In order to find out the causes of abnormal large displacement of high temperature reheat steam pipe and serious underload

overload and even crushing of several groups of supports and hangers after an ultra-supercritical 1 000 MW unit was put into operation

the calculation model and evaluation method of pipeline mechanics covering the measured performance indexes of constant support hanger were established

and the causes of abnormal displacement of high temperature reheat steam pipeline were systematically and quantitatively studied. The analysis shows that

the main causes of the abnormal displacement are the multi-bend and multi-undulating arrangement of the high temperature reheat steam pipeline

less rigid constraints in the vertical direction

more continuous arrangement of the constant support hangers

and the performance of the constant support hangers exceeds the standard. After the prevention and control measures of sectional restraint con20trol and load compensation were implemented

the measured value of the thermal displacement of the high-temperature reheat steam pipe is close to the calculated value

the abnormal large displacement has been eliminated

and the mechanical safety of the pipeline and the supports and hangers has been greatly improved.