The invention relates to an apparatus for closing hollow bodies having at least one substantially cylindri¬ cal opening, particularly for testing such bodies under fluid pressure, the apparatus having a closing device with means for sealingly clamping the closing device to the cylindrical opening of the body to be tested.

An apparatus of this kind is known from Dutch Patent Application 65.0094-1. This known apparatus is particular¬ ly intended for closing (steel) boiler tubes, and the whole closure device is disposed in the interior of the tube. The clamping segments and sealing means used in this arrangement are pressed against the inner wall of the tube.

The known device is less suitable, if not completely unsuitable, for use in the pressure testing of, for example, tubes of relatively rather easily defor able material, such as plastics tubes. In the first place, if excessive clamping forces should be applied by the clamping segments, the end portion of the tube would tend to be deformed outwardly, so that the clamping force would be reduced. In addition, the self-clamping action of this known apparatus is minimal because of the shape and location of the clamping segments.

Another disadvantage of the known apparatus is that the dimensional tolerances of the inside diameter have to be small.

The object of the invention is to provide an appara¬ tus which does not have the above mentioned disadvantages, and according to the invention this object is achieved in that the closing device consists of a cylindrical closing head which, at the end intended for being placed on the cylindrical opening of the body to be tested, is provided with a cylindrical cavity of which the inside diameter substantially corresponds to the outside diameter of the cylindrical opening of the body to be tested, in

which cavity an expander is disposed which has a conical outer surface, together with a clamping device consist¬ ing of a number of clamping segments disposed around the periphery of the conical expander, said clamping segments lying with at least a part of the inner surfaces thereof against the conical outer surface of the conical expander and being joined together in such a manner as to be' radially movable relative to one another, while means are provided for producing a relative axial movement between the conical expander and the clamping device, the arrangement being such that on relative movement of one of said devices with respect to the other in the direction of the closing head the clamping segements are pressed radially outwards and the portion of the wall of the cylindrical opening of the body to be tested, which is situated between the clamping segments and the inner wall of the cylindrical cavity in the closing head is clamped thightly therebetween.

Because, for example, the end of a tube to be tested which is to be closed,is clamped, between the clamping segments and a part of the closing head enclosing the side of the tube, there is no danger of deformation of the tube by the clamping forces applied by the clamping segments. In addition, due to this clamping of the end or of both ends of the tube during the pressure testing of a length of tubing, an axial force is exerted on the latter, so that any deformation of the tube under heavy internal pressure is counteracted. Moreover, with the apparatus according to the invention the advantage is obtained that a tube under test having an oval cross-section is forced, after the fitting of the closing head, to assume ^' a circular cross- section corresponding to the shape of the cylindrical cavity in the closing head, so that the apparatus is also suitable for use with tubes which do not have an exact cylindrical shape.

Various forms of construction of the apparatus

according to the invention are possible.

Particularly in the case of tubes having a relative¬ ly small diameter, for example a diameter of 75 to 250 mm, an appropriate form of construction is obtained by attaching the conical expander to means effecting its axial movement, while its conical outer wall tapers from the end remote from the closing head to the end facing the closing head, the clamping segments being so shaped that in the clamped state their edge directed towards the closing head lies against the bottom of the cylindri¬ cal cavity in the latter.

In this embodiment a length of tubing, one end of which is disposed in the circular cavity in the closing head, is clamped thightly by pulling the conical expan- der inside the clamping segments by means known £β s _^ e for the purpose. This apparatus has an excellent self- clamping action because the conical expander is pressed further into the clamping segments by the test pressure built up inside the tube being tested. In fact, the expander only needs to be pulled into the clamping segments until good sealing of the tube relative to the closing head is achieved. The required clamping action is then achieved automatically.

Another embodiment, which is particularly suitable for tubes having a relatively large diameter of the order of magnitude of 315 to 800 mm, is obtained in that the clamping device consisting of clamping segments is attached to means bringing about its axial movement, while the conical expander consists of a coaxial shell fastened in the cylindrical cavity in the closing head and having a conical outer surface which tapers from the end facing the closing, head towards the end remote from the closing head.

In this embodiment the clamping segments are pulled along the conical outer wall of the fixed shell, whereby they are spread apart and grip the inner wall of the tube under test. A self-clamping action is obtained because the pressure built up in the tube tends to push

the clamping segments along the conical surface in the direction of the closing head.

In a very effective embodiment of the invention the clamping segments, which cooperate with a moving expander, have an outer surface of which an end portion facing the closing head tapers in the inward direction, while in the clamping position the clamping segments lie with the end edge of the tapering part against the end wall of the cylindrical cavity of the closing head. In this embodiment the self-clamping action is improved because the end edge lying against the closing head forms a pivot about which the clamping segments turn when the expander or the clamping segments are further pulled, so that the clamping action is increased. This pivot movement can be further improved if the edge of each clamping segment, facing the closing head, is rounded and is seating in a correspondingly rounded recess in the end wall of the cylindrical cavity of the closure head. These rounded parts also have the effect that, when the expander is pulled, the clamping segments simultaneously act on a fixed hinge pivot, so that uniform clamping is achieved.

In order to improve the grip of the clamping seg¬ ments on the wall of the tube, according to the invention the outer wall of the clamping segments is provided, at least over a part of the portion remote from the closing head, with toothing formed by grooves made in the periphery of the segments, the teeth having substantially a rectangular trapezium shape, the root of each tooth being formed by the longest of the parallel sides and the sloping side is extending from the crown of the tooth to' the root on the side of the tooth remote from the end face of the cylindrical cavity in the ϊl-osing head.

The means for bringing about relative axial movement of the said members may consist of means known _j De _j r ^e.

In a very appropriate embodiment, however, the means for bringing about an relative axial movement of the said members consist of a hydrauli piston-and-cylinder assembly,

in which the pirson rod is connected to the member in question, while that part of the cylinder which is situated at the side of the piston facing the closing head is connected to a passage extending through the closing head provided with a non-return valve and debouching into the cylindrical cavity in the closing head at a point lying inside the portion of the cylindri¬ cal cavity which is surrounded by the tube under test. With this embodiment, the internal pressure is admitted into the hydraulic cylinder through the opening of the non-return valve in the connecting passage, if the internal pressure in the tube exceeds the pulling pressure in the hydraulic cylinder, so that this pressure contributes to increasing the pulling force exerted by the hydraulic cylinder and therefore also the clamping force. According to a very effecient embodiment of a hydraulic operating device for an apparatus having moving clamping segments and a fixed expander, the piston of the hydraulic operating device consists of an annular piston which is movable up and down in an annular chamber provided in the closing head, the annular piston and the chamber extending above all clamping segments, the annular piston being provided with a number of piston rods, each of which is connected with its bottom side to a clamping segment, the part of said chamber lying at that side of the piston which is directed towards the cylindrical cavity in the closing head being connected on the one hand via a non¬ return valve to a source of pressure medium for the primary operation of the hydraulic apparatus, and on the pther hand via a non-return valve to the cylindrical cavity inside the coaxial shell.

In this embodiment an equal and simultaneous pulling of the clamping segments is achieved, so that uniform clamping is achieved over the entire periphery. The invention will now be explained with reference to the drawings, in which some embodiments of the apparatus according to the invention are shown as examples.

Figure 1 nhous an embodiment, partly in section, of a closing device according to the invention, applied to an open end of a tube.

Figure 2 shows a cross-sectio of a modified embodi- ment of a part of a closing device according to the invention, applied to the end of a tube of relatively large diameter.

The closing device shown in Figure 1 is particularly intended for fitting to cylindrical tube openings of relatively small diameter, for example a diameter of 75" to 250 mm. This closing device comprises a cylindrical closing head 1, which has a cylindrical cavity 2 having an inside diameter substantially equal to the outside diameter of the end of the tube 3 on which the closing head 1 is applied. Inside the cavity 2 is a clamping device consisting of a conical expander 3 and a number of clamping segments which are situated around the latter and of which one can be seen in cross section in the figure and is designated 5. The clamping segments 5 are shaped in such a manner that the bottom part 6 of their inner wall comes to lie against the conical outer surface of the expander 4 when the latter is moved axially up¬ wards in the figure, while the clamping segments 5 will be spread out radially on continuation of the movement of the expander. The clamping segments are held together by 0-rings 7 and 8 respectively, which are disposed in respective grooves 9 and 10 formed in the outer surface of the clamping segments. The conical expander 4 is with its top end screwed thight to the end of a rod 12 which extends slidably through an axial bore 11 in the closing head 1 and which on its part extending beyond the closing head is provided with a screwthread, on which part a hand- wheel 14 is screwed. On turning-of the handwheel 13 the axial movement of the rod 12, and therefore also of the expander 4, is brought about. The rod is sealed in the bore 11 by a sealing 15 disposed in the wall of the bore. The clamping segments 5 lie with a tapering upper part 16 against the top surface of the cylindrical cavity 2 of the

closure head, while the expander 4 is pulled upwards by means of the hadnwheel in such a manner that the clamping segments, which are spread out as result of this move¬ ment, clamp the wall of the tube 3 against the inside wall of the cavity 2. The outside wall of the tube 3 is at the same time sealingly pressed against the inside wall of the cylindrical cavity 2, the sealing action being ensured by Sealing 20'. The clamping segments have a cylindrically rounded top edge 17, which in the clamping position, as shown in the drawing, lies in a centered position against a cylindrically shaped recess 18 in the top wall of the cylindrical cavity. This rounded top edge 17 forms on the one hand with the cylindrically shaped recess 18 a pivot when clamping segments are spread-out, so that an additional torque is provided for the clamping, which on the one hand produces an additional clamping force or on the other hand enables a determined clamping force to be more easily achieved. In addition, with illustrated embodiment it is ensured that the clamping segments 5 will simultaneously engage a fixed pivot when the expander 4 is pulled upwardly, so that uniform clamping is achieved over the entire periphery of the tube 3. Since in the clamping position the clamping segments 5 lie with their top edge 6 against the closing head 1, a very good self-clamping action is achieved through the fact that the conical expander 4 is pressed further upward between the clamping segments 5, which are blocked against axial movement, through the action of the test pressure built up in the tube. In order to achieve an increased grip on the wall of the tube 3, the clamping segments 5 are provided with toothing on the lower part of the outer wall, the teeth 19 having, in cross-section a substantial rectangular trapezium shape, the root of each tooth being formed by the longer of the parallel sides and the sloping side 20 extending from the crown of the tooth to the root at the side remote from the end face of the cylindrical cavity 2. Through this specific shape of the teeth 19 it is ensured

that the clamping segments are self-releasing, so that no additional tools are necessary for releasing of clamping segments which have fixed themselves in the material of the tube. Referring now to Figure 2, there can be seen in this figure a closing apparatus which is particularly intended for fitting to cylindrical tube openings of a relatively large diameter, for example of the order of magnitude of 315 to 800 mm. This closing apparatus comprises a cylin- drical closing head 21 having a cylindrical cavity 22 of which the inside diameter is substantially equal to the outside diameter of the end of the tube 33 on which the head is fitted. Inside the cavity is a fixed ciaxial shell 34 having a conical outer surface 35 which tapers from the top to the bottom. Around the outside periphery of the conical shell 34 are disposed clamping segments 36 which lie with their conical inner surface 37 against the outside surface 35 of the fixed conical shell 34. The clamping segments 36 are axially movable along the conical outer surface 35 by means of a hydraulic device, whicft will now be further described.

The hydraulic operating device for the clamping segments 36 comprises an annular chamber 38 which is provided in the closing head and is closed at the top by an annular cover 39 fastened by screws. In the chamber 38 an annular piston 40 is disposed adapted to shift up and down in the chamber 38 and which is sealed against the walls of the latter by means of a sealing ring 41. The annular piston 40 is connected to the different clamping segments 36 by means of piston rods 42, of which one can be seen in the drawing. Each piston rod 42 is free slidable through a vertical bore 43 in a guiding bush 44 disposed in a vertical bore 45 in the closing head. The piston rods 42 are sealed with respect- to the vertical bore 45 by means of a packing ring 46. The space of chamber 38 under the piston 40 is, via a passage 47 passing through the closing head and provided with a non¬ return valve 48, in communication with a connecting

clamping cylinder 49 supplying pressure medium to the chamber 38 for operation of the hydraulic actuating device for the clamping segments. In addition, the space of chamber 38 is under the piston 40 is in communication with the interior of the tube 33 by way of a passage 50 extending through the closing head and provided with a non-return valve 51.

For operation of the apparatus, pressure medium is passed through the non-return valve 48 and the passage 47 to the chamber 38, so that the piston 40 is forced upwards and thus the clamping segments 36 are moved upwards along the wall 35 of the shell 34, acting as expander, and are spread apart, whereby the tube 33 is clamped between the clamping segments and the inner wall of the cavity 22. The clamping segments are pulled up¬ wards simultaneously and very uniformly by this hydraulic actuating device. When the tube 33 is internally placed under pressure by means of a pressure medium intended for this purpose, via the pressure medium inlet 52 and the shut-off valve, then if the pressure inside the tube 33 exceeds the pressure in the chamber 38, the non-return valve 51 will allow pressure medium to pass from the tube to the chamber 38 through the passage 50, so that the pressure in the tube will produce an increased force on the piston 40 and the clamping action of the clamping segments will be increased. It may be observed that the clamping segments 36 are provided on the outer surface with a toothing similar to that of the clamping segments 5 in Figure 1. In addition, the closing head is provided with a seal 53, disposed on the inner wall of the cylin¬ drical cavity, for sealing the tube wall 33.

In both the illustrated embodiment the appartus according to the invention has a positive self-clamping action. In both cases the clamping segments need be pulled up only sufficiently far to clamp the wall of the tube with a good seal in the circular cavity in the closure head, after which the clamping force on the tube is automatically

increased by the increasing pressure in the tube.

It may be observed that the invention can be ap¬ plied to hollow bodies of all shapes which are provided with one or more cylindrical openings, such as T-pipes, containers having a cylindrical opening; a closure ap¬ paratus according to the invention can be fitted to all the openings provided. The most usual application is to lengths of tubing which have to be subjected to _^ pressure tests, for which purpose a closing apparatus according to the invention can be fitted to each end.

Because the closing head closes. the length of tubing being tested by means of the circular cavity, relatively high test pressures can be applied without deforming the tubes. Moreover, the tubes need not be exactly cylindrical. Tubes having an oval cross-section are automatically deformed into a circular shape when the closing head according to the invention is used, so that the required sealing in relation to the closing head is achieved automatically around the entire periphery. Finally, it may be remarked that the invention is not restricted to the embodiments indicated, but extends to modified embodiments which are obvious to those skilled in the art and which come within the scope of the invention.