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Buttweld Fittings, Pipe Fittings, Technical Library

Stub End (ASA, MSS)

Stub End (ASA, MSS)

A stub end is used in connection with a lap joint flange to execute cost-effective flanged joints. The combination of a stud end and a lap joint flange has two key advantages over connections made with welding neck flanges: reduces the cost of the flanged connection (the lap joint flange can be of a lower grade than the pipe material); the lap joint flange can be rotated to facilitate the alignment of the flanges bolt holes. Stud ends are available in two main shapes, short and long pattern (ASA and MSS stub ends), in sizes up to 80 inches and multiple material grades.

 

STUB END FLANGED JOINT

A stub end is a butt weld fitting that can be used for cost-effective flanged joint connections. A flanged joint made with a stud end requires two different parts:

  • 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 or a Slip-on flange, which is used to actually bolt the two lengths of pipes together.

Stub end                lap joint flange

Generally, the material grade of the lap joint (or slip-on) flange is lower than the material grade of the stub end. Hence, for a. stainless steel pipeline, for instance, a stainless steel stub end is used in combination with carbon steel lap joint flanges. Such a flanged joint uses, therefore, less high-grade material (stainless steel) than a flanged joint executed with a full stainless steel weld neck flange, thus reducing the overall cost of the flanged connections of the pipeline.

 

STUB END APPLICATIONS

A stub end suits the following applications:

  • All cases that require a rotating back flange to facilitate the bolting activities;
  • High-grade pipelines (stainless steel upwards): the use of stub ends reduces the overall weight of expensive materials in high-grade piping and therefore reduce the overall cost of the flanged connections (savings can be substantial for large diameter or long pipelines). For example, in a stainless steel 316 piping system, the contractor may use stainless steel stud ends (and weld them to the pipes) and carbon steel lap joint flanges (indeed the flange just supports the connection but does not come into contact with the fluid conveyed by the pipeline

It has to 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).

flanged joint with stub end

 

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

 

ASA AND MSS STUB END

Stub ends are available in two different patterns:

  • the short pattern, called MSS-A stub ends
  • the long pattern, called ASA-A stub ends

short and long pattern stub ends MSS 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

A/SA403 Stainless Alloys UNS B/SB366 Nickel Alloys UNS
304/304L S30403 HC22 N06022
304H S30409 HB-3 N10675
316/316L S31603 HG3 N06985
316H S31609 HX N06002
317L S31703 HC2000 N06200
904L N08904 HC276 N10276
309S/H S30908 NCI N06600
310S S31008 NC N04400
321 S32100 N N02200
6XN N08367 NL N02201
20CB N08020 NCMC N06625
347 S34709 NICMC N08825
254SMO S31254 NIC10 N08810
NIC11 N08811
A/SA815 Duplex Alloys UNS   A/SA234 Carbon Alloys UNS
2205 S31803/S32205 B K03006
Zeron 100 S32760
2507 S32750
410 S41000
B-361 Aluminum Alloys UNS   Copper Nickel Alloys UNS
6061 A96061 CUNI 90/10 C70600
6063 A96063 CUNI 70/30 C71500

 

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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