1. HPH® Bell-type Annealing Furnaces with BYPASS+JET Cooling for Carbon Steel Strip

HPH® Bell-type Annealing Furnaces with BYPASS+JET Cooling for Carbon Steel Strip

BYPASS+JET cooling allows highest productivity of the three cooling technologies designed by LOI. High efficient JET cooling hood is combined with a BYPASS system utilizing a gas-water heat exchanger to cool the process atmosphere directly.

Throughout the world, more than 8,500 LOI annealing bases have been installed. About 5,000 of these bases operate with HNx controlled atmospheres (5 % H2, 95 % N2). More than 3,500 bases use HPH® annealing technology with pure hydrogen annealing atmosphere. LOI is therefor also market leader in the field of high performance Bell-type Annealing Furnaces.

LOI has installed more than 300 bell-type-annealing plants in more than 30 countries and these plants are producing approx. 45 million tons of wide, medium-width and narrow strip each year.

In developing HPH® technology, LOI focused on the zero-error philosophy at the same time as building on existing furnace designs. As a result, even older Bell-type Annealing plants can be converted to HPH® operation.

LOI HPH® technology ensures atmosphere dew points below -60 °C. The extremely pure hydrogen annealing atmosphere and precise temperature control bring considerable quality benefits with a wide variety of steel grades.

BYPASS+JET cooling requires no open water in the plant while at the same time the BYPASS-System is suitable for a variety of energy recovery options.

More than 1,000 HPH®-bases with BYPASS+JET cooling technology have been built by LOI.

  • Value for Money

    Value for Money

    • Low operating costs
    • Low shop floor space consumption due to high efficiency
  • Efficiency


    • High efficient burner-individual recuperators
    • High convective heat transfer
    • Excellent temperature uniformity
  • Safety


    • Sophisticated process control
    • O2 concentration monitoring during prepurging
    • TÜV proven safety strategy
  • Value for Money

    Value for Money

    • Long service life
    • Sturdy cast diffusor system
    • No open water in the plant
  • Reference


    • > 60 years of experience in Bell-type Annealing
    • > 8,500 bases worldwide (> 3,500 HPH®)
    • > 1,000 HPH® bases with BYPASS+JET cooling
  • Environment


    • Selection of alternative cooling systems i.e. for low water quality or extended energy recovery
    • Suitable for sophisticated energy recovery measures
  • Digitalization


    • Fully automated control system
    • Various software modules for optimization
  • Technical Excellence

    Technical Excellence

    • World's first fully automated BAF plant
    • HPH®-Flameless combustion technology
  • ContactContact PersonPositionLegal EntityDepartmentPhoneFaxE-mailAddress
    LOI Thermprocess GmbH
    +49 201 1891-1
    +49 201 1891-321

    Am Lichtbogen 29

    45141 Essen


Carbon Steel