1. Be sure contamination is not coming from tanks.
2. Plan ahead and align the batches as closely as possible to similar products, especially with similar viscosities.
3. Trail each batch with a more viscous product.
4. Use larger batch sizes.
5. Keep flowrates as high as possible and always turbulent.
6. Do not stop pumping with an interface in the line.
7. 2. Study your contamination limits and optimize the batch train accordingly. Don't run head batches containing contaminates for a trailing batch (sulphur containing products etc. ahead of the low sulfur product).
8. Never lower pressures enough to reach vapor pressures of any product in the line.
9. use a closer heart cut
10. look for better pipe routing eliminating passages past dead ends.
11. increase valve operation speeds at interface generation points.
12. use full open valves
That was the quick list. If I think of more, I'll come back later.