The Industrial Internet of Things (IIoT) emphasizes the importance of equipment health and reliability, which is critical to maintaining operational efficiency and preventing costly downtime. This article introduces an innovative prognostics and health management (PHM) framework that synergistically combines blockchain technology with large language models (LLM) to pioneer safe, reliable, cutting-edge health monitoring and failure prediction services for IIoT devices new era. By leveraging the immutable and transparent properties of blockchain, the proposed framework ensures data integrity and security throughout the IIoT ecosystem. In addition, the solution employs advanced LLM for in-depth data analysis and prediction of potential failures, thereby facilitating pre-emptive maintenance actions. This dual approach enhances the safety and reliability of health monitoring data while simultaneously utilising the predictive power of LLM to analyse complex patterns and predict faults with high accuracy. Experimental results show that the framework is effective in improving the accuracy of fault prediction and the overall resilience of IIoT systems against cyber-physical threats.