Threaded bulkheads: why not install nuts on penetrators?

In the WTE guide, it says very strongly:

Thread the bulkhead into the threaded hole until it is finger-tight. Do not use a penetrator nut in the back of the bulkhead.

Why is this?

For context, we are putting together a custom faceplate with custom threads, and we want to make sure we do it properly. If for some reason adding the nut increases the chance of a leak, I’d like to avoid that, but we feel like a nut would make it more secure.

Hi @cda,

I asked internally to confirm, and was told: