This Topical Report from the Component Operational Experience, Degradation and Ageing Programme (CODAP) addresses operating experience insights on two types of piping systems that have the following features in common: 1) the two systems consist of small-diameter piping, and 2) a pipe failure anywhere in either of the piping systems can have immediate operational impact such as an automatic reactor trip. The electro-hydraulic control (EHC)1 and instrument air (IA) systems consist of significant lengths of small-diameter piping. The EHC system is vital for power generation. The IA system is an important support system for various plant safety functions. This Topical Report on EHC and IA piping reliability is an information resource developed by the CODAP Project Review Group. The report summarises an evaluation of the EHC- and IA-specific piping service experience data included in the CODAP Event Database and information from the CODAP Knowledge Base.