ASME B16.5 slip-on (SO) flange: dimensions and weight by class

Flange that slips over the pipe and receives two fillet welds, inside and outside. Cheaper and easier to align than the WN, for moderate service.

Technical review Oct 2026 · Source: ASME B16.5-2020

Slip-on in section. Two fillet welds; bore B is slightly larger than the pipe outside diameter.

StandardASME B16.5-2020

Classes150, 300, 400, 600, 900, 1,500

Range in class 150NPS ½ to 24

Unitsmm, kg; hole and bolt in inches

Dimensions by pressure class

Choose the class and click a row: the drawing changes to the scale and dimensions of that diameter.

Slip-on, class 150: dimensions in mm · raised face 1.6 mm · all types in class 150
NPS	DN	O	tf	X	Y	B	W	No. of holes	Hole Ø	Bolt Ø	Weight*
½"	15	89	9.7	30	14	22.4	60.5	4	⅝"	½"	0.4
¾"	20	99	11.2	38	14	27.7	69.8	4	⅝"	½"	0.6
1"	25	108	12.7	49	16	34.5	79.2	4	⅝"	½"	0.8
1¼"	32	117	14.2	59	19	43.2	88.9	4	⅝"	½"	1
1½"	40	127	15.9	65	21	49.5	98.6	4	⅝"	½"	1.3
2"	50	152	17.5	78	24	61.9	120.6	4	¾"	⅝"	2.1
2½"	65	178	20.6	90	27	74.7	139.7	4	¾"	⅝"	3.3
3"	80	190	22.4	108	28	90.7	152.4	4	¾"	⅝"	3.8
3½"	90	216	22.4	122	30	103.4	177.8	8	¾"	⅝"	4.8
4"	100	229	22.4	135	32	116.1	190.5	8	¾"	⅝"	5.4
5"	125	254	22.4	164	35	143.8	215.9	8	⅞"	¾"	6.1
6"	150	279	23.9	192	38	170.7	241.3	8	⅞"	¾"	7.4
8"	200	343	26.9	246	43	221.5	298.4	8	⅞"	¾"	12
10"	250	406	28.4	305	48	276.4	362.0	12	1"	⅞"	16.2
12"	300	483	30.2	365	54	327.2	431.8	12	1"	⅞"	26
14"	350	533	33.3	400	56	359.2	476.2	12	1⅛"	1"	34.3
16"	400	597	35.1	457	62	410.5	539.8	16	1⅛"	1"	44.5
18"	450	635	38.1	505	67	461.8	577.8	16	1¼"	1⅛"	48.3
20"	500	698.5	41.1	559	71	513.1	635.0	20	1¼"	1⅛"	59
22"	550	749	44.4	610	78	564.4	692.2	20	1⅜"	1¼"	70.7
24"	600	813	46.0	663	81	616.0	749.3	20	1⅜"	1¼"	85.7

Slip-on, class 300: dimensions in mm · raised face 1.6 mm · all types in class 300
NPS	DN	O	tf	X	Y	B	W	No. of holes	Hole Ø	Bolt Ø	Weight*
½"	15	95	12.7	38	21	22.4	66.5	4	⅝"	½"	0.6
¾"	20	117	14.2	48	24	27.7	82.6	4	¾"	⅝"	1.1
1"	25	124	15.7	54	25	34.5	88.9	4	¾"	⅝"	1.3
1¼"	32	133	17.5	64	25	43.2	98.6	4	¾"	⅝"	1.7
1½"	40	155	19.0	70	29	49.5	114.3	4	⅞"	¾"	2.5
2"	50	165	20.6	84	32	62.0	127.0	8	¾"	⅝"	2.9
2½"	65	190	23.9	100	37	74.7	149.4	8	⅞"	¾"	4.3
3"	80	210	26.9	117	41	90.7	168.1	8	⅞"	¾"	5.8
3½"	90	229	28.4	133	43	103.4	184.2	8	⅞"	¾"	7.3
4"	100	254	30.2	146	46	116.1	200.2	8	⅞"	¾"	9.6
5"	125	279	33.3	178	49	143.8	235.0	8	⅞"	¾"	12.1
6"	150	318	35.1	206	51	170.7	269.7	12	⅞"	¾"	15.7
8"	200	381	39.6	260	60	221.5	330.2	12	1"	⅞"	24
10"	250	444	46.0	321	65	276.4	387.4	16	1⅛"	1"	33.8
12"	300	521	49.3	375	72	327.2	450.8	16	1¼"	1⅛"	49.8
14"	350	584	52.3	425	75	359.2	514.4	20	1¼"	1⅛"	69.2
16"	400	648	55.6	483	81	410.5	571.5	20	1⅜"	1¼"	88
18"	450	711	58.7	533	87	461.8	628.6	24	1⅜"	1¼"	107.6
20"	500	775	62.0	587	94	513.1	685.8	24	1⅜"	1¼"	133.7
22"	550	838	65.0	641	100	564.4	743.0	24	1⅝"	1½"	157
24"	600	914	68.3	702	105	616.0	812.8	24	1⅝"	1½"	200

Up to NPS 3½, class 400 uses the same dimensions as class 600 (rows marked "= 600").

Slip-on, class 400: dimensions in mm · raised face 6.4 mm · all types in class 400
NPS	DN	O	tf	X	Y	B	W	No. of holes	Hole Ø	Bolt Ø	Weight*
½" = 600	15	95	14.2	38	22	22.4	66.5	4	⅝"	½"	0.7
¾" = 600	20	117	15.7	48	25	27.7	82.6	4	¾"	⅝"	1.2
1" = 600	25	124	17.5	54	27	34.5	88.9	4	¾"	⅝"	1.5
1¼" = 600	32	133	20.6	64	28	43.2	98.6	4	¾"	⅝"	2
1½" = 600	40	155	22.4	70	32	49.5	114.3	4	⅞"	¾"	3
2" = 600	50	165	25.4	84	37	62.0	127.0	8	¾"	⅝"	3.6
2½" = 600	65	190	28.4	100	41	74.7	149.4	8	⅞"	¾"	5.2
3" = 600	80	210	31.8	117	46	90.7	168.1	8	⅞"	¾"	7
3½" = 600	90	229	35.1	133	49	103.4	184.2	8	1"	⅞"	8.8
4"	100	254	35.1	146	51	116.1	200.2	8	1"	⅞"	11.1
5"	125	279	38.1	178	54	143.8	235.0	8	1"	⅞"	13.8
6"	150	318	41.1	206	57	170.7	269.7	12	1"	⅞"	18.2
8"	200	381	47.8	260	68	221.5	330.2	12	1⅛"	1"	28.5
10"	250	444	53.8	321	73	276.4	387.4	16	1¼"	1⅛"	38.8
12"	300	521	57.2	375	79	327.2	450.8	16	1⅜"	1¼"	56.8
14"	350	584	60.5	425	84	359.2	514.4	20	1⅜"	1¼"	78.7
16"	400	648	63.5	483	94	410.5	571.5	20	1½"	1⅜"	100.6
18"	450	711	66.5	533	99	461.8	628.6	24	1½"	1⅜"	121.7
20"	500	775	69.8	587	102	513.1	685.8	24	1⅝"	1½"	145.9
22"	550	838	73.2	641	108	564.4	743.0	24	1¾"	1⅝"	174.1
24"	600	914	76.2	702	114	616.0	812.8	24	1⅞"	1¾"	217.5

Slip-on, class 600: dimensions in mm · raised face 6.4 mm · all types in class 600
NPS	DN	O	tf	X	Y	B	W	No. of holes	Hole Ø	Bolt Ø	Weight*
½"	15	95	14.2	38	22	22.4	66.5	4	⅝"	½"	0.7
¾"	20	117	15.7	48	25	27.7	82.6	4	¾"	⅝"	1.2
1"	25	124	17.5	54	27	34.5	88.9	4	¾"	⅝"	1.5
1¼"	32	133	20.6	64	28	43.2	98.6	4	¾"	⅝"	2
1½"	40	155	22.4	70	32	49.5	114.3	4	⅞"	¾"	3
2"	50	165	25.4	84	37	62.0	127.0	8	¾"	⅝"	3.6
2½"	65	190	28.4	100	41	74.7	149.4	8	⅞"	¾"	5.2
3"	80	210	31.8	117	46	90.7	168.1	8	⅞"	¾"	7
3½"	90	229	35.1	133	49	103.4	184.2	8	1"	⅞"	8.8
4"	100	273	38.1	152	54	116.1	215.9	8	1"	⅞"	14.5
5"	125	330	44.4	189	60	143.8	266.7	8	1⅛"	1"	24.3
6"	150	356	47.8	222	67	170.7	292.1	12	1⅛"	1"	28.8
8"	200	419	55.6	273	76	221.5	349.2	12	1¼"	1⅛"	43.2
10"	250	508	63.5	343	86	276.4	431.8	16	1⅜"	1¼"	70.1
12"	300	559	66.5	400	92	327.2	489.0	20	1⅜"	1¼"	83.7
14"	350	603	69.8	432	94	359.2	527.0	20	1½"	1⅜"	98.3
16"	400	686	76.2	495	106	410.5	603.2	20	1⅝"	1½"	141.4
18"	450	743	82.6	546	117	461.8	654.0	20	1¾"	1⅝"	172.2
20"	500	813	88.9	610	127	513.1	723.9	24	1¾"	1⅝"	219.3
22"	550	870	95.2	663	133	564.4	777.7	24	1⅞"	1¾"	255.8
24"	600	940	101.6	718	140	616.0	838.2	24	2"	1⅞"	311.6

Up to NPS 2½, class 900 uses the same dimensions as class 1500 (rows marked "= 1500").

Slip-on, class 900: dimensions in mm · raised face 6.4 mm · all types in class 900
NPS	DN	O	tf	X	Y	B	W	No. of holes	Hole Ø	Bolt Ø	Weight*
½" = 1500	15	121	22.4	38	32	22.4	82.6	4	⅞"	¾"	1.8
¾" = 1500	20	130	25.4	44	35	27.7	88.9	4	⅞"	¾"	2.3
1" = 1500	25	149	28.4	52	41	34.5	101.6	4	1"	⅞"	3.4
1¼" = 1500	32	159	28.4	64	41	43.2	111.1	4	1"	⅞"	3.9
1½" = 1500	40	178	31.8	70	44	49.5	124.0	4	1⅛"	1"	5.4
2" = 1500	50	216	38.1	105	57	62.0	165.1	8	1"	⅞"	9.8
2½" = 1500	65	244	41.1	124	64	74.7	190.5	8	1⅛"	1"	13.5
3"	80	241	38.1	127	54	90.7	190.5	8	1"	⅞"	11.5
4"	100	292	44.5	159	70	116.1	235.0	8	1¼"	1⅛"	19.6
5"	125	349	50.8	190	79	143.8	279.4	8	1⅜"	1¼"	31.6
6"	150	381	55.6	235	86	170.7	317.5	12	1¼"	1⅛"	40.9
8"	200	470	63.5	298	102	221.5	393.7	12	1½"	1⅜"	70.2
10"	250	546	69.8	368	108	276.4	469.9	16	1½"	1⅜"	99.6
12"	300	610	79.2	419	117	327.2	533.4	20	1½"	1⅜"	131.8
14"	350	641	85.9	451	130	359.2	558.8	20	1⅝"	1½"	151.8
16"	400	705	88.9	508	133	410.5	616.0	20	1¾"	1⅝"	183.3
18"	450	787	101.6	565	152	461.8	685.8	20	2"	1⅞"	255.6
20"	500	857	108.0	622	159	513.1	749.3	20	2⅛"	2"	314.5
24"	600	1041	139.7	749	203	616.0	901.7	20	2⅝"	2½"	600.2

Slip-on, class 1500: dimensions in mm · raised face 6.4 mm · all types in class 1500
NPS	DN	O	tf	X	Y	B	W	No. of holes	Hole Ø	Bolt Ø	Weight*
½"	15	121	22.4	38	32	22.4	82.6	4	⅞"	¾"	1.8
¾"	20	130	25.4	44	35	27.7	88.9	4	⅞"	¾"	2.3
1"	25	149	28.4	52	41	34.5	101.6	4	1"	⅞"	3.4
1¼"	32	159	28.4	64	41	43.2	111.1	4	1"	⅞"	3.9
1½"	40	178	31.8	70	44	49.5	124.0	4	1⅛"	1"	5.4
2"	50	216	38.1	105	57	62.0	165.1	8	1"	⅞"	9.8
2½"	65	244	41.1	124	64	74.7	190.5	8	1⅛"	1"	13.5

Scale drawing

Section drawing, proportional to the table dimensions (mm).

O = outside diameter · tf = thickness without raised face · X = hub diameter at base · Y = overall length without raised face · B = bore · W = bolt circle. * Weight estimated from geometry in carbon steel.

Frequently asked questions

What is the asme b16.5 slip-on (so) flange: dimensions and weight by class used for?

Flange that slips over the pipe and receives two fillet welds, inside and outside. Cheaper and easier to align than the WN, for moderate service.

Do the dimensions include the raised face?

No. Since the 2017 edition, the thickness (tf) and length (Y) in ASME B16.5 are measured without the raised face. Add 1.6 mm for classes 150 and 300 and 6.4 mm from class 400 upward.

In which materials does Dustre supply it?

A105 and A350 LF2 carbon steel, F304L and F316L stainless, F51/F60 duplex, F53/F55 super duplex, F11, F22 and F91 Cr-Mo, nickel alloys and titanium, forged and machined with 3.1 certificate.

Slip-on in special alloysForged and machined at Dustre, in any class, with 3.1 certificate.

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