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Stub Ends for Flanged Joints

What is a stub end and why should it be used? Stub ends are buttweld fittings that can be used (in combination with a lap joint flange) alternatively to welding neck flanges to make flanged connections. The use of stub ends has two advantages: it can reduce the total cost of flanged joints for piping systems in high material grades (as the lap joint flange does not need to be of the same material of the pipe and the stub end but can be a lower grade); it speeds up the installation process, as the lap joint flange can be rotated to facilitate the alignment of the bolt holes. Stub ends are available in short and long pattern (ASA and MSS stub ends), in sizes up to 80 inches.

STUB END APPLICATION

A stud end and a lap joint flange can be used together as an alternative way to make a flanged connection than welding neck flanges.

The two devices to be combined, in this case, are:

  • The stub end, which is essentially a piece of pipe, with one end flared outwards and the other prepared to be welded to a pipe of the same bore size (NPS = nominal pipe size), material and wall thickness. The most widely used fabrication tool for stub ends is the flaring machine, which is able to flare the end of the pipe and then cuts it to length.
  • A Lap Joint Flange, which is used to actually bolt the two lengths of pipe together.

flanged joint with stub end

 BENEFITS OF LAP JOINT STUB ENDS

The use of stub ends has these two advantages:

Reduces the overall cost of the flanged joint

Generally, the lap joint flange is of a lower grade than the material of the stub end and the pipework, thus saving the total weight of high-grade material used for the flanged joint.

Example:

For an SS316 pipe, instead of using a full 316 welding neck flange, a combination of an SS316 stub end and a carbon steel lap joint flange would do the same exact job, but the total weight of SS316 material would be lower, and the cost as well.

Essentially, stub ends allow to minimize the weight of high-grade material in stainless, duplex, and nickel alloy piping, saving costs. Of course, the bigger the diameter and the class of the flanges, the higher the saving!

Facilitates the installation of the flange

The lap joint flange can be rotated on the pipe and simplify the alignment of the bolt holes of the mating flanges

It shall be noted that stud ends are becoming popular also in high-pressure applications (whereas they were used for low-pressure applications only in the past).

Stub end with lap joint flange

STUB END TYPES

Stub ends are available in three different types, named “Type A”, “Type B” and “Type C”:

  • The first type (A) is manufactured and machined to match standard lap joint backing flange (the two products have to be used in combination). The mating surfaces have an identical profile to permit a smooth loading of the flare face
  • Stub ends type B are have to be used with standard slip-on flanges
  • Type C stub ends can be used either with lap joint or slip-on flanges and are manufactured from pipes

Stub end types

SHORT/LONG PATTERN STUB ENDS (ASA/MSS)

Stub ends are available in two different patterns:

  • the short pattern, called MSS-A stub ends
  • the long pattern, called ASA-A stub ends (or ANSI length stub end)
Short and long pattern stub ends
Short pattern (MSS) and long pattern stub ends (ASA)

STUB END FINISH

Stub ends can be ordered with different ends finishing:

  • Beveled Ends
  • Squared Ends
  • Flanged Ends
  • Grooved Ends
  • Threaded Ends (Male Only)

STUB END MATERIALS

ASTM Grade UNS Equivalent
A234 WPB Carbon Steel B K03006
A403 Stainless Steel 304/304L S30403
304H S30409
316/316L S31603
316H S31609
317L S31703
904L N08904
309S/H S30908
310S S31008
321 S32100
6XN N08367
20CB N08020
347 S34709
254SMO S31254
A815 Duplex /Super Duplex 2205 S31803/S32205
Zeron 100 S32760
2507 S32750
410 S41000
A366 Nickel Alloys HC22 N06022
HB-3 N10675
HG3 N06985
HX N06002
HC2000 N06200
HC276 N10276
NCI N06600
NC N04400
N N02200
NL N02201
NCMC N06625
NICMC N08825
NIC10 N08810
NIC11 N08811

STUB ENDS DIMENSIONS

The chart shows the MSS and ANSI stub end dimensions in inches.

MSS Stub End ANSI Stub End Pipe OD Pipe WT Lap OD Radius Flange thk
NPS Sch Min Nom Max Min Nom Max Min Nom Max Min Nom Max Min Max  Min  Nom  Min  Max
1/2″ 05S 1.940 2 2.060 2.940 3.00 3.060 0.809 0.84 0.896 .057 .065 .073 1.350 1.380 3/32 1/8 .065 .127
10S .073 .083 .093 .083 .145
40S .095 .109 .123 .109 .171
80S .129 .147 .165 .147 .209
3/4″ 05S 1.940 2 2.060 2.940 3.00 3.060 1.019 1.05 1.106 .057 .065 .073 1.660 1.690 3/32 1/8 .065 .127
10S .073 .083 .093 .083 .145
40S .099 .113 .127 .113 .175
80S .135 .154 .173 .154 .216
1 05S 1.940 2 2.060 3.940 4.00 4.060 1.284 1.315 1.376 .057 .065 .073 1.700 2.000 3/32 1/8 .065 .127
10S .095 .109 .123 .109 .171
40S .116 .133 .150 .133 .195
80S .157 .179 .201 .179 .241
1 1/4 05S 1.940 2 2.060 3.940 4.00 4.060 1.629 1.66 1.716 .057 .065 .073 2.470 2.500 5/32 3/16 .065 .127
10S .095 .109 .123 .109 .171
40S .123 .140 .158 .140 .202
80S .167 .191 .215 .191 .253
1 1/2 05S 1.940 2 2.060 3.940 4.00 4.060 1.869 1.9 1.965 .057 .065 .073 2.850 2.880 7/32 1/4 .065 .127
10S .095 .109 .123 .109 .171
40S .127 .145 .163 .145 .207
80S .175 .200 .225 .200 .262
2 05S 2.440 2.5 2.560 5.940 6.00 6.060 2.344 2.375 2.456 .057 .065 .073 3.590 3.620 9/32 5/16 .065 .127
10S .095 .109 .123 .109 .171
40S .135 .154 .173 .154 .216
80S .191 .218 .245 .218 .280
2 1/2 05S 2.440 2.5 2.560 5.940 6.00 6.060 2.844 2.875 2.966 .073 .083 .093 3.900 4.120 9/32 5/16 .083 .145
10S .105 .120 .135 .120 .182
40S .178 .203 .228 .203 .265
80S .242 .276 .311 .276 .338
3 05S 2.440 2.5 2.560 5.940 6.00 6.060 3.469 3.5 3.596 .073 .083 .093 4.970 5.000 11/32 3/8 .083 .145
10S .105 .120 .135 .120 .182
40S .189 .216 .243 .216 .278
80S .263 .300 .338 .300 .362
3 1/2 05S 2.940 3 3.060 5.940 6.00 6.060 3.969 4 4.096 .073 .083 .093 5.470 5.500 11/32 3/8 .083 .145
10S .105 .120 .135 .120 .182
40S .198 .226 .254 .226 .238
80S .278 .318 .358 .318 .380
4 05S 2.940 3 3.060 5.940 6.00 6.060 4.469 4.5 4.593 .073 .083 .093 6.160 6.190 3/8 7/16 .083 .145
10S .105 .120 .135 .120 .182
40S .207 .237 .267 .237 .299
80S .295 .337 .379 .337 .399
5 05S 2.940 3 3.060 7.940 8.00 8.060 5.532 5.563 5.683 .095 .109 .123 7.280 7.310 3/8 7/16 .109 .171
10S .117 .134 .151 .134 .196
40S .226 .258 .29 .258 .320
80S .328 .375 .422 .375 .437
6 05S 3.440 3.5 3.560 7.940 8.00 8.060 6.594 6.625 6.743 .095 .109 .123 8.470 8.500 7/16 1/2 .109 .171
10S .117 .134 .151 .134 .196
40S .245 .280 .315 .280 .342
80S .378 .432 .486 .432 .494
8 05S 3.940 4 4.060 7.940 8.00 8.060 8.594 8.625 8.743 .095 .109 .123 10.590 10.620 7/16 1/2 .109 .171
10S .130 .148 .167 .148 .210
40S .282 .322 .362 .322 .384
80S .438 .500 .563 .500 .562
10 05S 4.910 5 5.090 9.910 10.00 10.090 10.719 10.75 10.913 .117 .134 .151 12.690 12.750 7/16 1/2 .134 .196
10S .144 .165 .186 .165 .227
40S .319 .365 .411 .365 .427
80S .438 .500 .563 .500 .562
12 05S 5.910 6 6.090 9.910 10.00 10.090 12.719 12.75 12.913 .137 .156 .176 14.940 15.000 7/16 1/2 .156 .218
10S .158 .180 .203 .180 .242
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
14 05S 5.910 6 6.090 11.910 12.00 12.090 13.969 14 14.170 .137 .156 .176 16.190 16.250 7/16 1/2 .156 .218
10S .165 .188 .212 .188 .250
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
16 05S 5.910 6 6.090 11.910 12.00 12.090 15.969 16 16.180 .144 .165 .176 18.440 18.500 7/16 1/2 .165 .227
10S .165 .188 .212 .188 .250
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
18 05S 5.910 6 6.090 11.910 12.00 12.090 17.969 18 18.190 .144 .165 .176 20.940 21.000 7/16 1/2 .165 .227
10S .165 .188 .212 .188 .250
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
20 05S 5.910 6 6.090 11.910 12.00 12.090 19.969 20 20.240 .165 .188 .212 22.940 23.000 7/16 1/2 .188 .250
10S .191 .218 .245 .218 .280
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
24 05S 5.810 6 6.190 11.910 12.00 12.090 23.969 24 24.240 .191 .218 .245 27.190 27.250 7/16 1/2 .218 .280
10S .219 .250 .281 .250 .312
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
26 05S 5.810 6 6.190 11.810 12.00 12.190 25.969 26 26.240 29.190 29.250 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
28 05S 5.810 6 6.190 11.810 12.00 12.190 27.969 28 28.240 31.690 31.750 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
30 05S 5.810 6 6.190 11.810 12.00 12.190 29.969 30 30.240 33.690 33.750 7/16 1/2
10S .273 .312 .351 .312 .374
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
32 05S 5.810 6 6.190 11.810 12.00 12.190 31.969 32 32.240 35.940 36.000 7/16 1/2
10S
40S .328 .375 .422 .375 .422
80S .438 .500 .563 .500 .563
34 05S 5.810 6 6.190 11.810 12.00 12.190 33.969 34 34.240 37.940 38.000 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
36 05S 5.810 6 6.190 11.810 12.00 12.190 35.969 36 36.240 40.190 40.250 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
38 05S 5.810 6 6.190 11.810 12.00 12.190 37.969 38 38.240 42.690 42.750 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
40 05S 5.810 6 6.186 11.810 12.00 12.190 39.969 40 40.240 44.690 44.750 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
42 05S 5.810 6 6.186 11.810 12.00 12.190 41.969 42 42.240 46.940 47.000 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
44 05S 5.810 6 6.186 11.810 12.00 12.190 43.969 44 44.240 49.190 19.250 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
46 05S 5.810 6 6.190 11.810 12.00 12.190 45.969 46 46.240 51.190 51.250 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .563 .500 .562
48 05S 5.810 6 6.190 11.810 12.00 12.190 47.969 48 48.240 53.190 53.250 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
50 05S 5.810 6 6.190 11.810 12.00 12.190 49.969 50 50.240 55.190 55.250 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
52 05S 5.810 6 6.190 11.810 12.00 12.190 51.969 52 52.240 57.190 57.250 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562
54 05S 5.810 6 6.190 11.810 12.00 12.190 53.969 54 54.240 59.440 59.500 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .563 .500 .562
60 05S 5.810 6 6.190 11.810 12.00 12.190 59.969 60 60.240 65.440 65.500 7/16 1/2
10S
40S .328 .375 .422 .375 .437
80S .438 .500 .563 .500 .562

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