Gasketed plate heat exchangers are the workhorse of mild-duty heating and cooling, but they hit a wall at high temperature, high pressure, or aggressive media - the elastomer gasket simply degrades. All-welded plate heat exchangers remove the gasket entirely: the plates are welded into a rigid pack, so there is no soft seal to fail. That single change opens a whole range of duties gasketed units cannot touch.
What changes without a gasket
- Higher temperature and pressure. Welded packs routinely run where gaskets would soften or leak, making them suitable for hot gas and process streams.
- Corrosive and aggressive media. With stainless or alloy plates and no gasket contact, they handle chemicals, flue gas and acidic streams.
- No gasket-leak path. Fewer failure modes means lower maintenance and safer operation with valuable or hazardous fluids.
- Compact, high turbulence. The plate geometry still gives strong heat transfer in a small footprint.
Where they are used
Across the HVAC and process industries these show up wherever heat must move under tough conditions:
- Chemical and petrochemical processing - intermediate and utility stream heating/cooling.
- Boiler flue-gas preheating - recovering stack heat to raise incoming combustion air temperature and cut fuel use.
- Desulfurization and denitrification (GGH / SGH) - the gas-gas heat recovery loops in flue-gas treatment plants.
- High-temperature gas-to-gas and liquid-to-liquid recovery - including precious-metal vapor condensation and similar severe services.
Choosing all-welded vs plate-and-frame
Use a gasketed plate-and-frame unit when you need frequent opening for cleaning and the duty is mild. Choose all-welded when temperature, pressure or fluid aggressiveness rules out gaskets, or when you want a near-maintenance-free installation. For air-to-air duties at very high temperature, welded or heavy-duty plate cores are the right call; for standard ventilation heat recovery, a plate or rotary air-to-air core is lighter and cheaper.
For air-to-air heat recovery - plate, rotary and cross-flow cores, including high-temperature and corrosion-resistant builds - see the Zibo Qiyu product range. For liquid or process all-welded duties, talk to our engineering team about specifications.
Key takeaway
When the gasket is the weak link, weld it out. All-welded plate exchangers extend heat recovery into the hot, pressurized and corrosive corners of the plant where gasketed designs simply will not survive.