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Análise da causa de falha de um sistema AVAC e de sistema AQS de uma unidade hoteleira
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 4.41 MB | Adobe PDF |
Authors
Abstract(s)
O Instituto de Soldadura e Qualidade (ISQ), uma empresa que desenvolve soluções integradas de serviços de engenharia, inspeção, ensaios e testes, entre outros, foi consultado pelo departamento de manutenção de uma unidade hoteleira para analisar as causas de falha de um circuito de água quente. Foram analisadas as causas de degradação de um troço de tubo de um sistema Aquecimento, Ventilação e Ar Condicionado (AVAC) e de troços de tubo de um sistema de Água Quente Sanitária (AQS) pertencentes à unidade hoteleira em causa. Concluiu- se que a degradação do tubo do circuito AVAC deveu-se à acumulação de água sob isolamento devido a fugas nos acessórios de ligação que provocaram um fenómeno de corrosão sob isolamento. Nos tubos do circuito AQS foram observados dois fenómenos de degradação. Nas superfícies externas ocorreu um fenómeno de corrosão sob tensão resultante das tensões residuais devidas à soldadura, à presença de um metal suscetível e devido à acumulação de água entre a superfície metálica e o isolamento térmico. Esta água poderá ter tido origem em fugas nos acessórios ou em picadas e/ou fissuras trespassantes com origem na superfície interna dos tubos. Atribuiu-se a corrosão interna aos microrganismos presentes na água numa ação combinada com a presença de cloretos e potenciada pela deficiente qualidade das soldaduras que promoveu fenómeno de corrosão intersticial.
Abstract The Instituto de Soldadura e Qualidade (ISQ), a company that develops integrated solutions for engineering, inspection, and testing, among others, was consulted by the maintenance department of a hotel to investigate the root causes of a hot-water circuit failure. The causes of degradation of pipes from HVAC and Domestic Hot Water (DHW) systems belonging to an hotel were analyzed. It was concluded that the degradation of the pipes in the HVAC circuit was due to the accumulation of water beneath the insulation caused by leaks in the connecting fittings, which led to a phenomenon of corrosion under insulation. In the pipes of the DHW circuit, two degradation phenomena were observed. On the external surfaces, there was a phenomenon of stress corrosion cracking resulting from the residual stresses due to welding, the presence of a susceptible metal, and the accumulation of water between the metal surface and the thermal insulation. This water may have originated from leaks in the fittings or from pinholes and/or through cracks originating from the internal surface of the pipes. The internal corrosion was linked to microorganisms present in the water, which, combined with the presence of chlorides, lead to intense the corrosion. Additionally, the poor quality of the welds contributed to the development of interstitial corrosion.
Abstract The Instituto de Soldadura e Qualidade (ISQ), a company that develops integrated solutions for engineering, inspection, and testing, among others, was consulted by the maintenance department of a hotel to investigate the root causes of a hot-water circuit failure. The causes of degradation of pipes from HVAC and Domestic Hot Water (DHW) systems belonging to an hotel were analyzed. It was concluded that the degradation of the pipes in the HVAC circuit was due to the accumulation of water beneath the insulation caused by leaks in the connecting fittings, which led to a phenomenon of corrosion under insulation. In the pipes of the DHW circuit, two degradation phenomena were observed. On the external surfaces, there was a phenomenon of stress corrosion cracking resulting from the residual stresses due to welding, the presence of a susceptible metal, and the accumulation of water between the metal surface and the thermal insulation. This water may have originated from leaks in the fittings or from pinholes and/or through cracks originating from the internal surface of the pipes. The internal corrosion was linked to microorganisms present in the water, which, combined with the presence of chlorides, lead to intense the corrosion. Additionally, the poor quality of the welds contributed to the development of interstitial corrosion.
Description
Relatório de Estágio para obtenção do grau de Mestre em Engenharia Mecânica, na Área de Especialização de Manutenção e Produção
Keywords
Aço carbono Aço inoxidável 316L Falha por corrosão AVAC AQS Carbon steel Stainless steel 316L Corrosion failure HVAC DHW
Citation
AUGUSTO, Sónia Nascimento – Análise da causa de falha de um sistema AVAC e de sistema AQS de uma unidade hoteleira. Lisboa: Instituto Superior de Engenharia de Lisboa. 2024. Dissertação de Mestrado.