Summary When pressure vessels are constructed, the goal is to obtain the properties of resilience and tenacity necessary to the non-propagation of fissures by applying appropriate dehydrogenation treatments (DHT) for the zones close to the weld and a relaxation (ISR) for the welds. This study, carried out on steel of the grade 13CrMoV9.10, shows that intermediate treatments can be optimised for temperature and duration, provided that a final post treatment (PHWT) at 705°C for 8 to 10 hours is ensured. Document presented during the European Symposium on Pressure Equipments 2004 (ESOPE 2004), in the Manufacture, Welding and Control commission. This event took place from the 28th to the 30th September 2004 at the Palais des Congrès, Paris.