FR2795482A1 - SECURITY GROOVE APPLICABLE TO PRESSURE TANKS - Google Patents

Abstract

Safety groove applicable to pressure vessels consisting of a linear groove of variable thickness (11), (12) both on fixed equipment (in this case, the groove will be on the cylinder) as on portable equipment: then, the groove will be made far from the cylindrical zone and at the place where the angle formed by the tangent to the bottom of the cylindrical wall is at least 60degre, that is to say at the place where the angle resistant is 30degre. It can have all types of sections and can be produced using various tools such as an angular milling cutter or a laser. The tank may be covered with a material in which will be incorporated a line of porous material or a line of similar material not resistant to pressure, which will be placed on the area having the least thickness. Use for carbon dioxide beverage containers, fire extinguishers, compressed air tanks and liquefied petroleum gas tanks.

Description

SAFETY GROOVE APPLICABLE TO PRESSURE TANKS

DES C R I PT ION

OBJECT OF THE INVENTION

  This descriptive memory refers to a patent application, relating to a safety groove applicable to pressure vessels, as can be the packaging containers of carbonic drinks, compressed air tanks, GLP tanks, etc. Likewise, in this descriptive memory, considered to be the subject of the invention, we also seek to study the application on the mentioned groove of a porous material of low resistance, in the specific case of containers provided with a covering, which would make it possible, from the incorporation of the porous material, to eliminate the increase in the rupture pressure, which the covering would cause, and consequently, to further reduce the minimum thickness remaining in the

  constituent material of the container.

  The aforementioned safety groove functions as a safety valve at a pre-established pressure, which makes it possible to avoid explosion once the normal rupture pressure of the container is reached and, which also makes it possible to reduce in same time

  possible risks of human or material damage.

FIELD OF THE INVENTION

  This invention finds its application in the field of industry relating to the manufacture of pressure vessels -2-, as is the case of carbon dioxide drinks containers, fire extinguishers, as well as compressed air tanks , GLP containers or tanks, manufactured using materials of all kinds, regardless of whether the material used is metal, plastic, composite, etc., this is also the case for containers manufactured using several materials such as metal containers

  covered with rubber or polyurethane.

PREVIOUS OF THE INVENTION

  Generally, pressure vessels are designed to withstand at least 1.5 times the design pressure; normally the actual relationship between working pressure and breaking pressure is much greater, given that, regardless of whether it has to withstand pressure, the pressure vessel must have a resistance capable of guaranteeing structural stability, which normally raises the thicknesses to values much higher than the design values, and consequently, to the value of the breaking pressure. This type of container already has, or during its installation, safety elements such as valves, discs, etc., which normally are located very close to the pressure adjustment equipment. However, it has been realized that fraudulent manipulation can occur in the incorporated security system, which, in the eventuality of the containers used as packaging for storing beer, carbonic drinks, etc., - 3 - can pressurize the container beyond the pressure stipulated by the manufacturer, thereby succeeding in creating an inherent risk of explosion of

the same packaging or container.

  If the explosion happens to occur while the container is filled with gas, the effects caused by it are usually quite serious, even disastrous if the explosion happens to occur in a closed place, with beings humans inside, as may be the case if the explosion occurs in a restaurant, bar or private property, etc. With regard to other types of containers, as may be the case with GLP container containers, they can be subjected to extreme situations such as for example fire, freezing of the safety valve etc., circumstances which can create the same situation, given that in the event of a fire, the risk to which firefighters are exposed is aggravated by the mechanical risks of explosion, which can occur if the container in question does not have an element

  able to avoid the risk of explosion.

  The solicitor is aware beforehand of the fact that, for all types of receptacles, as can be barrels or receptacles of the same kind, and with a view to eliminating the risk mentioned, rupture discs provided with 'a constant thickness and having a circular or square shape intended to be placed on the packaging, have been created. In addition, these rupture discs were designed to guarantee the explosion

  localized at minimum pressure, of course.

  -4- However, the existence of these discs does not completely eliminate the possible destructive effects since these same discs can cause the instantaneous rupture of the entire internal surface where they are placed, which can also lead to leakage. of all the gas contained inside the packaging, thus causing such a reaction that propels the container with a rapid and strong movement ("jet" effect), the results of which have been observed in

  some cases are considered to be catastrophic.

  By means of Patent DE 375977 C2 / BLEFA, we are aware of the existence of an invention proposing the production of a slit of circular shape and of uniform depth, without however reaching 30 , which would make it possible to eliminate the possible risk of detachment of the internal zone from the zone delimited by the slot, since it functions as a junction point or hinge, and thus presents itself in the same way as during of a manual opening operation of a beverage can. This solution avoids the violent detachment of part of the container, but does not make it disappear

  in no case the "jet" effect and its risks.

  As further progress, the canvasser has

  knowledge of the existence of the EP- Invention Patent

  0686120 B1 / SCHAEFER in which we describe and claim the fact that, if the slit is made in a circular fashion and has a variable depth in one of the bottom of the container which has a collar in the middle, the result obtained when the increase in pressure occurs, causes the rupture gradually, which eliminates the "jet" effect which occurred in the case of the solution described previously in the Patent for Invention applied for in Germany under the number

3757977.

  However, it should be noted that the solution presented in Patent EP-0686120 poses the following problems. Namely: - The inexcusable necessity of the existence of a

collar in the middle or a patty.

  - The difficulty of technical thickness control. - The risk of accidental rupture during

normal use.

  - The additional difficulty in the case of

  the existence of an overlap in the safety zone.

  Concerning the necessity of the existence of a collar in the middle or of a cake, it should be emphasized that in the cited invention patent, known as

  the number EP-0686120, and also in the description

  of this Patent for Invention only in its claims,

  in particular in claims 1,3,7 and 8, one

  reflects and proposes that the invention requires the presence at least in one of the bottom of the container of a collar in the middle or a pancake in order to be able to produce

  the notch on the lateral part of the collar in question.

- 6 -

  As for the control of the minimum thickness, it should be noted that, the fact of making the safety disk in the form of a total circle or a semicircle, and the fact of placing it in a cap, which is normally obtained by means stamping, creates difficulties during the precise production of the disc, since the minimum remaining thickness must be independent both of the initial thickness which varies from one piece to another and in particular of the shape of the cap, the shape of its curvatures which can cause the position of the material to vary relative to the control point

  along the length which delimits the disc.

  Considering what has been advanced before, it is advisable to seek an area capable of having a greater thickness in order to obtain the same specified and recommendable pressure for placing the disc.

  in the area close to the cake or the collar.

  Regarding the risk of accidental rupture during use, it should be noted that it is obvious that, unlike the advantages specific to the disappearance of the possible risk of explosion, the rupture disc system has an ease of sabotage or even accidental rupture, due to external force

  located on the very surface of the disc.

  Similarly, it should be noted that with regard to the additional difficulty in the event of the existence of an overlap in the safety zone, and as indicated on the Patent for Invention EP-0686120, the use of recoveries by themselves cause an increase in the rupture pressure of the disc, which oscillates between 5 bars and 10 bars, which represents the number of bars required by the mechanical production of the 7 - disc in question, concerning the rupture pressures they oscillate between 12 bars and 17 bars, and in the case of a design of the base-cover assembly, they oscillate between 22 bars, or from 25 bars to 30 bars, in the case of a design of the assembly base-covering, they oscillate

between 35 bars.

  Placing the disc in the base material of the container at 12 bar instead of 22 bar requires a further reduction in thickness, a very complex operation since it involves placing the disc in question in the area close to the slab, without taking into account the aspect of mechanical safety in relation to the possibility of sabotage, nor the negative aspects in connection with the direct exit of the jet of escape, and without the advantage of being able to direct it against other elements as it is the case of the barrel circles, the handles of the cylinders, etc., This part considers that as a solution to the need to have the central collar mentioned above, it is advisable to have a invention which, due to its design as regards the groove, not only does not need this collar at all, but which in addition, could be carried out as well on the bottoms as

  on the cylindrical part of the container.

  As a solution to the difficulty of technical thickness control, there should be an invention allowing the groove to be made on any part of the cap, since the control of the minimum residual thickness should be carried out. by using, in particular, as a reference point, a point of the line of reduced thickness, instead of all the points of the circular line,

  that is, from the limit of the surface of the disc.

  In addition, one should count on the guarantee that the part is in the correct position. In this case, one should only demand pressure on a

  point, instead of the entire outline of the disc.

  Regarding the risk of accidental rupture during normal use, there should be an invention that can significantly reduce this possibility in case there is not a debilitated surface as is the case with other solutions, but rather a small

  length which does not cause the concentration of efforts.

  Finally, concerning the additional difficulty in the absence of a covering in the upper zone, the invention considered to be the most suitable should use in the weakest zone of the groove a porous material incorporated inside the covering. , without causing an increase in pressure, which would make it possible to locate the rupture zone in the most suitable situation for safety and to make the groove on the basic material without the need to reduce the thickness, this being possible thanks to the covering produced when making the groove in question for the same pressure as that fixed for the base-covering assembly, that is to say, that fixed in the examples considered from 22 to 35 bars, instead of

12 to 25 bars.

  However, in this specific case, the applicant is not aware of the current existence of an invention having the characteristics -9 considered to be the most suitable for the

  current problematic solution in this matter.

DESCRIPTION OF THE INVENTION

  The safety groove applicable to the tanks

  under pressure that the invention proposes, constitutes in itself

  even an obvious find in its specific field of application, since it tackles in a global and complete way the problem mentioned before. More concretely, the safety groove applicable to pressure vessels, considered to be the object of the invention, has the advantage of having an opening programmed gradually at a pre-set pressure, which allows d 'get the following effects. Namely: - Only opens the area provided to the extent necessary to evacuate the flow that enters or occurs inside, so that instead of a

  explosion, an exhaust occurs.

  - The outlet is oriented in the desired direction, and most of the released flow leaves towards the intended direction, which allows to adapt the

drawing at the slightest risk.

  - The realization and the mechanization of the groove are done in a simple and precise way and are independent of the position of the container, which thus guarantees the existence of a residual thickness, independent of the curvature and which allows the calibration of

  the tool with maximum reliability.

- 10 -

  - Regarding the safety groove which is proposed in this invention, a groove designed for the lowest rupture pressure and by means of the use of a porous material placed in its point of commencement of rupture (minimum thickness), its properties are not lost when using overlays, regardless of the thickness thereof, if the increase is completely eliminated which, without this solution, could be 5 - 10 bars. To do this, it is possible to maintain an acceptable value at the point of minimum thickness which, if not, could cause ruptures following

little knocks.

  - As a consequence of what has been said before, the risk of accidental rupture during normal use of the container, when it is subjected to external forces, that is to say, to blows, shocks, etc. , localized, is minimal, since it does not present a debilitated surface but rather a

  length, which eliminates the concentration of effort.

  Likewise, it should be stressed that, if one takes into account that most pressure vessels have a central cylindrical part which closes by means of two hemispherical, semi-elliptical, etc. surfaces, safety must be carried out in the most appropriate way and in the most adequate area to obtain

the target set.

  In the invention, there is the use of a conical tool which, since it is

  asymmetrical, opens in the desired direction.

- he -

  As a consequence of what has been mentioned, the use of one or more linear grooves made on a package by means of any system having a variable depth of 0 maximum, circular, triangular, trapezoidal, etc. causing a debilitation of the sheet metal or of the material used, causes in the event of an increase in pressure, beyond the working pressure, rupture at the pressure provided for in a controlled manner, as well as with regard to the size of the opening only in terms of direction and exhaust outlet, thus maintaining maximum impact resistance during normal use and without the need to reduce the thickness of the mechanized part, to compensate for the increase in resistance covering using a porous material for this purpose on the area covered by the groove.

DESCRIPTION OF THE DRAWINGS

  To complete the description carried out in

  at this time and in order to help a better understanding of the characteristics of the invention, the present descriptive memory, considered to be an integral part of the latter, is accompanied by a set of very illustrative and non-limiting plans in which The following is represented: FIG. number 1. Corresponds to a series of different types of pressure vessels, on which the incorporation of the object of the invention is achieved, namely a safety groove applicable to pressure vessels . It is obvious that it can also be incorporated into other types of pressure vessels not reflected in this figure, as may be the case.

- 12 -

  a tank of GLP, beer barrels or similar liquids, tanks and a

bottle of GLP.

  Figure number 2.- Shows the upper zone of a pressure vessel, in which are reflected the tensions which occur on any

what a finite element of the surface.

  Figure number 3.- Shows the object represented in figure number 2, in which a restangular or elliptical projection groove, made on the

  bottom or on the ferrule is incorporated.

  Figure number 4.- Corresponds to a view by

  A-A 'of the object shown in figure number 3.

  Figure number 5.- Shows a view by B-B 'of

  the object shown in figure number 3.

  Figure number 6.- Corresponds to a groove that differs from those mentioned in Figures numbers 3 and 4, both in terms of its projection, as in terms of its section, since it is obtained at by means of a conical tool, which makes it possible to obtain, by means of this drawing, the rupture and

  opening in the desired or preset direction.

  Figure number 7.- Shows a view by C-C 'of

  the object shown in figure number 6.

  Figure number 8.- Shows a view by D-D 'of

  the object shown in figure number 6.

  Figure number 9.- Shows a sectioned side elevation view of a package, on

- 13 -

  which have been made the relevant groove and the subsequent coating of the groove in question by means of a covering material, where the porous material is

  found incorporated on the safety groove.

  Figure number 10.- Finally, corresponds to a view by E of the object shown in Figure 9.

  PREFERABLE EMBODIMENT OF THE INVENTION

  Considering these figures, we can observe how the safety groove applicable to pressure vessels, is presented as a linear groove of variable thickness, produced on equipment or containers (1), (2), (3) and ( 4), or on others having a similar application, intended to contain gases or liquids under pressure; the purpose of the groove in question is to act as a safety element or zone for the exit of the contained product when the pressure for which it was designed is exceeded, it constitutes, in addition to the characteristics of the material in which the groove has been achieved, the element which defines the minimum thickness remaining at the location of the maximum depth of the groove in question. In addition, each of the equipment or containers can

have one or more grooves.

  The security groove can be made in the most suitable place depending on the design and use, and as concrete solutions proposed, the following solutions are considered to be priority:

- 14 -

  In stationary equipment, which is normally produced in accordance with what has been indicated above, the groove will preferably be produced on the cylinder, as is reflected in FIGS. 3,4,5,6 and 7, grooves marked with references (11), (12), and (13), while in portable equipment, the groove will preferably be made on one of the bottoms, preferably on the upper bottom, as is reflected in the figures mentioned . The groove will be located far from the cylindrical zone and near the place where the angle formed by the tangent, at the bottom and the wall of the cylinder is 60, that is to say, where o

the resistance angle is 30.

  As can be seen in the accompanying figures, the shape of the groove may be different; this partly depends on the production process as seen in Figures 3,4 and 5, the grooves (11) and (12) have a section obtained by means of a rotary cutting tool, or by means of a triangular punch, concretely marked with the reference (12), although it must be indicated that the production of the grooves by means of a laser can be obtained from

any shape.

  The section of the groove can take practically any shape, as can be seen in figure number 5, that is, it can be

  rectangular, triangular, trapezoidal, half

  circular, etc., According to figures numbers 6, 7 and 8, the groove (13) may have an asymmetrical section, for example in the case where it would be produced by means of a conical cutter, which has the advantage of allowing

- 15 -

  the orientation of the exhaust in a pre-

  fixed. According to figures numbers 9 and 10, it is noted that in the reservoirs (1), (2), (3) and (4), which are sometimes covered with basic material (20), in which a certain type of imprint thus locally reducing the resistance of the material, as well with regard to the solutions of constant thickness as with those of variable thickness, the covering in question was applied by the next, placing the equivalent porous material (21), with practically no resistance to pressure, material placed just above the point having

the most reduced thickness.

  No need to expand further

  on this description so that any expert in

  the material understands the scope of the invention while

  like the benefits that it has.

  As well the materials, the shape, the size, as well as the arrangement of the elements can vary if however this does not suppose any alteration to the nature

essential of the invention.

  The terms used to describe this memory should always be considered in their most meaningful sense.

  broad and not in their limiting sense.

Claims (5)

  1. Safety groove applicable to pressure vessels, in particular those intended to be incorporated in equipment or in receptacles such as receptacles (1), (2), (3) and (4), designed to contain gases, or liquids under pressure, said groove being intended to serve as a safety zone when the pressure for which the tank has been designed is exceeded and it is characterized in that the groove (11), (12) or (13) has a thickness corresponding to a rupture of the container when the pressure value has exceeded a determined threshold, said groove being able to be unitary or in several places of the container. 2. Safety groove applicable to pressure vessels, according to the first claim, characterized in that in the case of fixed equipment, it is preferably carried out on the cylinder and longitudinally.20 3. Safety groove applicable to pressure vessels, according to the first claim, characterized in that in the case of portable equipment, it is preferably carried out on one of the bottoms, concretely on the upper part and far from the cylindrical zone but at the place where the angle formed by the tangent to the bottom and the wall of the cylinder is 60 minimum, that is to say, where the resistant angle has 30 maximum, in a situation tangent to bottom circle. 30 4. Safety groove aDopplicable to pressure vessels, according to the first claim, characterized in that the section of the groove can adopt practically all possible forms, that is to say, it can   be rectangular, triangular, trapezoidal, half   circular, etc. 5. Safety groove applicable to pressure vessels, according to the first claim, characterized in that in the case of tanks provided with an overlay in which a certain type of imprint has been produced, thereby locally reducing the resistance of the material and to which the covering (20) is applied, porous material or the like material (21) will be placed, material without resistance to pressure, and which will be   located above the point with the smallest thickness.