Lifetime and obsolescence of components for computer-based systems poses issues for continued usage and maintenance of the systems. This thesis investigates possible alternatives for lifetime extension of a train identification system used in Stockholm Metro. Research of other train identification systems available on the market were made to enable a cost comparison between lifetime extension and system replacement. Methods for extending lifetime of computer-based system, where components are obsolete, were investigated. Since most system documentation was inaccessible a reverse- engineering approach was chosen. Through usage of electrical schematics acquired and open-source hardware descriptions a hardware emulator was developed, which is directly compatible with the existing hardware. The total amount of resources used indicates it is possible to extend the systems lifetime at a low cost, as compared to the cost of system replacement. / Livslängd och åldrande av komponenter för datorbaserade system utgör problem för fortsatt användande och underhåll av systemen. Den här avhandlingen undersöker möjliga alternativ för livstidsförlängning av ett tågidentifieringssystem som används i Stockholms tunnelbana. Efterforskningar av andra tågidentifieringssystem tillgängliga på marknaden genomfördes för att möjliggöra en kostnadsjämförelse mellan livstidsförlängning och systemutbyte. Metoder för förlängning av livslängd av datorbaserade system, där komponenter är föråldrade, undersöktes. Då stora delar av systemdokumentationen inte var tillgänglig valdes baklängesutveckling som strategi. Genom användande av förvärvade elscheman och öppen-källkod hårdvarubeskrivningar kunde en hårdvaruemulator utvecklas, vilken är direkt kompatibel med befintlig hårdvara. Den totala resursanvändningen indikerar att det är möjligt att förlänga systemets livslängd till en låg kostnad, jämfört med kostnaden för ett systembyte.

Degradation of steel pipes in district heating systems is often a result of corrosion processes. To maintain the power in the systems the pipes gets replaced when they have been worn-out, resulting in high cost and long service time due to excavation. A more affordable and time- effective method is known to be relining which implies renovation and facing of the already existing pipes. This thesis covers an initial review of the applicability of a polyamide curing solvent-free epoxy based relining for lifetime extension of corroded pipes in Stockholm Exergi's pipeline network. The research study is comprised of a literature search focusing on the permeability properties of epoxy coatings, an experimental part where the actual coating was tested for defined parameters similar to the prevailing ones in the system of Stockholm Exergi and finally an evaluation of the usability of the coating. Critical parameters such as the adhesion between the coating and the steel substrate, the sorption of water within the coating and the emit of Bisphenol A were carefully investigated during the analysis. Analysis methods such as pull of test, TGA, DSC and GC-MS were utilized in order to investigate the critical parameters. The adhesion between the coating and the substrate was found to be inadequate for the purpose, the TGA and DSC analysis showed a time-dependent increasing water sorption when exposure to 120 °C. At a higher temperature of 190 °C the sorption decreased. It was concluded that the coating cured at higher exposure temperatures which implied higher degree of conversion and thus a more brittle epoxy matrix. Additionally, the hydrophobicity decreased during 28 days of exposure, at both 120 °C and 190 °C, which can be supposed to affect the flow in the pipeline system during service. It can be stated that a spray coating consisting a polyamide curing solvent-free epoxy will not answer to a total solution for a lifetime extension for the pipes in Stockholm Exergi's pipeline network. An extended investigation regarding the exterior isolation of the pipes is suggested in order to circumvent the most critical breakdowns due to corrosion.