sealing gasket groove 23 by riveting the retaining groove 24 increases the friction between the valve disk 21 and the sealing gasket 22 to keep the sealing gasket 22 from being torn out of the sealing gasket groove 23 in fig3 the cross section of the retaining groove 24 is rectangular in other embodiments within the scope of the present disclosure the retaining groove 24 may be arc shaped trapezoidal triangular or have another shape in fig3 only one retaining groove 24 is provided in other embodiments within the scope of the present disclosure a plurality of retaining grooves may be provided in fig3 the retaining groove 24 is depicted on an inner side 26 of the sealing gasket groove 23 in other embodiments within the scope of the present disclosure the retaining groove 24 may be placed on the outer side 25 of the sealing gasket groove 23 or one or more retaining grooves 24 may be placed on both the inner side 26 and outer side 25 of the sealing gasket groove 23 in fig4 a sealing gasket groove 33 is arranged on a valve disk 31 and the sealing gasket groove 33 is used for accommodating a sealing gasket 32 in fig4 the retaining device is a plurality of annular retaining grooves 34 placed on the inner side 36 of the sealing gasket groove 33 although three retaining grooves 34 are depicted in fig4 the retaining device may include a different number of retaining grooves 34 such as two retaining grooves 34 or four retaining grooves 34 in fig5 a sealing gasket groove 43 is arranged on a valve disk 41 and the sealing gasket groove 41 is used for accommodating a sealing gasket 42 in fig5 the retaining device.