1. Roller Hearth Furnace for Stainless Steel Tubes and Bars

Roller Hearth Furnace for Stainless Steel Tubes and Bars

LOI Thermprocess, with its predecessors Matthias Ludwig and Nassheuer, has been building Continuous roller hearth furnace plants under protective gas atmosphere for tubes, bars, wire coils and semi-finished annealing goods for more than 60 years. Throughout the world, more than 350 LOI roller hearth furnace plants under protective gas atmosphere have been installed.

Bright annealing combined with solution annealing is the most important heat treatment procedure for stainless steel tubes in roller hearth furnaces.

The heat treatment usually takes place at temperatures of max. 1.250 °C. To achieve the bright annealing effect, an atmosphere of 100 % hydrogen is used as reaction gas during the heat treatment.

Moreover, the furnaces are suitable for 

  • stress relieving annealing,
  • recrystallization annealing,
  • normalizing, and 
  • soft annealing.


During the annealing of stainless steel, hydrogen mostly is the active or reactive component of the process gas. Nitrogen, in special cases argon or helium, is used for the furnace purging and forming. The selected instrumentation and used purging gases ensure a furnace operation at the highest safety level. A sophisticated safety logic guarantees safety for the personnel, machines and material at all times of operation.

Since a rapid material cooling is crucial for stainless steel, our furnaces distinguish themselves with a particularly short design of the physical separation between the heating and cooling zone. Due to jet coolers immediately downstream the furnace chamber, we achieve temperature gradients of more than 5 K/second at the latest in the range of 900 to 400 °C. Moreover, the recirculation fan speed can have an impact on the cooling gradient.

LOI’s roller hearth furnaces also suit duplex and super duplex steels that require a precisely adapted atmosphere. In our furnaces, the proper setting of the dew point avoids the individual annealing materials "sticking" together“.

In LOI’s roller hearth furnaces for stainless steel, currently up to two t/h of annealing good with a component length of max. 38 m are heat-treated in top quality. Leading manufacturers of stainless steel pipes apply our furnace plant technology throughout the world.

We design furnaces for longer products or higher throughput according to our customers’ requirements.

  • Value for Money

    Value for Money

    • High reliability
    • Long durability
    • Customized design
    • Chainable design
  • Efficiency

    Efficiency

    • Data reception from higher-level systems, e.g. ERP or MES
    • Process and capacity optimization
    • Consumption optimization and analysis
    • Easy production line integration
    • High efficiency heating systems
  • Safety

    Safety

    • According to DIN EN 746
    • Safety analysis and risk assessment
    • Redundant Atmosphere Control System
    • Protective gas flow metering
    • Safety Flow Control
    • Furnace Pressure
    • Failsafe Design
    • Consistent with local requirements
  • Service

    Service

    • Low-wear
    • High reliability
    • Maintenance Assistance System
    • Alarm - Management via e-mail/sms/app
    • Remote maintenance
  • Reference

    Reference

    • Centravis Group
    • Jiuli Hi-Tech Metals Co., Ltd.
    • Salzgitter Mannesmann Group
    • Sandvik Group
    • Tubacex Group (including SchöllerBleckmann Edelstahlrohr, Austria, and Salem Tube, USA)
    • Vallourec Group
  • Value for Money

    Value for Money

    • Recuperative burner system
    • Energy recovering systems, e.g. waste gas heat exchanger
  • Digitalization

    Digitalization

    • Industry 4.0
    • DMC (Data Management Center)
    • CQI 9 conformity
    • Production data recording and analyse at everytime
    • Level 0, 1, 2 design by LOI
  • Technical Excellence

    Technical Excellence

    • Customized design
    • Customized programming and visualization
    • 100% continuous roller hearth furnace plant under 100% H2 without lock systems
    • Different jet cooling systems
    • Arbitrary sub suppliers
    • After sales service with know-how in modification and modernization
  • ContactContact PersonPositionLegal EntityDepartmentPhoneFaxE-mailAddress
    LOI Thermprocess GmbH
    +49 201 1891-1
    +49 201 1891-321
    loi@tenova.com

    Am Lichtbogen 29

    45141 Essen

    Germany

Tubes and Bars