transfer of sound between the sections of pipe at the opposite sides of the flexible coupling.
It was further proposed to connect the flanges which are secured to the ends of the compensator by sound-absorbing connecting elements. Such elements include clamps in the form of yokes made of flat or profiled steel and secured to the flanges by bolts, screws or the like. The sound-absorbing characteristics are imparted by coating one or both sides of each clamp with rubber. The maximum permissible number of such clamps is relatively small due to space limitations and their useful life is short, especially if the flexible coupling is to take up substantial stresses. This is attributed to the fact that relatively thin coats of rubber on the clamps cannot stand substantial compressive and/or other stresses. Therefore, such clamps are used only in conjunction with flexible couplings which are expected to be subjected to relatively low stresses. This greatly reduces the utility of such couplings since a flexible coupling is often required to stand extremely high fluid pressures and/or other stresses which must be taken up by the compensator. Moreover, the compensator is not properly shielded against mechanical impacts or other influences which could result in puncturing and/or other damage thereto.
A further drawback of presently known flexible pipe couplings is that they must be assembled at the locale of use. Thus, the replacement of the damaged coupling with a new coupling takes up a substantial amount of time, first because the damaged coupling cannot be removed as a self-contained unit and secondly because the new coupling must be put together upon removal of the old coupling. The assembly of flexible couplings at the locale of use is undesirable on the additional ground that proper assembly depends to a large extent on the ability of workmen and also that it is not possible to insure that each of a series of flexible couplings will be assembled with a requisite degree of reproducibility, especially as concerns the connections between the compensator and the flanges or hubs, the initial positions of flanges or hubs relative to each other, and/or the distribution and mounting of rubber-coated clamps. The situation is aggravated when the flexible coupling must be inserted between two misaligned or angularly offset pipes; improper mounting of the coupling under such circumstances is likely to result in premature destruction of the compensator. Also, improper mounting of the compensator reduces its ability to prevent or reduce the transfer of sound and/or vibrations. As a rule, a flexible pipe coupling which is installed in a pipe line for water should reduce or eliminate noise which is being propagated by the conveyed fluid.