Internal line-up clamp for pipe lines

Abstract

Abstract actuated drive means for propelling the clamp axially forwardly through a pipeline section together with associated control means for automatically stopping, reversing and positioning the clamp at the open end of the welded-in pipe section in position to receive the next set-in pipe section. The invention is explained in detail hereinbelow by reference to a specific clamp apparatus incorporating the features of the invention. Such apparatus is not meant to be limiting inasmuch as it will be understood that it constitutes but one of the ways in which the principles of the invention may be applied. An internal line-up clamp which incorporates a pair of interconnected but independently operable clamping assemblies, each of which includes a set of radially movable pipe engaging shoes adapted to clampingly engage the inner circumferences of a pair of pipe sections in the zones adjacent their ends. At least two axially movable pneumatic actuators are operatively associated with each set of clamping shoes in a manner such that axial movement of the actuators effects radial movement of the shoe set with which they are associated. The clamping assemblies are interconnected by a plurality of axially extending rods which are adapted to maintain the assemblies in axial alignment while permitting them to be moved axially with respect to each other a limited distance. A fifth pneumatic actuator means is provided for effecting such reciprocal axial movement of the clamp assemblies. This invention relates to a line-up clamp for use in the welding of pipelines and, more particularly, to a pipe line-up clamp for clamping the internal surfaces of a pair of adjacent pipe ends and positioning and maintaining the pipe ends in precisely aligned relationship for welding by either manual or automatic welding means. In the construction of pipelines, a large number of individual pipe sections are welded together in end-to-end relationship. It is the usual practice to utilize an internal line-up clamp to align adjacent pipe ends prior to welding and maintain them in aligned position during the welding operation. Many such internal pipe line-up clamps are known and in commercial use. However, the known clamps are deficient in many respects. For effective welding, particularly with automatic welding equipment, the pipe ends must not only be coaxial but the pipe walls must be accurately aligned around their entire circumferences. Steel pipe sections used in the pipeline construction industry are not always exactly cylindrical nor are the ends precisely square. Also, during transportation to and handling on the job site, the pipe sections are often bent out of round. As a result, when a set-in pipe section is positioned in end-to-end relationship with the open end of the welded-in portion of the pipeline, the adjacent pipe ends often exhibit different degrees of roundness and, also, the end faces do not abut even though the pipes may be coaxial. Conventional line-up clamps are generally not capable of exerting a sufficiently great pressure upon the adjacent ends of out-of-round pipe sections to bring them into precise alignment, particularly in the case of the relatively large diameter pipes which are becoming increasingly common in the pipeline industry. In addition, in using the prior art clamps it is often difficult to bring the end faces of the pipe sections in to proper abutting relationship since the set-in pipe is positioned entirely by mechanical means external to the clamp itself, e.g. by manipulation of the set-in pipe support sling and movement of the side-boom tractor carrying the set-in pipe. This proceDure, of course, is tedious and time consuming particularly where the end faces of pipe sections are not exactly square. For these reasons particularly, the prior art line-up clamps are generally unsuitable for use in conjunction with automatic welding equipment which requires extremely precise alignment of the pipe ends and, preferably, accurate spacing between the adjacent surfaces which are to be joined. The prior clamps also are are generally difficult to manipulate and position within the pipeline section preparatory to clamping each new section in place for welding. Moreover, difficulty is often encountered in moving the prior line-up clamps through curved pipe sections because of the very small clearance normally provided between the pipe engaging clamping shoes and the internal surfaces of the pipe. Although many attempts have been made to overcome the foregoing and other disadvantages of the prior art clamps, non, as far as is known, has been provided which has been entirely satisfactory in commercial operations. Accordingly, it is an object of the present invention to provide an apparatus for axially aligning adjacent pipe ends which is capable of exerting very high radial forces on the inner circumference of the pipe ends to force each into a truly circular configuration. Another object of the invention is the provision of apparatus for aligning pipe ends which is capable of clamping the end of a set-in pipe and drawing it into abutting, axially aligned relationship with the pipe end to which it is to be joined. Another object of the invention is to provide an internal pipe line-up clamp which may be quickly and automatically positioned and clamped at the end of the welded in-pipe section in position for receiving the set-in pipe section. Still another object of the present invention is to provide a pipe line-up clamp which functions to (a) securely clamp and round out the open end of the welded-in pipe in an initial clamping action, (b) clamp the set-in pipe end after it is brought into rough end-to-end alignment with the welded-in pipe, (c) draw the set-in pipe towards the welded-in pipe to bring the end faces of the two pipes into engagement, (d) securely clamp and round out the end of the set-in pipe in a secondary clamping action and, finally, (e) back-space the end face of the set-in pipe a predetermined distance of the welded-in pipe end face to provide a uniform gap between the adjacent pipe end faces while still maintaining the pipe walls in accurate alignment. Yet another object of the present invention is the provision of apparatus for aligning pipe ends which incorporates pipe-engaging clamping elements capable of relatively large retractive radial movement from an operative to a non-operative position thereby permitting the clamp to traverse curved pipe sections without damage to the pipe or clamping elements. A still further object of the invention is to provide apparatus for positioning and aligning pipe ends which is relatively inexpensive to manufacture, simple to operate and rugged and durable in use. According to the invention, these and other objects and advantages are obtained by an internal line-up clamp which incorporates a pair of interconnected but independently operable clamping assemblies, each of which includes a set of radially movable pipe engaging shoes adapted to clampingly engage the inner circumferences of a pair of pipe sections in the zones adjacent their ends. At least two axially movable pneumatic actuators are operatively associated with each set of clamping shoes in a manner such that axial movement of the actuators effects radial movement of the shoe set with which they are associated. The clamping assemblies are interconnected by a plurality of axially extending rods which are adapted to maintain the assemblies in axial alignment while permitting them to be moved axially with respect to each other a limited distance. A fifth pneumatic actuator meanS is provided for effecting such reciprocal axial movement of the clamp assemblies. The double actuator means associated with each set of pipe engaging shoes enables each shoe set to be actuated independently and it also permits imposition of clamping forces which can be selectively increased through at least two stages to a level sufficiently great to round out large diameter, high strength pipe sections without difficulty. In a preferred embodiment of the clamp, the high clamping force capability of the compound actuator means is transmitted to the pipe engaging clamping shoes by means of a plurality of tandem pivot links which are adapted for retraction radially inwardly when the clamp is in a nonoperative or pipe-traversing state, thus ensuring ample clearance between the clamp shoes and the inner wall of the pipe through which it is traversed. An another preferred aspect, the clamp incorporates pneumatically

Inventors

• 👤 Edmund G Bradley
• 👤 Reginald P Whittingham

Bibliographic Details