Please see the following documents for excellent information from Alfa Laval on this technology:

General Plate Technology Brochure
Theory of Plate Heat Exchanger Technology

Information on all stainless steel plate heat exchanger:

http://www.gocesco.com/fusionbondedplateheatexchangers.html

Information on steam heater plate heat exchanger:

http://www.gocesco.com/gasketedsteamheaterplateheatexchangers.html