NAS1149 Flat Washer Part Number Decoder: Material, Size, Thickness and Finish Codes

What Does NAS1149C0432R Mean?

Type any NAS1149 part number below. The decoder splits it into its four parts (material code, size code, thickness code and finish code), checks each one against the NAS1149 tables, and tells you what is wrong if a code does not exist. Spaces, dashes and lower case are fine.

You can also type part of a number (for example C04) to list every valid NAS1149 washer that starts that way, or an AN960 number to find its NAS1149 substitute. For sizing a washer you have in hand, use the Washer Size Finder.

NAS1149 DECODER
material · size · thickness · finish NAS1149 Rev 4, Feb 2008
Examples:
Part numberSizeThk inID inOD inMaterialFinish
How a NAS1149 Part Number Is Built
NAS1149 standard C material: CRES 04 size: 1/4 in 32 thickness: .032 in R finish: passivate

Size and thickness together form the four-character "size and thickness code" of Table I. The finish letter is never optional.

Material and Finish Codes (Table II)
Material codeMaterialAllowed finish codes
GAlloy steel 4130
4130 (UNS G41300) per AMS 6345, 90 ksi min UTS		P cadmium plate
DAluminum alloy 2024-T3
2024-T3 (UNS A82024) per AMS-QQ-A-250/5, 58 ksi min UTS		H no finish; K anodize (electrically non-conductive); J chemical treat (electrically conductive)
AAluminum alloy 2024-T81
2024-T81 (UNS A82024) per AMS-QQ-A-250/5, 62 ksi min UTS		H no finish; K anodize (electrically non-conductive); J chemical treat (electrically conductive)
BBrass
Copper alloy 260 (UNS C26000) or 268 (UNS C26800) per ASTM B36, 49 ksi min UTS		H no finish
F7Carbon steel
1020 (UNS G10200) or 1025 (UNS G10250) per AMS 5046, or 1025 (UNS K02500) per ASTM A109 temper 2, 55 ksi min UTS		B black oxide; P cadmium plate
CCorrosion-resistant steel (300 series)
.016 thick only: 301 (UNS S30100) per AMS 5517, 1/4 hard, 125 ksi min UTS. All other thicknesses: 301 per AMS 5901, 302 per AMS 5516, 304 per AMS 5513, 316 per AMS 5524, 321 per AMS 5510 or 347 per AMS 5512, 75 ksi min UTS		B black oxide; R passivate
EA286 corrosion-resistant steel
A286 (UNS S66286) chemistry per AMS 5525, heat treated to 160 ksi min UTS		P cadmium plate; R passivate
TTitanium, commercially pure
CP titanium (UNS R50700) per AMS-T-9046 class CP-1 or AMS 4901, 80 ksi min UTS		H no finish; L anodize, deep blue
VTitanium 6Al-4V
6Al-4V (UNS R56400) per AMS-T-9046 class AB-1, AMS 4911 or AMS 4928, solution treated and aged to 160 ksi min UTS		H no finish; M anodize, blue-violet; N dyed light blue
Size and Thickness Codes (Table I)
SizeID (A), inOD (D), in.016.032.042.049.063.065.090Flatness F
No. 0c0.0680.188N016N0320.007
No. 270.0990.250N216N2320.007
No. 370.1050.250N316N3320.007
No. 470.1250.312N416N4320.007
No. 50.1400.438N516N532N5420.007
No. 60.1490.375N616N6320.007
No. 80.1740.375N816N8320.007
No. 970.1880.500N9490.007
No. 100.2030.4380316033203630.007
No. 1170.2340.62511650.007
No. 12d0.2600.4702N320.007
1/4 (.250)0.2650.5000416043204630.007
5/16 (.312)0.3280.5620516053205630.007
3/8 (.375)0.3900.6250616063206630.007
7/16 (.437)0.4530.7500716073207630.007
1/2 (.500)0.5150.8750816083208630.007
9/16 (.562)0.5781.0620916093209630.010
5/8 (.625)0.6401.1881016103210630.010
3/4 (.750)0.7651.3121216123212900.010
7/8 (.875)0.8901.5001416143214900.010
1 (1.000)1.0151.7501616163216900.010
1-1/16 (1.062)1.0781.8121716173217900.010
1-1/8 (1.125)1.1401.8751816183218900.010
1-1/4 (1.250)1.2652.0002016203220900.010
1-5/16 (1.312)1.3282.0622116213221900.015
1-3/8 (1.375)1.3902.1252216223222900.015
1-1/2 (1.500)1.5152.2502416243224900.015
1-5/8 (1.625)1.6402.3752616263226900.015
1-7/8 (1.875)1.8902.6253016303230900.015
2-1/4 (2.250)2.2653.0003616363236900.015
2-1/2 (2.500)2.5153.2504016403240900.015

ID ±0.010 and OD +0.020/−0.005 in, except No. 0: +0.000/−0.005 on both (note c). 7 = marked "see Note 7" (carried over from AN960). No. 12 (2N32) is made only as NAS1149C2N32R (note d). A blank cell means that size is not made in that thickness; inventing a code for it is prohibited (note b).

Thickness Tolerance by Material (Table III)
Material.016.032.042.049.063.065.090
4130 alloy steel (G)±0.002±0.003±0.004±0.004±0.005±0.005±0.006
Aluminum (D, A)±0.003±0.004±0.004±0.005±0.006±0.006±0.007
Brass (B)±0.005±0.006±0.007±0.007±0.008±0.008±0.010
Carbon steel (F)±0.002±0.003±0.004±0.004±0.004±0.004±0.004
CRES (C, E)±0.002±0.004±0.005±0.005±0.006±0.006±0.008
Titanium (T, V)±0.002±0.004±0.005±0.005±0.006±0.006±0.008
Reference Guide: Reading NAS1149
01

The Rules of the Code

Four parts, fixed order
  1. Material code: one letter (Table II). It is never N, so a code that starts with N (N816) has no material letter.
  2. Size and thickness code: four characters (Table I). The first two give the size, the last two the thickness in thousandths: 32 = .032 in.
  3. Finish code: one letter (Table II). Every NAS1149 number ends with one. "No finish" has its own code, H.

Spaces and dashes are not part of the number. NAS1149 C 0432 R and NAS1149-C0432R both mean NAS1149C0432R.

The size part
  • Numbered screw sizes: N plus the screw number: N2, N3, N4, N5, N6, N8, N9 (N216 = No. 2, .016 thick).
  • No. 10: 03 (0332 = No. 10, .032). No. 11: 11 (1165). No. 12: 2N (2N32).
  • Fraction sizes: the nominal size in sixteenths of an inch: 04 = 1/4, 06 = 3/8, 08 = 1/2, 12 = 3/4, 16 = 1, 40 = 2-1/2.
  • No. 0: N0 (N016, N032), with tighter diameter tolerances.
02

Finish Codes: Stainless Is Not "No Finish"

Each material has its own short list of finishes. The decoder flags any pairing the standard does not allow.

  • CRES (C) and A286 (E): passivation is a finish code, R. There is no "no finish" option, so a passivated stainless washer is NAS1149C0432R, not NAS1149C0432.
  • Aluminum (D, A): H (none), K (anodize, non-conductive) or J (chem film, conductive). Pick J when the washer must carry current or ground a bond.
  • Carbon steel (F): P (cadmium) or B (black oxide). It always needs a finish.
  • 4130 steel (G): P (cadmium) only.
  • Brass (B): H only.
  • Titanium: CP (T) takes H or L (blue anodize); 6Al-4V (V) takes H, M (blue-violet anodize) or N (dyed light blue).
Why people expect stainless to have no letter

On AN960, a CRES washer with no coating letter (AN960C416L) was passivated: the sheet listed "passivate, no code". NAS1149 spells it out instead. NAS1149 Table IV maps AN960C416L to NAS1149C0432R.

A letter B means black oxide when it is the last letter, and brass when it is the first letter after NAS1149: NAS1149BN816H is brass, NAS1149C0432B is black-oxide CRES.
03

Replacing AN960 with NAS1149

AN960 washers became inactive for new design on 6 August 1992. NAS1149 Note 7 and Table IV give a substitute for every AN960 part number. Type an AN960 number into the decoder to see its substitute; the decoded NAS1149 part lists the AN960 numbers it replaces. To read an AN960 number itself, use the AN960 decoder.

AN960NAS1149 substitute
AN960-416NAS1149F0463P
AN960C416LNAS1149C0432R
AN960XC416LNAS1149C0432B
AN960JD416LNAS1149D0416J
AN960B416NAS1149B0463H
Watch the "L"

In Table IV, the AN960 "L" (light) suffix maps to a .032 in washer for steel, CRES and brass, but to a .016 in washer for aluminum. AN960C416L becomes NAS1149C0432R, while AN960JD416L becomes NAS1149D0416J.

Sizes, thicknesses and the carbon steel material marked "see Note 7" exist mainly to replace AN960 parts. The sheet asks for caution when using them on a new design.

04

Sources and Limits

Everything on this page comes from NAS1149 Revision 4 (February 2008), Aerospace Industries Association, sheets 1 to 6: Table I (sizes and codes), Table II (materials and finishes), Table III (thickness tolerance) and Table IV (AN960 substitutes).

Other sheet requirements: faces parallel within .002 in, ID and OD concentric within the ID tolerance, surface texture 125 µin unless specified, CRES magnetic permeability below 2.0 (Note 8), titanium may be colored for identification (Note 6).

  • Check the current revision of NAS1149 before ordering. Codes added or removed after Rev 4 are not shown.
  • Part numbers typed with spaces, dashes or lower case are read the same, and the decoder shows the standard form. A number with no finish letter is flagged as incomplete.
  • Related: Washer Size Finder (identify a washer by measuring it).

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