Plant Shut Down Day 3

Today, the shutdown job for is described as less head ache. Everything seems to run smooth. Thank God. Everybody knows what to do.

Only one thing that made me shock in the early hours (6am). My operator called & told me that pressure for HP boiler hydro test has reached 52 bar. The water feed pump has been stopped. However, the pressure keeps on increasing gradually. I already instructed them to control the pressure between 50 – 60 bar. The increasing pressure worried me. I don’t want the pressure to reach above 70 bar without enough manpower observing the situation. After thinking, I called and instructed him to monitor the pressure closely. If the pressure exceeds 67 bar, slightly open/throttle the venting so that the pressure would not increase. I choose 67 bar simply because the HP boiler always run between 64-66 bar. Therefore, it will still be safe to operate or control the pressure at 67 bar.

The plant operators informed me that the increasing pressure might be the affect of conducting the hydro test and the “shell tube - cleaning in progress (CIP)” at the same time. The CIP temperature is maintained at 80^oC. The heat from the CIP have exerted some pressure into the other activity, which is the hydro test. This is because, in normal plant operation, very hot water from the HP boiler will transfer heat with oil in the shell tube heat exchanger. Therefore, we cannot do the hydro test. We have to give way for the CIP first. Then only we can proceed with hydro test to avoid the pressure build up as earlier.