FR2961194A1 - Manhole for tank body or tank lorry used for transporting e.g. liquid products, has sealing devices defining hermitically sealed annular chamber between annular and peripheral flanges when tightening unit connects flanges - Google Patents

Abstract

The manhole has a shell comprising an opening surrounded by an annular flange (9), and a cover surrounded by a peripheral flange (13). A tightening unit connects the flanges so as to hermetically seal the opening. Sealing devices (17, 18) assure sealing between the peripheral and annular flanges. One of the devices is spaced radially from the other device. The devices define a hermitically sealed annular chamber (19) between the annular and peripheral flanges when the tightening unit connects the flanges. A measuring unit i.e. manometer, measures the pressure in the chamber. An independent claim is also included for a method for verifying sealing of manhole of a tank or tank vehicle.

Description

MAN HOLE FOR TANK OR TANK VEHICLE AND METHOD FOR VERIFYING THE SEALING OF SUCH A MAN'S HOLE

TECHNICAL FIELD OF THE INVENTION The present invention relates to a manhole for a tank or tank vehicle having improved sealing. The present invention also relates to a tank or a tank vehicle for the transport of liquid, gaseous or powdery products comprising such a manhole. The invention also relates to a method of checking the tightness of the manhole of such a tank or tank vehicle.

STATE OF THE PRIOR ART The transport of liquid, gaseous or powdery products is generally carried out by tanker or tanker vehicle.

These cisterns or tank vehicles generally comprise a tank provided with a manhole. Such a manhole is for example described in document FR2627468.

The manhole is a hole that allows access to the inside of the tank from the outside. The manhole can in particular make it possible to visualize the contents of the tank without emptying it, to take samples from inside the tank, loading operations, cleaning operations or maintenance interventions in the tank. .

The manhole generally comprises a ferrule mounted on the tank of the tank and a cover which can be moved between an open position in which the interior of the tank is accessible, and a closed position in which the interior of the tank is accessible. tank is inaccessible from the outside. In the closed position, the cover must theoretically hermetically close the access port to the tank.

However, the manholes of the prior art sometimes have the disadvantage of not being completely hermetic, which is particularly detrimental when the tank contains perishable goods or hazardous materials.

In addition, in the tanks of the prior art, it is not possible to know if the manhole is properly closed or not, and therefore it is not possible to prevent the introduction of air or polluting particles in the tank.

Furthermore, in the tanks of the prior art, it is also not possible to prevent leakage of the materials contained in the tank to the outside, which is particularly detrimental in the case where the tank contains dangerous substances. or polluting.

SUMMARY OF THE INVENTION The invention aims to overcome the disadvantages of the state of the art by providing a manhole which has improved sealing.

Another object of the invention is to provide a manhole provided with means for detecting the poor sealing of the closure of the manhole. Another object of the invention is to provide a manhole whose sealing can be improved when it is not perfect.

Another object of the invention is to propose a tank or a tanker vehicle provided with a manhole whose closure is always perfectly hermetic. Another object of the invention is to propose a method enabling to check that the closing of a manhole is always perfectly hermetic.

Another object of the invention is to provide a method for adjusting the degree of tightening of the cover of a manhole so that this manhole is always closed in a perfectly hermetic manner.

To do this, is proposed according to a first aspect of the invention a manhole for tank or tank vehicle which comprises: 10 - A ferrule extending around a reference axis, the ferrule having an opening surrounded by a annular flange; a lid surrounded by a peripheral flange, the lid being able to seal the opening of the ferrule, the peripheral flange being located above the annular flange when the lid closes the opening of the ferrule, Clamping means adapted to secure the annular flange and the peripheral flange so as to seal the opening of the ferrule, the manhole further comprising: a first sealing device capable of sealing between the peripheral flange and the annular flange, - a second sealing device capable of sealing between the peripheral flange and the annular flange, the second sealing device; e being radially spaced from the first sealing device, the first sealing device and the second sealing device defining between the annular flange and the peripheral flange a hermetically sealed annular chamber when the clamping means secures the annular and peripheral flanges. means for measuring the pressure in the annular chamber. By "tank" is meant a tank designed to carry or store products. The invention is preferably intended for tanks with a capacity of more than 500 liters, more preferably for tanks with a capacity of more than 1000 liters, and even more preferentially for tanks with a capacity of more than 5000 liters. The term "tank" includes storage tanks in the common sense of the term, tanks, tank containers (tanks contained in a frame), tank swap bodies (tanks for transport by rail and road) ...

"Tanker" means a tank designed to carry products and equipped with motor means. The invention is preferably intended for tank-vehicles with a capacity greater than 1000 liters, and even more preferably for tank vehicles with a capacity greater than 5000 liters. The term "tanker vehicle" includes tanker trucks, trailers or semi-trailers, tank wagons, etc.

The manhole according to the invention first allows a better seal than the manholes of the prior art because it comprises two sealing devices between the peripheral and annular flanges. Advantageously, the sealing devices are concentric.

The sealing device closest to the reference axis is hereinafter referred to as "internal sealing device", and the sealing device furthest from the reference axis is called "sealing device" outside ".

In addition, the manhole according to the invention makes it possible to detect if one of the two sealing devices fails when there is a pressure difference between the inside of the tank and the outside, or when there is A difference in pressure between the inside of the annular chamber and the outside. The manhole according to the invention preferably further comprises means for injecting a fluid under pressure into the annular chamber. The fluid under pressure is preferably air.

Thus, the manhole according to the invention makes it possible to detect whether one of the two sealing devices has failed. Indeed, when the manhole is closed by means of the lid, a pressurized fluid is injected into the annular chamber and the evolution of the pressure in the annular chamber is measured. If this pressure varies, it means that the closure of the lid is not perfectly sealed.

According to a preferred embodiment of the invention, the clamping means are adapted to be adjusted to improve the sealing of the sealing devices.

Thus, when it is detected that the closure of the cover is not perfectly hermetic, it is possible to increase the tightening of the cover on the shell so as to improve the sealing of the sealing devices.

The cover can be attached to the ferrule with screws that connect the annular flange and the peripheral flange. In this case, the clamping means are constituted by the screws. Advantageously, the clamping means comprise six screws distributed around the periphery of the annular and peripheral flanges.

Advantageously, the annular and peripheral flanges are annular and have the same external diameter.

Advantageously, the annular and peripheral flanges have the same internal diameter.

The means for measuring the pressure in the annular chamber are preferably constituted by a manometer.

Advantageously, the annular flange has an upper surface, the peripheral flange having a lower surface, the lower surface facing the upper surface when the lid closes the opening of the ferrule.

According to one embodiment of the invention, each of the sealing devices is preferably formed by: - a groove dug in the upper surface of the annular flange, - a seal which gathers the groove, - an annular projection projecting axially the lower surface of the peripheral flange, the annular boss being adapted to bear in the groove when the lid closes the opening of the ferrule.

According to another embodiment of the invention, each of the sealing devices is preferably formed by: - a groove dug in the lower surface of the peripheral flange, - a seal which gathers the groove, - a projecting annular boss axial of the upper surface of the annular flange, the annular boss being adapted to bear in the groove when the lid closes the opening of the ferrule.

In these two embodiments, the grooves are preferably cylindrical and concentric, and the annular bosses are preferably cylindrical and concentric.

The manhole according to the invention also preferably comprises alert means capable of sending an alert when the pressure in the annular chamber varies. In this way, if the tightness of the closure between the annular and peripheral flanges decreases during transport, the driver is warned of this reduction of the seal, so that it can increase the clamping of the annular flange and the peripheral flange.

The invention also relates to a tank or tanker for the transport of liquid, gaseous or powdery products comprising at least one tank, the vessel being provided with a manhole according to the invention.

The invention particularly relates to tanks or tankers for the transport of perishable goods, such as foodstuffs (milk, flour, etc.), powdery or gaseous products, pressure products, liquid chemicals, or hazardous materials. .

The invention also relates to a method for verifying the leaktightness of the manhole of the tank or of the tank vehicle as described above, the method comprising the following steps:

(i) Closing the lid on the ferrule opening and tightening the clamping means; - (iii) Measuring the evolution in the pressure in the annular chamber.

Advantageously, step (iii) is performed when the inside of the tank is under pressure. This process is particularly useful prior to unloading the vessel and during pressurizing thereof. This method can also be used during the transportation of a product under pressure in the tank. In fact, in these three cases, the inside of the tank of the tank is at an internal pressure different from the external pressure. However, following closure of the lid, if the manhole is perfectly closed, and no pressurized fluid is sent into the annular chamber, the pressure in the annular chamber is equal to the external pressure. Therefore, if there is an increase in the pressure in the annular chamber during deposition or pressurization, it means that the seal is not correct.

The invention also relates to a method for verifying the leaktightness of the manhole as described above which comprises, prior to step (iii), the following step: (ii) Injection of a fluid under pressure in the annular chamber. This process is particularly useful when transporting a product that is not pressurized in the tank of the tank. Indeed, in this case, a pressurized fluid is sent into the annular chamber and if it is found that the pressure of the annular chamber varies (and in particular decreases), it means that the seal is not correct. .

Advantageously, the method according to the invention further comprises a step of adjusting the degree of tightening of the clamping means when a variation of the pressure in the annular chamber is detected. In this way, when it is detected that the seal is not correct, the tightening of the cover on the ferrule is tightened so as to improve the seal.

Advantageously, the tightening torque of the clamping means is adjusted using a method according to the invention. Indeed, the method according to the invention can make it possible to determine in advance the necessary torque to guarantee optimum clamping of the annular flange and the peripheral flange. BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: FIG. 1, a side view of a tank according to the invention; 2, a sectional view of a manhole according to the invention, FIG. 3, a top view of a manhole according to the invention, FIG. 4, a schematic representation of the circuit. 5, a sectional view of the annular and peripheral flanges of the manhole of FIG. 2. For the sake of clarity, identical or similar elements are indicated by signs identical reference numbers on all the figures.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT

Figure 1 shows a tank according to one embodiment of the invention. This tank comprises a tank 1 pierced by two manholes 2 and 3.

One of the manholes 2 is shown more precisely in FIG. 2. The manhole 2 comprises a ferrule 4 having a first end 5 and a second end 6. The first end 5 opens onto a hole made in the wall upper 7 of the tank 1. The second end 6 opens on an opening 8 of the ferrule on the outside. The shell 4 is preferably cylindrical. The ferrule extends around a reference axis 10.

Throughout this document, the terms "radial" and "axial" refer to this reference axis 10.

The opening 8 of the ferrule is surrounded by an annular flange 9 located around the second end 6 of the collar 4. The annular flange 9 preferably has an inside diameter equal to the outer diameter of the ferrule. The annular flange preferably has an outer diameter greater than the outer diameter of the ferrule. The annular flange is therefore preferably projecting radially from the outer wall of the ferrule. The manhole according to the invention also comprises a lid 11 which is able to close the opening 8 of the ferrule 4. This cover 11 can be secured to the shell 4 by a hinge 12, as shown in Figure 2, or it can be completely removable.

The cover 11 is surrounded by a peripheral flange 13 which is able to be positioned facing the annular flange 9 when the cover closes the opening 8 of the shell 4. The peripheral flange 13 preferably has the same radial dimensions as the flange. annular 9 so that when the lid is in the closed position, the annular and peripheral flanges are superimposed perfectly.

The manhole according to the invention also comprises clamping means 14 which make it possible to secure the annular flange 9 and the peripheral flange 13 so as to seal the opening of the shell through the cover. The clamping means preferably make it possible to control the seal between the annular flange and the peripheral flange by controlling the tightening torque of these clamping means.

FIG. 3 represents a view from above of the cover 11. As can be seen in this figure, the clamping means preferably comprises six screws 15 which are distributed over the periphery of the annular and peripheral flanges 13. The tightening torque of FIG. these screws 15 is preferably controlled by a torque wrench.

FIG. 5 represents a sectional view of the annular and peripheral flanges 13. The manhole according to the invention comprises at least two sealing devices 17 and 18 which make it possible to seal between the annular flange 9 and the peripheral flange 13 when the lid is in the closed position. Each sealing device 17 and 18 extends around the circumference of the annular and peripheral flanges. The two sealing devices 17 and 18 are concentric. The sealing device 17 which is closest to the reference axis is called the internal sealing device. The sealing device 18 which is farthest from the reference axis 10 is called external sealing device. The sealing devices 17 and 18 each seal the space between the annular flange 9 and the peripheral flange 13 when the lid is in the closed position and the clamping means 15 are tightened.

The sealing device 17 and 18 define between the annular flange 9 and the peripheral flange 13 an annular chamber 19 which is hermetically sealed when the sealing of each of the sealing devices is correct. The annular chamber preferably comprises an orifice 27 hollowed through the annular flange 9 and which makes it possible to connect the annular chamber 19 with means for injecting a fluid under pressure into the annular chamber.

This pressurized fluid is preferably air. This air preferably comes from an air tank 28 on board the tank (see Figure 1).

The manhole according to the invention also comprises means for measuring the pressure in the annular chamber 19. A preferred embodiment of the sealing devices will now be described with reference to FIG.

In this preferred embodiment, the annular flange 9 has an upper surface 16. Two concentric grooves 20 and 21 are recessed in the upper surface 16. These grooves are each packed with a gasket 22, 23. When the annular and peripheral flanges are cylindrical, the two grooves are also cylindrical, and therefore the joints that garnish them are also cylindrical. Furthermore, the peripheral flange 13 has a lower surface 24 which faces the upper surface 16 of the annular flange 9 when the lid is in the closed position. The peripheral flange 13 comprises two annular bosses 25 and 26 projecting axially from the lower surface 24. These two annular bosses 25, 26 are concentric. The two annular bosses 25, 26 are arranged to bear in the two grooves 20 and 21 so as to ensure a perfect seal between the annular flange and the peripheral flange. More precisely, the annular bosses bear against the seals 22 and 23 that line the grooves 20 and 21. The two annular bosses are cylindrical when the grooves 20 and 21 are cylindrical.

The two annular bosses 25, 26 preferably have a rectangular cross section as shown in Figure 5. The two grooves 20 and 21 preferably have a rectangular cross section. Each rectangular groove has larger radial dimensions than the annular boss that will bear in this groove.

Thus, each of the sealing devices 17 or 18 is constituted here: - Of one of the grooves 20 or 21, - Of one of the seals 22 or 23, - Of one of the annular bosses 25 or 26. The degree of clamping clamping means enables the annular bosses to be inserted more or less deeply into the grooves 20 and 21 in order to improve the tightness of each of the sealing devices.

The presence of the two sealing devices makes it possible to have a double hermetic closure between the inside of the manhole and the outside.

A method for checking the seal between the annular flange 9 and the peripheral flange 13 will now be described. The lid 11 is firstly closed and the clamping means 14 are tightened according to a previously defined torque which theoretically guarantees the seal between the annular and peripheral flanges 13.

When the tank 1 is under pressure, for example during the transport of a fluid under pressure in the tank, before the tank is discharged or during the pressurization of the tank, no pressurized fluid is preferably injected into the tank. the annular chamber.

The pressure in the annular chamber is measured. If the sealing devices 17 and 18 are perfectly hermetic, and in particular if the inner sealing device is perfectly hermetic, the pressure in the annular chamber is equal to the external pressure. On the other hand, if there is a leak in the internal sealing device 17, the pressure in the annular chamber will increase.

Thus, if it is detected that the pressure in the annular chamber increases, it means that the inner sealing device 17 is not perfectly sealed. We can then tighten the clamping means or change the seal 20 if it is worn.

This method thus makes it possible to detect a leak in the internal sealing device when the tank contains a fluid under pressure.

Another method according to the invention will now be described. This process is particularly useful when transporting products that are not under pressure in the tank.

In this case, it first closes the manhole through the clamping means. Then, a fluid under pressure is injected into the annular chamber 19 via the orifice 27.

When the two sealing devices are perfectly sealed, the annular chamber is perfectly hermetic and therefore the annular pressure does not vary in the annular chamber.

On the other hand, if one of the two sealing devices is not perfectly sealed, the pressure in the annular chamber 19 will decrease. Thus, the fact of monitoring the pressure in the annular chamber 19 during the transport of a product in the tank, will make it possible to know if the manhole remains closed tightly during the entire transport.

If a decrease in pressure is observed, then we can tighten the clamping means, or even change the seals of the sealing devices.

The method described above can also be used to calibrate the torque with which the clamping means must be tightened so that the seal is perfect between the annular and peripheral flanges.

FIG. 4 represents an example of a pneumatic circuit for injecting air into the annular chamber 19 and making it possible to measure the evolution of the pressure in the annular chamber 19. This pneumatic circuit comprises one or more orifices 27 distributed over the circumference of the annular chamber 19 and which allow to inject uniformly pressurized air into the annular chamber 19.

The pneumatic circuit also comprises the air reservoir 28. In order to connect the air reservoir to the orifice (s) 27, the pneumatic circuit also comprises a pressure limiter R2 and a pneumatic distributor D2.

The hydraulic circuit also comprises a pressure gauge G1 for measuring the pressure in the annular chamber 19.

Naturally, the invention is not limited to the embodiments described with reference to the figures and other variants may be envisaged without departing from the scope of the invention. In particular, one could consider making grooves having a rounded section or annular bosses which have a rounded lower surface. Other clamping means could also be used to hermetically seal the space between the annular and peripheral flanges.

Claims (10)

REVENDICATIONS1. Manhole for tanker or tanker vehicle, the manhole comprising: - A shell (4) extending around a reference axis (10), the shell (4) having an opening (8) surrounded by an annular flange (9), - a cover (11) surrounded by a peripheral flange (13), the cover (11) being able to seal the opening (8) of the shell (4), the peripheral flange ( 13) being located above the annular flange (9) when the cover (11) closes the opening (8) of the ferrule (4), - Clamping means (14) able to secure the annular flange (9) and the peripheral flange (13) so as to hermetically close the opening (8) of the ferrule (4), the manhole being characterized in that it comprises: a first sealing device (17) suitable for to ensure the seal between the peripheral flange (13) and the annular flange (9), - a second sealing device (18) able to seal between the peripheral flange (13) and the annular flange (9), the second sealing device (18) being radially spaced from the first sealing device (17), the first sealing device (17) and the second sealing device (18) defining between the annular flange (9) and the peripheral flange (13) an annular chamber (19) hermetically closed when the clamping means (14) secures the annular (9) and peripheral (13) flanges, - means measuring (G1) the pressure in the annular chamber (19). 2. Manhole according to the preceding claim, characterized in that it further comprises injection means (27, 28) of a fluid under pressure in the annular chamber (19). 3. Manhole according to any one of the preceding claims, characterized in that the clamping means (14) are adapted to be adjusted to improve the sealing of the sealing devices. A manhole according to any one of the preceding claims, wherein the annular flange (9) has an upper surface (16), the circumferential flange (13) having a lower surface (24), the lower surface (24) ) facing the upper surface (16) when the lid (11) closes the opening (8) of the ferrule (4), each of the sealing devices (17, 18) comprising: - A groove (20, 21) ) formed in the upper surface (16) of the annular flange (9), - A seal (22, 23) which surrounds the groove (20, 21), - An annular projection (25, 26) projecting from the surface of the surface lower part (24) of the peripheral flange (13), the annular boss (25, 26) being able to bear in the groove (20, 21) when the lid (11) closes the opening (8) of the ferrule (4). 5. Manhole according to any one of the preceding claims, characterized in that it further comprises alert means adapted to send an alert when the pressure in the annular chamber (19) varies. 6. Cistern or tanker for the carriage of liquid, gaseous or powdery products having at least one tank (1), the tank (1) being provided with a manhole (2, 3) according to any one of preceding claims. 7. A method of verifying the tightness of the manhole of the tank or the tank vehicle according to claim 6, characterized in that it comprises the following steps: - (i) closing the lid (11) on the opening (8) of the ferrule (4) and clamping of the clamping means (14), - (iii) Measurement of the evolution in the pressure in the annular chamber (19). 8. Verification method according to the preceding claim, characterized in that it comprises, prior to step (iii), the following step: - (ii) Injection of a fluid under pressure in the annular chamber (19) . 9. The verification method according to claim 7, characterized in that step (iii) is performed when the interior of the tank (1) is under pressure. 10. A method of verification according to any one of claims 7 to 9, characterized in that it further comprises a step of adjusting the degree of clamping of the clamping means when a variation of the pressure in the annular chamber ( 19) is detected. 20