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 methods (visual inspection, penetrant, ultrasonic, radiography testing and magnetic particle inspection)
• ultrasonic wall thickness measurement
• 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 has Accreditation Certificates that recognize that the Calibration Laboratory is competent according to HRN EN ISO/IEC 17025 and the Inspection Body is competent according to HRN EN ISO/IEC 17020 to carry out the following activities:
• pressure gauge calibration
• temperature gauge calibration
• pressure equipment inspection
• safety valve inspection
• horizontal cylindrical tank inspection
• inspection of petrol vapour recovery systems
• inspection of tyre pressure gauges
• inspection of scale bars and dispensers for LPG and liquid petroleum product for motor vehicles
• non-destructive inspection of industrial products and welded joints of metal materials.

Pursuant to the decision of the Ministry of Economy, Entrepreneurship and Crafts, STSI carries out inspections of low and high-hazard pressure equipment as the Inspection Body Type B.
For all of the abovementioned activities, STSI has been issued authorizations and certificates by:
• the Croatian Accreditation Agency (HAA)
• the Croatian Register of Shipping (CRS)
• the State Office for Metrology (DZM)
• the Ministry of Economy, Entrepreneurship and Crafts.