Composite tube orders from the pulp and paper industry

Composite tube orders from the pulp and paper industryKeywords: Sandvik Steel, Tubing

Sandvik Steel reports that it has recently received several large orders,valued at approximately SEK 60M ($3 million), for advanced composite tubes for use in the pulp and paper industry. The tubes are to be installed in black liquor recovery boilers in pulp and paper plants – a very corrosive environment with high demands on the properties of the material.

The orders have been received from customers regarded as world leaders in the construction of black liquor recovery. Among them is Kvaerner Pulping (Plate 1). Final delivery of the boilers will be to pulp and paper plants in the USA,Brazil, Spain, Sweden and Belgium.

Sandvik Steel is a major company in the production of composite tubes for black liquor recovery boilers following many years' investment in research and development in this field.

  Plate 1 A Kvaerner Pulping plant, Mestsa (Rauma pulp mill in Finland) uses Sanicro 38 composite tubes in the furnace floor

Composite tubes are used in environments where the demands on the inside and the outside of a tube are such that they cannot be met with one type of steel. They consist therefore of two types – an outer layer of a corrosion resistant high alloyed material – and an inner layer of a load-carrying,low-alloyed steel. Because of the protecting outer layer, tubes can reportedly be in operation three to five times longer or, even more in some cases, than traditional carbon steel tubes.

As a result, composite tubes are said to have become increasingly well established as a solution to corroded tubes caused by the harsh environment in black liquor recovery boilers. Downtime is very expensive, particularly since the boiler also generates energy used in other parts of the pulp mill.

Sandvik Steel informs us that it has developed an even more corrosion resistant composite tube product. Called Sandvik Sanicro 38, it claims improved corrosion resistance and is thought to be particularly suited to use in the highly corrosive lower part of a recovery boiler furnace. Composite tubes in this grade are included in the recent orders received.

Details available from: Sandvik Steel. Tel: +44 (0)01922 728800; Fax: +44(0)1922 728827; Web site: www.steel.sandvik.com