STSI performs vibration diagnostics and laser alignment as part of preventive maintenance, which ensures early detection of possible malfunctions and thus prevents more serious defects and equipment damage. By using computer programs, 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 laser machines are brought into an ideal line and thus it prevents potential increased vibrations during operation, as well as damage to bearings and stuffing boxes. Works are performed while installing the new machines or their condition is checked during exploitation.

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 the Republic of Croatia began in 2005, and STSI employees made a great contribution to its use by participating in the establishment of the Croatian Association for Infrared Thermography.

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 a condition assessment
• measuring the surface hardness of steel

STSI has accredited testing and calibration laboratories for:

• testing safety valves
• testing pressure vessels
• testing LPG tanks with a special storage tank
• fitting testing
• pressure gauge calibration
• temperature gauge calibration

Based on the decision of the Ministry of Economy, Entrepreneurship and Crafts issued in March 2017,
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 Zavod