Design comparison: gasketed, welded or double wall?

Platecore supplies plate heat exchangers in three designs: gasketed (plates clamped in a frame with elastomer gaskets, openable), welded (plates welded, for high pressures, temperatures and aggressive media) and double wall (two plates per separating wall, for processes in which the media must never mix). Four questions decide which design fits: How high are pressure and temperature? What is the medium? Does the unit have to remain openable? And may a leak mix the circuits?

The three designs at a glance

Criterion	Gasketed	Welded	Double wall
Plate joint	Elastomer gasket, clamped	Weld seam	Double plate, clamped with gaskets
Openable/extendable	Yes, plate count adjustable	No	Yes, plate count adjustable
Pressure (typical)	up to 25 bar	up to 35 bar	up to 25 bar
Temperature (typical)	-25 to 180 °C	-50 to 300 °C	-20 to 180 °C
Cleaning	mechanical and chemical (opened)	chemical only (CIP)	mechanical and chemical (opened)
Cost level	lowest purchase price, spare parts replaceable	higher, but gasket-free	higher, the second wall needs more area
Typical use	heating, district heating, industry, oil	chemical, oil & gas, steam, ammonia	drinking water, food, pharma

The pressure and temperature figures are conservative reference values; the actual rating depends on type, nominal pressure and gasket material.

Gasketed: openable, extendable, easy to maintain

In a gasketed plate heat exchanger pressed plates are clamped between a frame plate and a pressure plate; circumferential elastomer gaskets separate the two circuits. The decisive advantage is that it can be opened: the pack can be cleaned mechanically, and the plate count can be extended later when the duty grows.

The gasket sets the limits: temperature and pressure are bounded by the elastomer, and not every medium is compatible with every gasket material. Wherever regular cleaning or inspection is required - district heating substations, oil coolers, industrial plants with fouling tendency - the gasketed design is usually the most economical choice.

Welded: for high pressures, temperatures and aggressive media

In a welded plate heat exchanger the weld seam replaces the elastomer gasket on the media channels. This removes the component that fails first with aggressive media, solvents, steam or high temperatures: the design reaches operating limits up to 35 bar and 300 °C and remains resistant to media for which no gasket material is approved.

In return the unit gives up the flexibility of the gasketed design: the plate pack cannot be opened, cleaning is chemical. Typical applications are chemical and process plants, oil and gas, thermal oils, steam duties and ammonia refrigeration.

Double wall: when the media must never mix

The double-wall design is a safety variant of the gasketed design: every separating wall consists of two plates. If one plate fails, the medium escapes visibly to the outside instead of crossing into the other circuit. That makes it the first choice when mixing must be excluded under all circumstances - for instance in domestic hot water heating and in food and pharmaceutical processes. The additional wall costs heat transfer, so the unit is somewhat larger.

What about brazed plate heat exchangers?

Brazed plate heat exchangers are also common on the market: the plates are brazed together across their contact points, usually with copper filler. Without a frame and gaskets they are compact and cheap to buy, but they can neither be opened nor extended. Cleaning is limited to chemical flushing in the installed state, and an internal leak means replacing the complete unit.

Platecore does not offer brazed units. If you need to open, clean mechanically and extend the unit, the gasketed design is the right one; if you need a gasket-free design for high duty, the welded one.

Selection guide: which design for which application?

Application	Recommended design
Heating and district heating substation	Gasketed
Industrial oil cooler	Gasketed
Industrial plants with fouling tendency	Gasketed
Oil & gas	Welded
Chemical plants, aggressive media, solvents	Welded
Steam, high pressures and temperatures	Welded
Ammonia refrigeration	Welded
Drinking water heating with safe separation	Double wall
Food & pharmaceutical	Double wall

The table is an orientation - the sound decision is made during sizing, i.e. with medium, duty, pressure drop and operating conditions. The guide Sizing a plate heat exchanger shows how sizing works step by step.

Purchase price is not life-cycle cost

The most common mistake in choosing a design is comparing purchase prices only. The gasketed design is usually the cheapest to buy; in return there are planned costs for gasket sets, which are replaced after a few years depending on medium and temperature. The welded design costs more, but needs no gasket changes and withstands media for which no gasket material is approved - it can only be cleaned chemically. The double wall needs more area because of the second wall and therefore costs the most, but it rules out any mixing of the media. What maintenance and service life mean per design is covered in Maintenance, cleaning and service life; materials are covered in Plate materials and gaskets.

A tabular product comparison of the available designs with a recommendation per application is provided on the design comparison page.