Denna studie undersöker möjligheten att påverka fientliga konstruktioner genom användandet av en effektiv metod, som kan medge en liten risk att upptäckas. Den tänkta påverkan uppnås genom fenomenet Liquid Metal Embrittlement (LME), med vilken höghållfasta metaller kan påverkas så mycket att de kollapsar av sin egenvikt. Uppsatsen studerar LME på ett ofta använt konstruktionsmaterial både civilt som militärt. Ett experiment genomfördes i syfte att undersöka effekterna av LME på en aluminiumlegering, där en aluminiumdetalj exponerades för metallen gallium. Förförsök genomfördes i syfte att undersöka inom vilka tidsförhållanden LME uppstod och experimentets exponeringstider planerades därefter. Efter varje exponeringstid genomfördes ett dragprov för att påvisa en minskad hållfasthet och seghet hos aluminiumet. Resultatet blev en stor minskning av hållfasthet och seghet, där hållfastheten sänktes till 20% av referensvärdet och segheten till 1% av referensvärdet, även om resultatet var spritt. / The possibility to damage enemy constructions using an efficient method, which might permit a low risk of detection, is studied in this thesis. This damage is based on the phenomena Liquid Metal Embrittlement (LME) with which high strength metals can be affected so much that they collapse under their own weight. This thesis studies this effect in a material often used for various constructions, both civilian and military. An experiment was conducted in order to evaluate the effects of LME on an aluminium alloy by exposing the aluminium to the metal known as gallium. A pre-experiment was made in order to determine how the time of exposure affected the LME-process and time-periods were decided accordingly. At each of the timeperiods a yield test was conducted in order to measure losses in strength and elasticity of the aluminium. It was shown that a great reduction in strength and elasticity occurred, where the strength was reduced to 20% of the reference sample and elasticity to 1% of the reference sample.

With hydrogen playing a major role for reaching net zero emissions, the main challenge will be the integration of the energy carrier. This includes solutions for storage, production and transportation of the gas. Alternatives for hydrogen transportation could include either train, truck or boat. However, the current most economical and promising technology is pipeline transmission, especially in northern Sweden, with new green projects suchas H2 Green Steel and HYBRIT. They will create a market that needs a hydrogen infrastructure, which hydrogen pipelines could provide. This thesis will cover a techno-economic evaluation of hydrogen piping, involving material, compressor technology and pipeline dimensions. Hydrogen is briefy covered in its main production, applications and transportation options in the beginning of the thesis. This will ultimately converge into a in-depth analysis of hydrogen piping. This analysis includes alternatives for compressors, materials for pipes and main technical challenges. The gathered information concluded that hydrogen transport will most likely use either reciprocating or centrifugal compressors. Centrifugal compressors have the advantage of managing high gas flows, and the reciprocating compressors are mature and have a high capacity for pressure. For materials, embrittlement is the main challenge when transporting hydrogen gas, and standard ASME B31.12 provides current directions for hydrogen piping. A yield strength of 30% is required in the material, to compensate for hydrogen’s attributes. Generally the higher the strength of the material, the higher the risk of embrittlement and pipe damage. Careful selection has to be made in termsof micro structure, strength and coating to minimise leakage. To realise how hydrogen infrastructure could be constructed, three scenarios where created. These scenarios were based on assumptions and article values to best illustrate future hydrogen transportation. Main scenario settings include a pressure ratio of Pratio < 1.5, and length between compressors of maximum 135km. These assumptions help keep fnal results within a reasonable dimensions. The results from the initial calculations yielded an optimal diameter of 0.35m for Scenario A. At this diameter, an operational pressure of 85 bar and one compressor with 40 MWe optimally transported the gas. With compressor cost decreasing as pipe cost increases, a trade of in price is found at the lowest cost. For a higher diameter, optimising fow resulted in a lower OP, and a lower power consumption for compressors. Scenario B resulted in a diameter of 0.3 m, an OP of 150 bar, four compressors for a total of 405 km pipes. The lowest possible diameter yielded the lowest cost. If other factors are to be considered, a larger diameter could be used for a lower OP, thus reducing stress on material and compressors. Comparison with electricity (Scenario C) mainly resulted in a higher CAPEX for Hydrogen infrastructure, but a lower transmission cost per MWe per km. This concludes that hydrogen piping is better suited for carrying the energy, due to the large decrease in transfer cost. Finally, for material selection low strength carbonsteels are currently the best alternative for transportation of hydrogen. This is due to its commercial use, good composition, high strength and availability.