Blind Flange

Blind flange, also known as flange blind or blind flange, is a type of flange connection without a hole in the middle, mainly used for sealing pipeline ends or isolating systems.

Definition and Structure

Basic features: Blind flange is a solid circular metal sheet without a central hole, fixed to the flange surface of the pipeline by bolts, forming a sealed isolation.

Function and purpose

Sealing and isolation: used to permanently or temporarily seal the end of a pipeline, or to isolate fluids during maintenance to ensure safe operation.

Compared to other components: Similar in function to the head and pipe cap, but the blind flange is detachable and has higher flexibility.

Special type: such as an 8-shaped blind plate, with one end as a blind plate and the other end as a throttling ring, making it easy to switch between isolation and normal operation.

Material and sealing form

Common materials: carbon steel (such as Q235), stainless steel, alloy steel, plastic (PVC/PPR), etc., choose according to the medium and pressure.

Sealing surface design: including flat (FF), convex (RF), concave convex (MFM), mortise and tenon (TG), etc., to meet different sealing requirements.

Application scenarios

Maintenance and safety: Isolate the system during equipment maintenance and pipeline strength testing to prevent medium leakage.

System expansion: Provide temporary closure for reserved interfaces for future pipelines.

Multiple series devices: Blind plates are installed at the bifurcation of the boundary pipeline to achieve independent control.

Specification:

Sizes:1/2”-120”;DN15-DN3000

Materials: Carbon steel flange (CS) : ASTM A105, ASTM A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2, ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70;

Stainless steel flange (SS) : ASTM A182 F304, 304L, F316, 316L, 1Cr18Ni9Ti, 0Cr18Ni9Ti, 321, 18-8;

Alloy flange (AS) : ASTM A182F1, F5a, F9, F11, F12, F22, F91, A182F12, A182F11, 16MnR, Cr5Mo, 12Cr1MoV, 15CrMo, 12Cr2Mo1, A335P22, ST45.8;

Standards:

ASME B16.5; HG20592; DIN2527、2573、2627-2638、2673、2552、2653、2655、2656、2641、2642、2565-2569; GOST12820; JIS B2220

Application:

Water treatment; Power plant accessories; Chemical engineering; Shipbuilding; Nuclear energy; Garbage disposal; natural gas; petroleum

Nominal Sze DN	NPS	150LB	300LB	600LB	900LB	1500LB	2500LB	Nominal Size DN	0.6MPa	1.0MPa	1.6MPa	2.5MPa	4.0MPa
Nominal Sze DN	NPS	2.0MPa	5.0MPa	10.0MPa	15.0MPa	25.0MPa	42.0MPa
15	1/2	3	6	6	6	6	10
20	3/4	3	6	6	6	0	10	15	8	8	8	8	8
25	1	3	6	6	6	10	10	20	8	8	8	8	8
32	1.1/4	6	6	10	10	10	13	25	8	8	8	8	9/8
40	1.1/2	6	6	10	10	13	16	32	8	8	8	8	10/8
50	2	6	10	10	13	13	16	40	8	8	8	9/8	10/8
65	2.1/2	6	10	13	13	16	19	50	8	8	9/8	10/8	12/10
80	3	6	10	13	16	19	22	65	8	8	10/8	11/9	13/11
90	3.1/2	10	13	16				80	8	8	10/8	12/10	14/12
100	4	10	13	16	19	22	28	100	10/8	8	12/10	14/12	16/14
125	5	10	16	19	22	28	35	125	11/9	9/8	13/11	16/14	19/17
150	6	13	16	22	25	35	41	150	12/10	10/8	15/13	17/15	21/19
200	8	13	22	28	35	41	54	200	14/12	12/10	17/15	21/19	27/25
250	10	16	25	35	41	51	67	250	17/15	13/11	20/18	25/23	32/30
300	12	19	28	41	48	60	79	300	19/17	15/13	23/21	29/27	37/35
350	14	19	32	44	54	67		350	21/19	17/15	26/24	33/31	42/40
400	16	22	38	51	60	76		400	23/21	18/16	29/27	36/34	48/46
450	18	25	41	54	67	86		450	25/23	20/18	32/30	39/37	50/48
500	20	28	44	64	73	95		500	28/26	22/20	35/33	43/41	54/52
600	24	32	51	73	89	111		600	32/30	25/23	41/39	51/49	65/62

explain:								explain:
	1. This series of products complies with API590 requirements and is used for raised face flanges that meet the following requirements: ANSIB16.5, SH3406, SO7005-1, GB9112-9124, HG20615 (American system).							1. This series of products meets the requirements of HG21547-93 and is used for protruding flanges that meet the following requirements: GB9113-9122, HG20592 (European system), ISO7005-1, DIN, JB pipe flanges.
	2. The thickness of blind plates, insert rings, and eight shaped blind plates all include corrosion allowance: the allowance for carbon steel, low-alloy steel, and low-temperature steel is 13mm; Stainless steel allowance is 0mm							2. The thickness of blind plates, insert rings, and eight shaped blind plates all include corrosion allowance: carbon steel, low-alloy steel, and low-temperature steel allowance of 2.0mm; The stainless steel allowance is 0mm. The above table contains numerator/denominator, where the numerator represents the thickness of carbon steel and low-alloy steel, and the denominator represents the thickness of stainless steel.
	3. This series of products is suitable for flat gaskets. If used for other types of gaskets (such as octagonal gaskets, etc.), the manufacturer should be consulted and the thickness adjusted.							3. This series of products is suitable for flat gaskets. If used for other types of gaskets (such as octagonal gaskets, etc.), the manufacturer should be consulted and the thickness adjusted.
	4. It can also be produced according to the requirements of HG21547-93.