Tube sheet for a shell and tube heat exchanger , the tube sheet comprising: - a first tube sheet plate having a core and a plastics sheath surrounding the core, - a second tube sheet plate made of a temperature-resistant material, and - a third tube sheet plate having a core and a plastics sheath surrounding the core, the first, second and third tube sheet plates being stacked to form a stack, the second tube sheet plate being arranged as an intermediate plate between the first and the third tube sheet plate , such that a first surface of the second tube sheet plate is directed to the first tube sheet plate and an opposite second surface of the second tube sheet plate is directed to the third tube sheet plate , and the stack having at least one through-opening for receiving a relevant tube of the shell and tube heat exchanger, and wherein the tube sheet further has, for each of the at least one through-opening : - at least one sealing ring each for sealing the relevant pipe, - at least one seal seat each for receiving the at least one sealing ring , the seal seat being a recess in the second tube sheet plate that surrounds the relevant through-opening directly in an annular manner, characterised in that the temperature-resistant material has no substantial flow behaviour for temperatures up to at least 200°C and no substantial thermal expansion for temperatures between -50°C and 200°C. - a first tube sheet plate having a core and a plastics sheath surrounding the core, - a second tube sheet plate made of a temperature-resistant material, and - a third tube sheet plate having a core and a plastics sheath surrounding the core, the first, second and third tube sheet plates being stacked to form a stack, the second tube sheet plate being arranged as an intermediate plate between the first and the third tube sheet plate , such that a first surface of the second tube sheet plate is directed to the first tube sheet plate and an opposite second surface of the second tube sheet plate is directed to the third tube sheet plate , and the stack having at least one through-opening for receiving a relevant tube of the shell and tube heat exchanger, and wherein the tube sheet further has, for each of the at least one through-opening : the first, second and third tube sheet plates being stacked to form a stack, the second tube sheet plate being arranged as an intermediate plate between the first and the third tube sheet plate , such that a first surface of the second tube sheet plate is directed to the first tube sheet plate and an opposite second surface of the second tube sheet plate is directed to the third tube sheet plate , and the stack having at least one through-opening for receiving a relevant tube of the shell and tube heat exchanger, and wherein the tube sheet further has, for each of the at least one through-opening : - at least one sealing ring each for sealing the relevant pipe, - at least one seal seat each for receiving the at least one sealing ring , the seal seat being a recess in the second tube sheet plate that surrounds the relevant through-opening directly in an annular manner, characterised in that the temperature-resistant material has no substantial flow behaviour for temperatures up to at least 200°C and no substantial thermal expansion for temperatures between -50°C and 200°C. <EOS>