The present document constitutes the deliverable D8.1 “Predicted castability and cleanliness level” for Use case 2: “Smart sensor and model-based decision support system for ultra clean steel production” in the framework of the SPIRE project entitled “Optimization and performance improving in metal industry by digital technologies” (Project Acronym: INEVITABLE; Grant agreement no.: 869815). It is based on the project proposal form established in the Grant Agreement and signed by the European Commission and the project coordinator. The main objective of D8.1 is to define the initial metallurgical requirements and specifications related to predicting castability and cleanliness. It is linked to the online monitoring and control technology for ultra-clean steel production. The information shall be used in the continuation of the project as a guideline and for the validation of sub-models developed in WP4.