Slip On Flange Sizes (ASME B16.5)

Quick Reference

ASME B16.5 slip-on flange dimensions (NPS 1/2” to 24”) for Classes 150-2500. Bore larger than pipe OD to allow slip-in. Welded with two fillet welds (inside + outside).

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Need a printable version? Download the ASME B16.5 Flange Dimensions Chart for all flange types and pressure classes.

ASME Slip-On Flange Dimensions and Weights

The tables below show ASME B16.5 slip-on flange dimensions including: outside diameter (OD), flange thickness, hub OD, raised face diameter, pitch circle diameter (PCD), socket bore, bolt hole specifications, and weight.

Slip-On Flange Sizes in Millimeters

Slip-On Class 150

Slip on flanges dimensions ASME B1.65

NPS	DN	OD (mm)	Flange Thick.	Hub OD	Flange Length	RF Dia.	RF Height	PCD	Socket Bore	Bolts#	Bolt Size UNC	Machine Bolt Length	RF Stud Length	Hole Size	Metric Studs	Weight in kg
		A	B	C	D	E	F	G	H
1/2	15	90	9.6	30	14	34.9	2	60.3	22.2	4	1/2	50	55	5/8	M14	0.8
3/4	20	100	11.2	38	14	42.9	2	69.9	27.7	4	1/2	50	65	5/8	M14	0.9
1	25	110	12.7	49	16	50.8	2	79.4	34.5	4	1/2	55	65	5/8	M14	0.9
1 1/4	32	115	14.3	59	19	63.5	2	88.9	43.2	4	1/2	55	70	5/8	M14	1.4
1 1/2	40	125	15.9	65	21	73	2	98.4	49.5	4	1/2	65	70	5/8	M14	1.4
2	50	150	17.5	78	24	92.1	2	120.7	61.9	4	5/8	70	85	3/4	M16	2.3
2 1/2	65	180	20.7	90	27	104.8	2	139.7	74.6	4	5/8	75	90	3/4	M16	3.2
3	80	190	22.3	108	29	127	2	152.4	90.7	4	5/8	75	90	3/4	M16	3.7
3 1/2	90	215	22.3	122	30	139.7	2	177.8	103.4	8	5/8	75	90	3/4	M16	5
4	100	230	22.3	135	32	157.2	2	190.5	116.1	8	5/8	75	90	3/4	M16	5.9
5	125	255	22.3	164	35	185.7	2	215.9	143.8	8	3/4	85	95	7/8	M20	6.8
6	150	280	23.9	192	38	215.9	2	241.3	170.7	8	3/4	85	100	7/8	M20	8.6
8	200	345	27	246	43	269.9	2	298.5	221.5	8	3/4	90	110	7/8	M20	13.7
10	250	405	28.6	305	48	323.8	2	362	276.2	12	7/8	100	115	1	M24	19.5
12	300	485	30.2	365	54	381	2	431.8	327	12	7/8	100	120	1	M24	29
14	350	535	33.4	400	56	412.8	2	476.3	359.2	12	1	115	135	1 1/8	M27	41
16	400	595	35	457	62	469.9	2	539.8	410.5	16	1	115	135	1 1/8	M27	54
18	450	635	38.1	505	67	533.4	2	577.9	461.8	16	1 1/8	125	145	1 1/4	M30	59
20	500	700	41.3	559	71	584.2	2	635	513.1	20	1 1/8	140	160	1 1/4	M30	75
24	600	815	46.1	663	81	692.2	2	749.3	616	20	1 1/4	150	170	1 3/8	M33	100

Slip-On Class 300

NPS	DN	OD (mm)	Flange Thick.	Hub OD	Flange Length	RF Dia.	RF Height	PCD	Socket Bore	Bolts#	Bolt Size UNC	Machine Bolt Length	RF Stud Length	Hole Size	Metric Studs	Weight in kg
		A	B	C	D	E	F	G	H
1/2	15	95	12.7	38	21	34.9	2	66.7	22.2	4	1/2	55	65	5/8	M14	1.2
3/4	20	115	14.3	48	24	42.9	2	82.6	27.7	4	5/8	65	75	3/4	M16	1.4
1	25	125	15.9	54	25	50.8	2	88.9	34.5	4	5/8	65	75	3/4	M16	1.4
1 1/4	32	135	17.5	64	25	63.5	2	98.4	43.2	4	5/8	70	85	3/4	M16	1.8
1 1/2	40	155	19.1	70	29	73	2	114.3	49.5	4	3/4	75	90	7/8	M20	2.7
2	50	165	20.7	84	32	92.1	2	127	61.9	8	5/8	75	90	3/4	M16	3.2
2 1/2	65	190	23.9	100	37	104.8	2	149.2	74.6	8	3/4	85	100	7/8	M20	4.6
3	80	210	27	117	41	127	2	168.3	90.7	8	3/4	90	110	7/8	M20	5.9
3 1/2	90	230	28.6	133	43	139.7	2	184.2	103.4	8	3/4	95	110	7/8	M20	7.7
4	100	255	30.2	146	46	157.2	2	200	116.8	8	3/4	95	115	7/8	M20	10
5	125	280	33.4	178	49	185.7	2	235	144.4	8	3/4	110	120	7/8	M20	12.7
6	150	320	35	206	51	215.9	2	269.9	171.4	12	3/4	110	120	7/8	M20	17.7
8	200	380	39.7	260	60	269.9	2	330.2	222.2	12	7/8	120	140	1	M24	26
10	250	445	46.1	321	65	323.8	2	387.4	277.4	16	1	140	160	1 1/8	M27	36
12	300	520	49.3	375	71	381	2	450.8	328.2	16	1 1/8	145	170	1 1/4	M30	52
14	350	585	52.4	425	75	412.8	2	514.4	360.2	20	1 1/8	160	180	1 1/4	M30	75
16	400	650	55.6	483	81	469.9	2	571.5	411.2	20	1 1/4	165	190	1 3/8	M33	86
18	450	710	58.8	533	87	533.4	2	628.6	462.3	24	1 1/4	170	195	1 3/8	M33	113
20	500	775	62	587	94	584.2	2	685.8	514.4	24	1 1/4	185	205	1 3/8	M33	143
24	600	915	68.3	702	105	692.2	2	812.8	616	24	1 1/2	205

Slip-On Class 400

NPS	DN	OD (mm)	Flange Thickness	Hub OD	Flange Length	RF Dia.	RF Height	PCD	Socket Bore	Bolts#	Bolt Size UNC	RF Stud Length	Hole Size	Metric Studs	Weight in kg
		A	B	C	D	E	F	G	H
1/2	15	95	14.3	38	22	34.9	7	66.7	22.2	4	1/2	75	5/8	M14	1.3
3/4	20	115	15.9	48	25	42.9	7	82.6	27.7	4	5/8	90	3/4	M16	1.5
1	25	125	17.5	54	27	50.8	7	88.9	34.5	4	5/8	90	3/4	M16	1.8
1 1/4	32	135	20.7	64	29	63.5	7	98.4	43.2	4	5/8	95	3/4	M16	2.3
1 1/2	40	155	22.3	70	32	73	7	114.3	49.5	4	3/4	110	7/8	M20	3.2
2	50	165	25.4	84	37	92.1	7	127	61.9	8	5/8	110	3/4	M16	4.1
2 1/2	65	190	28.6	100	41	104.8	7	149.2	74.6	8	3/4	120	7/8	M20	5.9
3	80	210	31.8	117	46	127	7	168.3	90.7	8	3/4	125	7/8	M20	7.3
4	100	255	35	146	51	157.2	7	200	116.1	8	7/8	140	1	M24	11.8
5	125	280	38.1	178	54	185.7	7	235	143.8	8	7/8	145	1	M24	14.1
6	150	320	41.3	206	57	215.9	7	269.9	170.7	12	7/8	150	1	M24	20
8	200	380	47.7	260	68	269.9	7	330	221.5	12	1	170	1 1/8	M27	31
10	250	445	54	321	73	323.8	7	387.4	276.2	16	1 1/8	190	1 1/4	M30	42
12	300	520	57.2	375	79	381	7	450.8	327	16	1 1/4	205	1 3/8	M33	59
14	350	585	60.4	425	84	412.8	7	514.4	359.2	20	1 1/4	210	1 3/8	M33	82
16	400	650	63.5	483	94	469.9	7	571.5	410.5	20	1 3/8	220	1 1/2	M36	107
18	450	710	66.7	533	98	533.4	7	628.6	461.8	24	1 3/8	230	1 1/2	M36	130
20	500	775	69.9	587	102	584.2	7	685.8	513.1	24	1 1/2	240	1 3/4	M39	157
24	600	915	76.2	702	114	692.2	7	812.8	616	24	1 3/4	265	1 7/8	M45	232

Slip-On Class 600

NPS	DN	OD (mm)	Flange Thickness	Hub OD	Flange Length	RF Dia.	RF Height	PCD	Socket Bore	Bolts#	Bolt Size UNC	RF Stud Length	Hole Size	Metric Studs	Weight in kg
		A	B	C	D	E	F	G	H
1/2	15	95	14.3	38	22	34.9	7	66.7	22.2	4	1/2	75	5/8	M14	1.3
3/4	20	115	15.9	48	25	42.9	7	82.6	27.7	4	5/8	90	3/4	M16	1.4
1	25	125	17.5	54	27	50.8	7	88.9	34.5	4	5/8	90	3/4	M16	1.8
1 1/4	32	135	20.7	64	29	63.5	7	98.4	43.2	4	5/8	95	3/4	M16	2.3
1 1/2	40	155	22.3	70	32	73	7	114.3	49.5	4	3/4	110	7/8	M20	3.2
2	50	165	25.4	84	37	92.1	7	127	61.9	8	5/8	110	3/4	M16	4.1
2 1/2	65	190	28.6	100	41	104.8	7	149.2	74.6	8	3/4	120	7/8	M20	5.9
3	80	210	31.8	117	46	127	7	168.3	90.7	8	3/4	125	7/8	M20	7.3
4	100	275	38.1	152	54	157.2	7	215.9	116.1	8	7/8	145	1	M24	16.8
5	125	330	44.5	189	60	185.7	7	266.7	143.8	8	1	165	1 1/8	M27	29
6	150	355	47.7	222	67	215.9	7	292.1	170.7	12	1	170	1 1/8	M27	36
8	200	420	55.6	273	76	269.9	7	349.2	221.5	12	1 1/8	190	1 1/4	M30	52
10	250	510	63.5	343	86	323.8	7	431.8	276.2	16	1 1/4	215	1 3/8	M33	77
12	300	560	66.7	400	92	381	7	489	327	20	1 1/4	220	1 3/8	M33	91
14	350	605	69.9	432	94	412.8	7	527	359.2	20	1 3/8	235	1 1/2	M36	105
16	400	685	76.2	495	106	469.9	7	603.2	410.5	20	1 1/2	255	1 5/8	M39	150
18	450	745	82.6	546	117	533.4	7	654	461.8	20	1 5/8	275	1 3/4	M42	182
20	500	815	88.9	610	127	584.2	7	723.9	513.1	24	1 5/8	285	1 3/4	M42	232
24	600	940	101.6	718	140	692.2	7	838.2	616	24	1 7/8	330	2	M48	332

Slip-On Class 900

NPS	DN	OD (mm)	Flange Thickness	Hub OD	Flange Length	RF Dia.	RF Height	PCD	Socket Bore	Bolts#	Bolt Size UNC	RF Stud Length	Hole Size	Metric Studs	Weight in kg
		A	B	C	D	E	F	G	H
1/2	15	120	22.3	38	32	34.9	7	82.6	22.2	4	3/4	110	7/8	M20	1.8
3/4	20	130	25.4	44	35	42.9	7	88.9	27.7	4	3/4	115	7/8	M20	2.3
1	25	150	28.6	52	41	50.8	7	101.6	34.5	4	7/8	125	1	M24	3.6
1 1/4	32	160	28.6	64	41	63.5	7	111.1	43.2	4	7/8	125	1	M24	4.1
1 1/2	40	180	31.8	70	44	73	7	123.8	49.5	4	1	140	1 1/8	M27	5.5
2	50	215	38.1	105	57	92.1	7	165.1	61.9	8	7/8	145	1	M24	11.5
2 1/2	65	245	41.3	124	64	104.8	7	190.5	74.6	8	1	160	1 1/8	M27	16.5
3	80	240	38.1	127	54	127	7	190.5	90.7	8	7/8	145	1	M24	12
4	100	290	44.5	159	70	157.2	7	235	116.1	8	1 1/8	170	1 1/4	M30	24
5	125	350	50.8	190	79	185.7	7	279.4	143.8	8	1 1/4	190	1 3/8	M33	38
6	150	380	55.6	235	86	215.9	7	317.5	170.7	12	1 1/8	190	1 1/4	M30	50
8	200	470	63.5	298	102	269.9	7	393.7	221.5	12	1 3/8	220	1 1/2	M36	78
10	250	545	69.9	368	108	323.8	7	469.9	276.2	16	1 3/8	235	1 1/2	M36	112
12	300	610	79.4	419	117	381	7	533.4	327	20	1 3/8	255	1 1/2	M36	148
14	350	640	85.8	451	130	412.8	7	558.8	359.2	20	1 1/2	275	1 5/8	M39	182
16	400	705	88.9	508	133	469.9	7	616	410.5	20	1 5/8	285	1 3/4	M42	193
18	450	785	101.6	565	152	533.4	7	685.8	461.8	20	1 7/8	325	2	M48	258
20	500	855	108	622	159	584.2	7	749.3	513.1	20	2	350	2 1/8	M52	317
24	600	1040	139.7	749	203	692.2	7	901.7	616	20	2 1/2	440	2 5/8	M64	608

Slip-On Class 1500

NPS	DN	OD (mm)	Flange Thickness	Hub OD	Flange Length	RF Dia.	RF Height	PCD	Socket Bore	Bolts#	Bolt Size UNC	RF Stud Length	Hole Size	Metric Studs	Weight in kg
		A	B	C	D	E	F	G	H
1/2	15	120	22.3	38	32	34.9	7	82.6	22.2	4	3/4	110	7/8	M20	1.8
3/4	20	130	25.4	44	35	42.9	7	88.9	27.7	4	3/4	115	7/8	M20	2.3
1	25	150	28.6	52	41	50.8	7	101.6	34.5	4	7/8	125	1	M24	3.7
1 1/4	32	160	28.6	64	41	63.5	7	111.1	43.2	4	7/8	125	1	M24	4.1
1 1/2	40	180	31.8	70	44	73	7	123.8	49.5	4	1	140	1 1/8	M27	5.5
2	50	215	38.1	105	57	92.1	7	165.1	61.9	8	7/8	145	1	M24	9.8
2 1/2	65	245	41.3	124	64	104.8	7	190.5	74.6	8	1	160	1 1/8	M27	16.4

Slip-on Flange Tolerance

ASME B16.5 provides specific tolerances for slip-on flanges across various dimensions to ensure proper fit, alignment, and sealing capability within piping systems. While it’s important to refer directly to the ASME B16.5 standard for detailed tolerance values due to variations across different flange sizes and pressure classes, below are general examples of tolerances for slip-on flanges as outlined in the standard:

Diameter of Bolt Circle (P):

The tolerance for the diameter of the bolt circle is typically ±1.6 mm (±1/16 inch) for flanges up to and including NPS 24.

Diameter of Bolt Holes (Q):

The diameter of bolt holes is generally oversized to allow for ease of alignment and assembly, with a common tolerance of +3 mm (1/8 inch) on the nominal bolt hole size.

Flange Thickness (T):

Tolerance for flange thickness can vary, but a general guideline for flanges up to NPS 24 is ±3 mm (±1/8 inch), depending on the pressure class and size of the flange.

Hub Length (Length through Hub, Y):

For slip-on flanges, the hub length tolerance can be important, especially for alignment during welding. Tolerances can vary but might be around ±1.6 mm (±1/16 inch) for smaller sizes.

Outside Diameter (O):

Tolerance for the outside diameter of a slip-on flange might be around ±1.6 mm (±1/16 inch) for sizes up to NPS 24, ensuring the flange fits within standardized fittings and equipment.

Bore Diameter (B):

The tolerance of the bore diameter ensures the flange does not restrict flow or create turbulence. Tolerances vary by size and class but could be in the range of -0 mm/+3 mm (-0 inch/+1/8 inch) for smaller flanges.

Facing Finish:

The surface finish of the flange face where the gasket seats is critical for ensuring a proper seal. ASME B16.5 specifies the surface finish in terms of Ra (Roughness Average), with specific values depending on the type of gasket and sealing surface.

It’s important to consult the latest edition of the ASME B16.5 standard or work with a qualified engineer to obtain the exact tolerance values for the specific slip-on flanges being used in a project. Adherence to these tolerances is critical for the safety, reliability, and efficiency of piping systems.

Slip-on Flange Weights

Slip-On Flange Weight in Kgs.

The table shows the ASME B16.5 slip-on flange weights in Kgs. by Flange NPS and Class (carbon/alloy steel materials; for higher grades, consider adjusting weight using the delta-specific weight carbon/other grades)

NPS	Class 150	Class 300	Class 400	Class 600	Class 900	Class 1500
1/2	0.5	0.9	0.9	0.9	2.7	2.7
3/4	0.9	1.4	1.4	1.4	2.7	2.7
1	0.9	1.4	1.6	1.8	3.4	3.6
1¼	1.4	2	2	2.3	4.5	4.5
1½	1.4	2.9	2.9	3.2	6.3	6.3
2	2.3	3.2	3.6	4.1	9.9	11.3
2½	3.6	4.5	5.4	5.9	13.9	16.2
3	4.1	5.9	6.8	7.2	16.2	21.6
3½	4	7.7	9.5	9.5
4	5.9	10.6	11.7	16.7	23.9	32.9
5	6.8	13	13.9	28.4	37.4	59.4
6	8.6	17.6	19.8	36	49.5	74.3
8	13.5	26.1	30.2	51.8	77.4	117
10	19.4	36.5	40	79.7	110.3	196.2
12	28.8	51.8	58.5	96.8	146.7	300.2
14	40.5	74.3	85	116.6	180	423
16	47.7	94.5	113.9	164.7	206.6	562.5
18	58.5	113.9	139.5	214.2	291.2	731.3
20	74.3	141.8	170.1	275.4	356.4	922.5
22	83.3	166.5	182.3	265.5
24	99	220.5	242.6	394.2	666	1271

Slip-On Flange Weight in LBS.

The table shows the ASME B16.5 slip-on flange weights in Lbs. by Flange NPS and Class (carbon/alloy steel materials; for higher grades, consider adjusting weight using the delta-specific weight carbon/other grades)

CLASS 150	Nominal Pipe Size	Slip On Weight in Lbs./unit
	½	1
	¾	2
	1	2
	1¼	3
	1½	3
	2	5
	2½	8
	3	9
	3½	11
	4	13
	5	15
	6	19
	8	30
	10	43
	12	64
	14	90
	16	106
	18	130
	20	165
	22	185
	24	220
CLASS 300	Nominal Pipe Size	Slip On Weight in Lbs./unit
	½	2
	¾	3
	1	3
	1¼	4.5
	1½	6.5
	2	7
	2½	10
	3	13
	3½	17
	4	23.5
	5	29
	6	39
	8	58
	10	81
	12	115
	14	165
	16	210
	18	253
	20	315
	22	370
	24	490
CLASS 400	Nominal Pipe Size	Slip On Weight in Lbs./unit
	½	2
	¾	3
	1	3.5
	1¼	4.5
	1½	6.5
	2	8
	2½	12
	3	15
	3½	21
	4	26
	5	31
	6	44
	8	67
	10	91
	12	130
	14	191
	16	253
	18	310
	20	378
	22	405
	24	539
CLASS 600	Nominal Pipe Size	Slip On Weight in Lbs./unit
	½	2
	¾	3
	1	4
	1¼	5
	1½	7
	2	9
	2½	13
	3	16
	3½	21
	4	37
	5	63
	6	80
	8	115
	10	177
	12	215
	14	259
	16	366
	18	476
	20	612
	22	590
	24	876
CLASS 900	Nominal Pipe Size	Slip On Weight in Lbs./unit
	½	6
	¾	6
	1	7.5
	1¼	10
	1½	14
	2	22
	2½	31
	3	36
	4	53
	5	83
	6	110
	8	172
	10	245
	12	326
	14	400
	16	459
	18	647
	20	792
	24	1480
CLASS 1500	Nominal Pipe Size	Slip On Weight in Lbs./unit
	½	6
	¾	6
	1	8
	1¼	10
	1½	14
	2	25
	2½	36
	3	48
	4	73
	5	132
	6	165
	8	260
	10	436
	12	667
	14	940
	16	1250
	18	1625
	20	2050
	24	2825