STSI

What STSI does

STSI - Integrirani tehnički servisi d.o.o. is a Croatian limited liability company founded on 20 December 2001 and headquartered in Zagreb, operating as the wholly-owned single-service company of INA, d.d., the Croatian national oil and gas group. The company delivers six interconnected service lines to oil, gas and process-industry operators: maintenance of refineries, oil and gas facilities, offshore platforms, pipelines and gas stations; engineering and project management for new builds and reconstructions; certified manufacturing of pressure vessels, pipelines and steel structures; waste management and environmental protection (including bioremediation of hydrocarbon-contaminated soil); technical control, diagnostics and a calibration laboratory (vibration diagnostics, laser alignment for rotating equipment up to 5.5 MW, infrared thermography, non-destructive testing); and inspection, legal metrology verification and HSE testing. Customers are primarily INA Group affiliates — INA, CROSCO, INA Maziva, JANAF, LNG Hrvatska, Podzemno skladište plina and ED-INA — with additional Croatian and regional clients including PETROKEMIJA, Končar-Inženjering, PETROLSZOLG (Hungary) and SLOVNAFT MONTÁŽE (Slovakia).

The technical foundation is built on a dense portfolio of accredited and certified capabilities rather than proprietary software. Production is certified under HRN EN ISO 3834-2 for pressure-equipment categories II, III and IV, compliant with EU Directive 2014/68/EU. Inspection is accredited by HAA under registration No. 6317 per HRN EN ISO/IEC 17020, with calibration laboratory accreditation under HRN EN ISO/IEC 17025. The company also holds integrated management system certifications for ISO 9001:2015, 14001:2015, 45001:2018 and 50001:2018, plus SCC (Safety Checklist for Contractors), and statutory authorizations from the Ministry of Labor, Ministry of Interior, Ministry of Economy and the State Measuring Office. Production facilities in Zagreb and Graberje Ivanićko span over 3,500 m² with four industrial cranes (2-20 ton capacity), supported by operational bases in Kostrena/Rijeka and Sisak. There is no public-facing API, software product or AI/ML component disclosed.

The business model is enterprise B2B services delivered through long-term framework contracts with INA Group companies and competitive procurement tenders ("nadmetanja") for external clients, using SAP Ariba internally. Distribution is direct field-service delivery to client sites across Croatia and selected international projects. STSI does not publish pricing, does not raise external capital (no funding rounds on file), and its go-to-market is built on tender participation, INA Group referrals and direct enterprise sales rather than marketing-led demand generation. Revenue figures are not publicly disclosed.

Name

STSI

Legal name

STSI - Integrirani tehnički servisi d.o.o.

Website

https://stsi.hr

Company type

Private

Founded year

2001

Operating status

Operating

Headcount range

1,001–5,000 employees

Short description

STSI is a Croatian integrated technical services provider and wholly-owned INA Group subsidiary delivering maintenance, engineering, equipment manufacturing, diagnostics, waste management and HSE testing for oil, gas and process-industry clients across Croatia and neighboring markets.

Ownership category

akta.pro rank

Product category

Industrial Technical Services

NAICS

Oil and Gas Pipeline and Related Structures Construction (237120), Oil and Gas Pipeline and Related Structures Construction (23712), Testing Laboratories and Services (54138), Engineering Services (54133), Engineering Services (541330)

SIC

Oil & Gas Field Services, Nec (1389), Services-Testing Laboratories (8734), Services-Engineering Services (8711), Oil & Gas Field Machinery & Equipment (3533), Pipe Lines (No Natural Gas) (4610)

akta.pro primary industry

Tank, Vessel & Pipeline Inspection/Cleaning/Repair (API/ASME) (IMAIACAH)

akta.pro secondary industries

Integrity Management Programs & Compliance (IMP, Risk Assessment, Regulatory Reporting) (TLAGALAE), Pipeline Construction & Right-of-Way Services (EUALADAL), Crude Oil Pipeline Integrity Management & In-Line Inspection (ILI) (TLAGAAAK), Aircraft Ground Support Equipment (GSE) Maintenance & Repair (EDAOAFAL)

Keywords

• Industrial maintenance services
• Process plant engineering
• Pressure equipment manufacturing
• Non-destructive testing
• Environmental waste management

Headquarters

HQ city

Hrvatski Leskovac

HQ country

Croatia

HQ region

Europe

Offices4 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Operations, Supply Chain, Technology or R&D, Infrastructure, Marketing or Sales

Revenue model

1. Održavanje (Maintenance Services): Maintenance services for refinery plants, oil-gas installations, gas stations, compressor stations and pipelines, offshore platforms, and drilling rigs. Provided through framework contracts with INA Group and external clients.
2. Projektiranje i upravljanje projektima (Engineering and Project Management): Design and project management services for construction and reconstruction of industrial facilities in Croatia and abroad.
3. Proizvodnja opreme i rezervnih dijelova (Equipment Manufacturing): Production of pressure vessels, pipelines, steel structures, and underground/aerial well equipment. Includes manufacturing of heat exchangers, pressure vessels, and air coolers.
4. Gospodarenje otpadom i zaštita okoliša (Waste Management): Waste management services including hazardous waste collection, storage, processing/recovery, emergency pollution prevention, and transportation services.
5. Tehnička kontrola, dijagnostika i ispitivanja (Technical Control, Diagnostics and Testing): Technical inspection, vibration diagnostics, laser alignment, infrared thermography, NDT testing, and HSE testing services with accredited laboratories.

Go-to-market motion2 records

Distribution channels3 records

Marketing channels3 records

Core offering

STSI provides integrated technical services for oil, gas, and process industry infrastructure. Its core offerings span six service lines: industrial maintenance of refineries, pipelines and offshore platforms; engineering and project management for new construction and reconstruction; certified manufacturing of pressure vessels and spare parts; waste management and environmental protection (including bioremediation); technical control, vibration diagnostics, thermography, NDT and an accredited calibration laboratory; and inspection, legal metrology verification and HSE testing under multiple governmental authorizations.

Product overview

STSI (Integrirani tehnički servisi) operates as a single-service company within the INA Group, providing integrated technical services primarily for oil, gas, and process industry infrastructure. The company offers a portfolio of six interconnected core service lines: (1) Maintenance services for refineries, oil/gas facilities, offshore platforms and drilling installations; (2) Engineering and project management covering design, procurement, construction supervision and commissioning for new builds and reconstructions; (3) Manufacturing of pressure equipment and spare parts (ISO 3834-2 certified) with facilities in Zagreb and Graberje Ivanićko; (4) Waste management and environmental protection services including hazardous waste handling and bioremediation of hydrocarbon-contaminated soil; (5) Technical control, diagnostics and calibration laboratory offering vibration diagnostics, laser alignment, infrared thermography and non-destructive testing (NDT); and (6) Inspection, legal metrology verification and HSE testing services with authorized inspection body status. These services are designed to work together as an integrated offering for maintaining and operating complex industrial process facilities.

Differentiator

Problem solved

Functional benefit

Products and services

• Održavanje (Maintenance Services) Comprehensive maintenance services for refinery plants, oil and gas facilities, gas stations, compressor stations and pipelines, offshore platforms, and drilling/remediation installations, primarily delivered to INA Group and external industrial clients.
• Projektiranje i upravljanje remontima i projektima (Engineering and Project Management) Design and management of construction and reconstruction projects for refinery plants, oil and gas production facilities, LNG terminals, pipelines, and offshore platforms, including engineering design, procurement, construction supervision and commissioning support.
• Proizvodnja opreme i rezervnih dijelova (Equipment and Spare Parts Manufacturing) Certified manufacturing of pressure vessels and piping systems under HRN EN ISO 3834-2 for categories II, III and IV. Production facilities in Zagreb and Graberje Ivanićko span over 3,500 m² with four industrial cranes (2-20 ton capacity), producing steel structures, pipelines, well equipment and rehabilitated pipelines.
• Gospodarenje otpadom i zaštita okoliša (Waste Management and Environmental Protection) Comprehensive waste management services including waste brokerage, collection, temporary storage, and processing/recovery of hazardous waste. Implements bioremediation as a primary treatment method for hydrocarbon-contaminated soil restoration.
• Tehnička kontrola, dijagnostika i umjerni laboratorij (Technical Control, Diagnostics and Calibration Laboratory) Vibration diagnostics and laser alignment for preventive maintenance, infrared thermography (ICT) for early detection of electrical and rotating equipment anomalies, including FLIR IR camera gas leak detection, plus accredited non-destructive testing (NDT) covering visual, penetrant, ultrasonic, radiographic and magnetic particle inspection.
• Inspekcija, ovjeravanje zakonitih mjerila i HSE ispitivanja (Inspection, Legal Metrology Verification and HSE Testing) Inspection of pressure equipment (authorized inspection body type B), verification of legal measuring instruments, and HSE system testing including process safety, fire protection, electrical installations and lightning protection systems; accredited inspection body per HRN EN ISO/IEC 17020.

Quantifiable outcome

• Bioremediation restores contaminated soil to original state through natural microbiological processes
• +2 more outcomes

Named customers11 records

Segments3 records

Ideal customer profiles2 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature6 records

Partnerships

Three partnerships are on record, tiered core and minor.

• INA, d.d.coreOthersSTSI was founded in 2001 by INA as a single service company (d.o.o.) with headquarters in Zagreb. STSI operates as a wholly-owned subsidiary within INA Group, providing integrated technical services primarily to INA and its affiliated companies.
• CROSCO d.o.o.minorOthersCROSCO is an oil services company within INA Group. STSI collaborates with CROSCO on projects and services in the oil and gas sector.
• LNG Hrvatska d.o.o.minorOthersLNG Hrvatska operates the LNG terminal on Krk island. STSI has participated in construction projects for the terminal facilities.

Scale indicators4 records

Recent moves8 records

Expansion highlights2 records

Direct peers

• Bilfinger: Global industrial services provider offering maintenance, engineering, and inspection for oil & gas, refining, and petrochemical facilities; closest direct comparable to STSI's integrated service model across the asset lifecycle.
• Stork (a Fluor company): Specializes in maintenance, modification, and integrity management for oil & gas and process industry assets; directly comparable to STSI's maintenance + NDT + integrity service stack.
• Tehnomont: Croatian industrial engineering and construction firm serving oil & gas, energy, and process industry clients; the most direct regional peer to STSI, competing for many of the same SEE maintenance and construction tenders.

Broad incumbents

• Petrofac: Integrated energy services company providing engineering, operations, maintenance, and integrity services to upstream and midstream clients; broader portfolio but same service categories as STSI.
• KBR: Global engineering, procurement, construction and services company serving hydrocarbons and energy clients; relevant comparable for STSI's engineering, project management, and government-authorized inspection workstreams.
• Worley: Large-scale energy project and operations services firm covering engineering, procurement, construction, and maintenance; overlaps with STSI's engineering and project management services at a broader scale.
• Siemens Energy (Industrial Application & Services): Provides industrial services, rotating equipment maintenance, and digital condition monitoring for process industries; overlaps with STSI's vibration diagnostics, laser alignment, and IR thermography services as part of a much broader portfolio.
• Wood (Wood Group / John Wood Group): Global energy services and engineering firm delivering maintenance, modification, and integrity solutions to upstream and downstream operators; broader scale but directly comparable maintenance/engineering workstreams.

Regional players

• DESCON Engineering: Middle East-based EPCM and industrial services company with oil & gas, refining, and pipeline execution capabilities; comparable service stack but different geography from STSI.

Emerging players

• CROSCO: INA Group affiliate providing oilfield services including drilling rigs, workover, and offshore platform support; overlaps with STSI on offshore platform maintenance even though its core is oilfield operations.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks5 records

Key highlights6 records

Customer concentration

• LinkedInlinkedin.com/company/482708

Compliance9 records

Revenue estimate

Valuation estimate

Number of profiles

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about STSI