Method of leakage test and testing apparatus

Abstract

The present invention relates to a test method and testing apparatus for detecting leak- ages in valve units, such as ball valves, comprising mandrels for sealing off the connection ends of the valve housing. At least one robotic arm with at least one gas detection probe is moved into position relative to the external surface of the valve housing or a gas leakage channel in the mandrels. Air trapped in the enclosed valve housing is evacuated by at least one evacuation unit. Tracer gas is supplied into the enclosed valve housing and any gas leakage is detected by the gas detection probes. A control unit controls the movement of the robotic arm to position the gas detection probe correctly relative to the valve unit.

Description

[0001] Method of leakage test and testing apparatus

[0002] Field of the Invention

[0003] The present invention relates to a method of performing a leakage test of valves, such as ball valves, comprising arranging a valve element within a test unit, applying a tracer gas into the valve element, and detecting a gas leakage from the valve element.

[0004] The present invention further relates to a testing apparatus for leakage test of valves as mentioned above.

[0005] Background of the Invention

[0006] It is known that ball valves are widely used in pipelines for regulating a fluid flow by frequently opening and closing the valve element. This causes wear on the valve seat and may lead to internal or external leakages and thus production losses over time. Therefore, the ball valves are tested after production to test the quality of welding and sealing. If no leakages are detected, then the ball valves have passes and are ready for use.

[0007] One widely accepted test method is the hydraulic pressure testing where a testing fluid, such as water, is introduced into the ball valve, when the valve element is positioned in the half-open position, and the open ends of the valve housing are plugged off. The ball valve is then pressurised for a testing period, in which a worker manually inspects the external surfaces for water drops or wet spots. After which the valve element is closed off and a water pressure is applied to one side of the ball valve. The water pressure is then monitored to detect any pressure decay. This test method requires a manual, visual inspection which depends on the experience and knowledge of the worker. Furthermore, it is difficult to translate the pressure decay per time unit to an exact leakage rate.

[0008] Another widely accepted test method is to introduce a gas into the ball valve, when the valve element is positioned in the half-open position, after which the open ends of the valve housing are plugged off. The pressurised ball valve is then lowered into a container of water for a testing period, in which a worker manually inspects the external surfaces of the ball valve or the water surface for gas bubbles. After which the valve element is closed off and a gas pressure is applied to one side of the ball valve. The gas pressure is then monitored on the opposite side of the ball valve to detect any pressure increase. Optionally, a bubble glass is connected to the opposite side and the number of gas bubbles are counted. This test method requires a manual, visual inspection which depends on the experience and knowledge of the worker, and a stable workpiece and ambient temperatures. Furthermore, it is difficult to translate the pressure decay per time unit to an exact leakage rate. Also, this test setup is highly dependent on stable temperatures in the valve components and surroundings.

[0009] Instead of a water container, the pressurised ball valve may be arranged within a vacuum chamber and air is evacuated from the vacuum chamber. The air pressure within the vacuum chamber is then monitored to detect any pressure increase. After which the valve element is closed off and a gas pressure is applied to one side of the ball valve. Gas is then evacuated from the opposite side of the ball valve and the gas pressure is monitored to detect any pressure increase. This test method requires filler bodies to be arranged within the ball valve and in the vacuum chamber to reduce volume and testing time. Also, complex test equipment is required as many potential factors may adversely affect the test results. Furthermore, this test method is not suited for testing ball valves bigger than DN50 due to testing time. It also requires more test cells to be arranged in parallel.

[0010] The vacuum chamber may be used together with a tracer gas, typically a mixture of helium and nitrogen. However, helium gas is scarce and expensive. Furthermore, helium is known to adhere to steel surface which may lead to contamination of test equipment and test results, particularly after bursts or large gas leakages. Cleaning of the test equipment and valve unit is thus required which is time consuming and adds to the total costs.

[0011] WO 2019 / 131536 Al discloses a testing apparatus for partially assembled valve units, where the partially assembled valve unit is arranged in the testing apparatus and the valve openings are closed off by clamping fixture members against the ends of valve housing. A housing forming a gas detection chamber is lowered into position over the housing portion for the valve stem, where a packer element is attached to the valve stem. The housing of the gas detection chamber is provided with gas sensors and a fan. A hydrogen tracer gas is then supplied into the valve housing and pressurized, where the internal gas pressure is monitored using an exhaust gas sensor. Any gas leakage is detected by the gas sensors in the gas detection chamber.

[0012] It is stated that if no gas leakage is detected, then the assembly of the valve unit is completed and the assembled valve unit is arranged in another, larger testing apparatus. The entire valve unit is positioned within another, larger gas detection chamber, where the stem is turned so that that the valve element is positioned in the half-open position. The hydrogen tracer gas is then supplied into the valve housing and pressurized, where any gas leakage is detected by the gas sensors in the enlarged gas detection chamber.

[0013] US 2020 / 0109999 Al discloses a testing apparatus for leak testing of valve units, such as ball valves, where the test valve is positioned on fixed jig and a cover is placed over the test valve to form an isolated inspection chamber. Gas sensors are arranged at fixed positions within the cover. A search gas is supplied into the test valve and pressurised, where any search gas leaking out of the test valve measured by the gas sensors.

[0014] US 2019 / 0302045 Al discloses a similar testing apparatus for leak testing of valve units, such as ball valves, where the test valve is positioned within an isolated inspection chamber. Gas sensors are arranged on rotatable arms on upper and lower arc-shaped plate elements suspended from the cover housing. The arms are rotatably driven by servo motors from a retracted position to an extended position near the outer surface of the test valve.

[0015] In a remote technical field, WO 2023 / 057107 Al discloses a leak testing method for detecting leaks at joints of a pipe system within a refrigerator. Cameras and a light source are positioned relative to the refrigerator and used to determine the measuring positions. A gas detecting probe arranged at the free end of a robot arm is moved between the measuring positions to detect any tracer gas leaking out of the refrigerator. This robotic system cannot be used for leak testing of ball valves without modifications to the test setup.

[0016] Therefore, there is a desire to provide an improved, or at least an alternative, test method for valve units. Object of the Invention

[0017] One object of the present invention is to overcome the abovementioned problems of the cited prior art.

[0018] One object of the present invention is to provide a test method and testing apparatus that allows for an automated testing of ball valves.

[0019] One object of the present invention is to provide a test method and testing apparatus that allows for a faster and more versatile testing of ball valves.

[0020] Description of the Invention

[0021] One object of the present invention is achieved by a test method of detecting leakages in valve units, as mentioned in claim 1, comprising:

[0022] - providing a valve unit with a valve housing with a central part and two connection ends, the central part and connection ends being arranged co-axially where the connection ends extend away from the central part, wherein a valve element is arranged internally within the central part and relative to at least one valve seat arranged in the central part;

[0023] - sealing off the connection ends of the valve housing using mandrels;

[0024] - supplying a tracer gas into the enclosed valve housing via at least one gas inlet, and pressurising the valve housing; wherein

[0025] - positioning at least one gas detection probe relative to an external housing surface of the valve housing or relative to at least one gas leakage channel in at least one of the mandrels, the least one gas detection probe being configured to detect tracer gas leaking from the valve unit, wherein the least one gas detection probe is provided on a free end of at least one robotic arm, and where the movement of the at least one robotic arm is controlled by a control unit.

[0026] This provides an improved leakage test of valve units compared to conventional leakage test methods. The present invention provides a fast and accurate detection of internal as well as external leakages by using of a tracer gas detection instead of measuring a pressure increase or decay. The present invention allows for a faster changeover time due to a minimum of exchangeable components in the testing apparatus. This eliminates the need for filler bodies and vacuum chamber due to faster test times. The valve unit, at least with pre-assembled valve element and valve seat, is simply positioned in the testing apparatus. The valve housing is then sealed off by clamping the mandrels against the connection ends. If not already connected to the mandrels, the gas supply and the evacuation unit are coupled to the mandrels. The worker may then select the type of leakage test on the control unit and adjust or enter the testing time, testing pressure or other test parameters before initialling the leakage test.

[0027] The gas detection probes may be operated manually by the worker during testing, or automatically as described later. This allows for local gas detection in potential leak points instead of overall gas detection in vacuum or gas detection chambers. Thereby, allowing for faster gas detection due to lower volume and higher mixture.

[0028] In one embodiment, the valve unit is ball valve and the valve element is a ball with at least one through-going aperture.

[0029] The present invention is particularly suited for leakage testing of ball valves as there is a desire for reducing downtime and faster overall testing time of multiple valve units. However, the present invention may also be used for leakage test of other types of valve units.

[0030] The gas detection probe may be arranged on the free end of a robotic arm, where the movement of the robotic arm and thus the gas detection probe is controlled by a control unit. The robotic arm may have at least 6 degrees of freedom (6 DOF). This allows for an automatic movement of the gas detection probes.

[0031] The robotic arm with gas detection probe may be used for both internal as well as external leakage tests of the valve unit. Thereby, reducing the changeover time and overall number of components in the testing apparatus. No need for vacuum chambers, water chambers or gas detection chambers.

[0032] The movement of the robotic arm and thus gas detection probe may be controlled autonomously by the control unit. Alternatively, the worker may control the movement of the robotic arm via a user terminal in the control unit. A single robotic arm or at least two robotic arms may be arranged in the testing apparatus relative to the valve unit. This allows for local gas detections at the gas leakage channel or along critical points on the external valve housing surface.

[0033] In one embodiment, the valve element is connected to a stem element at one end, which is further connected to a turning unit at the other end, wherein the valve element is rotated between a first test position and a second test position.

[0034] The stem element, or valve stem, may be coupled to an electrically operated actuator or turning unit, which may be controlled by the control unit. Alternatively, the valve stem may be coupled to a manually operated turning unit. Thereby, allowing the valve element to be turned (rotated) into a first or second test position during the leakage tests. The turning of the valve element may be performed automatically by the control unit, thus reducing the manual labour during the testing.

[0035] In one embodiment, air inside at least a portion of the enclosed valve housing is evacuated through at least one gas outlet before or during the supply of the tracer gas.

[0036] During the internal leakage test, the valve element may be closed, and one side of the valve housing may be evacuated by the evacuation unit while the other side of the valve housing may be supplied with tracer gas by the gas supply. Once the first step of the internal leakage test is completed, the tracer gas may be extracted from said other side of the valve housing by the evacuation unit while said one side of the valve housing may be supplied with tracer gas by the gas supply. Once the second step of the internal leakage test is completed, the tracer gas may be extracted from said one side of the valve housing by the evacuation unit.

[0037] Alternatively, the valve element may be turned into the second test position for external leakage test. The entire valve housing may then be supplied with tracer gas by the gas supply. Once the external leakage test is completed, the tracer gas may be extracted from the valve housing by the evacuation unit.

[0038] During internal or external leakage testing, the gas pressure may be increased to and maintained at a predetermined testing pressure for a predetermined testing time. Further, air or tracer gas in the valve housing may be evacuated to and maintained at a predetermined negative pressure.

[0039] In one embodiment, the gas leakage detection is performed automatically by the control unit.

[0040] The control unit may be programmed to perform the internal and / or external leakage tests autonomously, thus eliminating the manual labour to a minimum. This also reduces testing time as the same gas detection probe(s) is used for both tests. The flow of tracer gas and / or the evacuation of air may be controlled by the control unit.

[0041] In one embodiment, an internal gas leakage test is performed when the valve element is the first test position and an external gas leakage test is performed when the valve element is the second test position, wherein the same gas detection probe is used for detecting gas leakage in both the internal and external gas leakage tests.

[0042] The valve element may be rotated into a first test position by the turning unit for the internal leakage test. Further, the valve element may be rotated into a second test position by the turning unit for the external leakage test. The turning unit may also be used to rotate the valve element into other positions, such as the closed and open positions.

[0043] Using the same gas detection probe allows for a faster exchange between test setups, as there is no need for replacing or switching between different gas detection sensors. Further, changing the flow of tracer gas and evacuation flow of air may be performed without having to reconnect the respective flow lines between the mandrels, the gas supply and the evacuation unit. Thus, the same overall test setup may be used for both leakages tests.

[0044] In one embodiment, the test method further comprises the step of cleaning the valve unit before and / or after the detection of gas leakages in the valve unit.

[0045] Cleaning of the valve housing after completion of the leakage test may be performed using the evacuation unit and optionally a separate air inlet. The air inlet may be arranged on the gas supply unit and may be connected to the flow line system. Surrounding air may be sucked into the valve housing and exited via the evacuation unit to remove any residual tracer gas inside the valve housing and valve element. Optionally, clean air or another cleaning gas may be supplied into the valve housing via the evacuation unit. The air may flow through a filter system before entering the valve housing as clean air. This allow the tracer gas to be effectively removed from the valve unit after the leakage test.

[0046] The use of a tracer gas eliminates the risk of any residual water remaining in the valve unit after the leakage test. Also, no subsequent heating of the valve unit is needed.

[0047] Optionally, the valve unit may be cleaned before the leakage test using the evacuation unit and the optional air inlet. Surrounding air or clean air may be sucked into the valve housing and exit via the evacuation unit to remove any contaminations inside the valve housing and valve element. This allows for a more reliable leakage test.

[0048] One object of the present invention is also achieved by a testing apparatus for detecting leakages in valve units, as mentioned in claim 8, comprising:

[0049] - mandrels configured to seal off the connection ends of the valve unit;

[0050] - at least one gas inlet connected to at least one gas supply for supplying a tracer gas into the enclosed valve housing;

[0051] - at least one gas outlet connected to at least one gas evacuation unit for evacuating the tracer gas or air from the enclosed valve housing; wherein

[0052] - the testing apparatus comprises at least one gas detection probe configured to detect tracer gas leaking from the valve unit, the least one gas detection probe is provided on a free end of at least one robotic arm, and where the movement of the at least one robotic arm is configured to be controlled by a control unit.

[0053] This provides an improved testing apparatus compared to conventional testing apparatus. The present testing apparatus can be used for internal as well as external leakage tests using the same overall test setup. No need for large vacuum chambers or water chambers due to the use of tracer gas. The present testing apparatus provides a simple and cheap testing apparatus compared to conventional testing apparatus. The testing apparatus comprises mandrels adapted to seal off the connection ends of the valve housing. At least one of the mandrels may be moveable so that the valve unit can be positioned between and clamped to the mandrels. The testing apparatus comprises a single or two local gas supplies or be provided with gas couplings for the connection to external gas supplies. The testing apparatus comprises a single or two local evacuation units or be provided with gas couplings for the connection to external evacuation units.

[0054] The mandrels, the gas supply and the evacuation unit are interconnected by a flow line system. A separate air inlet may be provided on the testing apparatus, the gas supply or the evacuation unit. The air inlet may be connected to the one or both mandrels via the flow line system.

[0055] The testing apparatus further comprises a single or at least two gas detection probes, which is electrically connected to a control unit in the testing apparatus. The gas detection probes are configured to detect tracer gas leaking out of the valve unit. This allows for local gas detection instead of using a gas detection chamber. Further, no dirt or welding splatter is sucked out from the vacuum chamber and into the valves in the testing apparatus. Thereby, less maintenance is required.

[0056] In one embodiment, at least one of the mandrels is provided with a local gas inlet channel and a local gas outlet channel, the gas inlet channel is connected to the gas supply and the gas outlet channel is connected to the gas evacuation unit.

[0057] The first mandrel and / or the second mandrel may be provided at least one local gas inlet channel and at least one local gas outlet channel. The gas inlet channel and the gas outlet channel each may have an inlet or outlet opening located at an external surface and an inlet or outlet opening located in a surface facing the interior spacing of the valve housing. The inlet or outlet opening in the external surface may be shaped to be coupled to the flow line system. This allows tracer gas and air to be supplied or extracted via the mandrels.

[0058] Some conventional testing apparatus have a single channel used for both inlet and outlet. Hence, tracer gas cannot be supplied while evacuating air at the same time. In one embodiment, the at least one mandrel is further provided with a separate gas leakage channel having an opening arranged in an external surface.

[0059] The first mandrel and / or the second mandrel may further be provided with at least one gas leakage channel. The gas leakage channel may have an outlet opening located at an external surface and an inlet opening located in a surface facing the interior spacing of the valve housing. This allows internal gas leakage to be detected using the gas detection probes. No need for pressure sensors to monitor the pressure increase or decay.

[0060] The testing apparatus may comprise a single or at least two robotic arms each with a free end for attachment of a tool. The gas detection probes may be connected to the free end by a coupling. The movement of the robotic arms may be controlled by the control unit so that the gas detection probes may be correctly positioned relative to the gas leakage channel or the external surface of the valve housing. This allows for automatic movement of the gas detection probes between potential leak points on the valve unit. In one embodiment, the testing apparatus further comprises a turning unit configured to be connected to one end of a stem element of the valve unit, wherein the turning unit is configured to rotate the valve element of the valve unit between a first test position and a second test position.

[0061] A turning unit may be coupled to the first end of the valve stem for rotating the valve element. The operation of the turning unit and thus the rotation of the valve element may be controlled by the control unit. The turning unit may be a rotating actuator, which is electrically, pneumatically or hydraulically operated. A local encoder or angular sensor may optionally be used for determining the rotational position of the valve element. This allows the valve element to be automatically rotated between the first and second test positions, and other desired positions.

[0062] In one embodiment, the control unit is configured to perform an internal gas leakage test when the valve element is rotated into the first test position, and the control unit is further configured to perform an external gas leakage test when the valve element is rotated into the second test position. The present testing apparatus may be configured to perform an internal leakage test and / or an external leakage test using the same overall test setup. The internal and external leakage tests may be performed sequentially on the same valve unit. The steps of the internal and external leakage tests may be controlled by the control unit. This allows for a faster and more accurate leakage test compared to conventional leakage tests.

[0063] In one embodiment, the control unit is configured to automatically control the operation of the testing apparatus so that the internal and external gas leakage tests are performed automatically.

[0064] The control unit may be configured to autonomously perform the leakage tests, thereby reducing the manual labour to a minimum. Alternatively, the leakage tests may be performed in a semi-automatic process.

[0065] In one embodiment, the tracer gas is hydrogen gas, preferably comprising between 1- 10% hydrogen.

[0066] The tracer gas may be an inert or non-toxic gas, which can dissolve into the surrounding air safety without the risk of combusting. No need for added gas protection around the valve unit. The tracer gas may be hydrogen gas comprising a mixture of hydrogen and nitrogen or another gas. The amount of hydrogen in the mixed gas may be between 1- 10%. This allows for the use of a non-combustible gas that does not adhere to steel surfaces. However, other suitable tracer gas may also be used, such as carbon dioxide.

[0067] Thus, the need for cleaning the test equipment and valve unit after leakage testing can be reduced, or even eliminated.

[0068] Description of the Drawing

[0069] The present invention is described by example only and with reference to the drawings, wherein:

[0070] Fig. 1 shows an exemplary embodiment of a valve unit,

[0071] Fig. 2 shows a cross-sectional view of the valve unit of fig. 1 along the longitudinal axis,

[0072] Fig. 3 shows an exemplary embodiment of a testing apparatus, where the testing apparatus is set up for internal leakage detection, Fig. 4 shows a first flow of tracer gas inputting the valve unit through the second mandrel,

[0073] Fig. 5 shows the flow of tracer gas exiting the valve unit through the second mandrel,

[0074] Fig. 6 shows a second flow of tracer gas inputting the valve unit through the first mandrel,

[0075] Fig. 7 shows the flow of tracer gas exiting the valve unit through the first mandrel,

[0076] Fig. 8 shows the testing apparatus of fig. 3, where the testing apparatus is set up for external leakage detection,

[0077] Fig. 9 shows a third flow of tracer gas inputting the valve unit through the first and second mandrels, and

[0078] Fig. 10 shows the flow of tracer gas exiting the valve unit through the first and second mandrels.

[0079] In the following text, the figures will be described one by one, and the different parts and positions seen in the figures will be numbered with the same numbers in the different figures. Not all parts and positions indicated in a specific figure will necessarily be discussed together with that figure.

[0080] Detailed Description of the Invention

[0081] Fig. 1 shows an exemplary embodiment of a valve unit 1 in the form of a ball valve, such as a floating ball valve. The valve unit 1 comprises a valve housing 2 made of two housing parts 2a, 2b that are welded together along a welding seam 3 extending along a circumference direction of the valve housing 2. Alternatively, the valve housing may be made of a single continuous housing part.

[0082] The valve housing 2 has two connection ends 5a, 5b attached to a central part 4 where the connection ends 4 face in opposite axial directions of the valve housing 2. The connection ends 5a, 5b are shaped to be connected to an adjoining pipe section (not shown). Here, the central part 4 is formed by two central ends of the housing parts 2a, 2b that are welded together along a single welding seam 3, as illustrated in fig. 1.

[0083] A valve stem 7 is arranged in a valve bonnet 6 projecting from the valve housing 2. The valve stem 7 extends along a radial axis arranged perpendicular to the longitudinal axis. Fig. 2 shows a cross-sectional view of the valve unit 1 along the longitudinal axis. The valve stem 7 further has a second end shaped to be connected to a valve element 8 arranged on at least one valve seat 9. The valve element is in this exemplary embodiment formed as a ball with at least one through-going aperture 10.

[0084] The valve stem 7 has a first end 7a and an opposite second end 7b. The first end 7a is shaped to be connected to a handle or an actuator. The second end 7b is shaped to be inserted into and engage with a stem opening 11 in the valve element 8. The valve stem 7 is configured to rotate around the radial axis and rotate the valve element 8 between a closed position and an open position, as illustrated in fig. 2.

[0085] Here, the central part 4’ is formed as a central housing part that is welded together with the housing parts 2a, 2b along two separate welding seams 3’, as illustrated in fig. 2.

[0086] Here, the valve bonnet 6 is welded to the housing parts 2a, 2b along a welding seam 3” extending along a circumference direction of the valve bonnet 6. Alternatively, the valve bonnet 6 may form an integrated part of the central housing part.

[0087] Fig. 3 shows an exemplary embodiment of a testing apparatus 12, where the testing apparatus 12 is set up for internal leakage detection. Here, the valve element 7 is rotated into a first test position, e.g., the closed position.

[0088] A first mandrel 13 is arranged at a first connection end 5a for sealing off the connection end. Further, a second mandrel 14 is arranged at a second connection end 5b for sealing off the connection end. Thereby, forming an enclosed space within the valve housing 2.

[0089] A first robotic arm 15 with a first gas detection probe 23 is moved into position relative to the valve unit 1 or first mandrel 13. Further, a second robotic arm 16 with a second gas detection probe 23 is moved into position relative to the valve unit 1 or second mandrel 14. The first and second gas detection probes 23 are configured to detect a tracer gas leaking internally from the valve unit 1. The output signals from the first and second gas detection probes 23 are inputted to a control unit 21, which is configured to control the movement of the robotic arm 15 relative to the valve unit 1 or mandrel 13, 14. The tracer gas is supplied into the enclosed valve housing 2 by a gas supply 22 via at least one gas inlet. Here, the gas inlet is formed by a gas inlet channel 17 in the first or second mandrel 13, 14. Further, the tracer gas and / or any air in the enclosed valve housing 2 is extracted via at least one gas outlet channel 18 in the first and / or second mandrels 13, 14.

[0090] A gas leakage channel 19 is formed in the first and second mandrels 13, 14 for detecting an internal gas leakage of the valve unit 1.

[0091] A turning unit 20 is coupled to the first end 7a of the valve stem 7 for rotating the valve element 8 during gas leakage testing. The movement of the turning unit 20 is controlled by the control unit (as illustrated by dotted line) or via a manually operated handle (not shown).

[0092] Fig. 4 shows a first flow of tracer gas 24 inputted in the valve unit 1 through the second mandrel 14. The tracer gas 24 is trapped inside the valve housing 2 between the second mandrel 14 and the valve element 8. The pressure of the tracer gas 24 is increased to and maintained a predetermined testing pressure.

[0093] The second gas detection probe 23 is moved into position relative to the gas leakage channel 19 of the first mandrel 13. The amount of gas exiting the gas leaking channel 19 is monitored over a predetermined testing period. Thereby, enabling any tracer gas leaking through the valve seats 9 or valve element 8 to be detected by the second gas detection probe 23.

[0094] The control unit 21 optionally determine the increase in tracer gas per time unit based on the inputted measurement from the second gas detection probe 23. If the increase in tracer gas per time unit exceeds a threshold, then an alert signal is optionally generated.

[0095] Fig. 5 shows the flow of tracer gas 24 exiting the valve unit 1 through the second mandrel 14 via the gas outlet channel 18 after completion of the testing period. Before the supply of tracer gas 24, air trapped inside the enclosed valve housing 2 between the first mandrel 13 and the valve element 8 is evacuated by a first evacuation unit (see fig. 8) via the gas outlet channels 18 in the first mandrel 13.

[0096] Optionally, air trapped inside the enclosed valve housing 2 between the second mandrel 14 and the valve element 8 is evacuated by a second evacuation unit (see fig. 8) via the gas outlet channels 18 in the second mandrel 14.

[0097] Fig. 6 shows a second flow of tracer gas 24 inputted in the valve unit 1 through the first mandrel 13. The tracer gas 24 is trapped inside the valve housing 2 between the first mandrel 13 and the valve element 8. The pressure of the tracer gas 24 is increased to and maintained a predetermined testing pressure.

[0098] The second gas detection probe 23 is moved into position relative to the gas leakage channel 19 of the second mandrel 13. The amount of gas exiting the gas leaking channel 19 is monitored over a predetermined testing period. Thereby, enabling any tracer gas leaking through the valve seats 9 or valve element 8 to be detected by the second gas detection probe 23.

[0099] The control unit 21 optionally determine the increase in tracer gas per time unit based on the inputted measurement from the second gas detection probe 23. If the increase in tracer gas per time unit exceeds a threshold, then an alert signal is optionally generated.

[0100] Fig. 7 shows the flow of tracer gas 24 exiting the valve unit 1 through the first mandrel 13 via the gas outlet channel 18 after completion of the testing period.

[0101] Before the supply of tracer gas 24, air trapped inside the enclosed valve housing 2 between the second mandrel 14 and the valve element 8 is extracted by a second evacuation unit (see fig. 8) via the gas outlet channels 18 in the second mandrel 14.

[0102] Optionally, air trapped inside the enclosed valve housing 2 between the first mandrel 13 and the valve element 8 is extracted by a first evacuation unit (see fig. 8) via the gas outlet channels 18 in the first mandrel 13. Fig. 8 shows the testing apparatus 12, where the testing apparatus 12 is set up for external leakage detection. Here, the valve element 7 is rotated into a second test position, e.g., the open or half-open position.

[0103] The first and second robotic arms 15, 16 are moved into individual positions relative to an external housing surface of the valve housing 2. Here, the first and second gas detection probes 23 are configured to detect a tracer gas leaking externally from the valve unit 1. The output signal from the first and second gas detection probes 23 are inputted to the control unit 21.

[0104] The tracer gas 24 is supplied into the enclosed valve housing 2 by at least one gas supply 22 via at least one gas inlet. Optionally, the tracer gas 24 is supplied into the enclosed valve housing 2 via the gas inlet channels 17 in both the first and second mandrels 13, 14.

[0105] Any air trapped in the enclosed valve housing 2 is evacuated via at least one gas outlet channel 18 in at least one of the mandrels 13, 14. Optionally, the air in the enclosed valve housing 2 is evacuated via the gas outlet channels 18 in both the first and second mandrels 13, 14.

[0106] Fig. 9 shows a third flow of tracer gas 24 inputted into the valve unit 1 through the first and second mandrels 13, 14. The tracer gas 24 is trapped inside the valve housing 2 between the first mandrel 13 and the second mandrel 14. The pressure of the tracer gas 24 is increased to and maintained a predetermined testing pressure.

[0107] One or both gas detection probes 23 are moved into position relative to an external housing surface of the valve housing 2. The amount of gas leaking through the valve housing 2 is monitored over a predetermined testing period. Thereby, enabling any tracer gas leaking through the housing parts 2a, 2b or the welding seam(s) 3, 3’, 3” to be detected by the second gas detection probe 23.

[0108] The control unit 21 optionally determine the increase in tracer gas per time unit based on the inputted measurement from the gas probe(s) 23. If the increase in tracer gas per time unit exceeds a threshold, then an alert signal is optionally generated. Fig. 10 shows the flow of tracer gas 24 exiting the valve unit 1 through the first and second mandrels 13, 14 after completion of the testing period.

[0109] Before the supply of tracer gas 24, air trapped inside the enclosed valve housing 2 be- tween the first and second mandrels 13, 14 is evacuated by a first evacuation unit 25 via the gas outlet channels 18 in the first mandrel 13.

[0110] Optionally, air trapped inside the enclosed valve housing 2 between the first mandrel 13 and the second mandrel 14 is evacuated by a second evacuation unit 25 via the gas outlet channels 18 in the second mandrel 14.

[0111] Once the leakage testing is completed, the valve unit 1 is optionally cleaned by supplying clean air, e.g., compressed air, into the valve housing 2 via the gas inlet channels 17. The air is then let out of the valve housing 2 via the gas outlet channels 18.

Claims

Claims1. A test method of detecting leakages in valve units (1), comprising:- providing a valve unit (1) with a valve housing (2) with a central part (4) and two connection ends (5a, 5b), the central part (4) and connection ends (5a, 5b) being arranged co-axially where the connection ends (5a, 5b) extend away from the central part (4), wherein a valve element (8) is arranged internally within the central part (4) and relative to at least one valve seat (9) arranged in the central part (4);- sealing off the connection ends (5a, 5b) of the valve housing (2) using mandrels (13, 14);- supplying a tracer gas (24) into the enclosed valve housing (2) via at least one gas inlet(17), and pressurising the valve housing (2); wherein- positioning at least one gas detection probe (23) relative to an external housing surface of the valve housing (2) or relative to at least one gas leakage channel (19) in at least one of the mandrels (13, 14), the least one gas detection probe (23) being configured to detect tracer gas (24) leaking from the valve unit (1), wherein the least one gas detection probe (23) is provided on a free end of at least one robotic arm (15, 16), and where the movement of the at least one robotic arm (15, 16) is controlled by a control unit (21).

2. The test method according to claim 1, wherein the valve unit (1) is ball valve and the valve element (8) is a ball with at least one through-going aperture (10).

3. The test method according to claim 1 or 2, wherein the valve element (8) is connected to a stem element (7) at one end, which is further connected to a turning unit (20) at the other end, wherein the valve element (8) is rotated between a first test position and a second test position.

4. The test method according to any one of claims 1 to 3, wherein air inside at least a portion of the enclosed valve housing (2) is evacuated through at least one gas outlet(18) before or during the supply of the tracer gas (24).

5. The test method according to any one of claims 1 to 4, wherein the gas leakage detection is performed automatically by the control unit (21).

6. The test method according to any one of claims 1 to 5, wherein an internal gas leakage test is performed when the valve element (8) is the first test position and an external gas leakage test is performed when the valve element (9) is the second test position, wherein the same gas detection probe (23) is used for detecting gas leakages in both the internal and external gas leakage tests.

7. The test method according to any one of claims 1 to 6, wherein the test method further comprises the step of cleaning the valve unit (1) before and / or after the detection of gas leakages in the valve unit (1).

8. A testing apparatus (12) for detecting leakages in valve units (1) using a method according to any one of claims 1 to 7, comprising:- mandrels (13, 14) configured to seal off the connection ends (5a, 5b) of the valve unit (i);- at least one gas inlet connected to at least one gas supply (22) for supplying a tracer gas (24) into the enclosed valve housing (2);- at least one gas outlet connected to at least one gas evacuation unit (25) for evacuating the tracer gas (24) or air from the enclosed valve housing (2); wherein- the testing apparatus (12) comprises at least one gas detection probe (23) configured to detect tracer gas (24) leaking from the valve unit (1), wherein the least one gas detection probe (23) is provided on a free end of at least one robotic arm (15, 16), where the movement of the at least one robotic arm (15, 16) is configured to be controlled by a control unit (21).

9. The testing apparatus according to claim 8, wherein at least one of the mandrels (13, 14) is provided with a local gas inlet channel (17) and a local gas outlet channel (18), the gas inlet channel (17) is connected to the gas supply (22) and the gas outlet channel (18) is connected to the gas evacuation unit (25).

10. The testing apparatus according to claim 9, wherein the at least one mandrel (13, 14) is further provided with a separate gas leakage channel (19) having an opening arranged in an external surface.

11. The testing apparatus according to any one of claims 8 to 10, wherein the testing apparatus (12) further comprises a turning unit (20) configured to be connected to one end (7a) of a stem element (7) of the valve unit (1), wherein the turning unit (20) is configured to rotate the valve element (7) of the valve unit (1) between a first test position and a second test position.

12. The testing apparatus according to claim 11, wherein the control unit (21) is configured to perform an internal gas leakage test when the valve element (7) is rotated into the first test position, and the control unit (21) is further configured to perform an external gas leakage test when the valve element (7) is rotated into the second test position.

13. The testing apparatus according to claim 12, wherein the control unit (21) is configured to automatically control the operation of the testing apparatus (12) so that the internal and external gas leakage tests are performed automatically.

14. The testing apparatus according to any one of claims 8 to 13, wherein the tracer gas (24) is a hydrogen gas, preferably comprising between 1-10% hydrogen.

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