A magnetic core (106) is adapted for a solenoid valve (100). The magnetic core (106) includes a base (113), a stem (112), and an inner cavity (115). The inner cavity (115) is formed in a portion of the base (113) and in a portion of the stem (112). The inner cavity (115) defines a thin wall (108) of the stem (112). The magnetic core (106) further comprises a non-magnetic pressure retaining sleeve (420). The non-magnetic pressure retaining sleeve (420) is arranged in such a way that either the non-magnetic pressure retaining sleeve surrounds at least a portion of the thin wall of the stem or that at least a portion of the thin wall portion surrounds the non-magnetic pressure retaining sleeve.