A container assembly for accommodating a carbonated beverage, said carbonated beverage defining a temperature dependent internal carbonization pressure, said container assembly comprising: a beverage container having a body part defining an inner volume for accommodating said carbonated beverage and a cylindrical neck part defining a gas filled head space, said cylindrical neck part further defining a circumferential rim defining an opening and an outwardly oriented surface extending between said rim and said body part, said outwardly oriented surface having an outwardly oriented circumferential flange, said beverage container further defining a burst pressure being higher than said temperature dependent internal carbonization pressure at room temperature, which is considered to be between 0°C and 60°C, a closure comprising a closure plate and a cylindrical part, said closure plate covering said opening at said rim and said cylindrical part covering said neck part between said rim and said circumferential flange, said cylindrical part comprising a locking part for arresting said outwardly oriented circumferential flange of said neck part, and a flexible sealing ring movable between a first position in which said sealing ring is accommodated in a compressed state entirely within a circumferential cavity defined between said cylindrical part of said closure and said outwardly oriented surface of said neck part at a location between said rim and said circumferential flange when said temperature dependent internal carbonization pressure is lower than or equal to said temperature dependent internal carbonization pressure at said room temperature, and, a second position in which a larger part of said sealing ring is accommodated in a compressed state within said circumferential cavity defined between said cylindrical part of said closure and said outwardly oriented surface of said neck at a location between said rim and said circumferential flange, and a smaller part of said sealing ring is located in an uncompressed state within a groove in said cylindrical part and/or in said outwardly oriented surface and located adjacent said circumferential cavity for allowing fluid communication between said gas filled head space and the exterior of said beverage container when said temperature dependent internal carbonization pressure is higher than said temperature dependent internal carbonization pressure at said room temperature. a beverage container having a body part defining an inner volume for accommodating said carbonated beverage and a cylindrical neck part defining a gas filled head space, said cylindrical neck part further defining a circumferential rim defining an opening and an outwardly oriented surface extending between said rim and said body part, said outwardly oriented surface having an outwardly oriented circumferential flange, said beverage container further defining a burst pressure being higher than said temperature dependent internal carbonization pressure at room temperature, which is considered to be between 0°C and 60°C, a closure comprising a closure plate and a cylindrical part, said closure plate covering said opening at said rim and said cylindrical part covering said neck part between said rim and said circumferential flange, said cylindrical part comprising a locking part for arresting said outwardly oriented circumferential flange of said neck part, and a flexible sealing ring movable between a first position in which said sealing ring is accommodated in a compressed state entirely within a circumferential cavity defined between said cylindrical part of said closure and said outwardly oriented surface of said neck part at a location between said rim and said circumferential flange when said temperature dependent internal carbonization pressure is lower than or equal to said temperature dependent internal carbonization pressure at said room temperature, and, a second position in which a larger part of said sealing ring is accommodated in a compressed state within said circumferential cavity defined between said cylindrical part of said closure and said outwardly oriented surface of said neck at a location between said rim and said circumferential flange, and a smaller part of said sealing ring is located in an uncompressed state within a groove in said cylindrical part and/or in said outwardly oriented surface and located adjacent said circumferential cavity for allowing fluid communication between said gas filled head space and the exterior of said beverage container when said temperature dependent internal carbonization pressure is higher than said temperature dependent internal carbonization pressure at said room temperature.