Knowledge base
In short
A plate heat exchanger leaks either to the outside, where the liquid shows at the joints, or internally, where the two liquids slowly mix. Other common problems are lost performance and blocked channels. Most are caught early by watching the unit, and the remedy depends on the type of exchanger and the cause.
Plate heat exchangers are reliable machines, but they are not immune to trouble. A drip under the frame, a circuit that slowly loses liquid or a product that suddenly shows traces of cooling water are all signs that something has gone wrong inside. This guide explains in plain words what the usual problems are, how to spot them early and what is normally done about them.
Leaks To The Outside
An outside leak is the one everybody notices: liquid shows at the edge of the plate pack, at a connection or on the floor beneath the unit. In a gasketed exchanger the usual cause is a gasket that has aged, hardened or been squeezed unevenly, or a pack that was closed incorrectly after service. In a brazed or welded unit an outside leak is rarer and usually points to a crack or to damage from outside.
A small outside leak is more than an untidy floor. It wastes liquid, it can stain or corrode what lies beneath, and it is often the first sign of a problem that will get bigger.
Leaks Between The Two Liquids
The more serious fault is an internal leak, where a crack, a pinhole or a failed seal lets one liquid pass into the other. It cannot be seen from the outside. The signs are indirect: one circuit needs topping up while the other fills, the liquid changes colour or smell, a treated circuit loses its treatment, or a sample shows traces of the other liquid. Corrosion, fatigue from repeated pressure changes and damage during cleaning are the usual causes.
Because the whole purpose of the exchanger is to keep the liquids apart, an internal leak should be treated as urgent. Where the product is valuable or the circuit protects an engine, the unit is normally taken out of service until it has been checked.
Lost Performance And Blockages
Not every problem is a leak. A unit that no longer reaches its temperatures, or whose pressure drop has crept up, is usually fouled, partly blocked or running with air trapped inside. Frozen liquid, a closed valve or a pump running below its duty can look the same from the control room, so the first step is to check the circuit around the exchanger before blaming the plates.
Fouling and its cleaning have a guide of their own; the point here is that a performance complaint and a leak call for different remedies, and it helps to know which one you have.
What Is Done About It
The remedy depends on the type and the cause. A gasketed unit can be opened, inspected, cleaned and fitted with new gaskets or replacement plates, and many outside leaks end there. A brazed unit cannot be opened and is usually replaced, and a welded unit is assessed case by case. After any repair the unit is pressure tested before it goes back into service.
Prevention is simpler than repair: clean and treated liquids, a protected circuit, steady operation without hard pressure shocks and a regular look at the unit. TECS Engineering designs and delivers plate heat exchanger solutions for engine, power plant and industrial cooling circuits; send the unit details and a description of the fault, and the engineering team will answer.
In Short
- Outside leaks show at joints and connections, mostly from gasket ageing
- Internal leaks let the two liquids mix and cannot be seen from outside
- Signs: liquid level changes, colour or smell changes, lost treatment
- Poor performance is often fouling or a circuit fault, not a leak
- Gasketed units can be opened and repaired; brazed units are usually replaced
- A repaired unit is pressure tested before it returns to service
What To Send With An Enquiry
- The type and age of the unit, if known
- The liquids on both sides
- A description of the fault and when it started
- Whether the leak is outside or between the liquids
- What has been done to the unit and circuit recently
- Photographs of the unit and its nameplate
Questions We Are Often Asked
Why does a plate heat exchanger leak?
Most outside leaks come from aged or poorly seated gaskets, and most internal leaks from corrosion, cracks or fatigue in the plates.
How do I know the two liquids are mixing?
Look for one circuit that needs topping up while the other fills, a change in colour or smell, lost treatment or traces of the other liquid in a sample.
Is a small leak a problem?
Yes. It wastes liquid and is often the early sign of a fault that will grow, so it is better checked than ignored.
Can a leaking plate heat exchanger be repaired?
A gasketed unit can usually be opened and repaired with new gaskets or plates. Brazed units are normally replaced, and welded ones are assessed case by case.
What if the temperatures are not reached but nothing leaks?
The cause is often fouling, trapped air or a fault in the circuit around the exchanger, so the whole circuit is checked first.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
