ASME B16.9 254SMO Fittings Supply

In this blog, we introduce the supply of 254SMO fittings manufactured to the ASME B16.9 standard. 254SMO, also known as UNS S31254 or Alloy 254, is a super austenitic stainless steel known for its exceptional corrosion resistance in harsh environments. Paired with the rigorous specifications of ASME B16.9, these fittings offer solutions for chemical processing, oil and gas, and marine applications.

ASME B169 254SMO Fittings Supply

254SMO is a high-alloy austenitic stainless steel designed for superior resistance to pitting, crevice corrosion, and stress corrosion cracking, particularly in chloride-rich and acidic conditions.

Its chemical composition includes approximately 19.5-20.5% chromium, 17.5-18.5% nickel, 6.0-6.5% molybdenum, 0.18-0.22% nitrogen, and 0.50-1.00% copper, with a low carbon content (max 0.02%) to minimize carbide precipitation.

Overview of 254SMO Material

Mechanically, it exhibits a minimum tensile strength of 650-680 MPa, yield strength of 300 MPa, and an elongation of 35%, making it both strong and ductile. These properties stem from its molybdenum and nitrogen enhancements, achieving a Pitting Resistance Equivalent Number (PREN) of ≥42.5, far surpassing standard austenitic grades like 316L.

When fabricated into fittings under ASME B16.9, 254SMO ensures compliance with pressure ratings, tolerances, and testing requirements, making it ideal for high-integrity piping systems.

Manufacturers supply 254SMO buttweld fittings to facilitate direction changes, branch connections, and diameter transitions in piping systems. These are primarily manufactured to ASTM A403/ASME SA403, the standard specification for wrought austenitic stainless steel piping fittings.

254SMO Buttweld Fittings Types

Elbows: Used to change the direction of flow. These are available in standard 90-degree and 45-degree angles, with Long Radius (LR) and Short Radius (SR) variants. Long Radius elbows have a center-to-face dimension of 1.5 times the nominal pipe size, while Short Radius elbows have a radius equal to the pipe size. Specialized elbows like 3D, 5D, and 180-degree return bends are also available for specific flow requirements.

Tees: These allow for branch connections. Equal Tees have all three outlets of the same size, while Reducing Tees have a branch outlet that is smaller than the main run.

Reducers: Facilitate a change in pipe diameter. Concentric Reducers are symmetrical, with a common centerline, whereas Eccentric Reducers have one flat side, used to maintain either the top or bottom of the pipe run level.

Caps: These permanently seal the end of a pipe.

Stub Ends (Lap Joint Stub Ends): Used with lap joint flanges to create a boltable connection point in the system.

Crosses: Provide connections for four pipes meeting at one point.

Specifications for 254SMO ASME B16.9 fittings adhere to ASTM A403 WP-S31254 for wrought austenitic stainless steel, with wall thicknesses matching Schedule 10S through 160 or XXS, depending on pressure requirements.

GENERAL NOTE: All dimensions are in millimeters.

Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel	Center-to-End
Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel	Run, C	Outlet, M [Notes (1) and (2)]
1/2	15	21.3	25	25
3/4	20	26.7	29	29
1	25	33.4	38	38
1 1/4	32	42.2	48	48
1 1/2	40	48.3	57	57
2	50	60.3	64	64
2 1/2	65	73.0	76	76
3	80	88.9	86	86
3 1/2	90	101.6	95	95
4	100	114.3	105	105
5	125	141.3	124	124
6	150	168.3	143	143
8	200	219.1	178	178
10	250	273.0	216	216
12	300	323.8	254	254
14	350	355.6	279	279
16	400	406.4	305	305
18	450	457	343	343
20	500	508	381	381
22	550	559	419	419
24	600	610	432	432
26	650	660	495	495
28	700	711	521	521
30	750	762	559	559
32	800	813	597	597
34	850	864	635	635
36	900	914	673	673
38	950	965	711	711
40	1000	1016	749	749
42	1050	1067	762	711
44	1100	1118	813	762
46	1150	1168	851	800
48	1200	1219	889	838

Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel	Center-to-End, A
1	25	33.4	25
1 1/4	32	42.2	32
1 1/2	40	48.3	38
2	50	60.3	51
2 1/2	65	73.0	64
3	80	88.9	76
3 1/2	90	101.6	89
4	100	114.3	102
5	125	141.3	127
6	150	168.3	152
8	200	219.1	203
10	250	273.0	254
12	300	323.8	305
14	350	355.6	356
16	400	406.4	406
18	450	457	457
20	500	508	508
22	550	559	559
24	600	610	610

Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel	Center- to- Center, O	Back- to- Face, K
1	25	33.4	51	41
1 1/4	32	42.2	64	52
1 1/2	40	48.3	76	62
2	50	60.3	102	81
2 1/2	65	73.0	127	100
3	80	88.9	152	121
3 1/2	90	101.6	178	140
4	100	114.3	203	159
5	125	141.3	254	197
6	150	168.3	305	237
8	200	219.1	406	313
10	250	273.0	508	391
12	300	323.8	610	467
14	350	355.6	711	533
16	400	406.4	813	610
18	450	457	914	686
20	500	508	1016	762
22	550	559	1118	838
24	600	610	1219	914

Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel Run Outlet		Center-to-End
Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel Run Outlet		Run, C	Outlet, M [Note (1)]
1/2 x 1/2 x 3/8	15 × 15 × 10	21.3	17.3	25	25
1/2 x1/2 x 1/4	15 × 15 × 8	21.3	13.7	25	25
3/4 x 3/4 x1/2	20 × 20 × 15	26.7	21.3	29	29
3/4 x 3/4 x 3/8	20 × 20 × 10	26.7	17.3	29	29
1 × 1 x 3/4	25 × 25 × 20	33.4	26.7	38	38
1 × 1 x 1/2	25 × 25 × 15	33.4	21.3	38	38
1 1/4 x 1 1/4 × 1	32 × 32 × 25	42.2	33.4	48	48
1 1/4 × 1 1/4 × 3/4	32 × 32 × 20	42.2	26.7	48	48
1 1/4 x 1 1/4 x 1/2	32 × 32 × 15	42.2	21.3	48	48
1 1/2 x 1 1/2 x 1/4	40 × 40 × 32	48.3	42.2	57	57
1 1/2 x 1 1/2 × 1	40 × 40 × 25	48.3	33.4	57	57
1 1/2 x 1 1/2 x 3/4	40 × 40 × 20	48.3	26.7	57	57
1 1/2 x 1 1/2x 1/2	40 × 40 × 15	48.3	21.3	57	57
2 × 2 × 1 1/2	50 × 50 × 40	60.3	48.3	64	60
2 × 2 × 1 1/4	50 × 50 × 32	60.3	42.2	64	57
2 × 2 × 1	50 × 50 × 25	60.3	33.4	64	51
2 × 2 × 3/4	50 × 50 × 20	60.3	26.7	64	44
2 1/2 x 2 1/2 × 2	65 × 65 × 50	73.0	60.3	76	70
2 1/2 x 2 1/2 x 1 1/2	65 × 65 × 40	73.0	48.3	76	67
2 1/2 × 2 1/2 × 1 1/4	65 × 65 × 32	73.0	42.2	76	64
2 1/2 × 2 1/2 × 1	65 × 65 × 25	73.0	33.4	76	57
3 × 3 × 2 1/2	80 × 80 × 65	88.9	73.0	86	83
3 × 3 × 2	80 × 80 × 50	88.9	60.3	86	76
3 × 3 × 1 1/2	80 × 80 × 40	88.9	48.3	86	73
3 × 3 × 1 1/4	80 × 80 × 32	88.9	42.2	86	70
3 1/2 x 3 1/2 × 3	90 × 90 × 80	101.6	88.9	95	92
3 1/2 × 3 1/2 × 2 1/2	90 × 90 × 65	101.6	73.0	95	89
3 1/2 × 3 1/2 × 2	90 × 90 × 50	101.6	60.3	95	83
3 1/2 × 3 1/2 × 1 1/2	90 × 90 × 40	101.6	48.3	95	79
4 × 4 × 3 1/2	100 × 100 × 90	114.3	101.6	105	102
4 × 4 × 3	100 × 100 × 80	114.3	88.9	105	98
4 × 4 × 2 1/2	100 × 100 × 65	113.3	73.0	105	95
4 × 4 × 2	100 × 100 × 50	114.3	60.3	105	89
4 × 4 × 1 1/2	100 × 100 × 40	114.3	48.3	105	86
5 × 5 × 4	125 × 125 × 100	141.3	114.3	125	117
5 × 5 × 3 1/2	125 × 125 × 90	141.3	101.6	124	114
5 × 5 × 3	125 × 125 × 80	141.3	88.9	124	111
5 × 5 × 2 1/2	125 × 125 × 65	141.3	73.0	124	108
5 × 5 × 2	125 × 125 × 50	141.3	60.3	124	105

Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel		End-to-End, H	Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel		End-to-End, H
Nominal Pipe Size (NPS)	DN	Large End	Small End	End-to-End, H	Nominal Pipe Size (NPS)	DN	Large End	Small End	End-to-End, H
3/4 x 1/2	20 ×15	26.7	21.3	38	5 × 4	125 ×100	141.3	114.3	127
3/4 x 3/8	20 ×10	26.7	17.3	38	5 × 3 1/2	125 ×90	141.3	101.6	127
1 × 3/4	25 ×20	33.4	26.7	51	5 × 3	125 ×80	141.3	88.9	127
1 × 1/2	25 ×15	33.4	21.3	51	5 × 2 1/2	125 ×65	141.3	73.0	127
1 1/4 × 1	32 ×25	42.2	33.4	51	5 × 2	125 × 50	141.3	60.3	127
1 1/4 ×3/4	32 ×20	42.2	26.7	51	6 × 5	150 ×125	168.3	141.3	140
1 1/4 x 1/2	32 ×15	42.2	21.3	51	6 × 4	150 ×100	168.3	114.3	140
1 1/2 x 1 1/4	40 ×32	48.3	42.2	64	6 × 3 1/2	150 ×90	168.3	101.6	140
1 1/2 × 1	40 ×25	48.3	33.4	64	6 × 3	150 ×80	168.3	88.9	140
1 1/2 x 3/4	40 ×20	48.3	26.7	64	6 × 2 1/2	150 ×65	168.3	73.0	140
1 1/2 x 1/2	40 ×15	48.3	21.3	64	8 × 6	200 ×150	219.1	168.3	152
2 ×1 1/2	50 ×40	60.3	48.3	76	8 × 5	200 ×125	219.1	141.3	152
2 ×1 1/4	50 ×32	60.3	42.2	76	8 × 4	200 ×100	219.1	114.3	152
2 × 1	50 ×25	60.3	33.4	76	8 × 3 1/2	200 ×90	219.1	101.6	152
2 ×3/4	50 ×20	60.3	26.7	76	10 × 8	250 ×200	273.0	219.1	178
2 1/2 x 2	65 ×50	73.0	60.3	89	10 × 6	250 ×150	273.0	168.3	178
2 1/2 x 1 1/2	65 ×40	73.0	48.3	89	10 × 5	250 x 125	273.0	141.3	178
2 1/2 x 1 1/4	65 ×32	73.0	42.2	89	10 × 4	250 ×100	273.0	114.3	178
2 1/2 × 1	65 ×25	73.0	33.4	89	12 × 10	300 ×250	323.8	273.0	203
3 ×2 1/2	80 ×65	88.9	73.0	89	12 × 8	300 ×200	323.8	219.1	203
3 × 2	80 ×50	88.9	60.3	89	12 × 6	300 ×150	323.8	168.3	203
3 × 1 1/2	80 ×40	88.9	48.3	89	12 × 5	300 ×125	323.8	141.3	203
3 × 1 1/4	80 ×32	88.9	42.2	89	14 × 12	350 ×300	355.6	323.8	330
3 1/2 × 3	90 ×80	101.6	88.9	102	14 × 10	350 ×250	355.6	273.0	330
3 1/2 x 2 1/2	90 ×65	101.6	73.0	102	14 × 8	350 ×200	355.6	219.1	330
3 1/2 × 2	90 ×50	101.6	60.3	102	14 × 6	350 ×150	355.6	168.3	330
3 1/2 × 1 1/2	90 ×40	101.6	48.3	102	16 × 14	400 ×350	406.4	355.6	356
3 1/2 x 2 1/4	90 ×32	101.6	42.2	102	16 × 12	400 ×300	406.4	323.8	356
4 × 3 1/2	100 ×90	114.3	101.6	102	16 × 10	400 ×250	406.4	273.0	356
4 × 3	100 ×80	114.3	88.9	102	16 × 8	400 ×200	406.4	219.1	356
4 × 2 1/2	100 ×65	114.3	73.0	102	18 × 16	450 ×400	457	406.4	381
4 × 2	100 ×50	114.3	60.3	102	18 × 14	450 ×350	457	355.6	381
4 ×1 1/2	100 ×40	114.3	48.3	102	18 × 12 18 × 10	450 ×300 450 ×250	457 457	323.8 273.0	381 381

Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel		Center- to-End, A	Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel		Center- to-End, A
Nominal Pipe Size (NPS)	DN	Large End	Small End	Center- to-End, A	Nominal Pipe Size (NPS)	DN	Large End	Small End	Center- to-End, A
2 × 1 1/2	50 × 40	60.3	48.3	76	10 × 8	250 × 200	273.0	219.1	381
2 × 1 1/4	50 × 32	60.3	42.2	76	10 × 6	250 × 150	273.0	168.3	381
2 × 1	50 × 25	60.3	33.4	76	10 × 5	250 × 125	273.0	141.3	381
2 1/2 × 2	65 × 50	73.0	60.3	95	12 × 10	300 × 250	323.8	273.0	457
2 1/2 × 1 1/2	65 × 40	73.0	48.3	95	12 × 8	300 × 200	323.8	219.1	457
2 1/2 × 1 1/4	65 × 32	73.0	42.2	95	12 × 6	300 × 150	323.8	168.3	457
3 × 2 1/2	80 × 65	88.9	73.0	114	14 × 12	350 × 300	355.6	323.8	533
3 × 2	80 × 50	88.9	60.3	114	14 × 10	350 × 250	355.6	273.0	533
3 × 1 1/2	80 × 40	88.9	48.3	114	14 × 8	350 × 200	355.6	219.1	533
3 1/2 × 3	90 × 80	101.6	88.9	133	16 × 14	400 × 350	406.4	355.6	610
3 1/2 × 2 1/2	90 × 65	101.6	73.0	133	16 × 12	400 × 300	406.4	323.8	610
3 1/2 × 2	90 × 50	101.6	60.3	133	16 × 10	400 × 250	406.4	273.0	610
4 × 3 1/2	100 × 90	114.3	101.6	152	18 × 16	450 × 400	457	406.4	686
4 × 3	100 × 80	114.3	88.9	152	18 × 14	450 × 350	457	355.6	686
4 × 2 1/2	100 × 65	114.3	73.0	152	18 × 12	450 × 300	457	323.8	686
4 × 2	100 × 50	114.3	60.3	152	18 × 10	450 × 250	457	273.0	686
5 × 4	125 × 100	141.3	114.3	190	20 × 18	500 × 450	508	457	762
5 × 3 1/2	125 × 90	141.3	101.6	190	20 × 16	500 × 400	508	406.4	762
5 × 3	125 × 80	141.3	88.9	190	20 × 14	500 × 350	508	355.6	762
5 × 2 1/2	125 × 65	141.3	73.0	190	20 × 12	500 × 300	508	323.8	762
6 × 5	150 × 125	168.3	141.3	229	20 × 10	500 × 250	610	273.0	762
6 × 4	150 × 100	168.3	114.3	229	24 × 22	600 × 550	610	559	914
6 × 3 1/2	150 × 90	168.3	101.6	229	24 × 20	600 × 500	610	508	914
6 × 3	150 × 80	168.3	88.9	229	24 × 18	600 × 450	610	457	914
8 × 6	200 × 150	219.1	168.3	305	24 × 16	600 × 400	610	406.4	914
8 × 5	200 × 125	219.1	141.3	305	24 × 14	600 × 350	610	355.6	914
8 × 4	200 × 100	219.1	114.3	305	24 × 12	600 × 300	610	323.8	914

Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel	Center-to-End
Nominal Pipe Size (NPS)	DN	Outside Diameter at Bevel	90 Deg Elbows, A	45 Deg Elbows,B
1/2	15	21.3	38	16
3/4	20	26.7	38	19
1	25	33.4	38	22
1 1/4	32	42.2	48	25
1 1/2	40	48.3	57	29
2	50	60.3	76	35
2 1/2	65	73.0	95	44
3	80	88.9	114	51
3 1/2	90	101.6	133	57
4	100	114.3	152	64
5	125	141.3	190	79
6	150	168.3	229	95
8	200	219.1	305	127
10	250	273.0	381	159
12	300	323.8	457	190
14	350	355.6	533	222
16	400	406.4	610	254
18	450	457	686	286
20	500	508	762	318
22	550	559	838	343
24	600	610	914	381
26	650	660	991	405
28	700	711	1067	438
30	750	762	1143	470
32	800	813	1219	502
34	850	864	1295	533
36	900	914	1372	565
38	950	965	1448	600
40	1000	1016	1524	632
42	1050	1067	1600	660
44	1100	1118	1676	695
46	1150	1168	1753	727
48	1200	1219	1829	759

Nominal Pipe Size(NPS)	DN	Outside Diameter of Barrel		Long Pattern Length, F[Notes (3), (4)]	Short Pattern Length, F[Notes (3), (4)]	Radius of Fillet, R[Note (5)]	Diameter of Lap, G[Note (6)]
Nominal Pipe Size(NPS)	DN	Max.	Min.			Radius of Fillet, R[Note (5)]	Diameter of Lap, G[Note (6)]
1/2	15	22.8	20.5	76	51	3	35
3/4	20	28.1	25.9	76	51	3	43
1	25	35.0	32.6	102	51	3	51
1 1/4	32	43.6	41.4	102	51	5	64
1 1/2	40	49.9	47.5	102	51	6	73
2	50	62.4	59.5	152	64	8	92
2 1/2	65	75.3	72.2	152	64	8	106
3	80	91.3	88.1	152	64	10	127
3 1/2	90	104.0	100.8	152	76	10	140
4	100	116.7	113.5	152	76	11	157
5	125	144.3	140.5	203	76	11	185
6	150	171.3	167.5	203	89	13	218
8	200	222.1	218.3	203	102	13	270
10	250	277.2	272.3	254	127	13	324
12	300	328.0	323.1	254	152	13	381
14	350	359.9	354.8	305	152	13	413
16	400	411.0	405.6	305	152	13	470
18	450	462	456	305	152	13	533
20	500	514	507	305	152	13	584
22	550	565	558	305	152	13	641
24	600	616	609	305	152	13	692

Nominal

Pipe Size

(NPS)

Outside

Diameter

at Bevel

Length, E

[Note (1)]

Limiting Wall

Thickness for

Length, E

[Note (2)]

1/2

3/4 1

1 1/4

1 1/2

2 1/2

3 1/2

100

125

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1000

1050

1100

1150

1200

21.3

26.7

33.4

42.2

48.3

60.3

73.0

88.9

101.6

114.3

141.3

168.3

219.1

273.0

323.8

355.6

406.4

457

508

559

610

660

711

762

813

864

914

965

1016

1067

1118

1168

1219

102

127

152

165

178

203

229

254

267

305

343

4.57

3.81

4.57

4.83

5.08

5.59

7.11

7.62

8.13

8.64

9.65

10.92

12.70

. . .

102

127

152

178

191

203

229

254

305

. . .

I hope this detailed guide is useful for your procurement and engineering needs. For further specification details, would you be interested in a more detailed breakdown of pressure-temperature ratings for different schedules of 254SMO fittings?