... several types of tubes: plain, longitudinally finned, etc. Shell and tube heat exchangers are typically used for high-pressure applications ... be remembered that long, thin tubes are difficult to take out and replace. 4. Tube pitch: when designing the tubes, it ... , which are, triangular (30°), rotated triangular (60°), square (90°) and rotated square (45°). The triangular patterns are employed to give ...