Integrity detection of mooring chains by the approach of thermography

Reliability and safety issues of mooring chains are causing concern in recent years. Accordingly, some efforts have been made for detecting the structural integrity of mooring chains. However, a fully successful mooring chain condition monitoring technique has not been achieved today. This is largely due to the fact that mooring chains are submerged in water and the currently available non-destructive testing technologies are difficult to apply in wet environment. To overcome this issue, a new mooring chain condition monitoring method is studied in this paper with the aid of thermography technique. The research is conducted based on two philosophies, i.e. (1) the mooring chain material has much higher thermal conductivity than that of water. Therefore, when the mooring chain is heated, the thermal energy will transmit mostly inside the chain, rather than dispersing in water; (2) the defects occurring in the mooring chain will disturb the transmission of thermal flow inside the mooring chain and consequently change the distribution of the temperature in the adjacent area. To demonstrate the effectiveness of the proposed method, both numerical and experimental researches are conducted in this paper. The research results have shown that thermography is indeed valid in detecting the integrity of mooring chains.