Plate Heat Exchangers

Compact, highly efficient and easy to maintain. Gasketed and brazed plate exchangers for steam heating, pasteurisation, DHW production and energy recovery — with free sizing service from Roffia technical team.

How plate heat exchangers work

A plate heat exchanger consists of a series of corrugated metal plates clamped between a fixed and a movable frame. The two fluids flow on alternate sides of the plates — always in counterflow to maximise the temperature difference across the heat transfer surface. The corrugated pattern forces turbulent flow at much lower velocities than tubular exchangers, achieving heat transfer coefficients 3–5 times higher than shell-and-tube designs of comparable duty.

This translates to significantly smaller footprints — a plate exchanger rated at 500 kW may occupy less than a quarter of the floor space of an equivalent tubular unit. The gasketed version can be fully dismantled for inspection and cleaning, or expanded by adding plates as the process duty grows. The brazed version is permanently sealed, extremely compact and cost-effective for fixed-duty applications.

For steam-heated applications, plate exchangers are typically the first choice in food, pharmaceutical and HVAC sectors. They require correct float steam trap sizing and careful air venting at startup to achieve rated performance.

Brazed plate heat exchanger — Roffia srl

Gasketed plate heat exchangers

  • Temperature range: –20 °C to +185 °C (EPDM gaskets)
  • Max pressure: up to 25 bar
  • Plates: AISI 316L, titanium, Hastelloy C-276
  • Gaskets: NBR, EPDM, HNBR, PTFE
  • Duty: 1 kW to several MW
  • Key advantage: fully dismantlable, expandable, cleanable

Brazed plate heat exchangers

  • Temperature range: –160 °C to +225 °C
  • Max pressure: up to 30–45 bar (nickel-brazed)
  • Plates: AISI 316L (copper- or nickel-brazed)
  • Duty: typically below 200–500 kW
  • Key advantage: no gaskets, no frame, very compact and lightweight
  • Note: not suitable for fouling fluids or CIP cycles

Typical applications

Steam heating and pasteurisation

In the food and beverage sector, gasketed plate exchangers heat milk, juices and liquids from process steam. EPDM or HNBR gaskets and electropolished AISI 316L plates meet 3-A Sanitary Standards and EHEDG guidelines. CIP cleaning is fully supported. For pasteurisation duties, the exchanger must maintain the required holding temperature; this involves precise sizing and steam trap selection to avoid condensate flooding.

District heating substations

In district heating networks, plate exchangers interface the primary network (high temperature, often 70–130 °C) with the building's secondary heating circuit. They provide hydraulic isolation between networks, are compact enough for small plant rooms and their high heat transfer efficiency minimises the primary return temperature — important for heat pump-assisted networks and biomass boiler efficiency.

Domestic hot water production

Brazed plate exchangers are the standard solution for instantaneous DHW production in boiler rooms and heat pump installations. Their very small water content means near-instant hot water response within seconds of demand. WRAS-approved versions are specified for direct potable water contact in the UK and equivalent certifications apply across EU markets.

Biogas and energy recovery

In biogas plants, plate exchangers recover heat from engine cooling water and CHP exhaust to heat the anaerobic digesters. The biogas slurry side may contain fibres and particulates — appropriate plate spacing (wide-gap or free-flow designs) and regular inspection are required. Titanium plates are often specified where the digestate is mildly corrosive.

Data required for sizing

Process data (both sides)

Fluid type, inlet and outlet temperatures, mass flow rate or duty (kW), operating pressure and maximum allowable pressure drop.

Fluid properties

For non-aqueous fluids: viscosity, specific heat and thermal conductivity at operating temperature. For steam: saturation pressure and whether steam is dry saturated or superheated.

Fouling factors

Expected fouling resistance for each fluid (TEMA values or process-specific). Critical for correct oversizing and maintenance interval planning.

Regulatory and connection requirements

PED category, food-grade certification requirements, connection sizes (DN, flange standard) and frame orientation (horizontal or vertical installation).

Domande frequenti

What is the difference between a gasketed and a brazed plate heat exchanger?
A gasketed plate heat exchanger is assembled with removable rubber or EPDM gaskets around each plate. The entire stack can be dismantled by loosening the tie rods, giving access to every plate for inspection, cleaning or replacement. This makes gasketed units the standard choice wherever fouling is expected — food and beverage, dairy, chemical processing — or where plates need periodic replacement due to corrosion. A brazed plate heat exchanger has plates vacuum-brazed together with copper or nickel filler: it cannot be opened, but is extremely compact (no frame, no gaskets), fully leak-proof and highly cost-effective for duty below 200 kW. Brazed units are widely used in domestic and commercial heating and DHW production. When in doubt: if the fluid is fouling, potentially corrosive or requires CIP cleaning, choose gasketed; if the duty is well-defined and permanent, brazed is lighter and less expensive.
What does plate corrugation pattern affect in a plate heat exchanger?
The herringbone corrugation angle (typically 30° "soft" or 60° "hard") is the main variable the designer can choose. A hard (high-angle) corrugation creates high turbulence and a high heat transfer coefficient, but also generates a high pressure drop. It is suited to fluids with low viscosity and processes where pressure drop is not a constraint. A soft (low-angle) corrugation gives a lower heat transfer coefficient but significantly reduced pressure drop — important with viscous fluids or where low ΔP across the exchanger is required by the pump head available. Most manufacturers offer mixed configurations where alternate hard and soft plates are combined to optimise the heat transfer/pressure drop balance. Roffia technical team performs the selection using manufacturer software once the process data (temperatures, flow rates, fluid properties, allowable ΔP) is available.
Which materials are available for plates and gaskets?
Plates: AISI 316L stainless steel (standard, suitable for water and most aqueous fluids), titanium (seawater, chlorides, aggressive cooling water), Hastelloy C-276 (strong acids, oxidising environments). Gaskets: NBR (water, brine, hydrocarbons up to 120 °C), EPDM (water, steam, dilute acids and bases, hot water CIP up to 160 °C), HNBR (oil/glycol, wider temperature range), PTFE (highly aggressive fluids, pharmaceutical SIP at 140 °C). For the food and beverage and pharmaceutical sectors, only FDA/EU 10/2011-compliant gasket materials should be specified. Roffia supplies both replacement gaskets and complete plate packs for all major brands.
How do I size a plate heat exchanger?
Sizing requires the following process data: hot side: fluid type, inlet temperature, outlet temperature (or flow rate), operating pressure; cold side: same data; duty (kW): if a target temperature is given for one side, the duty follows from the flow rate and specific heat; allowable pressure drops for each side; fouling factors if the fluid is known to foul. With these inputs, manufacturer software calculates the required number and size of plates, the corrugation angle and the connection size. A critical parameter for steam-heated exchangers is the steam trap selection: the trap must handle the peak condensate load at startup (typically 2–3× the steady-state load) as well as the design flow at operating pressure. Roffia performs sizing at no charge — send your process datasheet and we will return a plate selection with quotation.
Can a plate heat exchanger handle steam on one side?
Yes, with important caveats. Gasketed plate exchangers can handle steam typically up to 10–16 bar and 170–185 °C, limited by the gasket material (EPDM is most common for steam service). They are widely used for steam-to-water heating in food, pharmaceutical and HVAC applications. Brazed plate exchangers (copper brazed) are generally limited to steam pressures below 5–6 bar due to the lower mechanical strength of the copper braze — nickel-brazed versions extend this range significantly. The main concern with steam service is the steam trap: the condensate must be removed continuously by a float trap sized for the peak startup load; a flooded exchanger loses up to 70% of its thermal performance. Additionally, all-steam plate exchangers require careful venting of air at startup, typically achieved with the float trap's integral thermostatic air vent.
How often do plate heat exchanger gaskets need replacing?
Gasket life depends primarily on temperature cycling and fluid chemistry. Under stable conditions with clean water and EPDM gaskets within the recommended temperature range, gaskets typically last 5–10 years. Factors that accelerate degradation: frequent high-temperature CIP cycles (alkali + acid + hot water); chlorinated cleaning agents used on NBR gaskets; thermal shocks from wide temperature swings; and overpressure events that cause gasket extrusion. Signs of gasket failure include interleak (fluid mixing between sides) or external leakage at the plate edges. When replacing, always use genuine OEM gaskets or certified compatible alternatives with correct dimensional tolerances — oversize or undersize gaskets change the plate compression load and reduce service life. Roffia supplies replacement gaskets for all major plate heat exchanger manufacturers.

Plate heat exchanger sizing service

Send us your process data — fluids, temperatures, flow rates and pressures — and our technical team will return a plate selection with a detailed quotation. No obligation.

Richiedi preventivo Chiamaci ora
Privacy Policy Cookie Policy