Trouble description:Today while checking the SDA test, all units fe value is more than 2000 ppm, in-use fuel

Trouble description:Today while checking the SDA test, all units fe value is more than 2000 ppm, in-use fuel is VLSFO which was changeover from LSMGO 2 days back, cylinder oil feed rate was 1.1 g/kwh, which has been increased to 1.32g/kwh, as it could be due to cold corrosion.

Last test was carried out on 1 month back while LSMGO was in use and the fe content was less than 50 ppm in all units.

I have suspect on cold corrosion, so cylinder oil feed rate was increased to 1.32g/kwh.

Today we have planned to carry out the scavenge inspection.

As the FO analysis report, Cat fines is 24.

Calibration of testing was done and found to be in order.

Any other reason for rapid raise in fe content ?