Araldite® supports development of new manufacturing methods for compound liner clad steel pipes

Patricia Albisser 24/06/2011

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Erndtebrücker Eisenwerk (EEW) produces a variety of steel pipes for the offshore industry, oil and gas treatment plants, power plant construction, pipelines, chemical and petrochemical plants as well as for civil construction. Based in Germany, the privately owned, family run company is one of the leading industrial large diameter pipe-producing companies in the world.

The types of pipes EEW produces range from clad, line, process and structural pipes to risers and prefabricated sections.

In a recent project, EEW’s Research & Development team have been working with Huntsman Advanced Materials and its distributors in Germany, Bodo Möller Chemie, to produce a new economic type of clad pipes, the compound liner clad steel (CLC) pipe. The idea behind the CLC pipe was to produce a budget-priced product providing additional technical advantages to simple liner clad pipes, while serving to close the quality gap between metallurgically bonded clad pipes and liner pipes.

As the criterion for the CLC pipe were to produce a new, competitive budget-priced pipe, it was decided that the company’s standard facilities for pipe production would be used to create a composite plate compounded out of a CMn-steel plate and a corrosion resistance alloy (CRA) sheet, bonded together with a high performance epoxy.

The challenge lay in identifying an epoxy adhesive that could enable the cladding of steel plates with all commonly used grades of CRA sheets, prior to forming and welding the heavy composite clad plates into pipes.

EEW followed the principles of lean engineering in selecting single package system epoxy adhesives to include in a series of rigorous tests designed to assess differences in break strength and elasticity.

After assembling the composites for testing, the adhesives were hardened in a hot press at 180°C and differences in the resistance to shear and tensile forces were observed. For most of the products, disbonding occurred with some of the composite samples showing significant signs of breakage. However, one of the adhesives – Araldite® AV 4600 – emerged as a clear winner, forming a strong and durable joint without any signs of disbonding and displaying the highest shear strength values of all products on test.

“The stress in compound cladding often reaches maximum levels due to bending or shear force, so a bonding solution that helps enhance performance and prevents issues such as inner buckling of the pipe is critical,” said Markus Bockelmann, Leader of Research and Development at EEW.

“Araldite® AV 4600 proved to be ideal for this application in providing the strength needed to withstand both bending in production and the shear and tensile stresses that the pipe would be subject to in application offshore.”

Araldite® AV 4600 is a multipurpose, one component heat curing thixotropic paste. It offers good chemical resistance, exceptionally good impact strength at subzero temperatures as low as -40°C and is heat resistant to 120°C. The CLC pipes produced using this system show outstanding mechanical and physical properties, making them ideal for high-stress environments such as offshore applications / marine applications.

Markus Bockelmann added, “Deploying standard manufacturing methods means the materials we use have to meet very tough criteria. Not only do they have to obviously be strong – but temperature in combination with force is always an issue, with offshore pipes being exposed to extremes in temperature from the flow within and without.”

To produce the composite clad plate that forms the CLC pipe, EEW used Araldite® AV 4600 to bond the CMn-steel plate and CRA sheet together in combination with resistance spot welding. The bond has been proven to be strong enough to form pipe diameters even less than 180 mm.

Through successfully combining adherence with resistance spot welding, cost efficiencies are created through only needing to use standard bogie type furnaces for hardening as opposed to a hot press.

The successful development of this new production method sees EEW fulfilling its overall objective to efficiently use standard facilities equipment to produce a new budget-priced pipe for its customers.

EEW’s CLC pipes fulfil the specified requirements for liner pipes, providing more safety against inner buckling and collapse due to the bonding of Araldite® AV4600 and the grid of spot welds. They can also be produced in much larger diameters than liner pipes. Indeed, the production process of CLC pipes does not set any limitation to the pipe diameter.

Consequently, EEW’s CLC pipes provide a reasonable and efficient solution where the quality of metallurgically bonded clad pipes are not compulsory and where the quality of simple, mechanically bonded liner pipes is not sufficient.

Patricia Albisser
Huntsman Advanced Materials (Switzerland) GmbH
K-401.5.77
Klybeckstrasse 200
CH-4057 Basel
Switzerland
Phone: +41-61-299 2664
Fax: +41-61-966 8130
E-mail: patricia_albisser@huntsman.com
www.huntsman.com/advanced_materials