In recent years numerous approaches have been presented to support the activities in chemical process design by means of software tools, but significant improvements of the design process can only be achieved if it is supported in its entirety. Therefore, the integration of the existing software tools is of prime importance. All these tools are based on data models that capture the information handled during the design process. In this study, a conceptual data model is presented that has been designed for the integration of existing data models as a first step towards the integration of the software tools using these models. This conceptual lifecycle process model CLiP is based on the ideas of general systems theory. This universal approach renders the model very flexible and guarantees a well-defined structure for data model integration. Some integration mechanisms are presented and discussed. Finally, a conceptual model is proposed based on the architecture tool integration.