The irregular intermediate space circumferentially between the inner face of the outer pipe and the outer face of the inner pipe/the lining, as seen cross-sectionally, offers then sealing problems in the area for hot tap for water discharge.

From European patent application registration number 0 645 575 it is previously known a pipe armature for installation in a predrilled hole in a pipe. The pipe armature comprises a tubular body having an end portion widening conically in a direction axially outwardly and having outermost a radially outwardly directed annular flange. A deformable socket of e.g. polyethylene is disposed on a central or intermediate portion of the tubular body and is slidable in the longitudinal direction of the body. The socket has an outwardly directed flange at that end

positioned adjacent the conical end portion of the tubular body. This conical end portion and the deformable socket are dimensioned such in relation to each other that the socket is caused to expand radially upon relative displacement of the conical end portion and the socket in engagement with each other, so that the socket is brought to take a position exhibiting an outer diameter corresponding to a force fit within the predrilled hole in the pipe. The deformable socket-shaped, radially expandable packer which is axially displaceable in relation to the tubular body's conically widened end portion and surrounds the latter cooperatingly therearound, as well as its way of expansion outside a conical, rigid shape-permanent end portion of the tubular body of the known pipe armature, is, however, not fit for sealing the above-mentioned intermediate space between the outer pipe's internal side face and the inner pipe's or lining's external side face in the area of registering lateral holes for a straight-through nipple, where said intermediate space at the lateral holes has an irregular cross-sectional shape, the distance between said internal side face and external side face changes circumferentially.

The external side face, conical in operative position, and the short extent of the known deformable, axially displaceable and radially expandable, socket-shaped, known packer can, thus, not be utilized for the sealing purpose which the present invention has aimed at realizing.

Moreover, the known pipe armature is built up resulting in a relatively complex structure, comprising a plurality of loose, interconnectable parts and members, making the construction more expensive and reducing the reliability thereof.

A straight-through nipple according to the invention secures, with simple and cheap means, a reliable sealing at three places distribute along the length of the straight-through

nipple within the area of the lead-through thereof in preshaped, registering holes in (old) outer pipe and (new) inner pipe/lining/pipe stocking.

Said object is achieved by means of a straight-through nipple of the kind defined introductorily and distinguishing itself through the features appearing from the characterizing clause of claim 1.

When the complete straight-through nipple having an elongate, deformable, sleeve-shaped packer expanding radially upon axially directed compression has been pushed entirely through said registering predrilled lateral hole in the outer pipe and in the lining (inner pipe, pipe stocking), a nut is tightened, said nut together with washers and the elongate, sleeve-shaped packer's outwardly directed end flange being situated outside the outer, existing pipe, while a stop/locking ring at the opposite (inner) end of the straight-through nipple, which exhibits a conically widened portion in an inward direction, upon the tightening of the nut and the axial outwardly pulling of the tubular body during the sleeve-shaped packer's initial axial compression and radial expansion, slides inwardly and rests itself against an outwardly directed annular flange acting as a stop member axially outside the conical portion of the tubular body of the straight-through nipple.

Thus, the stop/locking ring is brought into its operative position in which its diameter is larger than the diameter of the registering holes of the pipes. The ring acts like an efficient stop against the undesired extraction of the straight-through nipple at this stage of the straight-through nipple's sealing fixing within the lined pipe, and forms simultaneously a stop face for the innermostly positioned packer portion during and after the following radial expansion of the sleeve-shaped packer both in the registering lateral holes, around the inner lateral hole (in inner pipe

or in lining) from the inner side, between the inner pipe/the lining and the outer pipe and around the lateral hole in the outer pipe from the outside. Within the lateral holes, the sleeve-shaped, deformable packer expands to rest clampingly and sealingly against the hole-defining edge faces restricting the expansion, while the narrow portions of the deformable, sleeve-shaped packer positioned within the lining/the inner pipe, between the same and the outer pipe and at the outside of the outer pipe, undergoes a larger expansion in the radial direction of the straight-through nipple, resting clampingly and sealingly against the adjacent faces of outer pipe and lining (inner pipe, pipe stocking).

In addition to a good sealing action from the inner side of the lining to the outside of the outer pipe, distributed among three places along the longitudinal axis of the tubular body of the straight-through nipple, the nipple mounted in this special way will sit very firmly.

On burried pipes, the nipple will be mounted freely, without any undue physical influence of any kind, within an adjusted clamp mounted on the outer existing pipe.

A straight-through nipple with a sealing device according to the invention may easily be adapted to the material thickness of the pipes and to circumferentially varying intermediate spaces between lining and outer pipe. Advantageously, the nipple may also be used in hot tab in order to prevent fouling in cast-iron pipes. The nipple has been pressure- tested up to 15 bars.

A non-restricting examplary embodiment of a straight-through nipple in accordance to the invention is further explained in the following, reference being made to attached drawings, wherein:

Figure 1 shows a straight-through nipple of the invention separately, one half being shown in side elevational view, the other half being shown in axial section; Figure 2 represents a partial view wherein a straight-through nipple shaped and designed in accordance with figure 1 just has been passed through aligned, predrilled holes for the nipple in an outer pipe and in a lining in the form of an inner pipe, wherein the upper part is shown in section, the lower part being shown in side elevational view; Figure 3 corresponds to figure 2, but here the externally available nut has been tightened, so that the deformable, radially expandable, sleeve-shaped packer has been compressed substantially in axial direction.

First, reference is made to figure 1, showing a complete straight-through nipple according to the invention in assembled, insertable condition with unexpanded sleeve-shaped packer, the nipple generally being denoted at reference numeral 10. The straight-through nipple 10 comprises an elongate, tubular body 12 having an externally threaded portion 12' having a circular, annular cross-section across approximately the whole length, i.e. except from a relatively short, but very important annular face portion 12" at one (the inner as referred to the position of use) end portion where the annular face portion 12" widens itself conically towards the adjacent end exhibiting a circle-cylindrical outer face 12"' having a larger diameter than the tubular body's long, threaded part.

The circle-cylindrical end portion is outermost terminated with an outwardly directed annular flange 14 having a stop face 14' facing away from the end edge proper.

Close by the conical face portion 12'' a stop/locking ring 16 divided into two parts has been threaded onto the externally threaded, long portion of the tubular body 12.

The divided ring 16 is expandable radially, so that it upon axially directed influence of force from right to left in figure 1 will be capable of being displaced up along the conical face portion in order to, eventually, land in a final position resting against the annular end flange's opposing stop face (figure 3). In this final position, this end portion of the straight-through nipple 10 will have a larger diameter than insertion holes in rehabilitated outer pipe and in lining.

Across most of its length, the straight-through nipple's tubular, inner, externally threaded body 12 is surrounded by a concentric, deformable, radially expandable packer 18 having an outwardly directed annular flange 18' at the opposite end of the straight-through nipple 10 intended to be positioned on the outside of the outer, existing pipe 20, figures 2 and 3, and wherein this end flange's 18' face 18'' facing towards the outer pipe 20 primarily acts as a stop face for resting against the outer face 20' of the outer pipe 20 around the insertion hole 22 thereof.

Axially outside the deformable, radially expandable packer's 18 end flange 18', a tightening nut 24 has been screwed onto the externally threaded end portion of the tubular body 12, the washers 26 associated therewith being disposed in the form of a sliding ring and a stop disc displaceably disposed between the nut 24 and the end flange 18' of the packer 18.

Non-conically within the rehabilitated outer pipe 20, a lining in the form of an inner pipe 28 has been disposed, usually made of a plastic material such as polyethylene.

Between the outer pipe 20 and the inner pipe 28, an irregular intermediate space M is formed, said space which is defined by the opposing, curved faces of the pipes 20, 28, narrows in cross-section in a downward direction. The inner pipe 28 has a predrilled lateral hole 30 aligned with the hole 22 of the outer pipe 20 in the axial (insertion) direction of the straight-through nipple (10).

Hitherto, in association with prior art, one has had difficulties in sealing around holes (22, 30) positioned in two adjacent bodies (20, 28), with an intermediate cavity having a width altering itself non-linearly circumferentially.

With the basis in those positions which the movable parts of the straight-through nipple take in relation to each other in figure 1, the straight-through nipple 10 is inserted through the holes 22 and 30 in the pipes 20 and 28, the end with the stop flange 14 and the conical face portion 12''' as leading end in the inserting direction until the deformable, radially expandable, sleeve-shaped packer's 18 end flange face 18'' comes to rest against the external face 20' of the outer pipe 20, figure 2.

Preferably, the packer sleeve 18 consists of rubber-elastical material. The rest of the straight-through nipple may consist of stainless steel. Diametrically opposing points on the external, outermost end edge av the inner tubular body 12 is provided with small edge cavities 32 which, together with each other, may form a screw notch.

The diameters of the end/stop flange 14 and the locking ring 16 correspond approximately to each other in the starting position of the locking ring 16 according to figure 2, and each diameter is insignificantly less than the diameter of the lateral holes 22, 30 during the insertion of the straight-through nipple 10 to the position shown in figure 2,

representing an inoperative position of readiness for the nipple 10.

In order to allow the externally threaded (12'), elongate body 12 to act as a motion screw in relation to the nut 24, the "screw" 12,12' or the nut 24 must be prevented from rotating while the other part is rotated, a displacement of the end at the "screw notch" 32 away from the opposing face of the nut 24 being aimed at.

Thus, the sleeve-shaped packer's 18 annular end face facing to the left side, will initially form a stop for the radially expandable stop/locking ring 16 which, then, during the axial extraction of the inner, tubular body 12 (towards the right side), successively becomes pushed up on the conical portion 12'' and, therefrom, up on the outer circle-cylindrical end portion 12"', where the locking/stop ring 16 is stopped permanently by the stop face 14' on the outwardly directed, annular end flange 14 of the pipe body 12. In this position, the locking/stop ring 16 has a larger diameter than the diameter of the lateral holes 22, 30 of the pipes 20, 28, and the straight-through nipple 10 is definitely secured against being pulled out axially, especially because the rubber- elastic packer sleeve 18 during its substantial axial compression has expanded radially such as shown in figure 3 and has, besides having plugged and sealed the lateral holes 22, 30, formed three 360° substantially radial packer portions 18a, 18b and 18c, wherein the innermost packer portion 18a improves the stop action of the locking/stop ring 16. The intermediate packer portion 18b is shaped and designed with an optimal sealing action, independently on the irregular shape of the intermediate space M in cross-section, and the outermost radial packer portion 18c is shaped through deformation of the flange portion 18' which, all the time, rests against the external face 20' of the outer pipe 20.

The radial packer portions 18a, 18b, 18c put themselves sealingly against pipe faces adjacent the lateral holes 22, 30 which, additionally, are sealed through the radially pressing contact of the packer portions against the edge faces defining the holes 22, 30.