Hydraulic mushroom-headed anchor screws for pressure vessels Sealing and opening of tanks with mechanical mushroom-headed anchor screws is time-consuming and difficult. In addition, operational errors will create a danger of expansion impact and therefore endanger the operating personnel. To solve this problem, an organization has developed clamping cylinders, which can replace these mechanical mushroom-headed anchor screws. These hydraulic, easily handled sealing elements are used mainly in the chemical industry.
The first hydraulic-mechanical mushroom-headed anchor screws were already developed in 1993 and used for vessels with a diameter of 400 to 600 mm.
As these vessels should remain movable, the pressure supply was connected directly on the vessel by means of a pneumatic-hydraulic pressure booster. The clamping force per mushroom-headed anchor screw is 25 kN. Hydraulic opening is carried out with 180 bar, whereby at first a forced changeover device ensures that only half of the mushroom-headed anchor screws can be released with continuous reduction in force. This prevents any form of expansion impact. During the following years this system was developed further and used with pressure vessels measuring up to 800 mm in diameter.
Hydraulically opening pressure suction devices now replace mechanical mushroom-headed anchor screws.
In addition, variations were produced for freeze-dryers and centrifuges. | 
