Orifice Flange Dimensions - Class 300 to Class 2500

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Orifice flange dimensions are covered in ASME B16.36. Orifice flanges are available from Class #300 to Class #2500. Class #300 flanges are available in threaded, slip-on, and weld neck end types. Whereas, Class# 600 and above flanges are available in only weld neck type end connection.

During an inspection of orifice flange, you should check for

Outer & Inner Diameter of body
Bolt Circle & Bolt hole Diameter
Thickness of weld end
Length of the Hub
Straightness and alignment of the bolt hole
Tap holes dimensions

Class 300 Orifice Flange Dimensions (Weld Neck Raised Face)

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	Hub OD	Weld Neck OD	Welding Neck Length	RF Dia.	RF Height	PCD	Orifice Hole dia	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E	F	G	H	I
1	25	125	36.6	54	33.4	81	50.8	2	88.9	6.4	4	5/8	125	3/4	M16	4.5
1 1/2	40	155	36.6	70	48.3	84	73	2	114.3	6.4	4	3/4	135	7/8	M20	6.5
2	50	165	36.6	84	60.3	84	92.1	2	127	6.4	8	5/8	125	3/4	M16	7
2 1/2	65	190	36.6	100	73	87	104.8	2	149.2	6.4	8	3/4	135	7/8	M20	7.5
3	80	210	36.6	117	88.9	87	127	2	168.3	9.5	8	3/4	135	7/8	M20	9.4
4	100	255	36.6	146	114.3	90	157.2	2	200	12.7	8	3/4	135	7/8	M20	13.2
6	150	320	36.6	206	168.3	98	215.9	2	269.9	12.7	12	3/4	135	7/8	M20	14.6
8	200	380	39.7	260	219.1	110	269.9	2	330.2	12.7	12	7/8	145	1	M24	30
10	250	445	46.1	321	273	116	323.8	2	387.3	12.7	16	1	165	1 1/8	M27	41
12	300	520	49.3	375	323.8	129	381	2	450.8	12.7	16	1 1/8	180	1 1/4	M30	62
14	350	585	52.4	425	355.6	141	412.8	2	514.4	12.7	20	1 1/8	185	1 1/4	M30	84
16	400	650	55.6	483	406.4	144	469.9	2	571.5	12.7	20	1 1/4	195	1 3/8	M33	111
18	450	710	58.8	533	457	157	533.4	2	628.6	12.7	24	1 1/4	205	1 3/8	M33	138
20	500	775	62	587	508	160	584.2	2	685.8	12.7	24	1 1/4	215	1 3/8	M33	171
24	600	915	68.3	702	610	167	692.2	2	812.8	12.7	24	1 1/2	240	1 5/8	M39	247

Class 600 Orifice Flange Dimensions (Weld Neck Raised Face)

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	Hub OD	Weld Neck OD	Welding Neck Length	RF Dia.	RF Height	PCD	Orifice Hole dia	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E	F	G	H	I
1	25	125	36.6	54	33.5	81	50.8	7	88.9	6.4	4	5/8	125	3/4	M16	5.5
1 1/2	40	155	36.6	70	48.3	84	73	7	114.3	6.4	4	3/4	135	7/8	M20	7.8
2	50	165	36.6	84	60.3	84	92.1	7	127	6.4	8	5/8	125	3/4	M16	8.3
2 1/2	65	190	36.6	100	73	87	104.8	7	149.2	6.4	8	3/4	135	7/8	M20	10.8
3	80	210	36.6	117	88.9	87	127	7	168.3	9.5	8	3/4	135	7/8	M20	12.6
4	100	275	38.1	152	114.3	102	157.2	7	215.9	12.7	8	7/8	150	1	M24	19
6	150	355	47.7	222	168.3	117	215.9	7	292.1	12.7	12	1	180	1 1/8	M27	37
8	200	420	55.6	273	219.1	133	269.9	7	349.2	12.7	12	1 1/8	195	1 1/4	M30	53
10	250	510	63.5	343	273	152	323.8	7	431.8	12.7	16	1 1/4	220	1 3/8	M33	86
12	300	560	66.7	400	323.8	156	381	7	489	12.7	20	1 1/4	230	1 3/8	M33	102
14	350	605	69.9	432	355.6	165	412.8	7	527	12.7	20	1 3/8	240	1 1/2	M36	150
16	400	685	76.2	495	406.4	178	469.9	7	603.2	12.7	20	1 1/2	260	1 5/8	M39	190
18	450	745	82.6	546	457.2	184	533.4	7	654	12.7	20	1 5/8	280	1 3/4	M42	240
20	500	815	88.9	610	508	190	584.2	7	723.9	12.7	24	1 5/8	300	1 3/4	M42	295
24	600	940	101.6	718	609.6	203	692.2	7	838.2	12.7	24	1 7/8	335	2	M48	365

Class 900 Orifice Flange Dimensions (Weld Neck Raised Face)

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	Hub OD	Weld Neck OD	Welding Neck Length	RF Dia.	RF Height	PCD	Orifice Hole dia	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E	F	G	H	I
1	25	150	38.1	52	33.5	83	50.8	7	101.6	6.4	4	7/8	150	1	M24	5.4
1 1/2	40	180	38.1	70	48.3	89	73	7	123.8	6.4	4	1	160	1 1/8	M27	7.8
2	50	215	38.1	105	60.3	102	92.1	7	165.1	6.4	8	7/8	150	1	M30	11.5
2 1/2	65	245	41.3	124	73	105	104.8	7	190.5	6.4	8	1	165	1 1/8	M27	15.8
3	80	240	38.1	127	88.9	102	127	7	190.5	9.5	8	7/8	150	1	M24	22
4	100	290	44.5	159	114.3	114	157.2	7	235	12.7	8	1 1/8	180	1 1/4	M30	22
6	150	380	55.6	235	168.3	140	215.9	7	317.5	12.7	12	1 1/8	195	1 1/4	M30	70
8	200	470	63.5	298	219.1	162	269.9	7	393.7	12.7	12	1 3/8	230	1 1/2	M36	119
10	250	545	69.9	368	273	184	323.8	7	469.9	12.7	16	1 3/8	240	1 1/2	M36	204
12	300	610	79.4	419	323.8	200	381	7	533.4	12.7	20	1 3/8	260	1 1/2	M36	303
14	350	640	85.8	451	355.6	213	412.8	7	558.8	12.7	20	1 1/2	280	1 5/8	M39	400
16	400	705	88.9	508	406.4	216	469.9	7	616	12.7	20	1 5/8	290	1 3/4	M42	510
18	450	785	101.9	565	457.2	229	533.4	7	685.8	12.7	20	1 7/8	330	2	M48	738
20	500	855	108	622	508	248	584.2	7	749.3	12.7	20	2	355	2 1/8	M52	932
24	600	1040	139.7	749	609.6	292	692.2	7	901.7	12.7	20	2 1/2	445	2 5/8	M64	1511

Class 1500 Orifice Flange Dimensions (Weld Neck Raised Face)

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	Hub OD	Weld Neck OD	Welding Neck Length	RF Dia.	RF Height	PCD	Orifice Hole dia	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E	F	G	H	I
1	25	150	38.1	52	33.5	83	50.8	7	101.6	6.4	4	7/8	150	1	M24	5.4
1 1/2	40	180	38.1	70	48.3	89	73	7	123.8	6.4	4	1	160	1 1/8	M27	7.8
2	50	215	38.1	105	60.3	102	92.1	7	165.1	6.4	8	7/8	150	1	M24	11.5
2 1/2	65	245	41.3	124	73	105	104.8	7	190.5	6.4	8	1	165	1 1/8	M27	15.8
3	80	265	47.7	133	88.9	117	127	7	203.2	9.5	8	1 1/8	185	1 1/4	M30	22
4	100	310	54	162	114.3	124	157.2	7	241.3	12.7	8	1 1/4	205	1 3/8	M33	22
6	150	395	82.6	229	168.3	171	215.9	7	317.5	12.7	12	1 3/8	265	1 1/2	M36	70
8	200	485	92.1	292	219.1	213	269.9	7	393.7	12.7	12	1 5/8	300	1 3/4	M42	119
10	250	585	108	368	273	254	323.8	7	482.6	12.7	12	1 7/8	345	1	M48	204
12	300	675	123.9	451	323.8	283	381	7	571.5	12.7	16	2	380	2 1/8	M52	303
14	350	750	133.4	495	355.6	298	412.8	7	635	12.7	16	2 1/4	415	2 3/8	M56	400
16	400	825	146.1	552	406.4	311	469.9	7	704.8	12.7	16	2 1/2	450	2 5/8	M64	510
18	450	915	162	597	457.2	327	533.4	7	774.7	12.7	16	2 3/4	500	2 7/8	M72	738
20	500	985	177.8	641	508	356	584.2	7	831.8	12.7	16	3	545	3 1/8	M76	932
24	600	1170	203.2	762	609.6	406	692.2	7	990.6	12.7	16	3 1/2	620	3 5/8	M90	1511

Class 2500 Orifice Flange Dimensions (Weld Neck Raised Face)

Size in Inch	Size in mm	Outer Dia.	Flange Thick.	Hub OD	Weld Neck OD	Welding Neck Length	RF Dia.	RF Height	PCD	Orifice Hole dia	No of Bolts	Bolt Size UNC	RF Stud Length	Hole Size	ISO Stud Size	Weight in kg
		A	B	C	D	E	F	G	H	I
1	25	160	38.1	57	33.5	92	50.8	7	108	6.4	4	7/8	150	1	M24	6.5
1 1/2	40	205	44.5	79	48.3	111	73	7	146	6.4	4	1 1/8	180	1 1/4	M30	13
2	50	235	50.8	95	60.3	127	92.1	7	171.4	6.4	8	1	185	1 1/8	M27	19
2 1/2	65	265	57.2	114	73	143	104.8	7	196.8	6.4	8	1 1/8	205	1 1/4	M30	24
3	80	305	66.7	133	88.9	168	127	7	228.6	9.5	8	1 1/4	230	1 3/8	M33	43
4	100	355	76.2	165	114.3	190	157.2	7	273	12.7	8	1 1/2	260	1 5/8	M39	66
6	150	485	108	235	168.3	273	215.9	7	368.3	12.7	8	2	350	2 1/8	M52	172
8	200	550	127	305	219.1	318	269.9	7	438.2	12.7	12	2	385	2 1/8	M52	261
10	250	675	165.1	375	273	419	323.8	7	539.8	12.7	12	2 1/2	490	2 5/8	M64	485
12	300	760	184.2	441	323.8	464	381	7	619.1	12.7	12	2 3/4	540	2 7/8	M72	730

Disclaimer – Please check with ASME B16.36 Before using.