Robotic pipe welding represents a key and rapidly evolving technology for the automation of pipe and pipe-joint welding processes with standard, intersecting, and complex geometries. This review analyses 84 studies published over the past three decades, categorising them into four primary research areas: general pipe welding, intersecting pipes, boiler and tube-to-tubesheet welding, and control and modelling. Two separate comparative analyses were conducted: one within intersecting pipe research and another within the control and modelling category. The aggregated findings reveal consistent, complementary patterns: simulation and laboratory experiments clearly dominate validation methods, while industrial-scale evaluations remain scarce. The results further demonstrate that control strategies, sensor integration, and validation levels are strongly interconnected, collectively determining system performance, reliability, and practical applicability. Despite significant progress, challenges remain, including system integration complexity, limited robustness in variable industrial environments, insufficient real-time adaptive control, and inconsistent quantitative performance evaluation. Further research should prioritise the development of digital twins, human–robot collaboration, multi-sensor fusion, reinforcement learning-based adaptive control, and scalable industrial deployment. This review provides an overview of current progress and outlines key directions for developing intelligent and reliable robotic pipe welding systems.

The Digital Twinning of Manufacturing Systems is continuously gaining in importance concerning the optimization of production processes and requirements for production efficiency improvements. Therefore, the finite state method will be presented in this work as a semi-analytical approach of the Production System Engineering based on Markov Chains. The presented method can efficiently calculate the probability distributions associated with each possible system state defined according to the number of buffers and their capacities. In this study, the finite state method is employed to describe the ship steel hull process as a platform for the implementation of digital twinning technology. The method is employed to rebuild a model of a real ship production process using a combination of serial and splitting lines. The key performance indicators such as the production rate, the work in process, and probabilities of starvation and blockade are calculated and compared to the corresponding results obtained through a simulation approach using the software tool Enterprise Dynamics. The conclusion highlights the advantages and disadvantages of methods employed in the context of Digital Twin Technology.