UKERC EDC: Publications

DTICC225_file19875.pdf

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Abstract:

The recently completed project 'Practical Improvements in Power Plant Engineering (PIPPE)' - part of the DTI Cleaner Coal Programme - has highlighted weld heat-affected zone "Type IV" cracking as a principal concern in advanced high temperature plant. Current creep test data, inevitably obtained on a much shorter timescale than the projected life of plant, suggest that weld performance could substantially deteriorate in the longer term. Better data and extrapolation techniques are needed to assess the extent of this threat to plant reliability and thus develop effective countermeasures that will gain the confidence of prospective plant purchasers and operators.

This project will help manufacturers gain a fundamental understanding of why the weld heat-affected zone is susceptible to "Type IV" cracking in high temperature service, how its susceptibility is related to steel composition and heat treatment, and, consequently, how advanced steels can best be selected and developed to minimise these risks. The main objectives are:

To generate longer term creep rupture test data on advanced steel weldments

To develop better techniques for the prediction of weld creep life in service from laboratory test data

To thereby assess the long term risks associated with "Type IV" cracking in welded high alloy steels for advanced plant

To determine the optimum steel choices for welded thick section advanced PF plant components such as headers and steam pipework

To determine appropriate limits on plant operating temperature and stress conditions to ensure the reliable long term operation of welded components

The FOURCRACK project will produce and assess cross-weld creep rupture test data on welds in advanced high temperature steels. The leading competitor materials will be critically compared. New welds will also be compared with simulated service aged and repair welds. Weld thermal simulation and microstructural assessment will be employed to gain a better understanding of the causes of "Type IV" cracking

This profile contains information on the project's:

Objectives

Summary

Cost

Duration

Contractor

Publication Year:

2001

Publisher:

Department of Trade and Industry

DOI:

No DOI minted