NPFC - FED-STD-H28/23
SCREW-THREAD STANDARDS FOR FEDERAL SERVICES SECTION 23 CLASS 5 INTERFERENCE-FIT SCREW THREADS
|Publication Date:||20 January 1989|
This section provides the standards for general purpose Class 5 interference-fit screw threads of modified National thread form in the Coarse Series (NC) for sizes 0.250 through 1.500 inches. Also provided are Navy ship specifications for special application interference-fit threads.
Interference-fit threads are intended to develop sufficient breakloose torques to prevent loosening of externally threaded parts in service where other, less costly methods are not deemed satisfactory.
The following classes of screw threads included in this section are listed below.
NC-5 HF Ferrous material external threads for driving in hard ferrous material with hardness greater than 160HB NC-5 CSF Ferrous material external threads for driving in copper alloy and soft ferrous material with hardness 160BB or less NC-5 ONF Ferrous material external threads for driving in non-ferrous materials other than copper alloys NC-5 IF All ferrous material internal threads NC-5 INF All non-ferrous material internal threads
NC-5 HFM Nickel-copper (Monel), nickel-copper-alumin
NC-5 HFK Nickel-copper-alumin
NC-5 TENTATIVE Hard steel external threads for driving in hard materials such as cast iron, steel and bronze NC-5 ALTERNATE Hard steel external threads for driving in hard materials such as cast iron, steel and bronze
The issues of the following documents in effect on the date of invitation for bids or request for proposal form a part of this standard to the extent specified herein.
Federal standards. FED-STD-H28/1 Nomenclature, Definitions and Letter Symbols for Screw Threads FED-STD-H28/6 Gages and Gaging for Unified Screw Threads-UN and UNR Thread Forms FED-STD-H28/20 Inspection Methods for Acceptability of UN, UNR, UNJ, M and MJ Screw Threads
(Activities outside the Federal Government may obtain copies of Federal specifications, standards and commercial item descriptions as outlined under General Information in the Index of Federal Specifications, Standards and Commercial Item Descriptions. The Index, which includes cumulative bi-monthly supplements as issued, is for sale on a subscription basis by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.
(Single copies of this standard and other Federal specifications, standards and commercial item descriptions required by activities outside the Federal Government for bidding purposes are available from the General Services Administration Specification Section, Room 6662, 7th and D Streets, S.W., Washington, DC 20407; telephone (202) 472-2205.)
(Federal Government activities may obtain copies of Federal standardization documents, and the Index of Federal Specifications, Standards, and Commercial Item Descriptions from established distribution points in their agencies.)
The following document forms a part of this standard to the extent specified herein. Unless a specific issue is identified, the issue in effect on date of invitation for bids or request for proposal shall apply.
American National Standards. ASME/ANSI B1.12-1987 - Class 5 Interference-Fit Thread
(Application for copies should be addressed to the American Society of Mechanical Engineers, United Engineering Center, 345 East 47th Street, New York, NY 10017-2330 or the American National Standards Institute, 1430 Broadway, New York, NY 10018-3308.)