Checking heat exchangers for leaks
for the dairy industry
Heat exchangers are essential in milk processing, serving crucial functions such as heating, pasteurization, and cooling. Maintaining the optimal temperature throughout these processes is paramount to guaranteeing the excellence of the final dairy product.
Heat exchangers are subjected to harsh operating conditions that increase their susceptibility to wear and corrosion. Factors like:
- aggressive chemical environments; high humidity;
- water hammer;
- vibrations.
The consequences of a defective heat exchanger extend beyond equipment failure. The presence of pathogenic microorganisms can proliferate in the finished milk product, posing significant risks to its safety. This increases the likelihood of spoilage, product returns, and customer complaints, leading to substantial financial losses, potential legal issues, and damage to the company’s reputation.
To mitigate these risks, regular rechecking the heat exchangers for tightness is essential. This re-verification of heat exchangers, carried out by employing engineering techniques, ensures the integrity of the heat exchanger’s structure. By confirming that the heat exchanger remains tightly sealed, manufacturers can uphold the bacteriological purity of milk, maintain product quality, and prevent potential financial, legal, and reputational losses
Types of damage caused to plate heat exchangers
- the capacity has dropped at the same time as the heating medium and electricity consumption has increased;
- the equipment has been idle for an extended period of time;
- the heat exchanger is being commissioned after repair or modernisation.
How to spot a hidden defect
per section
per 1 section test
- CIP washing of the heat exchanger is carried out.
- The pipes are disconnected.
- A gas mixture is started on one side of the heat exchanger: hydrogen 10% + nitrogen 90%. On the other side, a diaphragm pump presses air into the closed circuit.
- Hydrogen molecules will penetrate to the circulation side of the air mixture if there is damage in the section. The instrument will record the size and speed of the leakage. Based on this the size of the defect is determined.
- After the section has been checked, the seals are tested.
- confirmation of the presence or absence of defects;
- the size and description of the damage;
- photo fixation of the leakage defects;
- recommendations for repairing the damage and further operation of the heat exchanger.
Why a gas test is better than a disassembly
- Equipment downtime takes up to three days;
- Increased labour costs for the personnel;
- Even usable seals have to be replaced, and these cost from 7000 euros per set;
- There is a risk of damaging the plates.
Table comparing heat exchanger testing methods
condition
fatigue
Microcrack
< 30 microns
Microcrack
> 30 microns
hole
Benefits of the GasTest N2H2 to check the heat exchanger
AccuracyThe margin of error is as low as 1%. It is the most accurate method now available.- Safety
A non-flammable and non-toxic gas mixture is used, which does not contaminate the heat exchanger. The N2H2 gas test is suitable for the dairy industry. The methodology eliminates media overflow and dilution of the refrigerant, and minimises user error.
- Cost-effectiveness
The dye or hydraulic test requires water, increasing its consumption for purposes unrelated to finished product manufacture. Gas testing is energy efficient.
Highly sensitive equipment does most of the work. The labour required by the operating staff is reduced by up to 95%, as no disassembly of the equipment is required.
- SpeedDowntime of the heat exchanger is minimal compared with disassembly. Inspection of one section takes 15 minutes. We use flexible hoses for mixture and air supply, so that tests can even be carried out on equipment that is difficult to access.