The Fitness For Service work supports the assessment of an existing installation. The assessment is to determine whether the installation is still suitable for the current operating and design conditions. This FFS approach is used when the regular calculations codes show that the installation is not acceptable by a 'small margin'. The assessment fitness for service can be provided by Red-Bag. The assessments are done based on the API 579 / ASME FSS-1. The code considers anomalies such as: dents, pitting, corrosion, unroundness, etcetera.  Red-Bag has the calculation tools available to perform the analyses and the calculations.