The invention concerns a coupling in which the nut is provided with a recess suitably spaced inside the nut and extending roughly outward to the maximum diameter of the ***nut thread***.

sources:

[PDF] FPL-PX 12-25 mm FPL-PX 28-32 mm - PDF/Adobe Acrobat - Quick view
DK Træk ***"omløber" og spændering ind over rørenden. GB Thread the compression ring and the "nut"*** over the end of the pipe. DE Druckmutter und Klemmring auf das ...
www.tahydronics.com/Handlers/FileDownloaderHandler.ashx?pat...

Wavin 3/4" ***Omløber m/plumberingshul nut*** with hole | Wavin ... - Her får du Wavin 3/4' Omløber m/plumberingshul nut with hole. Vi sælger Wavin Skaffevarer til nettopris, lav fragt og levering til gadedør.
saninetto.dk/skaffevarer/.../plumberingshul-nut-with-hole -

engelsk ordbog [gevind] # oversætte ***[gevind] - (et -) thread [skruen er gået over gevind] the thread is broken*** [gå over gevind] (fig) go off the rails get out of control ...
da.w3dictionary.org/index.php?q=gevind -

Dictionary - Definition of unified screw thread - Central Danish, ***UN gevind (unified screw thread, unified thread)***, trekantgevind (American national thread, triangular thread, unified screw thread), ...
www.websters-online-dictionary.org/un/unified screw thread.... -