We always mask bolts and stud ends with tape or rags before painting. I made a printable cap instead: you pick the nut standard and size (ISO, DIN, JIS, heavy hex up to 2-1/2 inch for flange studs), type how far the bolt sticks out, and it fits over the nut and thread. Good for wet paint masking and for covering sharp ends. It will not survive powder coat oven temperatures, so for that you still need silicone caps. If you have a size or standard that is missing, tell me and I'll add it. Free link to generate and download yours is here: Link   submitted by   /u/Markbear15   to   r/pipefitter [link]   [comments]