STSI performs vibration diagnostics and laser alignment as part of preventive maintenance, which ensures early detection of possible malfunctions and thus prevents more severe defects and equipment damage. By performing frequent planned measurements, the condition of the equipment is monitored over time and vibration values are recorded, and the analysis of this data accurately determines the condition of the equipment and forecasts the need for servicing.
Laser alignment of machines with power up to 5.5 MW is a method by which the machines are brought into the needed position and thus it prevents potential increased vibrations during operation, as well as damage to machines and their parts (bearings and stuffing boxes). Works are performed while installing the new machines or their condition is checked and corrected during use.
STSI uses infrared thermography (IRT) in order to provide a preventive maintenance service and ensure early detection of irregularities in the operation of power plants and rotating equipment.
The latest method of use of IRT is to detect the leakage of gases by the FindIR camera, which can detect the leakage of 27 types of gas by recording the plant from a distance. The use of ICT in STSI began in 2005, and our employees made a great contribution to its use by participating in the establishment of the Croatian Association for Infrared Thermography (HUICT).

As part of technical control, there is also a laboratory for non-destructive testing of materials (NDT), which includes:
• non-destructive testing (visual inspection, penetrant, ultrasonic, gamma and X-ray testing, as well as magnetic particle inspection)
• ultrasonic measurements of wall thickness – other tests (MFL tests of corrosion damages of tank floors and pipelines, vacuuming welded joints of tank floors)
• making metallographic replicas and analyzing the structure of the material, including condition assessment
• measuring the surface hardness of steel
STSI owns the accredited calibration laboratory and inspection body for:
• inspecting safety valves
• inspecting pressure vessels
• testing LPG tanks with a special storage tank
• fitting testing
• pressure gauge calibration
• temperature gauge calibration
Pursuant to the decision of the Ministry of Economy, Entrepreneurship and Crafts, STSI conducts the activities of inspecting pressure equipment of low and high levels of hazard.
For all of the abovementioned activities, STSI has been issued authorizations and certificates by:
• Croatian Accreditation Agency (CAA)
• Croatian Register of Shipping (CRS)
• EX Agency,
• State Office for Metrology (SOM)
• Ministry of Economy, Entrepreneurship and Crafts
• TPK Institute