By Kang Yongtian, Ling Aijun and Liang Yuanhua, CCS Offshore Engineering Technology Center

With the rapid development of computer technology, the  structural health monitoring technology of mobile platforms and offshore installations has been developed rapidly, and has been used to monitor the structural safety, predict the structural risks, and improve the reliability of the structure and equipment of mobile platforms and offshore installations. At present, the monitoring system is widely used in offshore structures, but no unified technical standard is available for the  monitoring systems in the field of offshore engineering . The major classification societies have studied the digital system standards,  with some digital twin system standards and processes implemented and defined based on  the customer needs . The monitoring system is an important part of the digital system of offshore structures . China Classification Society  (CCS) has  carried  out relevant technical research considering the needs of the industry, and studied the applicability and technical requirements of the structure and equipment monitoring system standards for the mobile platforms and offshore installations Combining with the technical characteristics of the structures and equipment of the mobile platforms and offshore installation, CCS has prepared the Guidelines for Survey of Structure and Equipment Monitoring System of Mobile Platform and Offshore Installations"(hereinafter collectively referred to as the "Guidelines"), which support the technical services for survey of offshore structure monitoring  system,  and have  specified the technical requirements for the design, manufacturing, installation and commissioning of the system, to improve the safety and reliability of the system and provide technical supports for the engineering application of the monitoring system on mobile platforms and offshore installations.

Figure Layout of Environmental Sensors in Lingshui 17-2 Integrated Monitoring System

In the process of preparing the Guidelines, CCS has carried out the application of actual engineering cases, including the engineering projects such as  "Lufeng  15- 1 Deepwater Jacket Digital Twin System" and "Lingshui 17-2 Integrated Monitoring System", feeding back the key technical issues of design and survey encountered in engineering applications of the system to the guideline writing group, and thus compile the guidelines with practical engineering application value. Combined with the Lufeng  15- 1 Deepwater Jacket Digital Twin System Project, CCS has included the technical requirements for underwater sensors and secondary sensor packaging in the Guidelines, and proposed the technical requirements for the design review and on-site survey of the monitoring system, improving the safety and reliability of the system . Based on the Lingshui 17-2 Integrated Monitoring System  Project,  CCS  has  implemented the technical requirements for equipment certificate  list  and  system  component installation, fire protection and explosion proofing in the engineering application of the monitoring system, to ensure the safety of the system, with good feedback to the Guidelines.Meanwhile, the technical requirements and survey methods in the Guidelines are verified through actual engineering projects . In the follow-up upgrading and revision of the Guidelines, it is necessary to incorporate more

practical engineering project experience, so as to improve the applicability of the Guidelines.

The Guidelines are divided according to the monitoring system discipline, and a survey model of digital system is formed based on the technical characteristics of the design,construction and operation stages . CCS has carried out the design review, product survey,on-site verification and other technical services according to the architecture of the monitoring system, conducted the design review with reference to the functional requirements of the system, and integrated the structural mechanics,signal processing, probability statistics, pattern recognition, artificial intelligence, software engineering and other disciplines, making a breakthrough in the key survey technology for the monitoring system of offshore installations,and also forming a digital system survey and certification model with independent intellectual property rights.

The promulgation of the Guidelines for Survey  of Structure and Equipment Monitoring System of Mobile Platform and Offshore Installations is a small step in the development of digital technology for CCS offshore engineering equipment. Further study on digital technology for offshore engineering equipment is needed, the digital system survey model should be actively explored and the Guidelines should be continuously updated,so as to provide scientific and reasonable basis for the safe use, repair and conversion of the structures and equipment on mobile platforms and offshore installations.