Our History
Each of our brands have been at the forefront of trapped key interlocking for over 100 years.
Take a look at our history and see how what started as a simple design to protect people and assets, turned into a globally successful safety solutions business.

2023

Sentric announces it has acquired Zonegreen. Headquartered in Sheffield, United Kingdom, Zonegreen develops technologies, software and services that make working in rail depots safer and more efficient. Zonegreen’s products are used by rail customers across the UK, Ireland and Australia.
2022

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.
2022

Castell celebrates its 100th anniversary.
2019

Castell becomes ISO 45001 certified.
2017

Serv Trayvou Interverrouillage and Castell develop a digital solution for truck key management integrating Salvo and SKM together in 2017.
2016

The global leading group for interlock safety systems was formed back in 2016. It consists of three market-leading businesses, Kirk, Castell and STI, combining the expertise and high quality products of the three brands.
2014

In September 2014, Kirk moved operations and manufacturing to North Canton, OH, USA.
2012

Castell celebrates its 90th anniversary.
2012

Castell wins the Halma Manufacturing Excellence Award.
2011

In 2011 Kirk Key Interlock Company LLC was purchased by the holdings company Halma plc.
2009

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.
2008

STI launches the very first RFID access management system SKM and takes a step into the digital world and industry.
2005

Launch of new product range Salvo.
1999

In December of 1999, Kirk Key Interlock Company LLC separated from ABB and was completely independent, moving operations to Massillon, Ohio, USA.
1999

Castell purchases new product range Mistura.
1994

STI is certified ISO9001-2000, a must-have for quality assurance.
1990

Castell UK becomes ISO 9001 certified.
1987

Halma Group buys Trayvou and merges the French companies in 1987.
1983

Castell purchases Iso-Lok lockout tagout product range.
1974

UK Health and Safety at Work Act.
1971

Halma Investments Limited purchases Castell Locks Limited.
1962

In 1962, Halma Group buys SERV.
1961

Mr Barillet leaves Trayvou to establish the company SERV in 1961, the trapped key Interlocking business.
1933

Castell granted improvement to padlocks patent (patent number GB430168).
1932

In 1932, KIRK® trapped key interlocks were manufactured in Greensburg, Pennsylvania in the USA, as part of the Railway & Industrial Engineering Company which held the patent filed by R.L. Kirk.
1931

R.L. Kirk filed for his first patent “Safety Interlock for Electrical and Mechanical Equipment and Systems” in 1931 and Kirk became an authority in electrical safety.
1922

James Harry Castell establishes ‘Castell Locks.’
1921

Castell’s oldest recorded order placed by leading UK engineering and heavy industrial company
1920

James Harry Castell patents ‘Castell’ figure interlocking system to protect people during the electrification period in London.
1900

At the 1900 World Exposition in Paris, Mr Bouré triumphed with a gold award for his invention.
1895

In 1895, Trayvou manufacturers interlocking devices for the manufacturing industry and the railway industry.
1894

For the first time in the world, an interlocking system was designed in 1894.
1893

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