NZ551686A - Pipe forming apparatus and method - Google Patents

Abstract

A method of cold forming a tulip end in steel pipe including the steps of: providing a pipe-expanding die assembly including a circumferential array of die segments each being mounted on a base for radial movement from a closed up position allowing the array to pass into the open end of the pipe, each segment having an axial camming surface facing towards the axis of the array and adapted to cooperate with a corresponding surface on an axially movable wedging body operable by hydraulically drawing it through the array to spread the segments, the die segments each having a part annular die portion forming the shoulder of the tulip shape and a part conical die surface forming the bell of the tulip shape; moving the segments to the first position; passing the pipe end over the array; operating the wedging body hydraulically to spread the segments and expand the pipe end to partially conform to the die surfaces; and operating the wedging body to allow the segments to move toward the closed up position to release the pipe end.

Description

intellectual property office of n.z.

MAR 2007 1 RECEIVED PIPE FORMING APPARATUS AND METHOD This invention relates to a pipe forming apparatus and method.

This invention has particular but not exclusive application to a pipe forming apparatus and method for rendering pipe sealably joinable such as for fluid reticulation, and for illustrative purposes reference will be made to such application. However, it is to be understood that this invention could be used in other applications, such as conjoining pipe lengths generally.

PRIOR ART In the art of water reticulation, ductile iron and PVC pipe have been joined by use of a composite join wherein a plain pipe end is sealably inserted into a formed pipe including an end expanded from a shoulder to accept the OD of the pipe, the expanded part having an internal seal recess formed therein between the shoulder and the outer lip and adapted to receive a resilient seal. The outer lip is flared to facilitate insertion of a pipe end. The geometry of the joint is such that up to 5° of angle between pipe sections may be accommodated.

To this end, the expanded portion is essentially tulip-shaped, having the expansion at the shoulder greater than the expansion at the outer lip. Such an arrangement is that used for many years by TYCO in its ductile iron and PVC pipe. In use, the plain pipe end is simply inserted into the flared end to penetrate the plane of the seal and thus allow the seal to seal against the outer surface of the inserted pipe. In the case of ductile iron, the formed pipe end is necessarily hot formed. This is an intensive process which adds significantly to the price of the pipe. The corresponding end of PVC pipe is readily thermoformed.

Larger diameter pipe has been formed by spiral welding steel strip. The pipe so formed is produced in custom lengths to minimise joins. Several joining of n.z.

MAR 2007 RECEIVED solutions are used, including welding and the use of joiners which may in turn be associated with thrust blocks and the like where changes of direction are required. Where the pipe is lined to prevent corrosive or erosive attack, the joining means and method must preserve the integrity of the liner.

In recent times there has been a move toward welded steel tube for the smaller diameters hitherto done in ductile iron or PVC. In practical and economic terms it is not possible to hot form the ends of welded steel pipe in the manner of ductile iron. Cold working of pipe ends usually requires die forming of an end to allow the end to pass into the notional bore (NB) of the next pipe. There is no 10 common means of sealing; usually such pipe is welded which means that the method cannot be certified for water reticulation. The method has the disadvantage of causing a restriction in the pipeline, the reduction in cross section preventing a pig from passing down the finished line.

DESCRIPTION OF INVENTION 15 This invention in one aspect resides broadly in a method of cold forming a tulip end in seamless (drawn) pipe, electric resistance (longitudinally) welded (ERW) steel pipe, and spiral (helically welded) steel pipe including the steps of: providing an pipe-expanding die assembly including a circumferential array of die segments each being mounted on a base for radial movement from a closed 20 up position wherein the array may pass into the end of the pipe, each said segment having an axial camming surface facing toward the axis of the array and adapted to cooperate with a corresponding surface on an axially movable wedging body operable by hydraulically drawing it through said array to spread said segments, said die segments each having a part annular die portion forming the INTELLECTUALTW6" * > y UH-iUE OF N.2 MAR 2C07 RECEIVED shoulder of said tulip shape and a part conical die surface forming the bell of said tulip shape; moving said segments to said first position; passing said pipe end over said array; operating said wedging body hydraulically to spread said segments and expand said pipe end to partially conform to said die surfaces; and operating said wedging body to allow said segments to move toward said closed up position to release said pipe end.

In order that the die segments should impinge on the entire circumference 10 of the pipe, the base or the pipe may be configured to rotate into mutual index.

In a further aspect the present invention resides broadly in apparatus for cold forming a tulip end in electric resistance welded (ERW) steel pipe including: a supporting base; a pipe-expanding die assembly including a circumferential array of die 15 segments each being mounted on said base for radial movement from a closed up position wherein the array may pass into an end of a pipe, said die segments each having a part annular die portion forming the shoulder of said tulip shape and a part conical die surface forming the bell of said tulip shape, each said segment having an axial camming surface facing toward the axis of the array; 20 an axially movable wedging body having surfaces corresponding to respective ones of said camming surfaces, said wedging body being operable hydraulically to draw it through said array to spread said segments.

Either the pipe of the die segments may be adapted to allow rotational indexing of the pipe relative to the die segments, thereby providing for die action 25 on substantially the whole circumference of the pipe. This ensures that the tulip INTELLECTUSt'pliplrt^JrBCE of n.z.

MAR 2007 RECEIVED 4 from is as close to round as possible. For example, the pipe mat be mounted on rollers having axes parallel to the pipe axis and permitting free axial rotation of the pipe, and associated with motive means for rotating the pipe under control. Alternatively the base may be mounted in such a manner that it may be rotated 5 into index with a fixed pipe.

The cold formed tulip ended pipe may be post formed for water reticulation such as by rolling-out a circumferential groove adapted to accept a resilient seal for sealing pipe to pipe joins. The rolling of the seal groove may be advantageously performed such that a slight flare of the outer end of the tulip 10 shaped pipe end occurs. By this means the articulation of the joint to up to 5 degrees may be accommodated for pipeline work.

The formed or post formed ERW steel pipe may be sent directly to coating such as with epoxy lining and poly-laminate outer abuse layers for reticulation. The pickling or fire scale reduction necessary prior to coating hot formed product is 15 avoided. The coated ERW steel pipe products formed in accordance with the present invention are lighter per unit length for a given diameter and may be specified in longer lengths.

In order that the pipe lengths may have a soft lead-in, particular where the integrity of seals must be preserved, the opposite end of the pipe may be 20 collapsed by roll forming to form a lead in. On the other hand, a plain end will ensure that the pipeline remains able to be pigged-out, by presenting a bore with no occlusions.

The tulip form of the fundamental cold forming-process of the present invention has found a surprising application. In the drilling industry, drill pipe of 25 about 4.8 to 10 mm wall is generally joined by welding circumferentially spaced OF N.2 1 5 MAR 2Gt)7 RECEIVFD lugs to the outer surface of the pipe end to facilitate handling by a collar and particularly to assist in extraction of the drill pipe. The next pipe in the string is located in abutment with the pipe end and butt welded thereto. The alignment is assisted by extending the lugs past the end of the pipe so that the new pipe is 5 located coaxially with the lower pipe by the lugs. The ends of the pipe are chamfered to enable a full penetration fillet weld.

This arrangement has several inherent problems. Firstly there is the time consuming task of welding 4 or more lugs relatively precisely to the end of the pipe. Secondly there is the need for consider skill in welding the full-fillet, 10 circumferential butt weld joining the pipe ends, particularly considering the interruptions for the lugs. Thirdly there in the problem of corrosion in the full-thickness, heat affected zone.

A cold formed tulip end in accordance with the present invention is self-centering and is capable of being handled or extracted by a collar engagement 15 with the shoulder of the tulip shaped end. The weld is a simple surface weld since the plain pipe end is well supported at the inner end of the shoulder. The plain pipe end may be collapsed slightly or may have a machined end presenting a20 to 45 degree bevel to encourage stable self centering. Accordingly, in a further aspect this invention resides broadly in. a method of forming a drill pipe element 20 having a cold formed tulip shaped end and including the steps of: providing an electric resistance welded (ERW) steel pipe; providing an pipe-expanding die assembly including a circumferential array of die segments each being mounted on a base for radial movement from a closed up position wherein the array may pass into the end of the pipe, each said 25 segment having an axial camming surface facing toward the axis of the array and imCLLtUUflLTWc^iV UH-ICE OF til 1 5 MAR 2007 RECEIVED 6 adapted to cooperate with a corresponding surface on an axially movable wedging body operable by hydraulically drawing it through said array to spread said segments, said die segments each having a part annular die portion forming the shoulder of said tulip shape and a part conical die surface forming the bell of said tulip shape; moving said segments to said first position; passing said pipe end over said array; operating said wedging body hydraulically to spread said segments and expand said pipe end to partially conform to said die surfaces; and operating said wedging body to allow said segments to move toward said closed up position to release said pipe end.

In a further aspect the present invention resides in a method of forming a drill string including the steps of: (a) providing a drill pipe element having a cold formed tulip shaped end and a plain end; (b) drilling said drill pipe element into a substrate, leaving the tulip shaped end exposed; (c) inserting the plain end of a new drill pipe element into said tulip shaped end; (d) welding the outer lip of said tulip shaped end to the cylindrical side wall of said new drill pipe to form a drill pipe assembly; drilling said drill pipe assembly into said substrate, leaving the tulip shaped end of said new pipe exposed; and (e) repeating steps (c) and (d) until the drill string is complete.

BRIEF DESCRIPTION OF THE DRAWINGS M»icuxv,ruAi, wr- UlfiCE OF N j MAR 2007 RECEIVED In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein: FIG. 1 is a perspective view of forming apparatus in accordance with the 5 present invention; FIG. 2 is a grooving apparatus for post forming the product of FIG. 1 for water reticulation; FIG. 3 is a linear collapser for the plain end of pipes; FIGS. 4 and 5 are alternate pipe end collapsers to that of FIG. 3; 10 FIGS. 6 and 7 are pipe handling apparatus for use with the apparatus of FIG. 1; FIGS. 8 to 11 are sections through typical pipe ends in accordance with the present invention; and FIGS. 12 and 13 are typical coating and sealing arrangement s for use in 15 respect of the pipes of FIGS 8 to 11, for water reticulation.

DESCRIPTION OF THE EMBODIMENTS In the figures, there is provided a pipe system formed from pipe of Grade X42 (290Mpa Min Yield) and Design Yield Strength of 350Mpa. Such pipe is available in sizes 177 - 323mm OD @ 4.8mm Wall Thickness, 355 - 610mm OD 20 @ 6.4mm Wall Thickness, and 711 - 960mm OD @ 8.0mm Wall Thickness.

The expander of FIG. 1 consists of six anvils 10 moved radially along a face plate 11 by a centre wedge 12 actuated by hydraulic ram 13. Aluminium Bronze inserts 14 are added to the wedge faces to reduce pick-up. The expansion is carried out in at least two stages in order to achieve a 'round' shape.

INTELLECTUmi PROPERTY OFFICE OF N.Z 1 5 |W? 2007 F! V E D g The groove former of FIG 2 comprises a rolling die set forced together via hydraulic ram 15 to produce a groove in which the rubber 'O-ring' seats. A fixed lower shaft 16 is driven by 11kW gearmotor 17. A moving upper shaft 20 idles and is actuated vertically by the hydraulic ram 15. The lower die set 22 consists of two 5 halves which are spaced depending on the wall thickness being processed. Spacers are made for wall thicknesses 4.8mm through to 10mm. The upper die 23 is common to all wall thicknesses.

The collapser of FIG. 3 is a linear collapser. However, this type has limited application due to bulging. Preliminary tests were carried out to establish whether 10 the collapsed end could be produced by a rolling die set rather than a press.

Bulging problems were identified whereby the formed end collapsed but in doing so caused the OD to increase immediately following the taper.

A modified version of the groove former is a preferred method for collapsing pipe ends as illustrated in FIG. 4. Bulging problems were addressed by adding a 15 pressure roll to the design to retain the material in the problem area.

The collapser of FIG. 4 work son the top of the pipe. However, the embodiment of FIG. 5 is inverted so that it works on the bottom of the pipe.

The material handling apparatus of FIGS. 6 and 7 are capable of full production sizes including all sizes up to 960mm, with minimum set up required for 20 each size. Settings are precise with pins used to set positions for a give pipe size. A PLC is used to control sequencing and safe operation. A recipe system is used to customise setup to individual pipe sizes.

The pipe formed by the method and illustrated in Figs. 8 to 13 is produced from ERW steel pipe 30 to AS1646 which is provided with a bell end 31 and a intellectual rh^cufv office of nz 1 5 MAR 2007 RECEIVED lead-in end 32. typical proportions may be taken from details A to H, J to N, and P to S, which are substantially to scale in Figs 8 to 10.

In Figs. 12 and 13 there is illustrates the assembly of the bell end 31 and lead-in end 32, in the preferred coated and lined pipe. The pipe is coated on 5 substantially its entire outer surface by an outer trilaminate protective outer layer 35, comprising 120 microns of epoxy, 100 microns of polyglue and an outer abuse layer of 1 mm extruded HDPE. The protective layer 35 finishes short of the respective ends 31, 32 to the extent of the insertion overlap between adjacent pipe sections. An inner lining 36 of high build epoxy coating material is applied by 10 lance or dip and extends to the outer surface of the respective ends 31, 32 at 37, 38 to overlap the edges of the protective outer layer 35.

It will of course be realised that while the above has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to 15 fall within the broad scope and ambit of this invention as is herein set forth.

Claims (20)

1. A method of cold forming a tulip end in steel pipe including the steps of: providing an pipe-expanding die assembly including a circumferential array of die segments each being mounted on a base for radial movement from a closed 5 up position allowing the array to pass into the end of the pipe, each said segment having an axial camming surface facing toward the axis of the array and adapted to cooperate with a corresponding surface on an axially movable wedging body operable by hydraulically drawing it through said array to spread said segments, said die segments each having a part annular die portion forming the shoulder of 10 said tulip shape and a part conical die surface forming the bell of said tulip shape; moving said segments to said first position; passing said pipe end over said array; operating said wedging body hydraulically to spread said segments and expand said pipe end to partially conform to said die surfaces; and 15 operating said wedging body to allow said segments to move toward said closed up position to release said pipe end.

2. A method of cold forming a tulip end according to claim 1, wherein one or both of the base or the pipe is configured to rotate into mutual index. 20

3. A method of cold forming a tulip end according to claim 1 or claim 2, wherein the cold formed tulip ended pipe is post formed for water reticulation, 11

4. A method of cold forming a tulip end according to claim 3, wherein the post forming includes rolling-out a circumferential groove adapted to accept a resilient seal for sealing pipe to pipe joins.

5. A method of cold forming a tulip end according to claim 4, wherein the rolling of the seal groove is performed so as to cause a flaring of the outer end of the tulip shaped pipe end.

6. A method of cold forming a tulip end according to claim 5, wherein the pipe end remote the tulip formed end is formed with a soft lead-in by roll forming.

7. A method of cold forming a tulip end according to any one of claims 1 to 6, wherein the formed pipe is sent directly to coating for reticulation purposes.

8. A method of cold forming a tulip end according to claim 7, wherein the coating is selected from one or more of epoxy lining and poly-laminate outer abuse layers.

9. Apparatus for cold forming a tulip end in steel pipe including: 20 a supporting base; a pipe-expanding die assembly including a circumferential array of die segments each being mounted on said base for radial movement from a closed up position allowing the array to pass into an end of a pipe, said die segments each having a part annular die portion forming the shoulder of said tulip shape and a intellectual pitowrtv 0> OF N.Z. 15 MAR 2007 RECEIVED 12 part conical die surface forming the bell of said tulip shape, each said segment having an axial camming surface facing toward the axis of the array; an axially movable wedging body having surfaces corresponding to respective ones of said camming surfaces, said wedging body being operable 5 hydraulically to draw it through said array to spread said segments.

10. Apparatus for cold forming a tulip end according to claim 9, wherein one or both of the pipe and the die segments are adapted to allow rotational indexing of the pipe relative to the die segments, thereby providing for die action on 10 substantially the whole circumference of the pipe. 15

11. Apparatus for cold forming a tulip end according to claim 10, wherein the indexing is by means of pipe supporting rollers having axes parallel to the pipe axis and permitting free axial rotation of the pipe.

12. Apparatus for cold forming a tulip end according to claim 11, wherein the rollers are associated with motive means for rotating the pipe under control.

13. Apparatus for cold forming a tulip end according to claim 10, wherein the 20 indexing is by means of mounting the base for selective rotation into index with the pipe. 25

14. A method of forming a drill pipe element having a cold formed tulip shaped end and including the steps of: providing an electric resistance welded (ERW) steel pipe; 13 providing an pipe-expanding die assembly including a circumferential array of die segments each being mounted on a base for radial movement from a closed up position allowing the array to pass into the end of the pipe, each said segment having an axial camming surface facing toward the axis of the array and adapted to cooperate with a corresponding surface on an axially movable wedging body operable by hydraulically drawing it through said array to spread said segments, said die segments each having a part annular die portion forming the shoulder of said tulip shape and a part conical die surface forming the bell of said tulip shape; moving said segments to said first position; passing said pipe end over said array; operating said wedging body hydraulically to spread said segments and expand said pipe end to partially conform to said die surfaces; and operating said wedging body to allow said segments to move toward said closed up position to release said pipe end.

15. A method of forming a drill string including the steps of: (a) forming a drill pipe element by the method of claim 14; (b) drilling said drill pipe element into a substrate, leaving the tulip shaped end exposed; (c) inserting the plain end of a new drill pipe element into said tulip shaped end; (d) welding the outer lip of said tulip shaped end to the cylindrical side wall of said new drill pipe to form a drill pipe assembly; intellectual property office of N.Z. \ 5 MAR 2007 q r r Fi\/Fn j i *""*' tr lw" drilling said drill pipe assembly into said substrate, leaving the tulip shaped end of said new pipe exposed; and (e) repeating steps (c) and (d) until the drill string is complete.

16. A method according to any of claims 1 to 8, 14 and 15, wherein the steel pipe is selected from seamless (drawn) pipe, electric resistance (longitudinally) welded (ERW) steel pipe, and spiral (helically welded) steel pipe.

17. Apparatus according to any one of claims 9 to 13, and adapted to use on seamless (drawn) pipe, electric resistance (longitudinally) welded (ERW) steel pipe, and spiral (helically welded) steel pipe.

18. Steel pipe when produced by the method of any one of claims 1 to 8 and 14 to 16.

19. A method of cold forming a tulip end substantially as hereinbefore described, with reference to the accompanying drawings.

20. Apparatus for cold forming a tulip end substantially as hereinbefore 20 described, with reference to the accompanying drawings. END OF CLAIMS