The invention relates to a system and a method for installing a plug in a hole in a sleeve, where the sleeve is positioned between insulated pipes. The invention also relates to an improved plug which is inserted in the hole and tools for sealing the plug in the hole.

Background

When connecting insulated pipes, a (open) sleeve / shrink sleeve may be used. The insulated pipes normally comprise one or more inner pipes, a layer of insulation material and a layer of casing covering the insulation layer. Layers providing additional gas barrier functions may also be found, e.g. between the casing layer and the insulation layer. The casing layer will normally be a plastic layer such as a polyethylene (PE) or polypropylene (PP) layer, where the PE or PP layer can be cross-linked. The sleeve is typically made of similar materials, cross-linked or not cross-linked.

Before connecting two insulated pipes, the insulation layer and the casing are removed at the ends of the pipe such that a portion of the one or more inner pipes is exposed. In this way the inner pipe(s) on two different insulated pipes can be connected. Prior to connecting the inner pipes, a sleeve in the form of a shrink sleeve is pushed onto one of the insulated pipes. After connecting the inner pipes, the sleeve is moved such that it overlaps with the casing ends at the two insulates pipes and is shrunk onto these ends such that an annular space is created underneath the sleeve surface. As an alternative to a shrink sleeve, the sleeve may be a wrap, which is wrapped around the connecting between the two insulated pipes and welded whereby an annular space below the sleeve is created.

The annular space is normally filled with insulation material by first drilling at least one hole in the sleeve and subsequently filling this hole with liquid insulation material. Additional holes for ventilation may also be drilled.

After the foaming process is finished, the holes need to be thoroughly closed and sealed such that e.g. water, dirt or similar substances which could destroy the insulation properties of the insulation material are prevented from entering the insulation material.

One method for closing the holes is to use a conical shaped plug as the one described in US 4,645,557, where the shape of the hole matches the connical shape of the plug. In US 4,645,557 a special heating tool is used to simultaneously heat the plug and the inside surface of the hole to the same predetermined temperature. Once this temperature is reached, the plug is pushed into the hole thereby creating a welding connection between the plug and the hole. When the plug is inserted correctly into the hole, the hole in the plug is thoroughly closed and sealed.

However, since the installation of the plugs is normally done on site by a technician working on a tight schedule, the plug is often not inserted into the hole at the correct angle, as it requires a special tool in order to ensure that the plug enters the hole at the correct angels. Over the years this results in a plug-hole welding connection, which may more easily break at one side of the plug thereby allowing water or other substances to enter the insulation layer below the sleeve and thereby over the years decrease the insulation properties of the pipe.

An improved method is therefore needed to ensure a tight sealing of the holes in the sleeve.

Description of the invention

Disclosed herein in a first aspect of the invention is a method for sealing a hole in a sleeve connecting insulated pipes using a plug, wherein the sleeve has an outer surface and an inner surface.

The plug comprises a plug body having round cross-sectional diameters decreasing in size from a first end of the plug body to a second end of the plug body, and a plug collar with a proximal surface and a distal surface opposite the proximal surface, wherein the plug body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the plug collar.

The method comprises the steps of:

a) providing the plug and the sleeve with the hole; b) heating at least a first sealing surface of the plug and walls of the hole to a pre-determined temperature;

c) inserting the plug in the hole such that the plug collar connects to the outer surface of the sleeve surrounding the hole and such that the plug body fits in the hole in the sleeve, thereby creating a sealing connection, preferably by welding, between (i) the distal side of the plug collar and the surface around the hole, and (ii) the walls of the hole and the first sealing surface of the conical plug body. The hole in the sleeve is either conical in shape with a smaller diameter at the inner surface than at the outer surface of the hole prior to step a), or made conical with a smaller diameter at the inner surface than at the outer surface of the hole during the heating of the hole in step b). Disclosed herein in a second aspect of the invention is a system comprising a joint in the form of a sleeve or a wrap, the joint being for connecting insulated pipes.

The system also comprises at least one plug for closing at least one conical hole in the joint. The at least one plug comprises a plug body having round cross-sectional diameters decreasing in size from a first end of the plug body to a second end of the plug body, and a plug collar with a proximal surface and a distal surface opposite the proximal surface, wherein the plug body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the plug collar, wherein the at least one plug is made from a material being directly weldable in the at least one hole in the joint when the at least one plug and the at least one hole is heated to a pre-determined temperature.

Disclosed herein in a third aspect of the invention is a plug for sealing a hole in a sleeve connecting insulated pipes, the sleeve being made from non-cross-linked or cross-linked polyethylene or polypropylene.

The plug comprises a plug body having round cross-sectional diameters decreasing in size from a first end of the plug body to a second end of the plug body, and a plug collar with a proximal surface and a distal surface opposite the proximal surface, wherein the plug body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the plug collar, wherein the plug is made from a material being directly weldable in the sleeve hole when the plug and the hole in the sleeve are heated to a pre-determined temperature.

When reference to a sleeve or joint is made in any of the above aspects of the invention, it should be understood to also include sleeves of different shapes and sizes along with wraps and/or any other type of open joint. The terms are thus interchangeable.

By using the method of the first aspect of the invention, the system of the second aspect of the invention and the plug of the third aspect of the invention, a significant improvement in the sealing of the hole in the sleeve is obtained as the plug collar on the plug ensures that the plug is not inserted in the hole at a tilted angle resulting in a weak sealing at one side of the plug.

Further, as the surface areas on both the sleeve and the plug which can be welded together are further significantly increased by the plug collar on the plug this not only ensures the improved sealing; the lifetime of the whole sleeve is also prolonged. This also increases the lifetime of the insulated pipes which are connected by the sleeve, since the improved sealing of the hole in the sleeve prevents that water and water vapour obtain access to the insulation layer in the insulated pipe.

Also, the distal surface of the collar not connected to the plug body facilitates an additional welding surface on the plug, which is welded to the outer surface of the sleeve surrounding the hole. This creates a significantly better sealing between the plug and the sleeve. The large increase of the welding surface area is especially advantageous in thin walled sleeves - typically smaller sleeves - where the welding area may be increased by 50-150 % by using the plug according to this invention.

Advantageously, the plug according to the invention is not sensitive to an installation where the plug is inserted into the hole at a slightly twisted angle, since the surface area for welding is increased significantly by the addition of the plug collar to the plug. In fact, due to the collar, the positioning of the plug in the sleeve will normally be very well defined such that twisted angle insertion is basically avoided.

Also, due to the plug collar, the plug cannot be pushed through the plug hole as can be seen on the prior art solutions used today. This ensures a high level of reproducibility. It further minimizes the human/installer-induced insecurities during the installation.

The plug can advantageously be installed in both cross-linked and non-cross-linked sleeves.

Disclosed herein in a fourth aspect of the invention is a further system for sealing a hole in a sleeve for connecting insulated pipes, the system comprising a plug according to the above and a flat patch being larger than the plug collar, wherein, upon heating the patch to a predetermined welding temperature and positioning the patch on top of the plug sealed in the hole in the sleeve, the patch is welded onto the proximal surface of the plug collar and part of the sleeve with which the patch is in contact. The additional flat patch provides for a double sealing of the connection making the connection even more strong than the sealing, which the plug according to the invention already provides for. Furthermore it adds redundancy in the seal.

Disclosed herein in a fifth aspect of the invention is a drilling tool for drilling a hole in a sleeve for connecting insulated pipes. The drilling tool comprises a drilling tool body having round cross-sectional diameters decreasing in size from a first end of the drilling tool body to a second end of the drilling tool body; a drilling tool collar with a proximal surface and a distal surface opposite the proximal surface, wherein the drilling tool body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the drilling tool collar, and a connection protrusion for connecting the drilling tool to a drilling machine. The drilling tool body comprises cutters for drilling a hole in the sleeve and wherein the distal surface of the drilling tool collar comprises one or more rows of surface grinders for obtaining a recess in the sleeve surface surrounding the hole. The drilling tool can advantageously be used in commercially available drilling machines. The drilling tool ensures that the depth of the hole drilled in the sleeve is correct and not too deep as observed with equipment commercially available today. Also, the drilling tool allows for drilling of the hole and the recess at the same time. Disclosed herein in a sixth aspect of the invention is a plug heating tool for heating a welding plug for sealing a conical hole in a sleeve during sealing of a sleeve connecting insulated pipes.

The plug comprises a plug body having round cross-sectional diameters decreasing in size from a first end of the plug body to a second end of the plug body, and a plug collar with a proximal surface and a distal surface opposite the proximal surface, wherein the plug body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the plug collar. The plug heating tool comprises a first conically shaped heating surface for abutting and heating the surface of the plug body; a collar heating surface for abutting the distal surface of the collar and heating means for heating surfaces of the heating tool to a predetermined temperature, wherein the angle between the first heating surface and the collar heating surface is larger than 180°.

Brief description of the drawings

Figure 1 shows a plug according the known prior art.

Figures 2a-b show an embodiment of a plug according to the invention alone (figure 2a) and inserted in a hole in a sleeve (figure 2b).

Figures 3a-c show an embodiment of the plug viewed from different angles.

Figures 4a-c show different shapes of the plug collar seen in a top-view. Figures 5a-b show plugs with square and rectangular shaped collars. Figure 6a-e show different types of sleeves.

Figure 7 shows the procedure of drilling a hole in the sleeve for e.g. filing the annular space below the sleeve with insulation material.

Figure 8 shows a drilling tool for drilling a hole in a sleeve.

Figure 9 shows a plug heating tool. Figure 10 shows a plug pressing tool. Description of preferred embodiments

Figure 1 shows a prior art plug 100 similar to the one in e.g. US4,645,557 inserted in a hole 202 in a sleeve 200. The prior art plug 100 comprises a conical plug body 102 extending from a first end 104 to a second end 106 of the plug. The cross- sectional diameter d1 at the first end 104 of the plug body is larger than the cross- sectional diameter d2 at the second end 106 of the plug body. When the plug 100 is inserted into a hole 202 in a sleeve 200, a first welding surface area 108 - sealing the plug body 102 inside the hole 202 - can be defined.

Disclosed herein is a plug for sealing a hole in a sleeve connecting insulated pipes, the sleeve being made from non-cross-linked or cross-linked polyethylene or polypropylene.

The plug comprises a plug body having round cross-sectional diameters decreasing in size from a first end of the plug body to a second end of the plug body, and a plug collar with a proximal surface and a distal surface opposite the proximal surface, wherein the plug body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the plug collar, wherein the plug is made from a material being directly weldable in the sleeve hole when the plug and the hole in the sleeve are heated to a pre-determined temperature. In one or more embodiments, the plug body is conical or frustroconical.

In one or more embodiments, the plug body has a smooth surface without perforations or protrusions.

In one or more embodiments, the plug body surface and the distal surface of the collar form an angle larger than 90 degrees. In one or more embodiments, the plug is made from polyethylene or polypropylene.

In one or more embodiments, the smallest cross-sectional diameter of the plug body is between 18-26 mm, or between 25-30 mm, or between 30-35 mm. In one or more embodiments, the largest cross-sectional diameter of the plug body is between 22-30 mm, or between 28-37 mm, or between 35-45 mm.

In one or more embodiments, the largest cross-sectional diameter is between 15- 40%, or between 40-55% larger than the smallest cross-sectional diameter. In one or more embodiments, the largest cross-sectional diameter is between 5-50%, or between 30-50% larger than the smallest cross-sectional diameter.

In one or more embodiments, the collar has a thickness between 1 -5 mm, or between 2,5-4 mm, or between 2-3 mm, or 2.5 mm.

In one or more embodiments, the collar has an improved flexibility compared to the plug body being rigid.

In one or more embodiments, the collar bends downwards along an axis such that when the plug is welded in the hole, the collar follows the contour of the round sleeve.

In one or more embodiments, the plug further comprises a top protrusion extending from the proximal surface of the collar, preferably positioned symmetrically in relation to the plug collar, wherein the top protrusion is adapted for easy handling of the plug.

In one or more embodiments, the collar is circular in shape, or oval in shape, or rectangular in shape. A square shape may also be used.

In one or more embodiments, the collar is circular in shape and has a diameter between 2-8 cm, or between 3-6 cm, or between 5-8 cm, or between 3-5 cm, or between 3.5-4.5 cm or at 4 cm.

In one or more embodiments, the collar is oval having a major axis defining the largest diameter of the collar and a minor axis defining the smallest diameter of the collar, wherein when the plug is welded in the hole in the sleeve, the major axis is extending in the longitudinal direction of the sleeve.

In one or more embodiments, the plug comprises a centre axis extending along the first end of the plug to the second end of the plug, and wherein the plug body, the top protrusion, and possibly the plug collar are symmetric around the centre axis. Figure 2a shows an embodiment of a plug 1 10 according to the invention. Figure 2b shows the plug of figure 2a inserted in a hole 202 in a sleeve 200. The plug 1 10 contains a conical plug body 102 as also seen in the prior art plug 100 in figure 1 , and additionally contains a plug collar 1 12. The description and the numerals of the plug body of the prior art plug in figure 2a also apply to the plug body shown in figure 2b.

The plug collar 1 12 has a proximal surface1 14 pointing towards a viewer when the plug 102 is inserted in the hole 202 in the sleeve 200. Extending from the proximal surface 1 14 of the plug collar 1 12 is a top protrusion 1 16, which facilitates easy handling of the plug 1 10 when using it for sealing the hole 202 in the sleeve 200.

In one or more embodiments, the collar has a thickness between 1 -5 cm, or between 1.5-4 cm, or between 2-3 mm, or 2.5 cm. On the opposite side of the proximal surface 1 14 of the plug collar 1 12 is an exposed distal surface 1 18 which comes in contact with the surface of the sleeve 200 surrounding the hole 202, when the plug 1 10 is inserted in the hole 202 in the sleeve 200. The plug body 102 is extending form the distal surface 1 18 with the largest cross-sectional diameter d1 of the plug body 102 being closest to the plug collar 1 12.

When the plug 1 10 is inserted into a hole 202 in a sleeve 200, a second welding surface area 120 - sealing the plug collar 1 12 to the surface 204 of the sleeve surrounding the hole 202 - can be defined in addition to the first welding surface 108.

Normally, the outer surface 122 of the plug body 102 is smooth without any protrusions or recesses.

In figures 3a-c are shown different views of an embodiment of the plug 1 10, where figure 3a is a perspective view of the plug 1 10 seen primarily from above, figure 3b is a perspective view of the plug 1 10 seen primarily from below, and figure 3c is a side view of the plug 1 10.

In figure 3c, the cross-section diameter d2 of the plug body 102 at the second end of the plug, the cross-section diameter d3 of the plug collar 1 12 and the cross-section diameter d4 of the top protrusion 1 16 are marked. Figure 3c also shows a marking of the height hi of the plug body 102, the height h2 of the plug 1 10, the

height/thickness h3 of the plug collar 1 12 and the height h4 of the top protrusion 1 16.

In one or more embodiments, the smallest cross-sectional diameter d2 of the plug body is between 18-26 mm, or between 25-30 mm, or between 30-35 mm.

In one or more embodiments, the largest cross-sectional diameter d1 of the plug body is between 22-30 mm, or between 28-37 mm, or between 35-45 mm. From the first end of the plug to the second end of the plug is an axis 124 through the centre of the plug. The angle between the outer surface 122 of the plug body and the axis 124 is marked a. In one or more embodiments, the angle a is between 10-30 degrees, or between 15-25 degrees, or between 21 -23 degrees, or substantially 22.5 degrees.

The angle between the distal surface 1 18 of the plug collar and the surface of the plug body is marked β in figure 3c. The angle β is in one or more embodiments larger than 90 degrees, or between 100-120 degrees, or between 105-1 15 degrees, or between 1 1 1 -1 13 degrees, or substantially 1 12.5 degrees.

In figure 3b-c it can also be seen that the plug 1 10 may comprise a recess 126 at the bottom of distal side 128 of the plug body 102. The recess 126 lowers the use of material.

Figures 4a-c show plugs with different shapes of the plug collar 1 12 seen in a top- view. The cross-section diameters d1, d2 of the plug body 102 at the first end and the second end of the plug body, respectively, along with the top protrusion 1 16 are marked in figures 4a-c. The plug collar 1 12a in figure 4a is round in shape, whereas the plug collar 1 12b in figure 4b is oval and the plug collar 1 12c in figure 4c is rectangular in shape. Other shapes, such as e.g. rectangular, pentagonal and hexagonal, may also be imagined.

In one or more embodiments, the collar is circular in shape or oval in shape or square in shape.

In one or more embodiments, the collar is circular in shape and has a diameter between 2-8 cm, or between 3-6 cm, or between 5-8 cm, or between 3-5 cm, or between 3.5-4.5 cm or at 4 cm.

In one or more embodiments, the collar is oval having a major axis defining the largest diameter of the collar and a minor axis defining the smallest diameter of the collar, wherein when the plug is welded in the hole in the sleeve, the major axis is extending in the longitudinal direction of the sleeve. In one or more embodiments, the collar bends downwards along an axis such that when the plug is welded in the hole, the collar follows the contour of the round sleeve.

Figures 5a-b show plugs 1 10 with rectangular-shaped collars 1 12. In figure 5a, the collar 1 12 bends downwards on two opposite sides 130 of the plug body 102 such that the collar 1 12 may follow the contours of the round sleeve with the hole into which the plug is inserted. In figure 5b, the collar 1 12 does not bend.

The bended collar in figure 5a is rectangular in shape. The bending of the collar to follow the contour of the sleeve may also be found for round, oval or any other types of collar shapes. In one or more embodiments, the collar has an improved flexibility compared to the plug body being rigid. This allows the collar to more easily bend and be welded to the sleeve, which has a round contour in the transverse direction.

The relation between the hole diameter and the collar area may have multiple combinations and in principle only depends on the welding tools at disposal.

This invention also relates to a system comprising a plug 1 10 according to the above and a flat patch (not shown in the figures) being larger than the plug collar. Upon heating the patch to a predetermined welding temperature and positioning the patch on top of the plug sealed in the hole in the sleeve, the patch is welded onto the proximal surface of the plug collar and part of the sleeve with which the patch is in contact.

In one or more embodiments, the patch is made from polyethylene, or

polypropylene.

In one or more embodiments, the system further comprises a sleeve according to the above for connecting insulated pipes, the sleeve comprising at least one conical hole. Disclosed herein is also a system comprising a joint in the form of a sleeve or a wrap, the joint being for connecting insulated pipes, and at least one plug for closing at least one conical hole in the joint.

When reference to a sleeve is made, it should be understood to also include a wrap or any other type of open joint.

The at least one plug is a plug according to the above description exemplified by the plugs shown in the figures. The sleeve may be a sleeve according to any of the sleeves shown in figure 6a-e. The figures show different types of sleeves 200a-200e all containing two or more positions suitable for drilling holes in the sleeves or positions where a hole has been drilled. One hole or a larger multiple of holes may also be imagined.

In one or more embodiments, the hole in the joint is surrounded by a recess, thereby creating a deepening surface area around the hole wherein the plug collar fits when inserting the plug in the hole. In one or more embodiments, the hole in the joint is a foaming hole through which liquid insulation material can be added to fill the annular space between the insulated pipes, or an air ventilation hole used during a foaming process for foaming of the annular space between the insulated pipes. In one or more embodiments, the joint is one of the following types:

• a shrink sleeve having a tubular shape for connecting two insulated pipes;

• a T-shaped sleeve for connecting three insulated pipes;

• a T-shaped shrink sleeve for connecting three insulated pipes;

• an open joint, which is connected to an end of two insulated pipes by

wrapping the joint around the ends of the two insulated pipes such that the joint obtains a tubular shape. In one or more embodiments, the joint is made from a non-cross-linked and/or a cross-linked plastic material allowing the joint to shrink onto the insulated pipes upon being heated.

In one or more embodiments, the joint and the plug are made from polyethylene, cross-linked polyethylene, polypropylene or cross-linked polypropylene. Normally, the plug is not cross-linked.

Disclosed herein is also the use of a system according to the above when connecting insulated pipes, such as district heating or cooling insulated pipes.

Disclosed herein is further a method for sealing a hole in a sleeve connecting insulated pipes using a plug. The method comprises the steps of:

a) providing the plug and the sleeve with the hole;

b) heating at least a first sealing surface of the plug and walls of the hole to a pre-determined temperature;

c) inserting the plug in the hole such that the plug collar connects to the outer surface of the sleeve surrounding the hole and such that the plug body fits in the hole in the sleeve, thereby creating a sealing connection, preferably by welding, between (i) the distal side of the plug collar and the surface around the hole, and (ii) the walls of the hole and the first sealing surface of the conical plug body.

The hole in the sleeve is either conical in shape with a smaller diameter at the inner surface than at the outer surface of the hole prior to step a), or made conical with a smaller diameter at the inner surface than at the outer surface of the hole during the heating of the hole in step b).

Normally, the hole in the sleeve has an inner surface diameter where the hole penetrates the inner surface of the sleeve and an outer surface diameter at the outer surface of the sleeve, the outer surface diameter being larger than the inner surface diameter. The hole may in an embodiment be drilled circular with the same inside and outside diameter and then later be melted conical with the welding mirror.

In one or more embodiments, the hole in the sleeve is surrounded by a recess, thereby creating a deepening surface area around the hole wherein the plug collar fits when inserting the plug in the hole.

In one or more embodiments, the recess in the sleeve has a shape matching that of the plug collar.

In one or more embodiments, the recess extends to a depth being at the most the same as the thickness of the collar, wherein the thickness of the collar is smaller than the thickness of the joint surrounding the hole. In one or more embodiments, a heating tool is used for heating at least the first sealing surface of the plug and the walls of the hole in the sleeve to the predetermined temperature. An example of a heating tool is shown in figure 9. The heating walls of the hole in the sleeve and the welding surfaces of the plug body are heated to the pre-determined temperature.

In one or more embodiments, the pre-determined temperature is between 230- 270°C thereby facilitating welding between sealing surfaces of the plug and the walls of the hole and possibly the sleeve surface surrounding the hole. In one or more embodiments, the pre-determined temperature is between 240- 260°C.

In one or more embodiments, the pre-determined temperature is approximately 250°C.

In one or more embodiments, only the first sealing surface of the plug body and the walls of the hole are heated. In one or more embodiments, an adhesive is applied around the hole and/or on the exposed distal surface of the plug before inserting the plug in the hole.

In one or more embodiments, inserting the plug in the hole is done by the sub-steps of (1 ) providing a plug pressing tool, (2) arranging the plug body into the hole after heating, and (3) pressing the plug collar against an outer surface of the sleeve by means of the plug pressing tool so as to provide a welding between the distal side of the plug collar and the outer surface of the sleeve around the hole and the walls of the hole and the first sealing surface of the plug body.

An example of the plug pressing tool is shown in figure 10. The plug pressing tool comprises a collar support part for supporting the proximal surface of the collar, wherein the collar support part has a width which is larger than the width of the plug body.

In one or more embodiments, the method comprises the step of pressing the plug into the hole with a force of 1 -3 N/mm ² for 30-90 seconds.

In one or more embodiments, the plug collar and the outer surface of the sleeve are heated to the predetermined temperature, and wherein the pressing of the plug collar against an outer surface of the sleeve by means of the plug pressing tool provides a welding between the distal surface of the plug collar and the outer surface of the sleeve surrounding the hole. In one or more embodiments, the plug body surface and the distal surface of the collar form an obtuse angle between the plug collar and the surface of the plug body.

In one or more embodiments, where the sleeve is made from a cross-linked plastic material, the walls of the hole in the cross-linked material sleeve are pre-heated before heating the first sealing surface of the plug and the walls of the hole. This ensures that the cross-linked material reaches the required temperature allowing it to be welded to the non-cross-linked material of the plug. In one or more embodiments, the method for sealing the hole in the sleeve further comprises the steps of:

• providing a flat patch being larger than the plug collar;

• heating the patch to a predetermined welding temperature;

· positioning the patch on top of the plug sealed in the hole in the sleeve such that the patch covers the plug collar completely and such that the patch is welded onto the plug collar and part of the sleeve with which the patch is in contact. In one or more embodiments, the patch is made from polyethylene or polypropylene.

Figure 7 shows the procedure of drilling hole(s) in the sleeve. In one or more embodiments, the hole in the sleeve is a foaming hole through which liquid insulation material can be added to fill the annular space between the insulated pipe or an air ventilation hole used during a foaming process for foaming of the annular space between the insulated pipe.

Disclosed herein is therefore also a drilling tool for drilling a hole in a sleeve for connecting insulated pipes. The drilling tool comprises a drilling tool body having round cross-sectional diameters decreasing in size from a first end of the drilling tool body to a second end of the drilling tool body; a drilling tool collar with a proximal surface and a distal surface opposite the proximal surface, wherein the drilling tool body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the drilling tool collar and a connection protrusion for connecting the drilling tool to a drilling machine.

The drilling tool body comprises cutters for drilling a hole in the sleeve and wherein the distal surface of the drilling tool collar comprises one or more rows of surface grinders for obtaining a recess in the sleeve surface surrounding the hole.

In one or more embodiments, the drilling tool body is conical.

In one or more embodiments, the drilling tool body surface and the distal surface of the drilling tool collar form an angle larger than 90 degrees. The drilling machine 301 shown in figure 7 is a standard drilling machine where onto a drilling tool 300 is attached. Figure 8 shows a close-up of the drilling tool 300, which comprises a drilling tool body 302 with round cross-sectional diameters decreasing in size from a first end 304 of the drilling tool body 302 to a second end 306 of the drilling tool body 302. Like the plug shown in some of the preceding figures, the drilling tool also comprises a drilling tool collar 308, which has a proximal surface 310 and a distal surface 312 from where the drilling tool body 302 extends. The drilling tool 300 has a connection protrusion 314 for connecting the drilling tool 300 to a drilling machine 301 . The drilling tool body 302 comprises cutters 316 for drilling the hole in the sleeve. Also on the distal surface 312 of the drilling tool, the collar 308 comprises one or more rows of surface grinders 318 for obtaining a recess in the sleeve surface surrounding the hole when drilling the hole in the sleeve.

The drilling tool 300 with the surface grinders 318 may also have a built in stop, which can be used in order to optimize the contact area of the plug in the wall thickness area of the sleeve. The drilling tool may further optimize the preparation of the sleeve surface for welding and secure the right hole geometry.

The current welding tools which are on the market may be used with a new adaptor.

Disclosed herein is further a plug heating tool for heating a welding plug for sealing a conical hole in a sleeve during sealing of a sleeve connecting insulated pipes.

The plug comprises a plug body having round cross-sectional diameters decreasing in size from a first end of the plug body to a second end of the plug body and a plug collar with a proximal surface and a distal surface opposite the proximal surface, wherein the plug body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the plug collar.

The plug heating tool comprises a first conically shaped heating surface for abutting and heating the surface of the plug body; a collar heating surface for abutting the distal surface of the collar; and heating means for heating surfaces of the heating tool to a predetermined temperature, wherein the angle between the first heating surface and the collar heating surface is larger than 180°. Figure 9 shows an example of a plug heating tool 400 for heating a plug according to any of the shown embodiments in figures 2-5. The plug heating tool 400 comprises a first conically shaped heating surface 402 for abutting and heating the outer surface of the plug body and a collar heating surface 404 for abutting the distal surface of the collar. The first conically shaped heating surface 402 forms a conical receiving hole for receiving a conical plug body of a welding plug. The collar heating surface 404 substantially surrounds the receiving opening of the conical receiving hole.

The angle δ between the first heating surface 402 and the collar heating surface 404 is normally larger than 180°. The angle δ may be between 210° and 265°, such as substantially 250°.

The collar heating surface may have an annular shape and it may also be recessed. The plug heating tool 400 also has a conically shaped outer heating surface 406 for heating the walls of the hole in the sleeve, e.g. a sleeve as shown in figures 6a-e.

The conically shaped outer heating surface 406 comprises an annular recess 408 providing a heating surface for heating the outer surface of the sleeve surrounding the hole in the sleeve.

In one or more embodiments, the first conically shaped heating surface forms a conical receiving hole for receiving a conical plug body of a welding plug, wherein the receiving hole has a receiving opening substantially providing the largest cross sectional diameter of the conical receiving hole.

In one or more embodiments, the collar heating surface substantially surrounds the receiving opening of the conical receiving hole. In one or more embodiments, the angle between the first heating surface and the collar heating surface is between 210° and 265°, such as substantially 250°.

In one or more embodiments, the collar heating surface has an annular shape.

In one or more embodiments, the collar heating surface is recessed.

In one or more embodiments, the plug heating tool comprises a further, conically shaped outer heating surface for heating the surface of the conical hole in the sleeve.

In one or more embodiments, the further, conically shaped outer heating surface comprises an annular protrusion providing a heating surface for heating the outer surface of the sleeve surrounding the conical hole in the sleeve.

Disclosed herein is also the use of a plug heating tool according to the above for heating a welding plug and a hole in a sleeve, the plug comprising:

• a plug body having round cross-sectional diameters decreasing in size from a first end of the plug body to a second end of the plug body, and

· a plug collar with a proximal surface and a distal surface opposite the

proximal surface, wherein the plug body extends from the distal surface of the collar and has the largest cross-sectional diameter nearest the plug collar,

wherein the heating tool heats the plug body and the plug collar.

Figure 10 shows a plug pressing tool 500 for holding a plug during the step of pressing the plug into the hole in the sleeve. The plug pressing tool 500 has a handle 502, which the user uses when holding the tool 500 and pressing the plug into the hole in the sleeve.

The top protrusion of the plug will normally extend into a recess 504 in the plug pressing tool 500 during the pressing of the plug collar against the outer surface of the sleeve. The plug pressing tool 500 also has a collar pressing surface 506 for pressing the collar of the plug collar against the outer surface of the sleeve. In one or more embodiments, the collar support part of the plug pressing tool has a support surface for supporting on the proximal surface of the plug collar, and wherein the support surface preferably has a surface contour, such as an arched surface contour, substantially corresponding to the surface contour of the sleeve.

In one or more embodiments, the plug pressing tool comprises a handle for holding the plug pressing tool by hand during the pressing operation. In one or more embodiments, a top protrusion extends from the proximal surface of the collar, wherein the plug is arranged so that the top protrusion extends into a recess in the pressing tool during the pressing of the collar against the outer surface of the sleeve.

References

100 prior art plug

102 plug body

104 first end of the plug

106 second end of the plug

108 first welding surface area

1 10 plug according to the invention

1 12 plug collar

1 14 proximal surface of the plug collar

1 16 top protrusion

1 18 distal surface of the plug collar

120 second welding surface area

122 outer surface of the plug body

124 axis from the first end of the plug to the second end of the plug

126 recess at the distal side of the plug body

128 distal side of the plug body

130 downwards-bending sides on the plug collar d1 cross-section diameter of the plug body at the first end of the plug body d2 cross-section diameter of the plug body at the second end of the plug body d3 cross-section diameter of the plug collar

d4 cross-section diameter of the top protrusion

hi height of the plug body

h2 height of the plug

h3 height/thickness of the plug collar

h4 height of the top protrusion

a angle between the surface of the plug body and the axis 124

β angle between the distal surface of the plug collar and the surface of the plug body

200 sleeve

202 hole in the sleeve

204 surface surrounding the hole in the sleeve 300 drilling tool

301 drilling machine

302 drilling tool body

304 first end of the drilling tool body

306 second end of the drilling tool body

308 drilling tool collar

310 proximal surface of the drilling tool collar

312 distal surface of the drilling tool collar

314 connection protrusion

316 cutters

318 surface grinders

400 plug heating tool

402 first conically shaped heating surface

404 collar heating surface

406 conically shaped outer heating surface

408 annular protrusion

δ angle between the first heating surface and the collar heating surface

500 plug pressing tool

502 handle