The fouling rate is very dependent on the feed quality (concarbon) and the heater flux rate. Generally an anode coker that has a normal flux rate will operate with a 8 to 14 month window. One year operations used to be normal for sponge (anode) coke. In today’s world with vey heavy sour (SDA pitch) feeds the normal run time is about 3 to 6 months. We also design for online spalling and pigging to help this issue.