Dutchman
Dutchman turns up in 2 fields: valves, waterproofing. Here is what it means to the people in each one.
Dutchman in valves
A short filler piece of pipe cut in to close a gap or correct a misfit between two spools.
When fabricated spools come up short or a section has been cut out, fitters measure the gap, cut a dutchman to length and weld it in with two new joints. The word also covers patch pieces and short sections used to correct alignment. Supervisors dislike them because each one adds welds, inspection and fit-up time, and they hint that someone measured wrong.
"Spool came in two inches short, we'll have to cut a dutchman in, tell QC we've got two more welds to shoot."
Dutchman in waterproofing
A patch of new stone, brick or wood cut and set into a damaged area of an original piece.
Rather than replace a whole stone or sill, restoration masons cut out the damaged section to a clean geometric shape and fit a matching piece of new material into it, set in mortar or adhesive and often pinned. A well-made dutchman blends into the original. The term is also used by carpenters and metalworkers for similar inset repairs.
"Corner of that limestone sill is gone, cut it square and set a dutchman, no need to pull the whole sill."