The Basco^® type OP shell and tube heat exchanger is the preferred TEMA AEW product in the market, with double O-rings for sealing protection. For the product, the comprehensive inspection and cleaning of the tube side can be conducted without draining of the shell side or interference with the tube. The double O-ring design enables the tube bundle to expand and contract freely, preventing mixing of fluids. The O-rings can be maintained in the compression state without being affected by vibration and temperature, ensuring that any leakage is detected easily and the maintenance difficulty and cost are reduced.