Alfa Laval Industrial semi-welded line handles most refrigerants and is particularly suitable for applications involving ammonia. Semi-welded heat exchangers are used in both organic and inorganic chemical processing when the chemicals involved limit the selection of gaskets that can be used or when the required design pressure makes fully gasketed plate-and-frame heat exchangers insufficient.
The media passes through the welded channel facing the ring gasket sealing between the laser welded cassettes. Alfa Laval semi-welded heat exchangers employ the Alfa Laval RefTight™, a unique sealing system which guarantees high performance by positioning the laser weld on the outside of the ring gasket groove. The smooth ring gasket grove ensures equal sealing force over the entire porthole gasket.
Equipped with well-designed features, Alfa Laval Industrial semi-welded line of heat exchangers are easy to maintain and have a long service life. Some of the features available include:
- ClipGrip™ gasket – a glue free gasket with superior alignment that ensures a perfect seal and trouble-free maintenance.
- Glued gasket – two-component, oven-cured epoxy glue keeps the gasket in place during any possible cleaning condition.
- CurveFlow™ distribution area – ensures full use of the heat transfer area and minimizes fouling.
How it works 
The heat transfer area of a gasketed plate-and-frame heat exchanger consists of a series of corrugated plates, assembled between the frame and pressure plates, which retain the design pressure. For the highest thermal performance and to enable a very close temperature approach, fluids normally run counter-currently through the heat exchanger.
The sealing between the plates on the Industrial semi-welded line alternates between laser welds and gaskets. The laser welded channel allows use of fluids that are not compatible with normal gaskets and also allows for higher design pressure than fully gasketed plate-and-frame heat exchangers. Additionally, the Alfa Laval RefTightTM sealing system guarantees equal sealing force over the entire porthole gasket.
Industrial semi-welded line is available with various pressing depths and angles of the chevron pattern and various shapes of the corrugation which are carefully designed and selected to achieve optimal performance. The CurveFlowTM and the chocolate pattern distribution area are two design features available that ensure fluids are evenly distributed across the entire plate. The result is that the entire heat transfer surface is fully utilized and stagnant zones that can result in fouling are avoided.
High flow turbulence between plates results in higher heat transfer; however, the consequence is pressure drop. Our thermal design engineers will help you design and select the model and configuration that is suitable for your application needs while delivering maximum thermal performance and minimizing pressure drop.
The Industrial semi-welded line can be configured in many ways. The animation shows single pass configuration of a fully gasketed plate-and-frame heat exchanger. The flow principle of a semi-welded heat exchanger is the same. The difference is that every second channel is sealed with a laser weld instead of a gasket. Multi pass with 2 or more passes on each side is also possible.
Highly efficient with unique sealing system
Alfa Laval industrial semi-welded gasketed plate heat exchangers are suitable for liquids and gases incompatible with normal gaskets or at higher pressures. Commonly used in refrigeration applications for evaporation and condensation of ammonia and CO2.
The unique Alfa Laval RefTight™ sealing system guarantees a long life-time sealing between the welded channels because the laser weld is on the outside of the ring gasket groove. The smooth surface ensures a tight uniform seal over the entire gasket ring.
What make our plate heat exchangers so reliable, efficient and serviceable?
Equipped with well-designed features that make a difference, Alfa Laval Industrial semi-welded line of heat exchangers are easy to maintain and have a long service life.
