Introduction to forensic engineering
7 Piping problems
The two containment case studies were examples of problems capable of proceeding to litigation, but were resolved amicably by the insurers and their experts, who largely agreed about the causes. It is when the experts cannot agree, or come to quite different conclusions about causation, that litigation ensues. The case studies in this section will examine several problems that proceeded to litigation – and in one instance to trial – before settlement could be reached.
It is in the area of pipe and tubing that polymeric materials have become widely used in the last few years, often because they are more resistant to fluids, perhaps stronger than conventional materials, and certainly light and easy to install. Existing piping in materials such as steel, cast iron and ceramics is therefore increasingly being replaced by polyethylene, polypropylene and PVC.
Cast iron in particular was used widely in the Victorian period for water pipes, but it is susceptible to brittle cracking, causing leaking and loss of water supply. While water loss in the ground may be inconvenient, loss of gas is more serious, leaking cast iron mains having caused numerous explosions, fires and subsequent loss of life in the recent past. By contrast, polyethylene pipes are more flexible, so can accommodate imposed loads in the ground, and are much tougher or crack-resistant than cast iron. They can be easily welded and are easier to handle during fitment.
Polymers have also replaced many cast iron water supply systems for similar reasons, but problems can arise if the materials are susceptible to any chemicals in the supply. The particular problem we will examine in this section, arose from chlorine added for purification purposes. It caused stress corrosion cracking (SCC) of a plumbing fitting, which when it failed, led to substantial flood damage. The case led to litigation, which was only resolved by discovery of parallel problems in the USA.
Another critical application for tubing is in vehicle fuel lines, because if a break occurs, the proximity of a hot engine and electrical equipment can easily lead to a serious fire. The problem arose in the late 1970s after a serious incident in which a new car suffered fire damage, and other fires happened in the same model. The insurers commissioned a report that identified the causes of the problem, and a recall was initiated to replace the faulty fuel lines. Unfortunately, the recall was not fully implemented everywhere, and a serious accident in 1988 in the Republic of Ireland resulted in severe injury to two young children. The resulting High Court action revealed the nature of the problem, but discovery of key documents was resisted by the manufacturer, Fiat S.p.A. Subsequent investigation subsequently showed many fires in this particular model had occurred, and they were reconsidered in the light of the defective fuel lines.
One area of increasing litigation is that involving medical treatment that fails because of a product failure, and is an important aspect of medical negligence. As new materials are introduced into medical practice, the problems of poor material or design are highlighted because of the often severe personal consequences of failure. The human body is an aggressive environment for most materials, so care is needed in materials selection. On the other hand, such materials may fail for other reasons, and this was so in the final case study. The case also led to court action, but was settled just before trial when critical evidence regarding the mechanism of failure became available.