IES20070643A2 - Pipe welding method and apparatus - Google Patents

Abstract

A pipe welding method for thin-walled pipes (20,21) includes mounting a support sleeve (1) having a resilient unitary C-shaped body (2) across abutting ends (23,24) of the thin-walled pipes (20,21). Free ends (4,5) of the body (2) are pulled together to clamp the sleeve (1) about the pipes (20,21) bringing the pipes (20,21) into alignment. The pipe ends (23,24) are then tack welded together through welding access openings (6) in the body (2). After removal of the sleeve (1) the pipe ends (23,24) are fully welded together. <Figure 6>

Description

PIPE WELDING METHOD AND APPARATUS Introduction This invention relates to the welding of pipes, and in particular to the welding of thinwalled pipes.

The invention is particularly concerned with the fabrication of process systems for the pharmaceutical, beverage, and food industries which involves the installation of hygienic stainless steel O/D tube which is a thin-walled pipe. A key criterion for the pipework is a crevice-free internal surface and drainability of this pipework. A frequent problem encountered in welding two O/D pipes together is to get correct alignment of the two pipe ends. A further problem arises in that many of the pipe ends are somewhat eccentric due to the small wall thickness of O/D tube [approximately 1.5mm].

It is known, from Patent Specification No. SE 503694 and US 5,865,430 for example, to provide a C-shaped pipe clamp comprising a pair of pivotally connected semi20 circular members for clamping about butt-joined pipes to aid in welding the pipes together. Given the nature of their construction, these pipe clamps are relatively expensive to produce and are somewhat awkward to fit and release in use which is a disadvantage where a large number of pipe joints have to be welded.

The present invention is directed towards overcoming these problems.

According to the invention there is provided a method for welding thin-walled pipes together, including: inserting ends of two thin-walled pipes into an associated support sleeve, said support sleeve having a resilient unitary C-shaped body with an arcuate side wall terminating in spaced-apart free ends, a number of circumferentially spaced-apart welding access slots extending through the side wall to provide access to abutting pipe ends supported within the sleeve, ISO 70 6 43 positioning the ends of the thin-walled pipes at the welding access slots, pulling the free ends of the sleeve together for clamping the sleeve about the pipes and aligning the pipe ends, tack welding the two pipe ends together at each welding access slot, releasing the free ends of the sleeve and removing the sleeve from the pipes and, welding the pipe ends together fully about the pipe ends.

In one embodiment of the invention, the method includes clamping the sleeve about the pipe ends by engaging a clamp with associated lugs at free ends of the sleeve for pulling said free ends of the sleeve together.

In another embodiment the body is formed by a continuous band of material. in a particularly preferred embodiment the body is formed by stainless steel material.

In another embodiment the method includes welding an elbow piece to a pipe by mounting a support sleeve on the pipe, abutting an end of the elbow piece with the end of the pipe, sliding the support sleeve along the pipe for overlapping a side edge of the support sleeve with the elbow piece to align the elbow piece with the pipe, the support sleeve having one or more outer welding access slots along said side edge, pulling the free ends of the sleeve together for clamping the sleeve about the elbow piece and the pipe and aligning abutting edges of the elbow piece and pipe, tack welding the elbow piece to the pipe at each outer welding access slot, releasing the free end of the sleeve, removing the sleeve and welding the abutting ends of the elbow piece and the pipe together fully about said abutting ends.

In another aspect, the invention provides apparatus for carrying out the method of the invention, including a sleeve having a resilient unitary C-shaped body defining a socket for reception of the ends of complementary pipes to be welded together, said -3hody having an arcuate side wall with a number of circumferentially spaced-apart welding access slots extending through the side wall to provide access to abutting pipe ends supported within the sleeve in use, and means for gripping free ends of the sleeve side wall for puling said free ends together to clamp the sleeve about the pipe ends housed within the sleeve body in use.

In another embodiment, the gripping means comprises outwardly projecting lugs at each free end of the sleeve body.

In further embodiment, welding access slots are centrally located between side edges of the side wall.

In another embodiment, the welding guide slots are provided along at least one side edge of the side wall.

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which; Fig. 1 is a perspective view of pipe clamping apparatus used in the process of the invention; Fig. 2 is an elevational view of the pipe clamp apparatus; Fig 3 is an end elevational view of the pipe clamp apparatus; Fig.4 is an end elevational view of the pipe claim apparatus showing another ' of the pipe clamp apparatus; Fig.5 is a plan view of the pipe clamp apparatus; Fig.6 is a perspective view showing the pipe clamp apparatus in use mounted on a pair of adjoining pipes; i£Q 7 9 6 * 5 -4Fig.7 is an elevational view of the pipe clamp apparatus on the pipes corresponding to the view showed in Fig, 6; and Fig.8 is an end elevational view showing the pipe clamp apparatus clamped about the pipes by means of a clamp engaged with the pipe clamp apparatus.

Referring to the drawings, there is illustrated a pipe clamp sleeve according to the invention indicated generally better by the reference numeral 1. The sleeve 1 has a resilient unitary C-shaped body 2 with an arcuate side wall 3 terminating in spacedapart free ends 4, 5. A number of circumferentially spaced-apart welding access slots 6 extend through the side wall 3 to provide access to abutting pipe ends 23, 24 supported within the sleeve 1 as shown in Figs. 6 and 7.

The side wall 3 is a continuous band of stainless steel material. The body 2 is esilient in the sense that the free ends 4, 5 of the side wall can resiliently move together and apart for gripping and releasing pipes. The body 2 can be opened and closed due to its resilient nature.

In this case, circular access slots 6 are provided centrally located between opposite side edges 8,9 of the side wall 3. These welding access slots 6 are positioned at 90° spacings around the circumference of the side wall 3. It will be appreciated that the number and location of slots may be varied, with typically a greater number of slots on larger diameter tubes.

In addition, outer welding access slots 12 are spaced around one edge 9 of the side wall 3. In this case, outer welding access slots 12 are in alignment with the inner slots 6, although this need not necessarily be so.

The free ends 4,5 of the side wall 3 are formed by outwardly projecting lugs which can be readily easily gripped by a clamp such as a vice grips 15, as shown in Fig. 8., to damp the sleeve 1 about O/D pipes 20,21 as shown in Figs. 6-8.

Referring in particular to Figs. 6 to 8, the method of the invention will be described.

Two thin-walled O/D pipes 20, 21 are inserted into the support sleeve 1 as shown in j|li /0 6*3 -5Figs. 6 and 7, locating ends 23,24 of each pipe 20,21 within the sleeve 1. These ends 23, 24 of each pipe 20, 21 are positioned at the welding access slots 6 in abutting engagement. Next, the free ends 4,5 of the sleeve 1 are pulled together by engaging a clamp such as a vice grips 15, as shown in Fig. 8, with the free ends 4, 5 to pull the sleeve 1 tightly about the pipes 20, 21 bringing the pipes 20, 21 into alignment and forcing the pipe ends 23, 24 into concentricity. Then the pipe ends 23, 24 can be tack welded together at each of the welding access slots 6 to secure the pipe ends 23, 24 together. The vice grips 15 is then opened releasing the sleeve 1, which is removed from the pipes 20, 21. Then the pipe ends 23, 24 can be fully welded together about the pipe ends 23, 24.

To weld an elbow piece to an end of one of the pipes 20, 21, it would not be possible to use the inner welding access slots 6 due to the curvature of the elbow piece which uld not allow the sleeve 1 to slide sufficiently onto the elbow piece to centre the slots 6 at the joint. To overcome this problem the outer welding access slots 12 can be used. After sliding the side edge 9 into engagement with the elbow piece, the free ends 4, 5 of the sleeve 1 are pulled together as before to damp the elbow piece in alignment with the pipe 20, 21. Tack welds are then made at the joint at each outer welding access slot 12. After removal of the sleeve 1 the joint can then be fully welded.

It will be appreciated that apart from the cut-out welding access slots 6, 12, the side wall 3 is formed by a continuous band of material for even load distribution and preventing any localised pressure points which might distort the thin walled pipes 20, 21.

It will also be noted that the body 2 is of a simple unitary steel band construction nich is relatively cheap to manufacture and is readily, easily and quickly engaged and disengaged with the pipes 20,21 during use. 'he invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail within the scope of the appended claims.

Claims (5)

1. A method for welding thin-walled pipes together, including: 5 inserting ends of two thin-walled pipes into an associated support sleeve, said support sleeve having a resilient unitary C-shaped body with an arcuate side wall terminating in spaced-apart free ends, a number of circumferentially spaced-apart welding access slots extending through the side wall to provide access to abutting pipe ends supported within the 10 sleeve, positioning the ends of the thin-walled pipes at the welding access slots, pulling the free ends of the sleeve together for clamping the sleeve about 15 the pipes and aligning the pipe ends, tack welding the two pipe ends together at each welding access slot, releasing the free ends of the sleeve and removing the sleeve from the 20 pipes, and welding the pipe ends together fully about the pipe ends.

2. A method as claimed in claim one, including the step of clamping the sleeve 25 about the pipe ends by engaging a clamp with associated lugs at free ends of the sleeve for pulling said free ends of the sleeve together.

3. / method as claimed in claim 1 or claim 2 wherein the body is formed by a continuous band of material. jtjl

4. A method for welding thin-walled pipes together substantially as hereinbefore described with reference to the accompanying drawings.

5. A welding support sleeve for use in the method as claimed in any preceding -7c’airn wherein said welding support sleeve includes: a resilient unitary C-shaped body having an arcuate side wall terminating in spaced-apart free ends; means for gripping the free ends of the sleeve side wall for puling said free ends together; and a number of circumferentially spaced-apart welding access slots extended through the sidewall.