The replies on this post worry me quite a bit. I must have been doing it wrong all these years.
Every job I have ever done on tankers is different, CIP, (in place cleaning) is used mainly on dairy tankers carrying the same commodity every time.
Scopa is only used for carrying edible oils and is used by the Seed Crushers as a way of stopping the cowboys loading refined soya bean oil on top of grade 6 tallow or nuclear waste.
In almost 25 years, I have never had some bod pop out and hook you up, every delivery point is different, every product is different, every tanker is different. It also helps if you know the cleaning procedure. cleaning latex with hot water makes life easy 
putting cold water on molten maleic anhydride is fun too
If you are tipping tomato sauce, imagine what it’s like to pour onto your chips. and you cant turn the tanker upside down and pat it’s bottom.
I have just had some intensive training because I have changed units and have a different discharge system to before.
Some products are discharged by gravity, some by pump some by compressor, some are top discharge, some are vacuum, some are tipped with inert gas, some with compressed air, some with inhibitors to stop explosions.
A little knowledge is a dangerous thing. I am learning something new every day, sometimes I learn more than one thing.
That is before you get into the different regulations governing pressure vessels, working at height and contaminating water courses.