Method and apparatus for the maintenance of pipelines

Abstract

Method and apparatus for the maintenance of pipelines. A number of points along the pipeline ( 30 ) is selected and the pipeline is raised at these points by an amount that the height difference between these points does not exceed the international flexibility standards. The pipeline ( 30 ) is supported at these points and thereafter maintenance is performed on those segments which have been raised enough to allow performance of the maintenance procedures. The distance between two adjacent points may be 30 meters and the height difference between two adjacent points may be not more than and preferably close to 22 cm. The initial cross-section of the selected segments are allowed to rest on the beds of the trenches because of their weights.

1 . Method for the maintenance of pipelines, which comprises selecting a number of points along the pipeline and raising the pipeline at these points by such an amount that the height difference between these points does not exceed the international flexibility standards, supporting the pipeline at these points and thereafter performing maintenance on those segments which have been raised enough to allow performance of said maintenance.  
     
     
         2 . Method according to  claim 1 , wherein the distance between two adjacent points is 30 meters and the height difference between two adjacent points is not more than and preferably close to 22 cm.  
     
     
         3 . Method according to  claim 1 , wherein the initial cross-section of said selected segments are allowed to rest on the beds of the trenches because of their weights.  
     
     
         4 . Method according to  claim 2 , further comprising carrying out maintenance of the pipeline over those segments which are suspended between two points to allow performance of said maintenance thereof, lowering one segment, and raising another cross-section, spaced from the previous one, to such an extent as not to exceed the international flexibility standards.  
     
     
         5 . Method according to  claim 4 , comprising carrying out maintenance of the pipeline over a segment having a length of 30 meter, lowering said segment and raising another cross-section, spaced from the previous one by 30 meters, by an extent not exceeding 22 cm.  
     
     
         6 . Method according to  claim 4 , further comprising supporting the bottom of the pipeline, at any cross-section that has been raised, to permit carrying out the maintenance operations.  
     
     
         7 . Method according to  claim 4 , further comprising supporting the pipeline on the sides thereof against the sides of the trench, so as to maintain it in the desired alignment.  
     
     
         8 . Method according to any one of claims  1 - 7 , tightly engaging the bottom of a cross-section of the pipeline, which is to be raised, with raising means, so as to establish an initial vertical position of said cross-section, and then actuating the raising means to effect a predetermined lifting of said cross-section.  
     
     
         9 . Method according to  claim 8 , wherein the predetermined lifting of the pipeline cross-section is 22 cm for each length of pipeline of 30 meters.  
     
     
         10 . Method according to any one of  claims 1  to  9 , which comprises selecting two adjacent segments of pipeline having a given length, allowing the terminal cross-sections of said segments to rest on the bed of the trench in which the pipeline is laid, and raising the cross-section intermediate between said two segments to such an extent as not to exceed the international flexibility standards.  
     
     
         11 . Apparatus for the maintenance of pipelines, which comprises: 
 (a) at least one lifting frame, having telescopic legs and a transverse top beam;    (b) telescopic lifting arms supported in said top beam;    (c) flexible means connected to said lifting arms for engaging the bottom of the pipeline;    (d) first hydraulic means for telescopically extending and retracting said legs of the lifting frame; and    (e) second hydraulic means for telescopically extending and retracting said lifting arms.    
     
     
         12 . Apparatus according to  claim 11 , wherein the flexible means are chains.  
     
     
         13 . Apparatus according to  claim 11 , wherein the first hydraulic means have a limited power so that they can exert only the force required for placing the frame in the desired positioned relationship to the trench bed.  
     
     
         14 . Apparatus according to  claim 11 , wherein the second hydraulic means have sufficient power to exert the force required to lift the pipeline.  
     
     
         15 . Apparatus according to  claim 11 , wherein the second hydraulic means have a limited stroke and, when actuated, will shorten the lifting arms and therefore raise the pipeline by the exact predetermined amount permitted by the international flexibility standards.  
     
     
         16 . Apparatus according to  claim 11 , wherein the second hydraulic have a limited stroke and, when actuated, will shorten the lifting arms and therefore raise the pipeline by 22 cm.  
     
     
         17 . Apparatus according to  claim 11 , which comprises a single lifting frame.  
     
     
         18 . Apparatus according to  claim 11 , which comprises two parallel lifting frames, so as to exercise the lifting action on a short length of pipeline comprised between said two parallel frames.  
     
     
         19 . Apparatus according to  claim 11 , further comprising supports for the section of pipeline that is lifted.  
     
     
         20 . Apparatus according to  claim 19 , wherein the supports are composed of several stackable sections, so that they can be placed under the pipeline succesively as the pipeline is gradually lifted.  
     
     
         21 . Apparatus according to  claim 11 , further comprising lateral supports adapted to be placed on the sides of the pipeline and to be operatively connected thereto by flexible means, said supports being provided with extendable arms for engaging the sides of the trench.  
     
     
         22 . Apparatus according to  claim 18 , wherein two parallel lifting frames are connected to one another and are attached to a common element for lifting them and transferring them from one location to another.  
     
     
         23 . Apparatus for the maintenance of pipeline, substantially as described and illustrated.  
     
     
         24 . Method for the maintenance of pipelines, substantially as described and illustrated.