API 590 Specification

Description

API 590 Spectacle Blind Flange

API 590 is a standard issued by the American Petroleum Institute (API) that covers the requirements for steel line blanks used in piping systems. These line blanks, also known as spectacle blinds, paddle blinds, and spacer rings, are used to isolate sections of a pipeline for maintenance, inspection, or pressure testing.

Key Features of API 590:

• Specifies material requirements for steel line blanks.
• Covers dimensional standards for different types of blanks.
• Ensures pressure-temperature ratings comply with industry safety standards.
• Aligns with ASME B16.48, which is the primary standard for line blanks.

API 590 Dimensions

Class 150 Spectacle blind Dimensions

Size in Inch	Size in MM	Internal Dia.	Outer Dia.	Center to Center	Thick.	Web Width	Web Thick.	Hole Dia	Spec. Blind Weight in Kg	Paddle Blank Weight in kg	Paddle Spacer Blank Weight in kg
1/2	15	16	45	60	3	38	2	15.875	0.07	0.03	0.03
3/4	20	21	54	70	3	38	2	15.875	0.1	0.05	0.04
1	25	27	64	80	3	38	2	15.875	0.14	0.07	0.06
1 1/4	32	42	73	90	6.4	38	4	15.875	0.35	0.21	0.14
1 1/2	40	48	83	100	6.4	38	4	15.875	0.46	0.27	0.18
2	50	61	102	120	6.4	51	4	19.05	0.68	0.41	0.26
2 1/2	65	73	107	140	6.4	51	4	19.05	0.7	0.46	0.24
3	80	89	133	150	6.4	64	4	19.05	1.1	0.71	0.39
3 1/2	90	102	159	175	9.7	64	5	19.05	2.44	1.54	0.9
4	100	114	172	190	9.7	64	5	19.05	2.81	1.8	1.01
5	130	141	194	215	9.7	76	5	22.225	3.37	2.29	1.08
6	150	168	219	240	12.7	76	7	22.225	5.39	3.82	1.57
8	200	219	276	300	12.7	76	10	22.225	8.32	6.07	2.25
10	250	273	337	360	15.7	102	12	25.4	15.04	11.19	3.84
12	300	324	406	430	19.1	102	15	25.4	26.95	19.77	7.18
14	350	356	448	475	19.1	108	15	28.575	32.94	24.07	8.87
16	400	406	511	540	22.4	108	17	28.575	50.27	36.73	13.54
18	450	457	546	580	25.4	114	20	31.75	61.79	47.55	14.23
20	500	508	603	635	28.4	121	22	31.75	83.67	64.85	18.82
24	600	610	714	750	31.8	140	24	34.925	129.3	101.8	27.49

Class 300 Spectacle blind Dimensions

Size in Inch	Size in MM	Internal Dia.	Outer Dia.	Center to Center	Thick.	Web Width	Web Thick.	Hole Dia	Spec. Blind Weight in Kg	Paddle Blank Weight in kg	Paddle Spacer Blank Weight in kg
1/2	15	16	51	65	6.4	38	4	15.875	0.19	0.1	0.09
3/4	20	21	64	80	6.4	38	4	19.05	0.31	0.16	0.14
1	25	27	70	90	6.4	38	4	19.05	0.36	0.19	0.16
1 1/4	32	42	79	100	6.4	38	4	19.05	0.43	0.25	0.17
1 1/2	40	48	92	115	6.4	38	4	22.225	0.58	0.34	0.24
2	50	61	108	125	9.7	51	5	19.05	1.19	0.71	0.48
2 1/2	65	73	127	150	9.7	51	5	22.225	1.64	0.98	0.65
3	80	89	146	170	9.7	64	5	22.225	2.11	1.29	0.81
3 1/2	90	102	162	185	12.7	64	7	22.225	3.35	2.09	1.26
4	100	114	178	200	12.7	64	7	22.225	4.01	2.52	1.49
5	130	141	213	235	15.7	76	8	22.225	6.98	4.47	2.51
6	150	168	248	270	15.7	76	8	22.225	9.34	6.06	3.28
8	200	219	305	330	22.4	76	17	25.4	19.42	13.08	6.33
10	250	273	359	385	25.4	102	20	28.575	29.22	20.55	8.66
12	300	324	419	450	28.4	102	22	31.75	43.9	31.31	12.58
14	350	356	483	515	31.8	108	24	31.75	67.86	46.58	21.27
16	400	406	536	570	38.1	108	29	34.925	98.04	68.74	29.3
18	450	457	594	630	41.1	114	31	34.925	128.23	91.06	37.16
20	500	508	651	685	44.5	121	34	34.925	164.75	118.43	46.31
24	600	610	772	810	50.8	140	39	41.275	261.55	190.13	71.42

Class 600 Spectacle blind Flange Dimensions

Size in Inch	Size in MM	Internal Dia.	Outer Dia.	Center to Center	Thick.	Web Width	Web Thick.	Hole Dia	Spec. Blind Weight in Kg	Paddle Blank Weight in kg	Paddle Spacer Blank Weight in kg
1/2	15	16	51	65	6.4	38	4	15.875	0.19	0.1	0.09
3/4	20	21	64	80	6.4	38	4	19.05	0.31	0.16	0.14
1	25	27	70	90	6.4	57	4	19.05	0.36	0.19	0.16
1 1/4	32	37	79	100	9.7	57	5	19.05	0.67	0.38	0.29
1 1/2	40	43	92	115	9.7	67	5	22.225	0.91	0.51	0.4
2	50	55	108	125	9.7	57	5	19.05	1.23	0.71	0.52
2 1/2	65	67	127	150	12.7	67	7	22.225	2.21	1.28	0.92
3	80	83	146	170	12.7	67	7	22.225	2.85	1.7	1.15
3 1/2	90	96	159	185	15.7	76	8	25.4	4.07	2.49	1.58
4	100	108	191	215	15.7	76	8	25.4	6.04	3.59	2.44
5	130	135	238	265	19.1	86	10	28.575	11.4	6.79	4.6
6	150	162	264	290	22.4	86	12	28.575	15.91	9.8	6.11
8	200	212	318	350	28.4	95	22	31.75	28.05	18.03	10.01
10	250	265	397	430	35.1	105	27	34.925	54	34.74	19.26
12	300	315	454	490	41.1	105	31	34.925	80.78	53.2	27.58
14	350	346	489	525	44.5	114	34	38.1	100.19	66.82	33.36
16	400	397	562	605	50.8	124	39	41.275	151.24	100.76	50.48
18	450	448	610	655	53.8	133	41	44.45	183.62	125.71	57.9
20	500	497	679	725	63.5	133	48	44.45	269.2	183.85	85.35
24	600	597	787	840	73.2	152	55	50.8	405.6	284.72	120.88

Class 900 Spectacle blind Flange Dimensions

Size in Inch	Size in MM	Internal Dia.	Outer Dia.	Center to Center	Thick.	Web Width	Web Thick.	Hole Dia	Spec. Blind Weight in Kg	Paddle Blank Weight in kg	Paddle Spacer Blank Weight in kg
1/2	15	16	60	80	6.4	38	4	22.225	0.27	0.14	0.13
3/4	20	21	67	90	6.4	41	4	22.225	0.34	0.18	0.16
1	25	27	76	100	6.4	57	4	25.4	0.43	0.23	0.2
1 1/4	32	37	86	110	9.7	57	5	25.4	0.81	0.45	0.36
1 1/2	40	43	95	125	9.7	67	5	28.575	0.98	0.54	0.43
2	50	55	140	165	12.7	57	7	25.4	2.88	1.56	1.32
2 1/2	65	67	162	190	12.7	67	7	28.575	3.82	2.09	1.73
3	80	83	165	190	15.7	67	8	25.4	4.68	2.68	2
4	100	108	203	235	19.1	76	10	31.75	8.48	4.94	3.54
5	130	135	244	280	22.4	86	12	34.925	14.18	8.37	5.81
6	150	162	286	320	25.4	86	13	31.75	21.9	13.04	8.86
8	200	212	356	395	35.1	95	27	38.1	45.96	27.93	18.02
10	250	265	432	470	41.1	105	31	38.1	78.21	48.16	30.04
12	300	315	495	535	47.8	105	36	38.1	117.31	73.55	43.76
14	350	346	518	560	53.8	114	41	41.275	140.86	90.65	50.2
16	400	397	572	615	60.5	124	46	44.45	188.73	124.31	64.42
18	450	448	635	685	66.5	133	50	50.8	252.97	168.39	84.57
20	500	497	696	750	73.2	133	55	53.975	331.81	222.68	109.13
24	600	597	835	900	88.9	152	67	66.675	579.52	389.25	190.27

Class 1500 Spectacle blind Flange Dimensions

Size in Inch	Size in MM	Internal Dia.	Outer Dia.	Center to Center	Thick.	Web Width	Web Thick.	Hole Dia	Spec. Blind Weight in Kg	Paddle Blank Weight in kg	Paddle Spacer Blank Weight in kg
1/2	15	16	61	80	6.4	38	4	22.225	0.28	0.14	0.13
3/4	20	21	67	90	9.7	41	5	22.225	0.52	0.27	0.24
1	25	27	76	100	9.7	64	5	25.4	0.65	0.35	0.3
1 1/4	32	35	86	110	9.7	64	5	25.4	0.82	0.45	0.37
1 1/2	40	41	95	125	12.7	70	7	28.575	1.3	0.71	0.58
2	50	53	140	165	12.7	70	7	25.4	2.9	1.56	1.33
2 1/2	65	63	162	190	15.7	76	8	28.575	4.78	2.58	2.19
3	80	78	172	205	19.1	76	10	31.75	6.36	3.54	2.81
4	100	102	206	240	22.4	89	12	34.925	10.47	5.96	4.5
5	130	128	251	290	28.4	89	15	41.275	19.55	11.23	8.31
6	150	154	279	320	35.1	89	18	38.1	29.08	17.15	11.93
8	200	203	349	395	41.1	102	31	44.45	52.23	31.43	20.8
10	250	255	432	480	50.8	114	39	50.8	98.33	59.53	38.79
12	300	303	518	570	60.5	114	46	53.975	169.01	101.94	67.06
14	350	333	575	635	66.5	127	50	60.325	229.84	138.07	91.76
16	400	381	638	705	76.2	133	58	66.675	320.1	194.78	125.32
18	450	429	702	775	85.9	146	65	73.025	432.4	265.84	166.56
20	500	478	752	830	95.3	152	72	79.375	540.14	338.44	201.7
24	600	575	899	990	111.3	178	84	92.075	898.71	564.9	333.8

Class 2500 Spectacle blind Flange Dimensions

Size in Inch	Size in MM	Internal Dia.	Outer Dia.	Center to Center	Thick.	Web Width	Web Thick.	Hole Dia	Spec. Blind Weight in Kg	Paddle Blank Weight in kg	Paddle Spacer Blank Weight in kg
1/2	15	16	67	90	9.7	38	5	22.225	0.53	0.27	0.25
3/4	20	21	73	95	9.7	41	5	22.225	0.62	0.32	0.29
1	25	27	83	110	9.7	64	5	25.4	0.79	0.41	0.37
1 1/4	32	35	102	130	12.7	64	7	28.575	1.56	0.82	0.73
1 1/2	40	41	114	145	15.7	70	8	31.75	2.39	1.28	1.11
2	50	53	143	170	15.7	70	8	28.575	3.75	2.01	1.73
2 1/2	65	63	165	195	19.1	76	10	31.75	6.05	3.26	2.78
3	80	78	194	230	22.4	76	12	34.925	9.73	5.29	4.43
4	100	102	232	275	28.4	89	22	41.275	17.34	9.59	7.74
5	130	128	276	325	35.1	89	27	47.625	29.97	16.79	13.17
6	150	154	314	370	41.1	89	31	53.975	44.77	25.44	19.32
8	200	198	384	440	53.8	102	41	53.975	86.39	49.82	36.57
10	250	248	473	540	66.5	114	50	66.675	161.18	93.43	67.74
12	300	289	546	620	79.2	114	60	73.025	255.01	148.27	106.73

API 590 Grades

• Carbon Steel Grades:

  • ASTM A105 – Standard forged carbon steel for high-temperature service.
  • ASTM A516 Gr. 70 – Carbon steel plate used for moderate- to high-temperature service.
  • ASTM A350 LF2 – Low-temperature carbon steel for cryogenic applications.

• Stainless Steel Grades:

  • ASTM A182 F304/F304L – Austenitic stainless steel for general corrosion resistance.
  • ASTM A182 F316/F316L – Improved corrosion resistance, especially for chloride environments.

• Alloy Steel Grades:

  • ASTM A182 F11, F22 – Chrome-molybdenum alloy steel for high-temperature applications.
  • ASTM A182 F5, F9 – Used in high-pressure and high-temperature services.

• Nickel Alloys & Special Materials (For Highly Corrosive Environments):

  • Inconel 625, Inconel 825 – High corrosion resistance in extreme environments.
  • Monel 400 – Excellent resistance to seawater and acids.
  • Hastelloy C276 – Superior corrosion resistance in aggressive chemical environments.

Application

• Oil & Gas Industry
• Petrochemical & Chemical Plants
• Power Plants (Thermal & Nuclear)
• Water Treatment & Desalination Plants
• Pharmaceutical & Food Processing Industries
• LNG & Cryogenic Applications