Beyond TEMA, metallurgy and high pressure have lead to having a groove in the cladding of the shellside of a tubesheet. That is seen as a less expensive alternative to all alloy tubesheets, double tubesheets, and alloy sealwelded tube hole sleeve inserts. This is because tube rolling limitation and process cycling may not allow an adequate seal by tube-to-tubesheet expansion rolling. Seal welding tubes from the shellside is not unheard of, but that is expensive and does not permit retubing without full bundle replacement.