Failure investigation of Cu-DHP tubes due to ant-nest corrosion

Abstract

Purpose

The purpose of this paper is to address the main aspects of ant-nest corrosion failure mechanism of a Cu tube in heating ventilation and air-conditioning (HVAC) installations and analyze the possible root causes through various case studies presented.

Design/methodology/approach

Failure investigation process includes mainly stereo-, light optical and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy for elemental microanalysis, as the main analytical techniques for material characterization and root-cause analysis.

Findings

The investigation findings, obtained from corrosion products’ analysis in conjunction to metallographic evaluation in transverse sections, illustrate the principal characteristics (“fingerprints”) of ant-nest (formicary) corrosion mechanism.

Originality/value

This paper which deals with the presentation of applied failure analysis/case histories’ investigation, summarizing the main aspects of an important and insidious type of Cu corrosion, taken place in HVAC installation systems and, on the other hand, presenting a complementary analysis of the chemical processes involved in the progressive failure mechanism constitutes an integrated approach, aiming to become a concise contribution to this subject.

Citation

Vazdirvanidis, A., Papadopoulou, S., Papaefthymiou, S., Pantazopoulos, G. and Skarmoutsos, D. (2019), "Failure investigation of Cu-DHP tubes due to ant-nest corrosion", International Journal of Structural Integrity, Vol. 10 No. 3, pp. 325-336. https://doi.org/10.1108/IJSI-09-2018-0056