Maintenance
Special enclosure high-pressure heat exchanger chronicles : Tales of triumphs and tribulations
High-pressure heat exchangers are crucial in industrial operations , especially in hydrocarbon processing plants , where they operate at over
100 bar and 400 ° C . This article examines the challenges and lessons from using special enclosure high-pressure heat exchangers , with a focus on
Southeast Asia refineries .
Unlike conventional shell-and-tube designs , these systems require advanced sealing to withstand extreme conditions , exceeding standard TEMA configurations . Innovative designs like screw-threaded closures , metallic diaphragm plates , and push-bolting systems provide costeffective alternatives to bulky flanges and bolting , improving maintenance access and flexibility while introducing new complexities .
Muhammad Aizat Rasli Principal Engineer , Nurul Nadirah Staff Engineer , PETRONAS Group Technical Solution ( PGTS ), and Faqih Zaini
TEMA 11th Edition Stand Prior to 2023 , TEMA lacked detailed guidelines for specialized high-pressure heat exchangers , leading to inconsistencies and challenges due to the absence of a standardized reference . To address this , the 11th edition introduced the Type D classification , providing comprehensive guidelines tailored specifically to highpressure applications . The following sub section provides a detailed summary of the newly added guidelines for Type D .
RCB-9.3.3 channel cover seal and closure mechanism The joint between the channel cylinder and flat cover should use a sealing element and closure mechanism that suits the service pressure and temperature . Seals can be gaskets , O-rings , metallic seals , or welds , and closure mechanisms may include bolts , key rings , or other locks . The design must meet Code requirements and consider ease of maintenance and assembly . Ring / face gaskets work with closure mechanisms that generate gasket-seating loads , but pressure limits must be seen . O-ring seals have no gasket-seating load and can be used with various closure systems . Metallic seals , either self-energizing or wedge-sealing , are suited for different closure mechanisms . In welded seals , the weld is for sealing only , with the closure mechanism handling the pressure load . When combined with bolts , the seal may be a weld-ring or diaphragm seal . For diaphragm seals , the diaphragm must be welded to the channel and have the right thickness to ensure a dependable seal while conforming to the flat cover . Joint assembly with bolts must follow the Diaphragm Installation Procedure as prescribe in TEMA Section E-4.6 . Key rings and locking mechanisms don ’ t generate gasket-seating loads , so they should only be used with self-energizing or welded seals . These mechanisms include breechlocks , threaded hold-down rings , and other quickactuating covers . These require a system to safely relieve pressure before opening .
16 Heat Exchanger World February 2025 www . heat-exchanger-world . com