ANALISA STRUKTUR MIKRO, NILAI KEKERASAN DAN ESTIMASI REMAINING LIFE BERDASARKAN THICKNESS PADA PIPA OUTLET SUPERHEATER

Abstract

A superheater is one of the boiler’s components that works by heating wet steam from the
boiler into dry steam. The pipes in the superheater have the ability to withstand high temperatures and
pressure during the operation of the superheater machine. When lines are exposed to high temperatures
and pressures continuously, it causes degradation in the microstructure, reduces the remaining life of
the material, and changes the mechanical properties of the pipe, especially its hardness value. In this
study, experiments were carried out on the superheater outlet pipe which had worked for 39,312 hours
at the Shipbuilding Institute of Surabaya, so that it would analyze the percentage of chemical
composition, Hardness value, microstructure, and remaining life of the material. The results of this
study, the pipe being used is SA-106 with the chemical percentage shown by PMI in a row, namely the
element Iron (Fe) of 98.43%, 0.60% Manganese (Mn), 0.52% Copper (Cu), 0.27% Nickel (Ni), 0.10%
Chromium (Cr), 0.047% Lead (Pb), 0.024% Molybdenum (Mo). The remaining life of the front pipe is
8,4 years faster than the rear pipe is 37,05 years. The front of the pipe has a hardness value of 101 HV
while the hardness value on the back of the pipe is 110 HV. The microstructure degradation criteria on
the front of the pipe belong to stage A while the rear is in stage B. The correlation between the hardness
value and the microstructure condition criteria is that the higher the stage of the microstructure
condition on the material, the lower the hardness value.