Plate materials and gaskets: selection by medium and operating conditions

The choice of plate and gasket materials in a plate heat exchanger is not a detail question - it determines the unit’s service life, corrosion resistance and suitability for food-grade applications. Incorrectly chosen materials lead to pitting corrosion, premature gasket failure or contamination of the medium. This guide maps the common plate materials and gasket elastomers to their areas of application.

Which plate materials are available?

1.4301 (AISI 304)

The material number 1.4301 denotes the classic austenitic chromium-nickel steel without molybdenum. For water without significant chloride content it is sufficient and the most economical stainless steel plate. In the configurator 1.4301 is therefore the default for water circuits as long as no chloride content is entered.

Applications for 1.4301:

• Heating and cooling water without significant chloride
• Water-glycol mixtures
• Mineral oils, hydraulic oils and lubricating oils

Limits: 1.4301 is more sensitive to chloride than 1.4404. As soon as the water contains a relevant amount of chloride, 1.4404 is the safe choice.

1.4401 and 1.4404 (AISI 316 and 316L)

1.4404 corresponds to AISI 316L and contains 2 -⁠ 2.5 % molybdenum in addition to chromium and nickel. Molybdenum considerably improves resistance to chloride-induced pitting corrosion compared with 1.4301 (AISI 304). The configurator selects 1.4404 as soon as a chloride content is entered, for the double-wall design and on request.

Applications for 1.4404:

• Cooling and process water with chloride within the limits below
• Food and beverages (food-grade approved)
• Whey, fruit juices, mildly acidic media

Limits: how much chloride 1.4404 tolerates depends on the temperature at the plate wall, which lies between the temperatures of the two media. Our reference values: up to about 60 °C wall temperature roughly 300 mg/l chloride, up to about 130 °C only roughly 25 mg/l. Above 130 °C wall temperature or at higher chloride content, stainless steel is no longer safe. Seawater, chloride brine and chlorinated process water call for titanium.

1.4401 (without the “L” for low carbon) is also used; the difference lies in the maximum carbon content. 1.4404 (low carbon) is more resistant to sensitisation during welding and is therefore the preferred variant for plate heat exchangers.

Titanium (Grade 1 and Grade 2)

Titanium is the material of choice for chloride- and salt-bearing media where stainless steel would fail. It is practically immune to chloride pitting corrosion and resistant to seawater, brackish water, chlorinated cooling water and many acid solutions.

Applications for titanium:

• Seawater cooling circuits (offshore, shipbuilding, coastal sites)
• Brackish water and river water with high chloride content
• Chlor-alkali electrolysis and chlorine-bearing process water
• Brine circuits in refrigeration technology

Titanium is significantly more expensive than stainless steel - typically 3 -⁠ 5× additional cost for the plates. Where stainless steel is adequate, titanium is not economically justified. Titanium is not suitable for hydrofluoric acid and some reducing acid mixtures.

Special materials

For strongly corrosive acids and other special cases we assess special materials individually, based on concentration and temperature. We never release such a material across the board.

Which plate material suits which medium?

Medium	Recommended plate material
Heating and cooling water without significant chloride	1.4301 (304)
Water with chloride up to approx. 300 mg/l, wall up to 60 °C	1.4404 (316L)
Water with chloride up to approx. 25 mg/l, wall up to 130 °C	1.4404 (316L)
Water with more chloride, brackish water	Titanium
Seawater, chloride brine	Titanium
Chlorinated cooling water	Titanium
Food, whey, juices	1.4404 (316L)
Mineral oil, hydraulic oil	1.4301 (304)
Ammonia (refrigerant)	1.4301 or 1.4404
Chloride-bearing acid solution	Special material after individual review (concentration, temperature)
Chlor-alkali	Titanium

Which gasket materials are available?

EPDM (ethylene propylene diene monomer)

EPDM is the most widely used gasket material in plate heat exchangers. It is resistant to hot water, steam, dilute acids and alkalis, and many polar solvents. The continuous temperature limit is approximately 150 °C, with brief peaks up to 180 °C. EPDM is excellent for:

• Heating and cooling water applications
• Food and beverages (food-grade approved)
• Milk, whey, fruit juices
• Domestic hot water heating
• Steam condensate applications

EPDM is NOT resistant to mineral oils, fuels, aromatic hydrocarbons and chlorinated solvents. Contact with these media causes swelling and gasket failure.

NBR (nitrile butadiene rubber, Perbunan)

NBR is the standard for oil- and fat-bearing media. It is resistant to mineral oils, hydraulic oils, lubricating oil, fuels and aliphatic hydrocarbons. The temperature limit is approximately 120 °C (continuous), up to 135 °C under favourable conditions.

NBR applications:

• Mineral oils, hydraulic oils
• Lubricating and gear oil cooling
• Fuel applications

NBR is NOT suitable for hot water above 80 °C, ozone exposure, aromatic hydrocarbons (toluene, benzene) or esters. NBR must not be used for steam or long-term hot-water service.

Other gasket materials

FKM / Viton: fluoroelastomer for aggressive solvents, acids, aromatic hydrocarbons and high temperatures up to 200 °C. Significantly more expensive than EPDM/NBR.

PTFE: for highly corrosive media, broad chemical resistance, but poorer mechanical sealing properties; used as an encapsulation or insert.

Which gasket suits which medium?

Medium	Recommended gasket material
Heating water, cooling water	EPDM
Steam / hot water up to 150 °C	EPDM
Food, dairy, beverages	EPDM (food-grade approved)
Drinking water	EPDM (WRAS / KTW compliant)
Mineral oil, hydraulic oil	NBR
Lubricants, gear oil	NBR
Aromatic hydrocarbons	FKM / Viton
Concentrated acids	FKM / PTFE
Ammonia	Welded design preferred; gasketed only with EPDM after review

How do you prevent fouling and corrosion?

Beyond chemical resistance, the fouling factor indirectly influences the material choice: smooth plate corrugations and high-alloy steel reduce the adhesion of deposits and thus the fouling rate. Titanium forms an oxide passivation layer that resists biological and mineral fouling more effectively than unalloyed steel.

Important: dissimilar metals in the same fluid circuit can cause galvanic corrosion. If a titanium plate heat exchanger is connected to a stainless-steel piping system, appropriate measures (insulating pieces, potential equalisation) should be checked.

Summary

Material selection follows from a clear analysis of the medium, temperature and chloride content. For water without significant chloride and for oils, 1.4301 (304) is sufficient. 1.4404 (316L) covers chloride-bearing water within the limits and food-processing applications. Titanium is the right material for seawater, chloride brine and high chloride content where stainless steel would fail. For gaskets: EPDM for water and food applications, NBR for oil. For aggressive solvents and high temperatures, FKM should be considered.