US3680342A

US3680342A - Apparatus for laying pipelines

Info

Publication number: US3680342A
Application number: US5842A
Authority: US
Inventors: James D Mott; Richard B Feazle
Original assignee: FLUOR OCEAN SERVICES Inc
Current assignee: FLUOR OCEAN SERVICES Inc
Priority date: 1970-01-26
Filing date: 1970-01-26
Publication date: 1972-08-01
Anticipated expiration: 1989-08-01

Abstract

An apparatus for laying a pipeline from a barge-mounted reel including compound-bending means, tensioning means and vertical support means. Each means preferably has an endless chain composed of blocks linked together by connecting pins. The pins also support high-load carrying rollers. The rollers ride both on relatively stiff tracks and on relatively flexible tracks which are supported by hydraulically-controlled rods operable to cause the flexible tracks to assume a desired curvature for imparting to the pipe. In the tensioning means, two such moving chains are oppositely positioned to directly engage opposite sides of a generally rectilinear portion of said pipe, thereby exerting a series of longitudinally-spaced, continuously-effective tensioning forces in the pipe. The apparatus further includes hydraulically-operated stanchions for selectively and adjustably supporting said pipeline in a vertical plane to allow the pipe to enter a body of water at a desired vertical inclination.

Description

United States Patent Mott et al.

[54] APPARATUS FOR LAYING PIPELINES [72] Inventors: James D. Mott; Richard B. FeazJe,

both of Houston, Tex.

[73] Assignee: Fluor Ocean Services, Inc., Houston,

Tex.

[22 Filed: Jan. 26, 1970 21 Appl. No.: 5,842

[52] U.S.Cl. ..72/161, 61/72.1, 61/723, 226/172, 72/166, 72/199 [51] Int. Cl. ..B2ld 3/02 [58] Field of Search ..72/160, 161, 163; 61/72.], 61/723; 226/172, 171; 254/l34;-29/429 [56] References Cited UNITED STATES PATENTS 2,792,930 5/1957 Graham ..226/172 3,285,485 11/1966 Slator ..226/172 3,237,438 3/1966 Tesson ..72/161 3,372,461 3/1968 Tesson ..6l/72.3 X 2,391,419 12/1945 Holtz ..72/241 X 2,935,178 5/1960 2,868,356 1/1959 l-laaff ..226/172 X 15 f ,2 11F E F- I l 1 1 Aug. 1, 1972 FOREIGN PATENTS OR APPLICATIONS 516,889

Primary Examiner-Milton S. Mehr Attorney- -Michael P. Breston [57] ABSTRACT An apparatus for laying a pipeline from a bargemounted reel including compound-bending means, tensioning means and vertical support means. Each means preferably has an endless chain composed of blocks linked together by connecting pins. The pins also support high-load carrying rollers. The rollers ride both on relatively stiff tracks and on relatively flexible tracks which are supported by hydraulically-controlled rods operable to cause the flexible tracks to assume a desired curvature for imparting to the pipe. In the tensioning means, two such moving chains are oppositely positioned to directly engage opposite sides of a generally rectilinear portion of said pipe, thereby exerting a series of longitudinally-spaced, continuouslyefiective tensioning forces in the pipe. The apparatus further includes hydraulically-operated stanchions for selectively and adjustably supporting said pipeline in a vertical plane to allow the pipe to enter a body of water at a desired vertical inclination.

llllllill 39 Claims, 18 Drawing Figures 1/1953 Belgium ..226/172 PATENIED 1 3,680,342

James D. Mott Richard B. Feczz/e INVENTORS BY Michael P Bresfon ATTORNEY SHEET 2 UF 9 A TTORNE Y PATENTEDAus 1 I972 PA'TENTEflAus" 1 m2 SHEET 3 OF 9 FIG. 4

INVENTORS I James 0. Mo t2 Richard B Feaz/e BY Michael P Breston ATTORNEY PKTENTEU 1973 3.680 .342

James D M0 It Richard B. Feaz/e INVENTORS BY Michael P. Breston ATTORNEY P'ATENTEDMIH m2 3,680.342

sum 5 OF 9 James D. Mott Richard B.Feazle INVE N TORS BY Michael P Breston ATTORNEY P'A'TENTEmus 1 I972 3.680.342

SHEET 8 OF 9 [x I James D. Mott Richard B.Feaz/e IN VE N TORS BY Michael F. Breston A T TORNE Y PATENTEDAU: 1 1912 SHEET 7 BF 9 FIG. 77

James "0 Matt Richard B.Fec1z/e INVENTORS BY Michael PBreston ATTORNEY PATENTEDws 1 1912 saw 8 UF 9' James D. Mott Richard B. Feczzle INVENTORS BY Michael F. Breston ATTORNEY PNENTEmus 1 m2 SHEET 9 [IF 9 V lfsaz I FIG. 18

James D. Mott "Richard BFeaz/e INVENTORS Michael F. Breston A TTORNE Y 1 APPARATUS FOR LAYING PIPELINES CROSS-REFERENCES TO RELATED APPLICATIONS This invention is related to inventions disclosed and claimed in the following copending patent applications, Ser. Nos: 5,840, now U.S. Pat. No. 3,630,461 and 5,862.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to the field of processing relatively rigid members and is especially adapted for laying underwater pipelines from a reel which supports a coil of an elasto-plastic metal pipe and, more particularly, to apparatus for unwinding, straightening and processing such pipelines from a floating platform into a body of water.

2. Description of the Prior Art A known and presently used apparatus for unwinding, straightening and processing small-to-medium diameter pipelines from a barge-mounted reel is described in U.S. Pat. No. 3,237,438. In general, the

known apparatus involves, on one hand, pre-bending and winding the pipe, and on the other hand, unwinding and reverse-bending the pipe. The pre-bending and winding phase is accomplished by advancing straight sections of pipe toward a work station, joining the sections together as they progress through the work station to form a continuous pipeline, plastically prebending a span of the pipeline leading to the reel, rotating the reel preferably about a vertical axis, and winding the pipeline on the reel into a multi-layer coil. The unwinding and processing phase involves reverse-bending the span of pipe emerging from the reel and guiding under tension the straightened pipe from the barge to the floor of the body of water.

In particular, for a better understanding of the known apparatus, a detailed description will now be given, using the reference characters of the drawings in said patent. The emerging span of pipe 13 from reel 11 has its curvature removed by reverse-bending in a straightener 17 which is provided with two pairs of end rolls 41, 43 and a center pair of working rolls 42. Between the centers of the rolls 41 and 43 is defined a horizontal path line. The amount of straightening or reverse-bending of the emerging pipe span is determined by the horizontal distance from the center of working rolls 42 transverse to the horizontal path line. Straightener 17 is mounted on a platform 18 and is supported for reciprocal vertical movement on vertical posts to allow the horizontal path line to become in ver tical alignment with each pipe convolution as it unwinds from reel 1 1.

In the operation of the above apparatus one finds that the radius of curvature of the emerging pipe span from reel 1 l varies from a minimum radius corresponding to the innermost pipe layer to a maximum radius corresponding to the outermost pipe layer. Since the transverse horizontal distance from the working rolls 42 to the horizontal path line is generally maintained constant, the amount of reverse-bending is also constant, irrespective of the reduction in the diameter of the unwinding coil and, hence, irrespective of the curvature in the curvilinear pipe span emerging from reel 11. Since the transverse horizontal distance is selected on the basis of the average curvature of the emerging pipe span, it is appreciated that the spans of pipe emerging fi'om the outermost convolutions of reel 11 and from the innermost convolutions may not be completely straightened by straightener l7. Incomplete straightening may leave residual bending stresses and strains within the pipeline as it emerges from straightener 17. While the residual curvatures can be reduced in magnitude by the proper application of axial or longitudinal tension in the pipeline, they cannot be completely removed by such applied tension.

To alleviate the residual stress problem, an operator could continuously manually adjust the transverse horizontal distance between the working rolls 42 and the horizontal path line by an amount which is correlated with the instantaneous diameter of the coil as it unwinds. But, at the rate it is desired to lay the pipe, such a continuous manual adjustment would be a most diflicult job, even if a skilled operator could determine ,by observation or from instrumentation the amount of required adjustment. It may be also contemplated to provide for the working rolls 42 automatic adjusting and positioning means, but the cost, complexity and lack of reliability for continuous use of such automatic adjusting means make such a solution rather unattractive.

Another consideration in the practice of the above apparatus stems from a variable angle of entry into the pipe straightener 17. The above-mentioned horizontal path line is selected so as to be tangent to a middle layer in the coil, that is, to approximately bisect the angle sustained by the diameter of the full coil from the entry point to the straightener. Hence, the curved pipe span emerging from the outermost pipe layer on the coil will be at a maximum working angle of one polarity relative to this tangent in a horizontal plane, and when emerging from the innermost layer it will be at a maximum working angle of the opposite polarity. Consequently, if the pipes path line remains stationary in a horizontal plane, this working angle will decrease as the diameter of the unwinding coil becomes reduced. If the horizontal path line were made movable transversely to follow the reduction in the coils diameter, it would be necessary to mount the straightener both for reciprocal horizontalv movement as well as for reciprocal vertical movement. A straightener so mounted would require a wide span in a horizontal plane on the deck of the barge as well as cumbersome support structures which are normally coupled to the barge for guiding the pipe onto the floor of the body of water. 1

Yet another consideration in the practice of prior art straighteners is the fact that in order to assure a relatively long line of contact between the rolls and the pipe, relatively large wheels or rolls are required. Since the deck space on a lay barge is limited, the requirement for large wheels cannot always be met. Another problem, associated with roll-straighteners when used In the elastic or straight-line range the stress is proportional to the resulting strain. When the stress is released the strain returns to its original balanced value or zero curvature. The limit of the elastic range is reached when the strain no longer returns to zero curvature. This limit corresponds to the greatest stress the pipes material can withstand without producing a residual deflection or curvature.

In the plastic or flat-line range, the applied bending stress exceeds the pipes elastic limit, and the pro-- portional stress-strain relationship no longer holds. For a small increase in'applied bending stress, there now is obtained asubstantially greater increase in resulting curvature. The boundary between the elastic range and the plastic range is commonly referred to as the yield point.

As one continues to bend the pipe past its yield point, the bending stress or moment increases relatively slowly toward an ultimate value. The pipes curvature on the other hand increases to a critical curvature at which buckling impends. After the ultimate value, the reduced resistance to bending, due to flattening, will no longer support the applied moment and the pipe will buckle. Under these conditions, the use of the pipe either as a structural member or as a conduit may be seriously affected.

Although most of the mathematical theories of plasticity deal with ideal plastic materials, most standard line-pipe metals deviate somewhat from the ideal. It is therefore best to experimentally establish design parameters and to measure the critical moment required to bend the particular pipe to its critical curvature. The critical moment is a function of the pipes diametenwall thickness and grade.

A material whicl' is plastic becomes elastic whenv the applied stressis reduced in magnitude below the yield stress. Experimental curves show that upon progressively reducing the applied moment from any point on the flat plastic curve, there follows a descending elastic straight line substantially parallel to the original elastic line. The residual curvature is that curvature which remains after the applied moment is reduced to zero. The progressive re-application of the moment to the pipe will follow an ascending elastic straight line from the residual curvature which is substantially parallel to the original elastic line, and subsequently this ascending elastic line will join the plastic line after the yield point of the-pipes material is reached.

Since throughout this disclosure curvature is used extensively, a definition of the'term will be given. In mathematical terms the radius of curvature of a segment of a curve is the reciprocal of the curvature K, that is UK, in which K is equal to the change in the direction of the curve per unit length of arc. The radius of curvature of a straight line is infinite and that of a circle is the radius used to generate the circular curve. The radius of curvature of a complex curve is a variable which depends upon the curvatures of the infinitesimally-long circular arcs located at adjacent points on the curve. An inflection point is a point where the pipes curvature changes signs.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-mentioned prior art shortcomings and to provide newand improved apparatus for processing long relatively rigid members such as pipelines on and from floating platforms. The apparatus requires a minimum of adjustments, hand labor, complex instrumentation, deck space and pipe support structures.

These and other readily apparent objects are accomplished by initially bending the pipe span emerging from the reel to a desired constant radius of curvature sufiicient to prevent buckling. The pipe is bent over a finite arcuate length and subsequently straightened along a selected trajectory. The straightened pipe is then diverted downwardly under suitable tension corresponding to a particular angle of inclination with respect to the water surface.

The bending, counter-bending and tensioning of the pipe is accomplished by an endless chain having blocks linked together by connecting pins. The pins also support high-load carrying rollers which ride on stiff or flexible tracks depending on the stresses desired to apply to the pipe. The flexible tracks are supported by hydraulically-operated thrust rods which cause the flexibletracks to assume a desired curvature for imparting to the pipe. When two such moving chains are oppositely positioned, the pipe is placed under tension.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of the overall apparatus employed in laying a pipeline;

FIG. 2 is a schematic, transverse, elevational view of the apparatus shown in FIG. 1; v

FIG. 3 is a top view with upper plate removed of the bending tool used in the apparatus of FIG. 1;

FIGS. 4 and 5 are views on lines 4-4, 5-5 in FIG. 3;

FIG. 6 is a top view of the tensioner used in the apparatus of FIG. 1;

FIG. 7 is a side view in elevation of the tensioner shown in FIG. 6;

FIGS. 8 and 9 are views on lines 88, 9-9 in FIGS. 7 and 8, respectively.

FIG. 10 is a view on line 10-10 in FIG. 9;

FIG. 11 is a top view of the aligner in the apparatus shown in FIG. 1 together with the left mechanism for vertically reciprocating portions of the apparatus shown in FIG. 1;

FIG. 12 is an enlarged top view of a portion of the chain in the aligner of FIG. 11;

FIGS. 13 and 14 are views on lines 13-13, 14-14 in FIG. 12;

FIG. 15 is a view on line 15-15 in FIG. 1;

FIG. 16 is a schematic representation of the lifting mechanism employed in connection with the stanchions in the apparatus of FIG. 1;

FIG. 17 is a view on line 17-17 in FIG. 16; and

FIG. 18 is a view on line 18-18 in FIG. 1.

OVERALL INSTALLATION AND MODE OF OPERATION Referring now to FIGS. 1 and 2, wherein the showings are for the purpose of illustrating the preferred apparatus of the invention only, and not for the purpose of limiting same, a suitable barge l0 supports a reel 12 for rotation about a vertical axis 1]. Reel 12 winds and unwinds a continuous length of pipeline 16. While reel 12 is shown mounted for rotation about a vertical axis, it is appreciated that it could be equally mounted for rotation about a horizontal axis, but with appropriate changes in the positions of the pipe processing elements.

Pipeline 16 is preferably made of an elasto-plastic steel material of a suitable grade and may have a relatively large diameter, say between 4 to 12 inches, and even higher. For example, a standard X-Grade pipe could be a 12 inch line pipe, Schedule through 80, API 5L, Grade B, seamless, or a 6 inch line pipe, Schedule 20 through 180. For underwater applications, pipeline 16 is ordinarily covered with a suitable protective coating, although such coating is not essential.

It has been found, contrary to what might be expected, that neither the coating nor the pipeline becomes damaged by the consecutive bending and reverse-bending operations contemplated by the method of this invention.

Reel 12 can be rotated by any known suitable means.

During the winding and unwinding operation, a span of pipeline 16 passes through an apparatus 14 which includes a combined bending and level wind apparatus 18 and a tensioner 42. System 14 is mounted on a frame 24 which is reciprocable vertically on a plurality of posts 26.

To facilitate the winding of pipeline 16, the core 28 of reel 12 is made frusto-conical. The construction of reel 12 and the manner of its operation is fully described in copending application, Ser. No. 5,840 assigned to the same assignee. Pipeline 16 is wound into a multi-layer coil 30. Each pipe layer includes several pipe convolutions 32. The radius of curvature of the pipe s span 34 when emerging from the innermost layer 36 has the smallest radius of curvature and when emerging from the outermost layer 38 has the largest radius of curvature. Also, within each layer, the radius of curvature decreases as the pipe span 34 emerges from the bottom convolution to the top convolution.

As can be seen from FIG. 1, when the pipe span 34 emerges from the outermost layer 38 it is at a relatively small angle A from a transverse horizontal line B, and when it issues from the innermost layer 36 it is at a relatively large angle C from line B. Thus, the emerging pipe span 34 has a variable angle of entry into the bending apparatus 18. The instantaneous magnitude of the angle depends on the diameter of the particular convolution 32 from which pipe span 34 emerges.

The exact configuration of the emerging pipe span 34 between reel 12 and apparatus 18 depends on the physical characteristics of pipeline i6 and the stresses within the pipe. An inflection point 40 occurs within the emerging pipe span 34 between reel 12 and bending apparatus 18. Before reaching point 40 from reel 12, the span 34 has a positive curvature, and following point 40 a negative curvature. The terms positive and negative have been arbitrarily selected only for ease of description. As herein employed, a positive curvature is a curvature the radius of which has a center below the path of span 34 as shown in FIG. ll and, conversely, a negative curvature has its center above the path of span 34.

The inflection point 40 is therefore a point where the pipes curvature changes signs. The bending apparatus 18 is adapted to receive the emerging span 34 at a variable angle of entry and at a variable curvature and to automatically bend the pipe so as to render it substantially free of residual stresses and strains for subsequent use during the pipe-laying operation.

Bender 18 is designed to compound-bend the emerging pipe span 34 and includes three

tools

50, 52 and 54 positioned at spaced locations relative to each other and to reel 12. Pipe span 34 is extended through these tools, as shown. The peripheral face of each tool has a movable chain bearing resilient blocks that are arcuately shaped to receive and closely engage against one side of the pipe span. The radius of curvature of each chain in each of

tools

52 and 54 is adjustable from an infinite radius of curvature (flat) to a minimum radius sufficient to prevent pipe buckling, thereby allowing the variation of the amount of curvature imparted to or removed from the pipe span 34. The bending tool 50, on the other hand, applies a transverse force in a horizontal plane operable to impart to pipe span 34 a negative curvature corresponding to the radius of curvature of its peripheral face in engagement with the pipe span 34.

During the winding operation, pipeline 16 is plastically bent by yielding the metal of the pipe to set a positive curvature in each convolution 32. During the unwinding operation, bending tool 50 stresses the emerging span 34 as it passes through bender 18 to thereby yield the pipes material and to plastically bend span 34 to a negative curvature having a constant radius sufficient to prevent buckling the pipeline.

Accordingly, the emerging pipe span 34 exiting from bending tool 50 at a tangent point 56 will have a constant negative plastic curvature and a uniform stress distribution, irrespective of the diameter of the unwinding coil 30. Hence, the pipeline when entering bender apparatus 18 has both a non-uniform curvature and a non-uniform stress distribution, and when exiting from tool 50 has both a uniform curvature and a uniform stress distribution, irrespective of the diameter of the unwinding coil. Therefore, bending tool 50 may be considered as a stress uniformizer and as a curvature uniformizer.

Pipe span 34 is plastically bent on bending tool 50 over a finite selected arcuate length and exits from tool 50 tangent to point 56. It is the function of the remaining tools to transform the curvilinear profile of span 34 into a rectilinear profile. For this purpose the center bending tool 52 applies a moment to the pipe span 34 which imparts to it a positive curvature. This is accomplished by plastically reverse-bending pipe span 34 to a particular positive curvature. Thereafter, as the pipe moves past tool 52 and toward tool '54, the induced bending moment in span 34 is unloaded along a linearly elastic path, resulting in a pipe profile which is substantially rectilinear and which is characteristic of a state of substantially zero net moment in the pipe span 34. The rectilinear pipe span 34 will discharge on and be colinear with the desired trajectory which has a selected angle with respect to the surface of the body of water.

The tension-control mechanism 42 maintains the emerging pipe span 34 under tension while it is being compound-bent by bender apparatus 18. The tensioner 42 in the preferred embodiment includes two

opposed track chains

46,48, at least one of which is powered for rotation. Each chain also bears resilient blocks having a groove therein so shaped as to receive and snugly engage one side portion of the pipe. The chains move in the directions indicated by the arrows 49 during the unwinding operation and they also assist in pulling the pipe ofi reel 12.

Tool 54 defines with the center line of the tensioner 42 a horizontal path line 60, and the amount of working or bending by tool 52'is determined by the adjustable, transverse, horizontal distance from the periphery of tool 52 to this horizontal path line, as will be appreciated by those skilled in the art. It will be apparent that the pipe span 34 between

tools

50 and 52 sustains a sign reversal in its curvature and has a second inflection point 62 near bending tool 52. The curvature of the peripheral face of the center or working tool 52 is adjustable to accommodate pipes of varying diameters through the bender 18. I

One or more guide structures or stanchions, generally designed as 70, carry. supports 71 for guiding the rectilinear pipeline l6 exiting from the tensioner 42 along a vertically inclined pipe processing path 72 to facilitate the pipes entry into the body of water.

Suitable means 72 are employed to reciprocate vertically the supports 71 and the platform 24, on which are mounted

tools

50, 52, and 54, as well as tensioner 42. The reciprocation is synchronized with the rotation of reel 12. I

The apparatus 14 of the present invention allows the unwinding of a pipeline from a reel at a relatively high rate of speed without the need to continuously manually or otherwise adjust the bending tools of conventional benders. The apparatus accepts pipe of varying diameters and is especially beneficially employed with relatively-large diameter pipes, up to 12 inches and higher. The emerging curvilinear pipe from the reel is rendered substantially rectilinear without unbalanced residual moments remaining therein. Also, the system is substantially independent of the prior loading history of pipeline 16.

STRAIGHTENER APPARATUS AND MODE OF OPERATION Referring to FIGS. 1 and 3-5, there is shown the structure of bending tool 52 which is identical to bending tool 54. Bending tool 52 has a top plate 202 and a bottom plate 204, each preferably made of steel. Welded to the bottom plate 204 are two upright supports 206'for supporting a track assembly, generally designated as 208. Assembly 208 is oval shaped and includes two curved side tracks 210, a long rear track 212 and a long front track assembly 214. Each side track 210 is supported by a shoulder 216 slidably positioned in a recess 218 near the top of support 206. The rear track 212 is stiff and has a leg 220 resting on the bottom plate 204. The front track assembly 214 includes two relatively flexible chain tracks 222 and 224 separated from each other by a flexible plate 226 which also rests on a leg 228 supported by plate 204.

Each of

flexible tracks

222 and 224 is supported by an array 223 of support rods 230. Each rod 230 engages its flexible track in a slightly recessed area 232. To move rods 230 there is provided a hydraulic system generally designated as 234 having a main body 236 extending entirely between

plates

202 and 204. Body 236 defines a plurality of cylinders 238. Fitted inside each cylinder 238 is a cylindrical insert 240. Two O-rings 242 and 242' seal off a circumferential groove 244 which is in fluid communication with a transverse bore 246. Bore 246 communicates through an axial bore 248 with a cylinder chamber 250. The fluid pressure in cylinder 250 actuates a piston 252 which is fixedly secured to and slidably mounted with a bottom piston 254 of rod 230. Consequently, rod 230 reciprocates together with piston 252 in cylinder 250. Each cylinder 250 is in fluid communication through a branch line 251 with a main fluid reservoir 256 having a threaded cap 258.

The chain assembly is generally designated as 260 and is composed of a plurality of pairs of blocks 262 and 262', each pair is interconnected by linking pin 264 in a bushing 265. Each block 262 has four ears 266 overlapping four ears 266' of an adjacent block 262'. Also rotatably supported and suitably separated on pin 264 are two

main rollers

268 and 270. Roller 268 rolls on flexible track 222 and roller 270 rolls on flexible track 224. Each chain block 262 or 262" is provided with an insert space 272 for removably accepting an insert 274 which is secured to block 262 by a set screw 276. The insert can be easily changed when the top plate 202 is removed. lnsert 272 has a rubber-bonded liner 278 on its external cylindrical surface 280. Liner 278 is preferably made of polyurethane to better protect the pipes coating. Liner 278 is in engagement with the pipe 16 being straightened. Each block 262 is also provided with two small vertical-

positioning rollers

282, 284. Roller 282 is mounted on shaft 283 and rides on the bottom plate 204 and roller 284 is mounted on shaft 285 and rides on the upper plate. 202.

Plates

202 and 204 are provided with four horizontal end rollers 286 which ride on vertical rails 288 to allow the entire assembly 52 to move in a generally transverse horizontal direction perpendicular to path in FIG. 1. This is accomplished by two hydraulic cylinders 290, 290' actuated from a hydraulic source (not shown).

Plates

202 and 204 are also provided with one or more pairs of vertical rollers 292 which ride on horizontal rails 294. In this fashion the assembly 52 can be freely moved by the forces produced by the

cylinders

290 and 290.

The fundamental objects of the

bending tools

52 and 54 are (l) to apply the required high transverse forces to the emerging pipe span 34 in order to straighten it, (2) to position and maintain the pipe in a proper deflected configuration required for straightening, and (3) to protect both the pipe and its coating from damage due to excessive concentrated pressures and/or from difierential tangential velocities between the pipe and the chain blocks 262. These objects are achieved primarily by (1) providing for each block 262 the flexible liner pad 278 which contacts the pipe over a relatively long span and by 2) supporting the

flexible tracks

222 and 224 on an array of movable rods 230 connected for operation to the common fluid reservoir 256. In this fashion, each rod 230 transmits substantially the same pressure to each contact face 278 and hence to the engaged portion of the pipe. The relatively long roller tracks 222 and 224 assume substantially the same curvature as the pipe being engaged by the chain 260. Since the curvature of the

flexible tracks

222 and 224 is relatively small, it will be appreciated that there may only be an infinitesimal variation in the tangential velocities of the moving pipe and the moving blocks 262 of chain 260 which contact the pipe.

This is in contra-distinction to the prior art straighteners employing wheels where the concave face on the periphery of the wheel provides portions with siginificantly different radii from the center of the wheel. Since all portions of the wheel have to rotate at the same angular velocity at any one instant, the tangential velocity of any point on the periphery of the wheel depends on its distance to the center of the wheel. Accordingly, since the pipe moves in essentially a linear-type motion, there exists in known straighteners relative tangential velocities between those portions of the wheel which contact the pipe and which are at different'radii from the center of the wheel. As a consequence, there occurs scrubbing of the pipe as well as of the wheel surface in contact with the pipe.

in the apparatus of this invention, any scrubbing action between the chain block faces and the pipe is substantially eliminated. The bender 52 can be considered as a portion of a relatively large radius wheel, i.e., the benefits of a large radius wheel are obtained without having to occupy very valuable deck space. The portion of the wheel provides a long line of contact with the pipe which could only be obtained with a verylarge radiuswheel.

Scrubbing between the chain blocks and the pipe is further reduced due to the configuration of the curved side tracks 210. The radius of the side track 210 is relatively short compared to the radius of the main track 214. Accordingly, when the support blocks 262 move from the region of contact with the pipe 16 to the transition region between the main track 214 and the side tracks 210, they accelerate much more rapidly away from the pipe in a direction perpendicular to the longitudinal axis of the pipe, and therefore they rapidly disengage from the pipe. inversely, when the blocks 262 move toward the main track they rapidly engage the pipe. Another manner of explaining this phenomenon is to measure the acceleration of a front roller (in the direction of motion) and that of a rear roller of a particular chain block 262 moving toward a side track 210. Since the distance between their pivot pins 264 is relatively larger than the contact surface 278, this contact surface 278 will fall in line and fall-out of line very rapidly, thereby reducing any tendency of scrubbing the pipes surface.

All the pistons 252 have the same area and, consequently, since they are connected to a constant volume hydraulic fluid reservoir 256 they will be loaded uniformly and transfer this uniform load to the pipes surface in engagement with chain 260. Any displacement by any one of the rods 230 in the array 223 must be compensated by an equal displacement of the other pistons in the array to ensure that a constant fluid volume is maintained. This uniform pipe loading provided by each array of rods 230 is highly desirable in order to prevent large local load concentrations especially at the leading and trailing edges of the bending tool 52.

It will also be appreciated that the curvature of the flexible track 214 may be positive or negative (concave or convex) depending on the curvature desired to impart to the emerging pipe span 34. Thus while tool 52 presents a convex curvature, tool 54 presents a concave curvature in the arrangement shown in FIG. 1.

TENSlONlNG MECHANISM AND MODE OF OPERATION Referring to FIGS. 1 and 6-10, the tensioning mechanism 42 includes two

identical sub-assemblies

302 and 304, the separation between which is controlled by three top cylinders 306 and three bottom cylinders 308, cylinders 306 are mounted between

ears

310 and 312 and cylinders 308 between

ears

314 and 316. Each cylinder 306 is provided with two hydraulic lines 318, 320 for extending or retracting its rod 322, in a conventional manner. Each cylinder 308 is equally driven by hydraulic lines. Since the two

sub-assemblies

302 and 304 are in all respects identical, only sub-assembly 302 will be described in detail.

Sub-assembly 302 includes a top plate 330 and a bottom plate 332. A semi-cylindrical side wall 334 has one end welded to the bottom plate 332 and the other end is secured to the upper plate 330 by a bolt 336. A roller-track 338 between

plates

330 and 332 serves both to provide a riding track for the main rollers 340 of a chain assembly 46 and to provide another side wall between

plates

302 and 304. The chain 46 also has small vertical-positioning rollers 344 and is similar in construction to the chain assembly 260 previously described in connection with FIG. 3, except that three main rollers 340 are now mounted on each interconnecting linking pin instead of the two

main rollers

268 and 270 previously described.

To drive chain 46 there is provided a drive shaft 350 which is supported for rotation by

end bearings

352 and 354. A motor shaft 356 meshes with and drives the drive shaft 350. Mounted on shaft 350 is a three-strand drive sprocket 360. A driven sprocket 361 is mounted on a driven shaft 362 which also provides support for and rotates two-

large sprockets

364 and 366. Driven shaft 362 is suitably mounted in

end bearings

370 and 372. A three-strand roller chain 368 provides power transmission between

shafts

350 and 362. The top row of rollers 340 bears on the sprocket teeth of sprocket 364 and the bottom row of rollers 340 bears on the teeth of sprocket 366. In this fashion, the rotation of shaft 362 is transmitted by

sprockets

364 and 366 to the chain assembly 46.

Since large torques are involved, it is desired to provide another drive shaft assembly, identical to the drive shaft assembly of shaft 362, for driving a shaft 362' sup porting sprockets 366', etc., which also drives the chain assembly 46. Each motor shaft ,356 is driven by a motor 380 preferably of the hydraulic type. Four such hydraulic motors 380 are provided, one for each motor shaft 356. Two such motors are positioned above plate 330.

In operation, shafts 362 and 362' are driven in the same direction, either clockwise or counterclockwise, by their respective drive shafts and sprockets. For example, the rotation of the motor shaft 356 causes the rotation of the drive shaft 350,

sprockets

360 and 361, chain 368, shaft 362,

sprockets

364 and 366, and hence chainassembly 46. Chain assembly 46 will rotate in the direction 49 (FIG. 1) or in an opposite direction.

Rollers 340 bear on the sprocket teeth and also ride on the solid stiff track 338. To avoid slack in the chain assembly 46, a shorter opposite roller track 338 is also The simultaneous actuation of the top and

bottom cylinders

306 and 308 will cause their rods 322 to extend or retract thereby reducing or increasing the applied pressure on pipe 16 passing between the

chains

46 and 48 of the

assemblies

302 and 304, as shown in FIGS. 1 and 7.

THE ALIGNER MECHANISM AND MODE OF OPERATION Referring now to FIGS.- 1 and 11-15, the bending tool 50, since it aligns the pipe for straightening by tool 52, will hereinafter be called the aligner. Aligner 50 includes a bottom plate 400, a top plate 402 and an arcuate roller track 404. A roller chain assembly 406 carries a plurality of blocks 408, each block having 'two main rollers 410 and two vertical positioning rollers 412. The construction of chain 406 is in all respects similar to the construction of chain 260 previously described, as is evident from FIGS. 13 and 14. Rollers 410 ride on the rigidtrack 404 when the chain 406 is caused to move by the friction created by the movement of the emerging pipe span 34.

In FIG. 11 is shown the manner for supporting aligner 50 as well as platform 24. Posts 26 are provided with suitable braces 414 for adding the required structural rigidity. A main hydraulic cylinder 416 is fixedly secured at one end to a support 418. The operating rod 420 of cylinder 416 is connected to two

parallel cables

422 and 424 through a joint coupling 426. Line 422 branches out into lines 4220, 422b, 4220 and 422d. Similarly, line 424 is divided into lines 424a, 424b, and 424c. Cylinder 416 and hence rod 420 is actuated by a hydraulic system (not shown).

The manner of attaching a cable such as 422d to the platform 24 is shown in FIG. 15. For example, the cable passes over a direction-change pulley 430 into post 26, over another direction changing pulley 432, and its end is attached to platform 24 which is secured to a sleeve 434 slidably mounted on post 26. Consequently, a displacement of rod 420 is translated into a corresponding proportional displacement of platform 24 and of aligner 50.

STANCHION MECHANISM AND OPERATION Referring now to FIGS. 1, 16-18, connected to platform 24, in any suitable manner, is a positioning rod 500 which moves linearly in a vertical plane in correspondence with the displacement of platform 24. A suitable transmission 502 translates the linear displacement of rod 500 into an angular displacement of a shaft 504. Shaft 504 drives a belt 506 which in turn drives a pulley 507 on a main shaft 508. Mounted on shaft 508 are three sets of

cams

510, 518 and 520, one set for each pair of stanchions 70. Set 510 includes

cams

512, 514 and 516. Since the operation of the three cam sets is identical, only the .operation of cam set 510 is described.

Cam 512 (see FIG. 17) has its shape predetermined in accordance with the diameter of pipe 16 to be processed, the same holds for

cams

514 and 516. Shaft 508 can be shifted to the right or to the left depending on the size of pipe being processed, thereby engaging a corresponding cam from each set. Rotation of cam 512 is transmitted via a cam follower 522 and a sprocket 523 to the input shaft 524 of a conventional hydraulic feedback valve 526 which drives two

cylinders

528 and 530. The fluid for valve 526 and

cylinders

528 and 530 is supplied from a main fluid line 532. A branch line 534 is connected to the inlet of valve 526. The output line 536 from valve 526

providestwo branch lines

538 and 540, respectively coupled to

cylinders

528 and 530. I

Rotation of shaft 524 corresponding to a displacement of platform 24 causes fluid flow as shown by the LII dotted line 542 between

branches

536 and 534,'

thereby moving

pistons

544 and 546 in

cylinders

528 and 530, respectively.

Pistons

544 and 546 are provided with

rods

548 and 550, respectively.

A feedback chain 552 (FIG. 18) causes a feedback shaft 553 of valve 526 to rotate in a manner as to discontinue the fluid flow between

branches

536 and 534.

Rods

548 and 550 will now remain in this new position until another input is supplied by rod 500.

In FIG. 18 is shown a pair of stanchions 70, Stanchion 70 is shown in cross-section and stanchion 70' in elevation. The stanchions are fixedly mounted on the deck or ramp 562 (FIG. 1) Cylinder 528 is mounted in stanchion 70 and cylinder 530 is mounted in stanchion 70, as shown. Secured to the end of rod 548 is a sheave 564. A cable 566 has one of its ends fixedly attached to a support 568 and its other end to the pipe support or carriage 71. Carriage 71 is mounted on

tubular sleeves

572 and 574, slidably mounted on stanchions 70 and 70', respectively. It will be appreciated that the extension of

rods

548 and 550 will cause carriage 71 to move downwardly, and, inversely, the retraction of

rods

548 and 550 will'cause carriage 71 to move upwardly. Carriage 71 is provided with two rollers 576 and 576' each mounted for rotation about a horizontal axis and with two

rollers

578 and 578 each mounted for rotation about a vertical axis. The straightened pipe 16 passes between the rollers as shown. Mounted .on the feedback shaft 553 is a sprocket 580 and mounted near the top of stanchion 70' is another sprocket 582. The endless roller chain 552 rides on

sprockets

580 and 582. A clamp 586 fixedly secured to sleeve 574 and to chain 552 causes the chain to move clockwise or counter-clockwise depending on the direction of linear movement of sleeve 574. Motion of chain 552 is transmitted to the feedback shaft 553 thereby reducing the fluid flow as previously explained.

While this invention has been described with reference to specific embodiments it will be apparent that many modifications may be made in the apparatus particularly disclosed herein. The invention therefore is not to be limited to the preferred embodiments shown in the drawings but rather only by the scope of the appended claims.

What is claimed is: v

1. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including:

a first pipe-engaging tool, said tool comprising:

a first continuous chain; a first series of spaced blocks supported by said chain,

said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline;

a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other;

a series of rollers on said pins;

first roller-support track means, said rollers being adapted to roll on said track means;

means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses;

said first track means including relatively-flexible track portions for supporting the rollers which are associated with said pipe-engaging blocks;

hydraulically-operated means comprising longitu- (finally-displaced support rods for supporting said flexible track portions,

said support rods providing substantially-uniform support to said portion of said pipeline engaged by said first tool, and said support rods being automatically and reciprocatingly movable to uniformly distribute the load between said rods; and

said hydraulically-operated means including a plurality of hydraulic cylinders,

each cylinder having a reciprocating piston coupled to one of said rods, and

said pistons having substantially-equal, effective,

cross-sectional areas.

2. The apparatus of claim 1 in which said hydraulically-operated means include a common fluid reservoir in fluid communication with each of said pistons.

3. The apparatus of claim 2 in which said flexible track portions are operable to assume a desired curvature for imparting said curvature to said portion of said pipeline engaged by said first tool.

4. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including:

a first pipe-engaging tool, said tool comprising:

a first continuous chain;

a first series of spaced blocks supported by said chain,

each pin rotatably supports at least a pair of said rollers displaced from each other, and each roller of each of said pair of rollers forms part of a series of rollers riding on a distinct track means;

means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses, and

said track means having a substantially oval configuration.

- 5. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including:

a first pipe-engaging tool, said tool comprising:

a first continuous chain;

a first series of spaced blocks supported by longitudinally-spaced chain,

a series of rollers on said pins, each pin rotatably supports at least a pair of said rollers displaced from each other;

a bottom plate;

a top plate;

means rotatably supporting said chain for rotation between said plates; and

said rotatably supporting means being positioning rollers.

6. The apparatus of claim 5 and further including: at least two rails, and end rollers coupled to said plates for riding on said rails, thereby allowing said tool to move in a direction which is generally transverse to the path of travel of said portion of said pipeline.

7. The apparatus of claim 6 and further including hydraulically-operated means coupled to said tool and effective to reciprocatingly move said tool on said rails.

8. The apparatus of claim 7 in which said tool is effective to apply a series of longitudinally-displaced, relatively-high transverse forces against said portion of said pipeline engaged by said tool thereby avoiding excessive concentrated forces.

9. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including:

a first pipe-engaging tool, said tool comprising:

a first continuous chain;

a first series of spaced blocks supported by said chain,

a series of rollers on said pins;

' first roller-support track means, said rollers being adapted to roll on said track means;

means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses; and

said roller-support tracks means including:

two short-radius, cur v e dfside tracksseparated by two relativelylflat, main tracks, and each of said blocks having a length sufficiently shorter than the distance between two consecutive pins in said chain, thereby allowing each support block to rapidly accelerate in the transition region between a main track and an adjacent side track.

10. The apparatus of claim 9 in which said main tracks are relatively inflexible.

1 l. The apparatus of claim 9 in which said tracks are relatively flexible.

12. The apparatus of claim 9 and further including hydraulically-operated, track-separation means for controlling the slackness in said chain.

13. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including:

a first pipe-engaging tool, said tool comprising:

a first continuous chain;

a first series of spaced blocks supported by said chain,

a series of rollers on said pins;

a second pipe-engaging too], said second tool com prising:

a second continuous chain;

a second series of spaced blocks supported by said second chain, said second blocks having curved surfaces operable to engage longitudinallyspaced segments of a portion of said pipeline;

a second series of pins interlinking said blocks to allow said second blocks to pivotally move relative to each other;

a second series of rollers on said second pins;

second roller-support track means, said second rollers being adapted to roll on said second track means;

said second tool being operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said first and second blocks against their curved surfaces, thereby allowing said first and second pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses;

a third pipe-engaging tool, said third tool comprising:

a third continuous chain;

a third series of spaced blocks supported by said third chain, said third blocks having curved surfaces operable. to engage longitudinally-spaced segments of a portion of said pipeline;

main

a third series of pins interlinking said third blocks to allow said third blocls to pivotally move relative to each other;

third roller-support track means, said third rollers being adapted to roll on said third track means; and

said third tool being operatively coupled with said first tool and second tool for maintaining and selectively moving said portion of said pipeline on said first, second and third blocks against their curved surfaces, thereby allowing said first, second and third pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses.

14. The apparatus of claim 13 and further including: power means operable to efi'ectively move said tools relative to each other.

15. The apparatus of claim 14 wherein: said first and third tools are positioned on one side of the longitudinal axis of said pipeline, and said second tool is positioned between said first and third tools on the opposite side of said longitudinal axis. v

l6. The apparatus of claim 15 wherein: said first roller-support track means has a constant curvature thereby imparting to said portion of said pipeline said constant curvature.

17. The apparatus of claim 16 in which said portion of said pipeline sustains a change in curvature as it moves from said first tool toward said second tool.

18. The apparatus of claim 17 in which: said first, second and third pipe-engaging tools are effective to substantially straighten said portion of said pipeline.

19. The apparatus of claim 18 and further-including torque producing means for rotating said second and third chains.

20. The apparatus of claim 19 in which: each of first,

' second and third blocks includes a removably-mounted flexible insert defining said curved surface for engagement with said portion of said pipeline.

21. The apparatus of claim 18 in which: said second and third roller-support track means include track portions which are relatively flexible, said flexible track portions supporting the rollers which are associated with said pipe-engaging blocks, and further including: hydraulically-operated means comprising longitudinally-displaced support rods for supporting said flexible track portions.

22. The apparatus of claim 21 and further including tensioning means to effectively exert tensioning forces in said portion of said pipeline, while said portion of said pipeline moves through said first, second and third tools.

23. The apparatus of claim 21 wherein said second and third support rods provide substantially uniform support to said portion of said pipeline engaged by the respective tools.

24. The apparatus of claim 23 in which said support rods are automatically and reciprocatingly movable to uniformly distribute the load between said rods.

25. The apparatus of claim 24 in which said hydraulically-operated means include hydraulic cylinders,

each cylinder having a reciprocating piston coupled to one of said rods, and

said pistons having substantially equal effective cross-sectional areas.

26. The apparatus of claim in which said hydraulically-operated means include a common fluid reservoir in fluid communication with each of said pistons.

27. The apparatus of claim 26 in which said flexible track portions in said second and third tools are each operable to assume a distinct desired curvature for imparting said curvature to said portion of said pipeline engaged by said second and third tools.

28. The apparatus of claim 27 wherein each pin' rotatably supports at least a pair of said rollers displaced from each other.

29. The apparatus of claim 28 wherein each of said second and third track means has a substantially oval configuration.

30. The apparatus of claim 22 wherein:

said first, second and third tools, and said tensioning means are mounted on a platform, and further including power means to selectively and reciprocatingly move said platform in a vertical direction.

31. The apparatus of claim 29 wherein the amount of movement of said second tool relative to said first and third tools determines the amount of curvature imparted to or removed from said pipe during the pipe passage through said tools.

32. The apparatus of claim 31 wherein said pipeline is advanced generally along a longitudinal direction and in which:

successive portions of the advancing pipe are sub jected first to initial transverse bending forces to stress such portions above the pipes elastic limit in one direction, and

thereafter to opposite transverse bending forces to stress such portions beyond the elastic limit in an opposite direction, thereby substantially straightening said portion of said pipeline.

33. An apparatus for laying a pipeline on a marine bottom, said apparatus'comprising:

a floating platform,

a reel rotatably-mounted on said platform for supporting said pipeline,

winding and unwindingmeans including:

at least three continuous chains, each chain having a series of spaced blocks, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of the winding and unwinding pipeline;

a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other, power means for controllably moving at least one of said chains;

two of said chains being adapted to directly engage one side of a portion of said pipeline, and

one of said chains being disposed on the opposite side of said pipeline so as to compressively engage said portion of said pipeline and to exert aseries of longitudinally spaced continuously effective bending and counter-bending forces on said portion of said pipeline as it is being wound on and unwound from said reel.

34. An apparatus for straightening a long line of elasto-plastic metal pipe wound onto a coil mounted on a reel including:

first means for winding and unwinding the pipeline on and from the reel,

second means for plastically reverse-bending the pipe to a constant curvilinear configuration as it is being wound and unwound,

third means for subsequently plastically reversebending the pipe to a desired configuration after said pipe acquires said curvilinear configuration, and

said second means comprising:

a first continuous chain, a first series of spaced blocks supported by said chain,

- said blocks having curved surfaces operable to engaged longitudinally-spaced segments of a portion of said pipeline,

' a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other, i

a series of rollers on said pins, roller-support track means, said rollers being adapted to roll on said track means, and

said third means being operatively coupled with said second means for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinallyspaced operating forces.

35. The apparatus of claim 34 wherein said desired configuration is substantially rectilinear.

36. The apparatus of claim 35 and further including:

means for maintaining said pipe under tension during said winding and unwinding operations.

37. The apparatus of claim 36 and further including:

means for movably supporting said rectilinear portion of said pipeline at spaced positions in a vertical plane, and

said positions being adjustable to allow said pipeline to assume a progressively decreasing elevation and to enter into a body of water along a downwardly directed path.

38. An apparatus for handling a relatively-inflexible metal pipeline, said apparatus including:

a reel rotatable about its axis;

means for rotating said reel in opposite directions for respectively winding pipe thereon and unwinding pipe therefrom; I

combined bending and level wind means mounted adjacent said reel, said means comprising:

three movable chain assemblies,

each assembly being mounted for rotation about an axis extending substantially parallel to the axis of said reel,

each pair of chains being at opposite sides of the line of travel of said pipeline,

each of said chains comprising:

a series of spaced blocks supported by said chain,

said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion means operatively coupled with said chains for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced operating forces while said pipeline is being wound and unwound on and from said reel.

39. The apratus of claim 14 and further including: power means operable to effectively move said first

Claims

1. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including: a first pipe-engaging tool, said tool comprising: a first continuous chain; a first series of spaced blocks supported by said chain, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline; a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other; a series of rollers on said pins; first roller-support track means, said rollers being adapted to roll on said track means; means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses; said first track means including relatively-flexible track portions for supporting the rollers which are associated with said pipe-engaging blocks; hydraulically-operated means comprising longitudinallydisplaced support rods for supporting said flexible track portions, said support rods providing substantially-uniform support to said portion of said pipeline engaged by said first tool, and said support rods being automatically and reciprocatingly movable to uniformly distribute the load between said rods; and said hydraulically-operated means including a plurality of hydraulic cylinders, each cylinder having a reciprocating piston coupled to one of said rods, and said pistons having substantially-equal, effective, crosssectional areas.

4. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including: a first pipe-engaging tool, said tool comprising: a first continuous chain; a first series of spaced blocks supported by said chain, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline; a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other; each pin rotatably supports at least a pair of said rollers displaced from each other, and each roller of each of said pair of rollers forms part of a series of rollers riding on a distinct track means; means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses, and said track means having a substantially oval configuration.

5. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including: a first pipe-engaging tool, said tool comprising: a first continuous chain; a first series of spaced blocks supported by longitudinally-spaced chain, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline; a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other; a series of rollers on said pins, each pin rotatably supports at least a pair of said rollers displaced from each other; first roller-support track means, said rollers being adapted to roll on said track means; means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses; a bottom plate; a top plate; means rotatably supporting said chain for rotation between said plates; and said rotatably supporting means being positioning rollers.

9. An apparatus for operating on a relatively-inflexible movable pipeline, said apparatus including: a first pipe-engaging tool, said tool comprising: a first continuous chain; a first series of spaced blocks supported by said chain, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline; a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other; a series of rollers on said pins; first roller-support track means, said rollers being adapted to roll on said track means; means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses; and said roller-support tracks means including: two short-radius, curved, side tracks separated by two relatively-flat, main tracks, and each of said blocks having a length sufficiently shorter than the distance between two consecutive pins in said chain, thereby allowing each support block to rapidly accelerate in the transition region between a main track and an adjacent side track.

11. The apparatus of claim 9 in which said main tracks are relatively flexible.

13. An apparatus for operating on a relatively-inflexible Movable pipeline, said apparatus including: a first pipe-engaging tool, said tool comprising: a first continuous chain; a first series of spaced blocks supported by said chain, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline; a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other; a series of rollers on said pins; first roller-support track means, said rollers being adapted to roll on said track means; means operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses; a second pipe-engaging tool, said second tool comprising: a second continuous chain; a second series of spaced blocks supported by said second chain, said second blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline; a second series of pins interlinking said blocks to allow said second blocks to pivotally move relative to each other; a second series of rollers on said second pins; second roller-support track means, said second rollers being adapted to roll on said second track means; said second tool being operatively coupled with said first tool for maintaining and selectively moving said portion of said pipeline on said first and second blocks against their curved surfaces, thereby allowing said first and second pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses; a third pipe-engaging tool, said third tool comprising: a third continuous chain; a third series of spaced blocks supported by said third chain, said third blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline; a third series of pins interlinking said third blocks to allow said third blocks to pivotally move relative to each other; third roller-support track means, said third rollers being adapted to roll on said third track means; and said third tool being operatively coupled with said first tool and second tool for maintaining and selectively moving said portion of said pipeline on said first, second and third blocks against their curved surfaces, thereby allowing said first, second and third pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced stresses.

14. The apparatus of claim 13 and further including: power means operable to effectively move said tools relative to each other.

15. The apparatus of claim 14 wherein: said first and third tools are positioned on one side of the longitudinal axis of said pipeline, and said second tool is positioned between said first and third tools on the opposite side of said longitudinal axis.

16. The apparatus of claim 15 wherein: said first roller-support track means has a constant curvature thereby imparting to said portion of said pipeline said constant curvature.

19. The apparatus of claim 18 and further including torque producing means for rotating said second and third chains.

20. The apparatus of claim 19 in which: each of first, second and third blocks includes a removably-mounted flexible insert defining said curved surface for engage-ment with said portion of said pipeline.

25. The apparatus of claim 24 in which said hydraulically-operated means include hydraulic cylinders, each cylinder having a reciprocating piston coupled to one of said rods, and said pistons having substantially equal effective cross-sectional areas.

26. The apparatus of claim 25 in which said hydraulically-operated means include a common fluid reservoir in fluid communication with each of said pistons.

28. The apparatus of claim 27 wherein each pin rotatably supports at least a pair of said rollers displaced from each other.

30. The apparatus of claim 22 wherein: said first, second and third tools, and said tensioning means are mounted on a platform, and further including power means to selectively and reciprocatingly move said platform in a vertical direction.

32. The apparatus of claim 31 wherein said pipeline is advanced generally along a longitudinal direction and in which: successive portions of the advancing pipe are subjected first to initial transverse bending forces to stress such portions above the pipe''s elastic limit in one direction, and thereafter to opposite transverse bending forces to stress such portions beyond the elastic limit in an opposite direction, thereby substantially straightening said portion of said pipeline.

33. An apparatus for laying a pipeline on a marine bottom, said apparatus comprising: a floating platform, a reel rotatably-mounted on said platform for supporting said pipeline, winding and unwinding means including: at least three continuous chains, each chain having a series of spaced blocks, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of the winding and unwinding pipeline; a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other, power means for controllably moving at least one of said chains; two of said chains being adapted to directly engage one side of a portion of said pipeline, and one of said chains being disposed on the opposite side of said pipeline so as to compressively engage said portion of said pipeline and to exert a series of longitudinally spaced continuously effective bending and counter-bending forces on said portion of said pipeline as it is being wound on and unwound from said reel.

34. An apparatus for straightening a long line of elasto-plastic metal pipe wound onto a coil mounted on a reel including: first means for winding and unwinding the pipeline on and from the Reel, second means for plastically reverse-bending the pipe to a constant curvilinear configuration as it is being wound and unwound, third means for subsequently plastically reverse-bending the pipe to a desired configuration after said pipe acquires said curvilinear configuration, and said second means comprising: a first continuous chain, a first series of spaced blocks supported by said chain, said blocks having curved surfaces operable to engaged longitudinally-spaced segments of a portion of said pipeline, a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other, a series of rollers on said pins, roller-support track means, said rollers being adapted to roll on said track means, and said third means being operatively coupled with said second means for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced operating forces.

36. The apparatus of claim 35 and further including: means for maintaining said pipe under tension during said winding and unwinding operations.

37. The apparatus of claim 36 and further including: means for movably supporting said rectilinear portion of said pipeline at spaced positions in a vertical plane, and said positions being adjustable to allow said pipeline to assume a progressively decreasing elevation and to enter into a body of water along a downwardly directed path.

38. An apparatus for handling a relatively-inflexible metal pipeline, said apparatus including: a reel rotatable about its axis; means for rotating said reel in opposite directions for respectively winding pipe thereon and unwinding pipe therefrom; combined bending and level wind means mounted adjacent said reel, said means comprising: three movable chain assemblies, each assembly being mounted for rotation about an axis extending substantially parallel to the axis of said reel, each pair of chains being at opposite sides of the line of travel of said pipeline, each of said chains comprising: a series of spaced blocks supported by said chain, said blocks having curved surfaces operable to engage longitudinally-spaced segments of a portion of said pipeline, a series of pins interlinking said blocks to allow said blocks to pivotally move relative to each other, a series of rollers on said pins, roller-support track means, said rollers being adapted to roll on said track means, and means operatively coupled with said chains for maintaining and selectively moving said portion of said pipeline on said blocks against their curved surfaces, thereby allowing the pipe-engaging blocks to exert on the engaged portion of said pipeline a series of longitudinally-spaced operating forces while said pipeline is being wound and unwound on and from said reel.

39. The apratus of claim 14 and further including: power means operable to effectively move said first and second tools closer together or further apart depending on the strength of the desired tensioning forces, and said first and second chains are adapted to directly engage opposite sides of a generally straight portion of said pipeline so as to compress said pipeline and to exert a series of longitudinally-spaced, continuously-effective tensioning forces on said opposite sides of said straight portion of said pipeline.