MXPA01001204A - Pipe connection - Google Patents

Abstract

The invention relates to a pipe connection comprising a sleeve element (7). Said sleeve element comprises an inner threaded section (8) which axially extends inward from the end. A non-threaded section (10) connects to the inner threaded section. The inventivepipe connection also comprises a pin element (18) which comprises a threaded section (19) constructed to be complementary to the sleeve element (7). A non-threaded section (23) which extends up to the front end connects to said threaded section (19). The non-threaded sections (10, 23) come in contact with one another when they are screwed in and they form a metallic sealing system. The sealing system is provided with two axially interspaced contact zones of which at least one comprises geometrically different cross section contours.

Description

TUBULAR CONNECTION Description of the invention The invention relates to a tubular connection according to the preamble of claim 1. The connections for tubes serve to join tubular elements, for example pipes, which in particular transport fluids under pressure, as for example, gas or oil. In the case of the tubular connections that have been developed by various manufacturers for the aforementioned purpose of application, the tightness of the connection is achieved by a high contact pressure due to an overlap (excess of measurement) in the metal sealing seat. In this case, a configuration contact surface, for example cylindrical, formed in a thread-free portion of the sleeve element cooperates with a configuration contact surface, for example convex, of the spigot element. Frequently a connection of this type has a butt back of the sleeve and spigot elements. The back of the stop serves: as a limitation of the screwing and, by means of a corresponding pre-tension, it must be ensured that, despite an increase in the tensile stress, the adjacent metal seal seat remains active. It is assumed: generally that elastic expansions and crushes In addition to the sleeve and pin elements that are produced under load, the contact area with the greatest surface pressure at the vertex of the seat The metal seal can be opened axially so much, and the surface pressure reduced, which is no longer guaranteed, is guaranteed to be watertight for the maximum internal or external pressure admissible for the pipe. Several series of tests and calculations of mocellos have shown that this effect of the axial displacement of the contact area if it occurs, and this in a definitely significant magnitude for the guarantee of the hermetic function. Against this background it has been tried to guarantee a sufficient watertightness by means of an overlapping overlay as a construction measure. However, this principle leads to high contact stresses and carries the risk that: the metal Lico sealing seat will be plasticized. In order to overcome this problem it has already been proposed (DE 44 46 806 Cl) to provide a tubular connection that in the free: threaded portion of the sleeve and pin elements has two pairs of contact surfaces spaced from each other, whose sealing effect Basic due to stress is: independently reinforced in one and in another in a different way as a function of the effort, and of which at least one pair of contact surfaces has geometrically different cross-sectional contours.

The series and tests over several years have now shown that the approach on which the known construction of the obturator effect of both contact surface pairs rc is based always leads to the desired result, especially taking into account Manufacturing tolerances. The task of the invention consists in specifying a tubular connection which, taking into account manufacturing tolerances, ensures that a sufficient airtight effect of the metallically sealed shutter seat is guaranteed. all loading conditions. This task is described from the preamble in combination with the distinctive features of claim 1. Suitable improvements are the subject of the secondary claims. Unlike the known state of the art, a distance at the entrance of the thread whose geometric factor is determined directly proportional to the average value of the cross sections in the individual contact areas, and a degree of bending that in the sealing seat produces a surface pressure of lime minus six times the surface pressure theoretically required, but a maximum of 90% of the limit of elongation in relation to the material used, being that the measure of the radial deviation due to the bending is always greater than the overlap of the thread in the zone of the entrance of the thread. P02-flexion as the term is used in this case means: the following: In virtuc of the excess geometric dimension (superposiciores) in the contact areas and in the area of the thread, mainly at the entrance of the thread, so how through? the introduction of forces through a stop back, in the coiled state occurs in the sleeve element and spikes a line of curvature that has different local radial deviations in the form of bends. For the protective seat a defined distance is chosen at the end of the lip on the one hand and the sealing head on the other hand, as well as a degree of flexion of 1.15 to 1.30 times greater relative to the sealing seat. The lip concept is used here as synonymous with the thread-free portion of the element and spike. Depending on the degree of bending desired for the sealing seat, after screwing, with complete conservation of the sealing function even taking into account the superposition of the externally attacking moment loads, a total tension is achieved in the sealing seat that at the most is equal to c less than the elastic limit of the material used. . - "* & £ • _ '^ ^^^^^^^^^^^^^^^^^^^^ The nine focus on the construction according ccn the invention is taken into account in The position of the contact area of the metallic obturator seat and the curve of the moment of transverse force and fle > ion for the lip as a function of it, in order to produce negative radial, tangential and po also axial and thus minimize the differential voltage (Mises), avoiding the high tensile-flexion stresses as a consequence an inconvenient curve d 1 bending moment by the optimal positioning of the contact zone as well as by a controlled superposition of the transverse forces and bending moments introduced in another point. These transverse forces and overlapping bending commentary ls are produced by the protective seat which is placed at a considerably smaller distance from the end of the lip compared to the sealing seat. The protective seat simultaneously has the ability to stabilize the sealing seat by deflecting the external forces. He protective seat has a higher bending in the range from 1.15 to 1.30 vece > in relation to the obturator seat, depending on the degree of flexion of the obturator seat. For the ability to operate this system, certain distances between the end must also be respected 2 ^ of the lip and the contact zones (protective seat, shutter seat, thread entry) as well as establishment of the degree of flexion. In claim 2 these distances are established; individually by means of formulas depending on l? 5 respective dimension of the tube. The geometric factor that: determines the distance is directly proportional to the average value of the cross sections in the areas of: individual contact. In principle it is possible to structurally introduce other contact zones for the optimization of the curve of transverse force and moment of bending. The advantage of the proposed construction is that even given tolerances: 15 required manufacturing, by superimposing the transverse forces and bending moments that may occur in the protective seat for the sealing seat is total voltage when much is equal to or less than the elastic limit of the material used. In this manner, it is ensured that the sealing function of the sealing seat is maintained for all loading conditions. The prior art ..a (DE 44 46 806 Cl) already known: in the case of a tubular connection with back stop: alternatively the pin element has at the portion 25 threadless a straight contact surface That: ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .-MJ§gjXÉ¿ ^ * > ,; X? "extends inclined and sleeve element two W convex contact surfaces of convex configuration cooperating with it. For a tubular connection without back stop it is proposed to divide the surface of contact pin element in two portions with different inclination with ca, being the portion with the conical steep slope cooperates with the contact surface ae configured as a protective sleeve member seat ae. The tapered inclination on the protective seat must be at least 20% more pronounced than the inclination in the sealing seat and act as inhibition against excessive screwing. By means of the steepest cone of the orotector seat, a negative influence on the tension ratios of the sealing seat is avoided even in the case of excessive threading allowed due to the higher transverse forces of the protective seat. In the figures, the relations previously explained in Lo are schematically represented as diagrams referring to the distances between contact planes, transverse forces, bending and bending moments, and embodiments are also outlined. They show: figure 1 fundamental links of the influence of the distance of the contact pressure of the lip end, Figure 2 flexion (a), transverse forces (b) and bending moments (c) for a lip with two contact zones in the case of an optimal choice of distance without axial pre-tension, figure 3 as figure 2 , but with axial pre-tension, figure 4 influences the stop angle with axial pre-tension, figure 5 influences the choice of the distance between protective seat and sealing seat, figure 6 in longitudinal section a sleeve element and one of e spiga with an arrangement of protective seat and sealing seat, figure 7 in longitudinal section a system of protective seat and plug seat of a connection without stop. Figure 1 shows the fundamental considerations, s Reading that in the upper part is represented in partial section with forces introduced to the lip 4 = unthreaded portion of the tang element - like short hollow cylinder of thin ared with little variation in thickness the wall, which is considered as the most critical part compared to the sleeve element. In the lower part of figure i the results of the use of theoretical foundations of the theory of envo luras for a hollow cylinder with introduction of the force Fu at the end 5 of the lip 4 and with the introduction of force Fu 'are represented schematically a distance from end 5 of beat 4 and not subject to the influence of force Fu. The abscissa indicates the distance of the end 5 of the lip 4 and on the underside, provided with signs, the transverse force, the bending moment as well as the flexion as a function of the site. The left side in the diagram shows exemplary the ibicación of a contact zone in the lip 4. If now in this plane are introduced peripheral forces Fu, then these produce a flexion 1 (drawn line), forces: transverse 2 (striped line ) and bending moments 3 (dotted line), which vanish in the form of strongly damped oscillations. The frequency of these oscillations and consequently the longitudinal extension of the loads and geometric variations are determined in this case by the geometry of the lip 4 (radius, thickness). The magnitude of the loads and deformations is a function of the magnitude of the peripheral force and at what distance from the end 5 of the lip 4 it attacks. To obtain the same bending 1 as in the case of the load at the end 5 of the lip 4, depending on the distance required forces of up to four times the magnitude. In. the right part of the figure this case with the peripheral force FL 'higher is marked with the arrow F longer compared to Fu. As a result of the greater peripheral force Fu 'the transverse forces 2' and the bending moments 3 'are also considerably higher, the bending moments 3' having an inverted sign in the area of con: act, in comparison with the from the end 5 of the lip 4. These moments produce tension-bending stresses inconvenient for the differential tension instead of the pressure-bending stresses with the introduction of force at the end 5 of the lip 4. The peripheral forces are produced by a flexure pre-set to screw (superposition in the contact area). Depending on the location of the contact zone, the following effects are obtained for equal contact pressures (Hertzian surface pressure due to the peripheral force that is generated). a) Location of the contact area near the. end 5 of the lip 4: For the generation of the peripheral force required for the surface pressure, a high flexor (superposition) is required. However, this also causes strong tangential stresses that can exceed the limit strictness A retraction of the flexure is only possible with a reduction of the contact surface, or by means of the connection with a stop back which has an inverse inclination, that is, a negative shoulder 5 (see Figure 6). In the latter case, the peripheral forces increase due to the radial component of the pre-tension force. However, depending on various factors, it is not possible to sufficiently control the magnitude of the "surface pressure" additional "and the consequence will be an overload." Under axial tensile stress, the effect of the prestressing force is reduced again and eventually it is eliminated by completeness. and negative. b) Location at a greater distance from the end 5 of the lip 4. In the case of this location of the contact zone, a high surface pressure is already produced with little bending and little tangential tension. In the case óe to provide a stop shoulder the external axial loads (pre-tension by moment of shock, compression a > ial) include to a lesser degree in the contact zone. What has an inconvenient effect is the relatively high 2 'bending moment with the tensile-flexion stresses that result for the entire tension state. Figure 2 shows in the partial figures ac the flex on 1.2 - 1.2", the transverse forces 2.2 - 2.2" and the bending moments 3.2 -3.2"for a labic with two contact zones (seats) cor optimal choice of the distance between the seat 1 (seat is protective) and the seat 2 (seat plug) from the end to the lip or stop end on the one hand and the thread entry on the other hand The trazaaa line represents the ootimo, when in accordance with the invention the forces acting on the seat 1 (protective seat) influence the load of the seat 2 (seat shutter). Lines 1.2 ', 2.2', 3.2 'in each case with stripes show complementarily the curve if only one ashore 2 is located at a great distance from the end of the lip and lines 1.2", 2.2", 3.2"dotted if only a seat 1 is located a short distance from the end of the lip. In the partial figure a it can be seen that the flexure 1.2 in the seat 1 is chosen larger than in the seat 2, according to the invention, specifically in ure range of 1.15 to 1.30 times. The superposition of the forces and moments according to the invention in both seats 1, 2 is especially apparent from partial figures b and c. It is true that the arrangement of a protective seat (seat 1) reduces the transverse forces 2.2 compared to 2.2 ', / consequently the surface pressure, but the remaining amount still has a sufficient magnitude to obtain a sufficient sealing effect. The jumps of the curve that can be seen in the curve of the transversal force represent the peripheral forces introduced in the seats or contact zones, while its magnitude is reproduced by the height of the jump. What is essential for the total load is the minimization according to the invention of the harmful tension-bending stresses by positive bending moments 3.2 compared to 3.2 'according to partial figure c. Figure 3 shows the influence of a pre-tension force with the radial component 6 in the case of arranging a back with a small stop angle. The subdivision in the partial figures a-c is the same as in figure 2. In the partial figure b the radial component 6 is illustrated applied at the end of the beam, specifically as a positive transversal force. It can be seen that the transverse force 2.3 does not in fact have any influence on the seat 2 (sealing seat). The bending moment 3.3 of the partial figure c which is considered harmful was even reduced a little compared to figure 2 due to the pre-tension. Without the function of the protective seat (seat 1), even in the case of the small radial components 6 of the pre-tension that is established here, in the seat plug (seat 2) s' would produce surface pressures and flexure-tension stresses considerably larger harmful (lines 2.3 ', 3.3' compared to 2.3, 3.3). Figure 4 shows the influence of the angle of the back of the stop on the flexion (a), the transverse force (b) and the bending moment (c). In the partial figure b it can be seen that with a stop angle greater than 10 degrees (15 ° in the example) the transverse forces 2.4"in the sealing seat are reduced compared to 2.4, whereas in the seat 1 more than 'they are duplicated, which leads to differential tensions that' exceed the limit of stricture. Due to this, an angle of less than 10 degrees (6th in the example) must be chosen, which has no influence on the sealing seat (2.4 'in comparison with 2.4). The variation of the state of tension in the protective seat is also kept within admissible limits. From figures b and c, the protective function of the seat 1 can be clearly seen that the forces introduced at the end of the lip, even in the case of a small stop angle, show effects up to the entrance. you »* ^? ^^. ^ ¿^^, * & This is how they thread, but they do not exert any adverse influence on the sealing seat itself. Figure 5 shows the optimized distances according to the invention between the end of the lip and the protective seat, the protective seat and the sealing seat, the sealing seat and the entrance of the thread, and the bends, cross-sectional fuers and moments of flex that they result (lines 1.5, 2.5, 3.5). This results in values that were already discussed extensively in figure 2. If the seat 2 (seat plug) moves closer to the seat 1 with a simultaneous increase in distance with respect to the entry of the thread, then for this position of seat 2 'results in a transverse force 2.5', which is too small to guarantee a sufficient sealing effect. A seat location 2"too far from the seat 1 and close to the entrance of the thread results in very high transverse forces at this point and the exceeding of the allowable surface pressure Figure 6 shows a sleeve and ur element of a tang of constructive design according to the invention The sleeve element 7 comprises a portion 8 of internal thread extending from the front face 9 to the thread-free portion 10. The area 10 terminates in the shoulder 11 of stop. the invention, in portion 1C • --fe ^ ate., - -A - ^.-.- ^, ". .. < > »* A &A? ÍÍ X« *. Xs &aik? X *,: "._ ,, .. ^.? - T & A ^ J ^ ZI * In the contact area 12 of the sealing system, two seats 13, 14 of convex construction are arranged in the free-thread area. Of these, the seat 13 closest to the spain 11 is designed as a protective seat and the seat 14 plus 5 is moved away as a sealing seat. The radii of the bulges are characterized by the corresponding arrows. According to the invention, the stop back 11 comprises a slightly negative inclination of < 10 ejrados. intimate end 16 of the thread and the transition area 12 remains a transition portion 17 for removing the cutting tool from the thread. The pin member 18 comprises an external thread portion 19 configured in a complementary manner to the thread portion 8 of the sleeve element 7. The portion 19 of external thread is transformed when finished in the thickness 20 of exit of tube 21. Before the inlet 22 of the thread there is an unthreaded portion 23 which is then transformed into a stop back 24 which cooperates with the backrest 11 of the element 7 ae cuff. From the back 24, a conical jacket surface 25 extends beyond the position of the abutted seats 13, 14 of the sleeve element 7. The remaining shirt surface 26 of the portion 23 non-threaded can be extended with the same cone or, to increase the elasticity of the lip, be designed with a lower inclination or cylindrical. Figure 7 shows by segments the producer according to the invention of a tubular connection without stop. In contrast to the embodiment according to FIG. 6, the conical sleeve surface 25 of the bolster element 18 is replaced by a double cone contour. For this, the spigot element 30 then comprises two conical surfaces 32, 32 of different inclination to the remaining sleeve surface 31. In this case the sealing seat is formed by the seat 34 which is farthest from the front face 36 of the tang element 30, and the protective seat by the nearest seat 35, provided that it has a tapered surface 33 of greater inclination . In the sleeve element 37 a convex convex contour is provided in the area of the protective seat 38. Compared to the embodiment according to FIG. 6, it has a larger radius than the protective seat 13 and tops at the center 40 of the sleeve following a slope 39. Alternatively, it is also possible to lift a? conical jacket surface corresponding to the cone of the spigot eel 30 instead of the inclined and convex contour.

Claims (9)

1. CLAIMS 1. Tubular connection with a sl element comprising an internal thread portion extending axially from the end to the interior followed by a non-threaded portion, and with a tang element comprising a thread portion configured in a manner complementary to the of the sl element, followed by a non-threaded portion also called a lip extending to the front end, and in which the threaded portions come into contact with each other when being screwed to form a metallic sealing system, whereby in the The sealing system provides two contact zones axially spaced apart from each other and of which at the time a contact area has geometrically different cross-sectional contours, and the contact zone cue being at a shorter distance from the end of the lip is designed as a protective seat and the contact area that is farthest from the end of the lip is designed as a sealed seat r, characterized in that the internal front face of the sl element and the external front face of the shank element of the respective non-threaded portions are configured so as to form a stop back, and because for the obturator seat it is • «.goafea-rf. i ^ t, chooses a distance at the entrance of the thread whose geometric factor is determined directly proportional to the average value of the cross sections in the individual contact zones, and a degree of flexion that in the sealing seat produces: a surface pressure of at least six times the surface pressure theoretically required, but a maximum of 90% of the elongation limit in relation to the material used, being that the measure of the radial deviation due to flexion is always greater than the overlap of the thread in the area from the entry of the thread and defining as a thread entry a plane in which the threads of the pin and the sl have the first contact on the side of the lip, and because for the protective seat a distance is chosen cor end of the lip on the one hand and with respect to the obturator seat on the other hand whose geometric factor is determined directly proportional to the average value of the sections cross sections in the individual contact areas, as well as a degree of bending of 1.15 to 1.30 times greater in relation to the sealing seat, and that depending on the degree of flexion chosen for the sealing seat, after being screwed it results in the sealing seat a total tension that at most is equal to or less than the elastic limit of the material used, with the complete conservation of the sealing function X Xa and? K ¿g even taking into account manufacturing tolerances and overlapping loads and externally attacking moments. Tubular connection according to claim 1, characterized in that the =; distances between the protective seat and the former L-paddle on the one hand, and between the protective seat and the sealing seat on the other hand, as well as between the sealing seat and the thread entry satisfy the following conditions. XLS From 0.05 X fl to 0.08 x fi with fl = V AL + As sD From 0.10 X f2 to 0.20 x f2 with f2 = V As + AD XDG From 0.15 X f3 to 0.25 x f3 with f3 = AD + AG They mean: X distance A cross section fi, f2, f3 geometric factor indexes L lip end S seat protector D seat plug G thread entry iüUMMit ^ í ** & & amp; 'Sa .., - ~ íj & B ¿. ~~ m * ** »* 3. Tubular connection - according to claim 1 and 2 ,. characterized in that in the oblique back an inclination of < 15 degrees. Tubular connection according to claim 3, characterized in that the inclination is < 10 grades. Tubular connection according to any one of claims 1 - 4, characterized in that in the case of a tubular connection with abutting back the spike element comprises in the non-threaded portion a surface ce: straight contact which; it extends inclined, and the sl element two convex contact surfaces of: convex configuration cooperating with it. 6. Tubular connection according to any of claims 1 - 4, characterized in that in the case of A Tubular Backless Stop Connection The contact surface of the shank element comprises two portions with a different conical inclination, wherein the portion with the highest conical inclination cooperates with the contact surface of the sleeve element configured as a seat 20 protector. Tubular connection according to claim 6, characterized in that the inclination of the conical surface of the protective seat is designed at least 20% steeper than the conical surface of the sealing seat. 8. Tubular connection according to claims 1-7, characterized in that the < Convex convex contour of the obturator and protective seats is applied in the -or threaded portion of the shank element and the complementary part of the sleeve element has a conical-sleeve surface. Tubular connection according to claims 1-8, characterized in that the sealing system is arranged on the external side of the tubular connection. 10 ^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ i ^ 2 ^^^ £ ¡^ SUMMARY The invention relates to a tubular connection with?. n sleeve element comprising an internal thread portion extending to > from the end to the interior to which follows a non-threaded portion, and with a shank element comprising a thread portion configured in a complementary fashion to that of the sleeve element, followed by a non-threaded portion also referred to as lip extending to the front end, and in which the threaded portions come into contact with each other when being screwed to form a metallic sealing system, with two contact zones axially spaced apart from one another and being provided in the sealing system. : which at least one contact zone has geometrically different cross-sectional contours. The invention is characterized in that the contact area that is located at a smaller distance from the end (5) of the lip (4) is designed as a protective seat and the contact area that is located further away from the end (5) of the lip ( 4) is designed as an obturator shutter, being that for the sealing seat a distance is chosen at the entrance to the thread and a degree of bending (1) that in the seat-obturator produces a surface pressure of at least six times the surface pressure theoretically required, perc as a maximum of 90% of the limit of elongation in relation to the material used, being that the degree of flexion (1) is always greater than the overlap of the thread in the area of the entrance of the thread and defined as a plane enters in the thread in which the threads of the pin and the sleeve have the first contact on the side of the lip, and because for the protective seat a distance ccr is chosen with respect to the end (5) of the lip (4) by one p art and with respect to the sealing seat on the other hand, as well as a degree of flexion (1) of 1.15 to 1.30 times greater in relation to the obturator seat, than depending on the degree of flexion (1) chosen for the obturator seat, after being screwed it results in a sealing tension at the sealing seat which is at most equal to or less than the elastic limit of the material used, with the complete preservation of the sealing function even taking into account the manufacturing tolerances and the superposition of the charges and moments that attack externally. Fig. 1