série à 12 filets

CONT: [...] un filetage Unified National à filets fins de 1 po de diamètre et de 12 filets au po, se cote : 1-12 UNF.
CONT: L'utilisation type des diverses séries est la suivante : [...]. Série à 12 filets. Utilisée couramment en chaudronnerie, dans les diamètres jusqu'à 1 3/4 po, pour refaire les filets taraudés usés et pour un usage général comme le prolongement des filets fins.
OBS: ""12 N"" : pour le filetage American National; ""12 UN"" : pour le filetage Unified National.

CONT: Unified and American National screw thread standards for screws, bolts, nuts, and other threaded parts consist of six series of threads [UNC or NC; UNF or NF; UNEF or NEF; 8UN or 8N; 12UN or 12N; 16UN or 16N] and a selection of special threads that cover nonstandard combinations of diameter and pitch ... The 12-thread series (12UN or 12N) is a uniform pitch series that is widely used is industry for thin nuts on shafts and sleeves. This series is considered to be a continuation of the fine-thread series for diameters greater than 1 1/2 in.
OBS: ""12N"": for the American National thread. ""12UN"": for the Unified National thread.