MS16555 / NASM16555 Dowel Pin Part Number Decoder: Diameter, Length, Material and Shear Strength

What Size Is MS16555-647?

MS16555 dowel pins (.0002 in over nominal) carry no code in the number: the dash number is a lookup into the standard's tables. Type a part number and the decoder gives the diameter, length, material, tolerances and double-shear strength. NASM16555 numbers work too: they are the same.

Going the other way? Type a size, such as 1/4 x 1, to get the part number in plain steel, phosphate-coated steel and CRES.

MS16555 DECODER
dowel pins · .0002 over nominal MS16555 Rev C, Aug 1985
Examples:
Part numberDiaØ limits inLengthL inMaterialShear lb
How an MS16555 Part Number Works
1–145 carbon or alloy steel, plain (Table II) 301–444 steel, phosphate coated (Table III) 601–744 CRES 416 or 410 (Table IV)

The same size has the same last two digits in each range: MS16555-48, -348 and -648 are all 1/4 × 1 in. The one exception: 145 (3/32 × 3/16 in) is plain steel only.

Dash Numbers, Plain Steel (Table II). Add 300 for Phosphate, 600 for CRES
Length, in.0625.0781.0938.125.1562.1875.250.3125.375.4375.500.625.750.8751.000
.188 (3/16)1145
.250 (1/4)29
.312 (5/16)31017
.375 (3/8)4111825
.438 (7/16)5121926
.500 (1/2)613202734
.625 (5/8)71421283540
.750 (3/4)8152229364146
.875 (7/8)162330374247
1.000 (1)243138434853
1.250 (1-1/4)323944495460
1.500 (1-1/2)33455055616877
1.750 (1-3/4)5156626978
2.000 (2)525763707988
2.250 (2-1/4)5864718089101
2.500 (2-1/2)5965728190102
2.750 (2-3/4)66738291103117
3.000 (3)67748392104118132
3.250 (3-1/4)8493105119133
3.500 (3-1/2)8594106120134
3.750 (3-3/4)8695107121135
4.000 (4)8796108122136
4.500 (4-1/2)98110124138
5.000 (5)100112126140
6.000 (6)116130144

Columns are the nominal diameter in inches. Length tolerance ±.010 in. The .0781 (5/64) and .1562 (5/32) columns are inactive for new design after 8 April 1975.

Diameter, Point, Crown and Shear Strength (Table I)
Nominal sizeDiameter D, inPoint Ø B, inCrown C & R, inDouble shear, steel, lb minDouble shear, CRES, lb min
.0625 (1/16)0.0626–0.06280.042–0.0580.008–0.020800610
.0781 (5/64)10.0782–0.07840.058–0.0740.010–0.0261,240700
.0938 (3/32)0.0939–0.09410.074–0.0900.012–0.0311,8001,000
.125 (1/8)0.1251–0.12530.105–0.1210.016–0.0413,2001,800
.1562 (5/32)10.1563–0.15650.136–0.1520.020–0.0525,0002,800
.1875 (3/16)0.1876–0.18780.167–0.1830.023–0.0627,2004,000
.250 (1/4)0.2501–0.25030.230–0.2460.031–0.08312,8007,200
.3125 (5/16)0.3126–0.31280.293–0.3090.039–0.10420,00011,000
.375 (3/8)0.3751–0.37530.355–0.3710.047–0.12528,00016,000
.4375 (7/16)0.4376–0.43780.417–0.4330.055–0.14638,00022,000
.500 (1/2)0.5001–0.50030.480–0.4960.063–0.16750,00029,000
.625 (5/8)0.6251–0.62530.605–0.6210.078–0.20878,00045,000
.750 (3/4)0.7501–0.75030.730–0.7460.094–0.250114,00065,000
.875 (7/8)0.8751–0.87530.855–0.8710.109–0.293156,00088,000
1.000 (1)1.0001–1.00030.980–0.9960.125–0.333204,000110,000

1 Inactive for new design after 8 April 1975.

Reference Guide: MS16555 Dowel Pins
01

Reading the Number

MS16555 part numbers are the basic number plus a dash number from Table II, III or IV (Requirement 5). Nothing is coded in the dash number itself. Its range sets the material and finish; its position in the table sets the diameter and length.

  • MS16555-1: 1/16 in diameter, .188 in long, plain carbon or alloy steel (the sheet's own example).
  • MS16555-348: 1/4 × 1 in, phosphate-coated steel.
  • MS16555-648: 1/4 × 1 in, CRES.
Gaps in the numbering

Some numbers were never used: 75, 76, 97, 99, 109, 111, 113–115, 123, 125, 127–129, 131, 137, 139 and 141–143 (and the same plus 300 and 600). There is no 445 or 745, because 145 exists in plain steel only. The decoder says so when you type one.

02

Material, Hardness and Finish

  • Steel (1–145, 301–444): carbon or alloy steel per ASTM A29/A29M, sulfur ≤ .04%, phosphorus ≤ .05%. Core 47–58 HRC, case 60 HRC min, case at least .020 in deep. Pins 1/16 in and under may be 58–64 HRC throughout.
  • CRES (601–744): type 416 (UNS S41600) or 410 (UNS S41000) per ASTM A582 and A483, 36–42 HRC.
  • Plain steel: may be furnished with black oxide per MIL-C-13924, Class 1.
  • Phosphate: DOD-P-16232, Type Z, Class 2.
  • CRES: cleaned, descaled and passivated per ASTM A380.
  • Surface: 16 µin on the effective length S and 125 µin elsewhere, before coating. S is at least 75% of L.
CRES pins are about half as strong in double shear as the hardened steel pins of the same size (Table I).
03

Status: MS16555 and NASM16555

MS16555 Revision C (19 August 1985) was made inactive for new design in 1996 (Notice 1) and cancelled on 16 March 2000 (Notice 2), superseded by NASM16555. Notice 2 states that the part numbers are identical, so MS16555-647 and NASM16555-647 are the same pin.

Source: MS16555C sheets 1 to 3 and Notices 1 and 2, from the DLA ASSIST database (Distribution A). The related MS16556 covers dowel pins .001 in over nominal size.

Related: Washer Size Finder, NAS1149 decoder, AN960 decoder.

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