Yea, I guess part of my bias is because I worked at a boiler-works one summer. They had me crawling inside of the boilers after they welded the end caps on so that I could chip the slag out.
I soon learned that I was claustrophobic as all get out!
Were you a boilermaker? I’ve had to crawl into some pipes to weld them up and it was okay as long as I could see the light at the open end.