Quote: I've never used them in thick wall vessels....if I did I would cut threads first I think, especially hard materials like PVC.
The typical HDPE of 55 gal drums are fairly soft and may not need threads cut first.
Here's my take on installing HN's
https://www.backyardchickens.com/t/...ing-loaded-watering-nipples/210#post_14202676
https://www.backyardchickens.com/t/...ing-loaded-watering-nipples/330#post_14593735