Fully Welded Plate Type Heat Exchanger WS45

Structural Design

The plates of the fully welded plate heat exchanger are permanently fixed by welding, forming an inseparable integrated structure. There are no sealing gaskets, and all flow channels are sealed by welding. Usually, laser welding or brazing techniques are adopted, resulting in greater overall rigidity.

The detachable plate heat exchanger plates are assembled by pressing with bolts, allowing for disassembly for maintenance or component replacement. They rely on rubber gaskets (such as NBR, EPDM, etc.) to seal the flow channels, but the gaskets are prone to aging or corrosion.

Structural composition

The fully welded plate heat exchanger is a highly efficient and compact heat exchange device. Its structural composition combines the characteristics of traditional plate heat exchangers and shell and tube heat exchangers. The main components are as follows:

Plate assembly (core heat exchange component)

Corrugated plate: Made of corrosion-resistant materials such as stainless steel and titanium alloy, with special corrugations (such as herringbone, diagonal, etc.) pressed on the surface to increase turbulence and heat transfer area.

All-welded structure: The plates are permanently welded by laser welding or brazing, etc., without sealing gaskets, and can withstand high pressure and high temperature (usually up to over 300°C and a pressure of over 4MPa).

Frame and shell

End plate/compression plate: Located on both sides of the plate group, it provides structural support and withstands the pressure of the medium.
Housing: Some designs feature an external housing (such as semi-welded or fully enclosed) to protect the internal plates and withstand system pressure.

Takeover and Interface

Medium inlet and outlet: According to the process design (single process/multiple processes), it is usually divided into:

Fixed-end pipe connection: Directly welded to the plate flow channel.

Active end takeover : detachable design (for some models), convenient for maintenance.

Flange or threaded connection: used for connection with the piping system.

Diversion device

Distribution area: Design a diversion structure at the entrance of the plate to ensure the uniform distribution of the fluid across the plate surface.

Collection area: Fluid is collected at the outlet to reduce pressure drop.

Support and fixing components

Support frame: Large heat exchangers may be equipped with steel frames for easy installation and fixation.

Lifting lugs or base: Convenient for transportation and installation.

Optional attachments

Sewage outlet: Used for cleaning or discharging residual media.

Instrument interface: Install temperature and pressure sensors.

Insulation layer: Reduces heat loss under high-temperature working conditions.

Sealing performance and pressure/temperature resistance capability

The all-welded plate heat exchanger has no gaskets and completely avoids the problem of gasket leakage. It is suitable for high pressure (up to 4.0 MPa or above), high temperature (above 400°C) or extreme conditions (such as strong corrosive media). The welding process requires high standards. If there is an internal leakage, the entire unit needs to be reworked.

The detachable plate heat exchanger relies on gaskets for sealing and has lower pressure resistance (usually ≤ 2.5 MPa) and temperature resistance (generally ≤ 180°C).
Gaskets are susceptible to chemical media and temperature changes and need to be replaced regularly, resulting in high maintenance costs.

Maintenance and Cleaning

The fully welded plate heat exchanger is non-detachable and difficult to be mechanically cleaned. Usually, it can only be chemically cleaned or back-flushed. It is suitable for clean media or working conditions where scaling is not likely (such as gases, oils).

The detachable plate heat exchanger can disassemble the plates for mechanical cleaning, and is suitable for media prone to scaling or containing particles (such as cooling water, slurries). The gaskets are easy to replace, and the maintenance cost is low but the frequency is high.

Application Scenarios

The fully welded plate heat exchanger is used for high-temperature and high-pressure, corrosive media (such as acids and alkalis), and flammable and explosive fluids (such as liquefied gas and ammonia).
Typical applications: petrochemicals, pharmaceuticals, nuclear power, refrigeration (ammonia system).

The detachable plate heat exchanger is usually applied in HVAC (heating, ventilation, and air conditioning), food and beverage, low-pressure steam heat exchange, and domestic hot water systems.
Suitable for scenarios where frequent cleaning or replacement of the medium is required.

Cost and Lifespan

The fully welded plate heat exchanger has a high initial cost (due to the complex welding process), but it has a long service life (without the problem of aging of gaskets), and the overall operating cost may be lower.

The detachable plate heat exchanger has a low initial cost, but it requires regular replacement of gaskets and plates, and the long-term maintenance cost is higher.

Compactness and Efficiency

Both offer efficient heat transfer (through the plate-fin design which enhances turbulence). However, the fully welded type does not have the limitations of gaskets, allowing for smaller plate spacings and potentially a more compact volume.