Shell and tube heat exchangers are complex equipment. The tubesheet is facing on both sides different design conditions and also during start-up different conditions occur. The mechnical model and calculation codes require the engineer to assess the various conditions. Designing a heat exchanger requires experience of the do's and dont's. High pressure differences and high temperture differences at both sides of the tubesheet make heat exchanger design a challenging task. Red-Bag has provided the engineering service to calculate the already designed cover flange and the combination with the gasket at high pressure. Small modifications have been implemented for a successful pressure test. (Exotech)