Welded Plate Heat Exchanger

SONDEX® SondBlock
plate heat exchangers

Our SONDEX® SondBlock heat exchangers (SB/SBL) are compact and durable solutions for challenging applications that involve aggressive media, extreme temperatures, and/or high pressure. As SondBlock heat exchangers have no exposed gaskets, they can replace shell and tube heat exchangers and cover the same duties, yet offer numerous advantages in terms of cost, size, and performance.

SondBlock heat exchangers are much less prone to fouling and clogging and only require occasional inspection and cleaning.

Maintenance and cleaning is less time consuming and space demanding as all the panels on the heat exchanger can easily be removed. The entire plate pack is accessible from all sides with no additional space required.

Block heat exchangers in general mark the beginning of a new era of efficient heat transfer, even for the most challenging applications.

Features and benefits

  • Perfect as condensers that can be configured to handle duties with or without condensate sub-cooling. SondBlock heat exchangers are also good choices as steam heaters or reboilers for non-cyclic duties, and a smooth and stable steam control system.
  • A very durable heat exchanger that excels at handling aggressive and fouling media. Able to handle aggressive media on both sides, it is a perfect solution for crude oil refineries and petrochemical plants. A top choice for the most challenging duties.
  • Increased production output due to the extended uptime of the heat exchanger. Very low maintenance and service requirements. Removable side panels provide fast and easy access to the plate pack for inspection or cleaning.

Technical specifications

  • Connections from DN50 to DN1000 (2″ to 40″)
  • (Frames designed according to FEA and PED 2014/68/EU (EN13445) and ASME sec VIII, Div. 1 construction standards)
  • Plates made from AISI 304/316, titanium*
  • Shell materials: Carbon steel, stainless steel
  • Working pressure up to 25 bar (363psi)**
  • Working temperature -20 °C up to 300 °C (-40 °F to 572 °F)***

*other materials available upon request

**Higher pressure levels available upon request

***Lower temperatures available upon request

SONDEX® plate and shell
heat exchangers

Our SONDEX® plate and shell heat exchangers (SPS) are perfect choices for condensation and steam heating duties. A fully welded plate pack makes the heat exchangers well-suited for handling aggressive media as well as high pressure levels and temperatures. Less space demanding and much lighter in weight, they are good replacements for shell and tube heat exchangers.

SONDEX® plate and shell heat exchangers (SPS) combine the strengths of both shell and tube heat exchangers and plate heat exchangers, retaining the high working pressure and temperatures of the former coupled with the high efficiency of the latter. A “best of both worlds” solution, our plate and shell heat exchangers provide unmatched performance for a wide range of applications, particularly vapor condensation duties.

Features and benefits

  • Very adaptable heat exchanger. An excellent choice for handling condensation duties, especially duties without condensate sub-cooling. They are also perfect steam heaters of clean fluids, demineralized water, and clean thermal oils.
  • The heat exchanger is designed to be highly resistant to thermal shocks as well as thermal and pressure fatigue making it very well-suited for cyclic duties and other duties with sudden, large fluctuations in temperature.
  • Available in both bolted and fully welded designs. The fully welded types can handle higher temperatures and pressure levels than the bolted types but cannot be opened for cleaning. This can instead be done with CIP (Cleaning in Place) systems.

Technical specifications

  • Connections from DN25 to DN300 (1″ to 12″)
  • (Frames designed according to FEA and PED 2014/68/EU (EN13445) and ASME sec VIII, Div. 1 construction standards)
  • Plates made from AISI 304/316, titanium*
  • Shell materials: Carbon steel, stainless steel
  • Working pressure up to 40 bar (580 psi)
  • Working temperature -10 °C up to 250 °C (14 °F to 482 °F) for bolted types (up to 400 °C (752 °F) for the fully welded types)

*other materials available upon request

SONDEX® spiral
heat exchangers

Exceptionally well-suited for sludges, slurries, waste water, fouling, liquids with high viscosity, and liquids that contain fibers and solids, our SONDEX® spiral heat exchangers are the definitive solution for applications that require treatment of challenging fluids. The design allows for a countercurrent flow that makes it possible to achieve very close temperature approaches.

Since we use coiled metal sheets instead of tube bundles, we can achieve very high thermal performance without sacrificing the channel gap that lets the media flow unimpeded.

The spiral coil itself also contributes to the turbulent flow, and the single-channel design helps alleviate fouling with a “self-cleaning” mechanism. Accumulated deposits create local increases in velocity, creating a scrubbing effect that is enough to loosen the build-up in fouling in most cases. This allows our SONDEX® spiral heat exchangers to operate in very long sessions without maintenance or cleaning.

Some media, however, are so challenging that the heat exchanger requires more frequent maintenance and cleaning. With this in mind, we have designed hinged covers that are sealed with C-clamps, creating a swing door that is very easy to open and close without any special tools required, letting you access the entire coil for inspection and cleaning.

Features and benefits

  • Single-channel design that generates high shear rates which contribute to a self-cleaning effect, preventing clogging of the unit. Spiral heat exchangers are the perfect solution for challenging, high-viscosity media.
  • The channel size is selected to fit the flow and qualities of the media. The many variations in diameters and widths of the spiral coil allow for many different combinations, which mean that we can create the optimal solution for every duty.
  • Designed to handle a very aggressive temperature program and with a wide range of materials and plate thicknesses available, we customize each spiral heat exchanger to match the requirements of any application.
  • Limited need for maintenance and cleaning ensures extended operational uptime. If the need for cleaning arises due to particularly difficult media, the hinged covers provide easy access to the entire heat transfer surface.
  • Very compact solutions, our spiral heat exchangers have minimal space requirements. Despite their small stature, the long, curved flow paths allow for very high heat transfer coefficients up to twice as high as their shell and tube counterparts.

Technical specifications

  • Connections from DN32 to DN300 (1 1/4″ to 12″)
  • (Frames designed according to FEA and PED 2014/68/EU (EN13445) and ASME sec VIII, Div. 1 construction standards)
  • Shell materials: Carbon steel, stainless steel
  • Spiral materials: Carbon steel, stainless steel
  • Working pressure up to 16 bar (145 psi)*
  • Working temperatures from -20 °C to 200 °C (-4 °F to 392 °F)

*Higher pressure available upon request

SONDEX® brazed
plate heat exchangers

Danfoss and SONDEX® brazed heat exchangers (XB/SL) have been consolidated into a single, combined product portfolio for complete coverage of all applications. The durable, permanently sealed heat exchangers feature advanced technology and superior safety measures designed to provide you with the ultimate in heat transfer with minimal operational costs.

Our brazed plate heat exchangers (XB/SL) offer a compact and flexible solution designed for ultra-efficient performance for your high-pressure or extreme-temperature applications.

Features and benefits

  • Low operational costs, small hold-up volume, and high performance make our brazed heat exchanger solutions the ideal choice for many applications. Cut your costs and increase your profits with the help of our brazed portfolio.
  • The permanently sealed heat exchangers offer a durable solution with an extended lifetime. Enjoy peace of mind with the double-walled design that provides the ultimate protection against leaks.
  • With the energy-optimized, tried-and-true Fishbone technology, or the revolutionary Micro Plate™ technology; the combined Danfoss and SONDEX®product range offers the ultimate in brazed heat transfer solutions.

Technical specifications

  • Connections from ¾” threaded BSP/NPT to flange DN150 (6″)
  • Brazing materials: Copper, copper+, or stainless steel
  • Plate materials: AISI 316*
  • Plate heights from 0.202 m to 1 m (0.66 – 3.3 ft)
  • Flow rates up to 150 m3/h (661 gpm)
  • Working pressure up to 40 bar (580 psi)
  • Working temperature from -196 °C to 225 °C (-321 °F to 437 °F)

*other materials available upon request

fresh water distillers

Our SONDEX® fresh water distillers are designed to produce domestic, process, or even drinkable water by evaporating seawater. The vapor from the evaporated seawater is condensed and filtered, leaving behind freshwater which can be chemically purified if it is intended for drinking water.

When supplies of fresh water are scarce or unavailable, for instance on board vessels, platforms, and rigs the need for production becomes evident. Being able to produce fresh water on demand is paramount in the marine and offshore industry. Our SONDEX® fresh water distillers are based on two, or more, titanium plate packs that act as evaporators and condensers.

Features and benefits

  • High-vacuum design that lets the seawater evaporate at temperatures below 48 C°. This makes it possible to utilize excess heat from the cooling water of the engine jacket and put otherwise wasted energy to good use.
  • Our freshwater distillers require minimal supervision after startup, as they are fully automated and operate according to the given water flow and pressure. Furthermore, they are designed to require very little maintenance.
  • Featuring a salinometer, running-hour meter, and a chemical dosing unit by default, our freshwater distillers have all the equipment needed to ensure the correct salinity level for the desired freshwater output.
  • Our multi-stage freshwater distillers are based on regenerative energy utilization and are very well-suited for producing large quantities of freshwater, especially when the available energy is limited and costly to produce.

Technical specifications

  • Salinity of 1-10 ppm
  • Capacity of single-stage units: 1-100 metric tons of water/day
  • Capacity of multi-stage units: 30-200 metric tons of water/day
  • Construction materials: stainless steel, titanium


  • Marine/offshore industry
  • Drinkable water production
  • Process water production
  • Domestic water production