Our History

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Established in 1894

STI manufactures safety interlocks for industrial applications. Its products help companies to enforce safe operating procedures by ensuring operators follow a strictly defined sequence of steps when gaining access to a dangerous area. STI’s products include locks and switches for control circuits, switchgear and access points. The company also safeguards valves and warehouse loading bays.

Originally developed for railway applications, our products were swiftly accepted Industry-Wide due to their simplicity and efficiency. STI has supplied systems for staff protection in the fields of railway and power generation, chemicals and petrochemicals, the steel industry and the food industry.

Sentric Group

The global SPS formed in 2016, becomes Sentric Group, consisting of three sister companies Kirk in the US, STI in France and Castell in the UK. Our mission is to unite the world’s leading brands, product innovations, and experts to protect people in safety by mitigating the risk caused by human error. As Sentric, we share Purpose, Vision, Mission, and Values which bring unity, clarity and direction to everything we do. 

Halma SPS

In 2016, Serv Trayvou Interverrouillage, Castell and Kirk launch a partnership to be closer to their customers – under the name Halma SPS.

New digital solutions

Serv Trayvou Interverrouillage and Castell develop a digital solution for truck key management integrating SALVO and SKM together in 2017.

Serv Trayvou Interlock

In 2009, STI and HF Sécurité merge under the name Serv Trayvou Interverrouillage becoming the main safety interlocks company in France for the Industry & Manufacturing, Energy and Transport sectors.

The first RFID access management system

STI launches the very first RFID access management system SKM and takes a step into the digital world and industry.

ISO certification

In 1994, STI is certified ISO9001-2000, a must-have of seriousness and quality assurance.


Halma Group buys Trayvou and merges the French companies in 1987.

SERV is established

In 1962, Halma Group buys SERV.

SERV is established

Mr Barillet leaves Trayvou to establish the company SERV in 1961, the trapped Key Interlocking business.

Gold Award

At the 1900 World Exposition in Paris, Mr Bouré triumphed with a gold award for his invention.


In 1895, Trayvou manufacturers interlocking devices for the manufacturing industry and the railway industry.

A first for interlocking

For the first time in the world, an interlocking system was designed in 1894.

Creation of the engagement lock

In 1893, Paul Bouré creates engagement lock devices to ensures train traffic safety.