A device for testing the sealing of an installation : - of the type comprising a tank intended to store a first fluid in an interior space of this tank, or - of the type comprising two pipes and a junction between these two pipes, these pipes being intended to transport a first fluid in an interior space of these pipes, this device comprising: - a pressurisation system arranged to pressurise a test fluid in the device, and - a pressure measuring system arranged to measure the pressure of the test fluid in the device, this device further comprising: - a pressurisation chamber , and - a first sealing element arranged to isolate the pressurisation chamber from said interior space , the pressurisation system being arranged to pressurise the test fluid in the pressurisation chamber , and the pressure measuring system being arranged to measure the pressure of the test fluid in the pressurisation chamber , being characterised in that the pressurisation chamber is annular and delimited by a fixing flange, and in that the device further comprises a cover and the fixing flange , the fixing flange being arranged on the tank to fix a cover to the tank , the fixing flange being arranged to fix the cover to the tank , the cover and the fixing flange being arranged to delimit the pressurisation chamber , or in that the fixing flange is arranged on a pipe to form a junction with the fixing flange of a pipe, these fixing flanges being arranged to fix the two pipes together, and to delimit the pressurisation chamber . - of the type comprising a tank intended to store a first fluid in an interior space of this tank, or - of the type comprising two pipes and a junction between these two pipes, these pipes being intended to transport a first fluid in an interior space of these pipes, this device comprising: - a pressurisation system arranged to pressurise a test fluid in the device, and - a pressure measuring system arranged to measure the pressure of the test fluid in the device, - a pressurisation system arranged to pressurise a test fluid in the device, and - a pressure measuring system arranged to measure the pressure of the test fluid in the device, this device further comprising: - a pressurisation chamber , and - a first sealing element arranged to isolate the pressurisation chamber from said interior space , - a pressurisation chamber , and - a first sealing element arranged to isolate the pressurisation chamber from said interior space , the pressurisation system being arranged to pressurise the test fluid in the pressurisation chamber , and the pressure measuring system being arranged to measure the pressure of the test fluid in the pressurisation chamber , being characterised in that the pressurisation chamber is annular and delimited by a fixing flange, and in that the device further comprises a cover and the fixing flange , the fixing flange being arranged on the tank to fix a cover to the tank , the fixing flange being arranged to fix the cover to the tank , the cover and the fixing flange being arranged to delimit the pressurisation chamber , or in that the fixing flange is arranged on a pipe to form a junction with the fixing flange of a pipe, these fixing flanges being arranged to fix the two pipes together, and to delimit the pressurisation chamber . <EOS>