1953 – 1970

VEB Stahl- und Apparatebau Genthin (STAG) emerged from an insolvent metal processing company founded after the Second World War on May 1st, 1953. The production of pressure vessels and various steel construction components formed the core of the company's production program. The company developed into the most important manufacturer of galvanized water heaters as well as compressed air and water tanks in East Germany.

1970 – 1990

The previously district-managed company is assigned to the heavy machinery state combine "Ernst Thälmann" Magdeburg (SKET) as part of the concentration of economic capacities. In addition to the greatly expanded area of ​​water heater production for a modern housing construction program, medium-weight steel components for the combined mill and cement system program were manufactured and galvanizing services were offered for various industries. The start of the development, production and industrial repair of the latest technology for the military sector was associated with a sudden increase in sales, personnel, capacities and extensive investments as well as the expansion of the company premises to over 180,000 m².

At the same time, a large number of apartments were built and made available in the city of Genthin in order to secure the considerable personnel requirements for qualified skilled workers and engineers. In 1990, about 1,250 people were employed in the STAG.

1990 – 1993

The political changes after the fall of 1989 represented a turning point in the history of the company. In June 1990 the VEB Stahl- und Apparatebau Genthin was converted to Stahl- und Apparatebau GmbH with effect from May 1, 1990 as a SKET Magdeburg AG company, STAG GmbH was subordinate to the trust company created in Berlin in 1990. The years up to the end of 1993 were characterized by a large number of outsourcing and sales of parts of the company, a complete reorientation of the production profile as well as an extensive and painful reduction in personnel.

As a result of the redesign process, the industrial park "Am Werder" was created, which is now the largest producing industrial area in the old district of Genthin. Well-known companies are still based here today. The decision to produce LPG tanks for the large and medium-sized supply companies in Germany played a major part in the positive development of shrunken STAG GmbH. In a very short time, the tank production area was made fit for this production program and became the first of the East German manufacturers of liquid gas tanks being active on the market.

In parallel to the restructuring and investment measures, extensive privatization negotiations were held with various domestic and foreign investors with the participation of the trust agency. In December 1993 the sale of the company to the Dutch polynorm N.V. based in Bunschoten has been successfully completed.

1994 – 2000

With the takeover by Polynorm N.V. STAG GmbH became a member of the Flamco Group. The company now operated under the company name "Flamco STAG Behälterbau GmbH". In addition to the LPG tanks, the large vessel program was taken over for the Flamco Group. Through extensive technical developments numerous technical top products, e.g. the compressor or pump controlled pressure maintenance, has been perfected.

At the same time, the area of storage water heaters was further developed by numerous series of enamelled cylinders, buffer storage and corresponding special tanks. At the end of 1994 Flamco STAG Behälterbau GmbH was subordinated a number of subsidiaries such as Flamco Flexcon GmbH, Wemefa GmbH and another company in the Polynorm group.

2001 – 2013

In connection with a streamlining of the organizational structure of the Flamco group and the takeover of the Polynorm group by the Austrian group Voestalpine it was decided to separate the operational and the investment business of Flamco STAG Behälterbau GmbH. The operational business with all assets except the investments was brought into the new subsidiary "Flamco STAG GmbH".

Extensive investments in equipment for container production, numerous new product developments as well as an expansion of the production profile to include products from heating technology characterized the following years. From 2004 the sales company Flamco Wemefa GmbH (formerly Flamco Flexcon GmbH) took over the complete distribution of the products.

2014 - 2019

The entire Flamco Group was sold from the Austrian Voestalpine AG to the Dutch Aalberts Industries N.V. In this context the company's independence was strengthened from 2016. The responsibility for the sale of independently developed and produced products was completely taken over again. Furthermore, the name was changed to the old company name "STAG GmbH".

2020 - heute

In January 2020 100% of the company shares were taken over by the managing director Michael Jungk. The long tradition and the legacy of the company's history are preserved. A new chapter begins in an owner-managed compan, that is committed to sustainable, responsible and consistent further development.