The HAWLE laboratory continuously performs various tests to ensure quality workmanship. Raw materials are checked for their suitability, samples are taken at random and checked during each production step and finished goods are subject to periodic tests, audit and review. Both destructive and non-destructive procedures are applied in order to yield those test results needed to determine the product’s quality level and carried out according to HAWLE test methods by specially trained and experienced staff. All test results are documented and corrective measures are initiated if necessary.

Some of the tests used are:

laboratory_hawle_2_en 100% pressure testing corrosion test practice test burst test tensile tests

Corrosion test

HAWLE coats all metal products susceptible to corrosion in a fluidized bed containing epoxy powder. This coating process is constantly monitored and carried out according to the guidelines given by the Quality Association for Severe Corrosion "GSK" (Gütegemeinschaft Schwerer Korrosionsschutz).

The picture on the right side shows the interface between epoxy coat and metal surface as seen in a microscope. Notice in this cross section how the epoxy enters all possible grooves in the metal surface.

Temperature measurement
Cast product prior to epoxy powder dipping
Product with finished coat

The parameters monitored during the epoxy coating process include controlling the correct temperature which must be held constant between 190-210°C, continuous refilling of the epoxy powder and securing correct powder coat thickness. Special tools have been developed to ensure that the coat on each and every product meet the exact same criteria, both internally and externally. The soak time and motion within the fluidized bed has been optimized to provide the desired homogeneous coating layer with uniform thickness.

Measurement of coating thickness
Conductivity test

Statistically significant amount of random samples are taken from each batch for impact tests. In the impact test, a metal rod is elevated one meter and dropped free falling onto the product with a resulting force of 5 Nm. The surface may not be damaged more than to such an extent prescribed in the subsequent conductivity test, in which 3000 volts are applied between blank metal and the point of damage from the impact test. If any electrical conductivity can be measured, the product surface is damaged and does not pass the test. In such rare instances further testing of the batch must be implemented in order to certify their surface coat quality.

Adhesion test
Drilling for sub surface corrosion migration
Place in salt water with electric current
Preparation for corrosion measurement


All manufacturing processes performed at other HAWLE factories are monitored by laboratory technicians in the central HAWLE laboratory. Various tests are performed on finished products according to the given GSK guidelines, such as interconnected bonding, adhesion, sub surface corrosion migration in salt water, absence of pores and impact resistance.

Ageing behaviour

After 10 days
After 15 days
After 22 days

Specially designed ageing tests simulate the ageing behaviour and thus the quality of the protective coat. The finished product is placed in deionised water, a very aggressive media that attacks the protective surface coat with the intention of exposing potential weaknesses.

The quality of the product, workmanship and the ageing behaviour of the protective surface coat are visible within a few days.

There is no visible corrosion on the surface after 22 days in very aggressive media.