English term (edited): bc (diameter)

The source text in the web-page linked by Asker says:

SC diameter: 40 – 72 mm
BC diameter: 45 – 90 mm

The exact same specification is given in the page dealing with the CANBLO machine, used to make tin cans. Tin cans don't have screw caps, so SC = screw cap looks like a non-starter...

So, we have to ask ourselves: What do these machines actually do?
Answer: they take containers (plastic or metal) from a limited range of standard sizes and shapes, hold them inside a mould, and 'inflate' (blow) them with compressed air so they take on the shape of the mould.

In this scenario:
'SC' refers to the 'source container'
and
'BC' refers to the 'blown container'.

You will see in Asker's webref (for both plastic and plastic bottles) that BC is slightly larger that CS. It will also be true that the narrowest dimension of BC will be larger than the SC diameter (in the range 40 - 72 mm) - otherwise, it would not be possible to put the source container inside the mould, prior to blowing.

So, now, what are we to do with the French translation?
source container --> conteneur source --> "SC"
blown container --> conteneur soufflé --> "SC"

Solution: translate 'SC' as 'SC' in French, and 'BC' as 'BC'.

EOP.