Properties of P91 Steel Steam Conduit Pipe with Low Hardness in a 600 MW Power Plant

The hardness of P91 for HP loop pipes was lower than required in standard in a power plant which has run for about 35,000 hours. The experiments about Metallographic and conventional mechanical properties were done in this paper. The results show that the metallographic of P91 with low hardness was abnormal, creep damage was not found, and mechanical properties were poor.So the HP loop pipe with low hardness cant continue to be used safely.After re-heat treatment for HP loop pipe with low hardness,the results about metallographic and mechanical tests show that the performance of the pipe is good,and can continue to be used.

Creep Properties and Life Estimation of P91 Steel with Low Hardness

The creep properties and creep life estimation experiment was carried out on the P91 steel with low hardness (About 135HBHLD),and the creep life of P91 pipe was estimated.The result was that the ability for anti-plastic fracture, cracking and crack propagation of resistance to damage of high pressure steam conduit pipe with low hardness (About 135HBHLD) is very poor at 566°C and that the working life of low hardness zones (About 135HBHLD) from the creep crack propagation tests is about 5914 hours at 540°C.