portion 34 to a sealing surface 44 rim portion 36 extends outwardly from u shaped portion 34 to form a shoulder 46 opposite from rim sealing surface 44 a gasket groove 50 is formed into the rim sealing surface 44 of rim portion 36 along its entire length in a preferred embodiment gasket groove 50 is semi spherical in shape and is designed to support an o ring type seal rim portion 36 along with gasket groove 50 and rim shoulder 46 can be molded cast or forged as one piece with u shaped portion 34 depending on what material tube end connector 32 is made from in one embodiment shown in fig2 laterally extending lugs 60 can also be formed as one piece along with rim portion 36 and u shaped portion 34 of tube end connector 32 lugs 60 are provided with through holes 62 for allowing the passage of fastening means such as socket head cap screws to be used to connect tube end connector 32 to a respective tube sheet 26 or 28 in a second embodiment shown in fig5 and 6 connection of tube end connector 32 to a respective tube sheet 26 or 28 is achieved by the use of a special clamp 64 that has an inner periphery that fits snugly around the outer periphery of u shaped portion 34 at the point where u shaped portion 34 meets rim portion 36 clamp 64 is substantially rectangular in shape and therefore extends radially outwardly past the outer.