When removing a stubbed-out nipple from a wall with an extractor, you can put a coupling or thread protector on the nipple to reinforce it and to prevent it from splitting at the weld seam. However, when dealing with old nipples, I always run into nipples that are so old they are broken at the thread diagonally or completely severed, where adding a coupling or thread protector is not an option. When using a nipple extractor on an old nipple, they tend to split.