GOST 12821 Flanges | Weld Neck | Russian Standard

GOST 12821 flanges are steel weld neck (butt-welded) flanges made to the Russian state engineering standard GOST 12821-80, now modernized under the unified GOST 33259 specification. They serve mainly the markets of Russia and the Commonwealth of Independent States, and you can spot them by their long, tapered hub, or neck. That hub does real work. It carries stress smoothly from the pipe to the flange face, which cuts the stress concentration at the base of the joint. The hub end is chamfered to match the wall thickness and bore of the mating pipe, so the connection goes together with a single full-penetration circumferential butt weld. That solid integration gives the joint strong fatigue resistance under hard service. PM Industries manufactures, supplies, and stocks these flanges in a full range of sizes, classes, and grades.

The design lets GOST 12821 flanges take real pressure swings and thermal cycles. Ratings run from PN 0.6 MPa up to PN 20.0 MPa, which lines up with roughly PN 6 through PN 250 in European EN terms, across a size envelope from DN 10 to DN 2000. We forge them to suit the service: carbon steel like St20 for general work, low-alloy 09G2S for low-temperature arctic operation, and stabilized austenitic stainless such as 12X18H10T where chemical resistance is the priority. That material range guards against brittle fracture, absorbs sudden hydraulic shock, and keeps the joint from deforming under load.

Because they seal tight in high-stress piping, GOST 12821 weld neck flanges show up across heavy industry. You will find them on long-distance oil and gas transmission lines, municipal district heating loops, and thermal and nuclear power facilities. Their resistance to pitting and stress-corrosion cracking also makes them a sound pick for chemical processing, offshore rigs, and water distribution.

PM Industries holds GOST 12821 flanges in stock with face options including flat face, raised face, male-and-female, and ring-type joint (RTJ). Every flange ships with certification and test documentation to match your project spec. Tell us your DN size, PN rating, face type, and grade, and we will quote it.

Specification GOST 12821 Flanges

Standards	ANSI/ASME B16.5, B16.48, ANSI Flanges, GOST Flanges, DIN Flanges, EN-1092, B16.47 Series A & B, ASME Flanges, EN Flanges, AWWA Flanges, BS Flanges.
JIS Standard	5K, 10 K, 16 K 20 K, 30 K, 40 K, 63 K
DIN FLANGES	DIN 2527, 2627, 2631, 2656, 2576, 2673, 2629, 2628, 2566, 2641, 2637, 2655, 2634, 2636, 2632, 2633, 2638, 2642, 2573, 2635.
Pressure Rating	Class 150 LBS, 300 LBS, 600 LBS, 900 LBS, 1500 LBS, 2500 LBS
Types	Threaded, Plate, Screwed, Forged.
Supporting material	Gasket, Ring Joint, Flange Bolts
Size range	1/2" (15 NB) to 48" (1200NB) DN10~DN5000
Production technique	Forged, machined and Heat treated
Available Flange Type	Weld Neck Flanges, RTJ Flanges, Slip On Flanges, Spectacle Blind Flanges, Flanges Gaskets, Square Flanges, Standard Insert Flanges, High Hub Blinds Flanges, Flat Flanges, forged flanges, Weldo / Nipo Flanges, Jacket Insert Flanges, Tongue groove Flanges, Blind Flanges, Socket Weld Flanges, Large diameter Flanges, Long Weld Neck Flanges, Spacer Blinds, SWRF Flanges, SORF Flanges, Angle Face Rings Flanges, Spades Ring Spacers Flanges, WNRF Flanges, Screwed Flanges, Insert Flanges, flanges bolts, cf flange, Lap Joint Flanges, ASME B16.36 Orifice Flanges, Plate Flange, Expander Flanges, Ring Type Joint Flanges, Loose Flanges, Reducing Flanges, puddle flange, Threaded Flanges, blank flange, vacuum flange.
Connect Type/ Flange Face Type	Ring Type Joint (RTJ), Flat Face (FF), Tongue & Groove, Small Male-Female (SMF), Lap-Joint Face (LJF), Raised Face (RF), Large Male-Female (LMF), Small Tongue.
Custom design	As per your drawing
Test	Direct-reading Spectrograph, X-ray detector, UItrasonic flaw detector, Magnetic particle detector, Hydrostatic testing machine.
Origin	Indian / USA / Korean / West Europe / Japan
Pressure Class	PN 6 TO PN 100
Thickness	Normal Pipe Size ≤ 18
Bore Diameter	Normal Pipe ≤ 10
High Temperature	Above 200°C (400°F) For Class 150 Or Above 400°C (750°F)
Low Temperature	Above -29 Degree C (−20°F)
Coating/Surface Treatment:	Zinc Plated, Anti-rust Paint, Oil Black Paint, Yellow Transparent, Cold and Hot Dip Galvanized.
European/African/Russian Standard Flanges	Available
Gaskets Types	Full Face, Metallic Ring, Flat Ring Gasket
Marking Standard	Name of Manufacturer
	Schedule
	Type of Flange Facing
	Pressure Class
	Nominal Pipe Size, etc
Test Certificates	EN 10204/3.1B, NACE MR0103, NACE MR0175
	Raw Materials Certificate
	100% Radiography Test Report
	Third Party Inspection Report, etc

Flange Type Available

GOST 12821 80 flange Pressure rating

ASME/ANSI B 16.5	Lap Joint Flange, Ring Type Joint Flange, Threaded Flange, Blind Flange, High Hub Blind Flange, Socket Weld Flange, Slip on Flange, Welding Neck Flange.
PRESSURE CLASS	150, 300, 400, 600, 900, 1500, 2500
ASME/ANSI B 16.47	Blind Flange [Series A & B], Welding Neck Flange.
PRESSURE CLASS	75, 150, 300, 400, 600, 900
ASME/ANSI B 16.36	Slip on Flange, Threaded Flange, Welding Neck Flange.
PRESSURE CLASS	300, 400, 600, 900, 1500, 2500
BS 4504 SEC 3.1	Plate Flange, Welding Neck Flange, Hubbed Slip on Flange, Lapped Pipe End Flange, Loose Plate With Weld Neck Flange, Hubbed Threaded Flange, Blank Flange, Loose Plate Flange.
PRESSURE CLASS	PN 2.5 TO PN 40
BS 4504[PART 1]	Blank Flange, Loose Plate With Weld On Plate Collar, Welding Neck Flange, Plate Flange, Hubbed Slip-On Hubbed Threaded.
PRESSURE CLASS	PN 2.5 TO PN 400
BS 1560 BOSS	Blind Flange, Screwed Boss Flange, Welding Neck Flange,Slip-On Flange, Lapped Flange, Socket Welding Flange.
PRESSURE CLASS	150, 300, 400, 600, 900, 1500, 2500
BS10	Screwed Boss Flange, Plate Slip-On Flange, Slip-On Boss Flange, Blind Flange, Welding Neck Flange.
TABLE	D, E, F, H
DIN FLANGES	DIN 2527, 2632, 2635, 2673, 2566, 2655, 2631, 2627, 2634, 2576, 2636, 2629, 2633, 2573, 2656, 2638, 2637, 2642, 2641, 2628
PRESSURE CLASS	PN 6 TO PN 100

GOST 12821 Stainless Steel Flanges Weight Chart

Standard	Class	Diameter	Bolt Circle Diameter	Number of Bolts	Bolt Size	Diameter of Bolt Hole
AS4087 Flanges	PN14 Flanges	95	67	4	M12	14
AS 2129 Flange	Table C Flanges	95	67	4	13	14
	Table D Flanges	95	67	4	13	14
	Table E Flanges	95	67	4	13	14
	Table F Flanges	95	67	4	13	14
	Table H Flanges	114	83	4	16	17
	Table J Flanges	114	83	4	16	17
ANSI B16.5 Flanges	ANSI 150 Flanges	89	60	4	13	16
	ANSI 300 Flanges	95	67	4	13	16
	ANSI 600 Flanges	95	67	4	13	16
	ANSI 900 Flanges	121	83	4	19	22
	ANSI 1500 Flanges	121	83	4	19	22
ISO 7005 (DIN) Flange	PN6 Flanges	80	55	4	M10	11
	PN10 Flanges	95	65	4	M12	14
	PN16 Flanges	95	65	4	M12	14
	PN20 Flanges	90	60.5	4	M14	16
	PN25 Flanges	95	65	4	M12	14
	PN40 Flanges	95	65	4	M12	14

GOST 12821 Stainless Steel Flanges Weight Chart

Standard	Class	Diameter	Bolt Circle Diameter	Number of Bolts	Bolt Size	Diameter of Bolt Hole
AS4087 Flanges	PN14	95	67	4	M12	14
AS 2129 Flange	Table C	95	67	4	13	14
	Table D	95	67	4	13	14
	Table E	95	67	4	13	14
	Table F	95	67	4	13	14
	Table H	114	83	4	16	17
	Table J	114	83	4	16	17
ANSI B16.5 Flanges	ANSI 150	89	60	4	13	16
	ANSI 300	95	67	4	13	16
	ANSI 600	95	67	4	13	16
	ANSI 900	121	83	4	19	22
	ANSI 1500	121	83	4	19	22
ISO 7005 (DIN) Flange	PN6	80	55	4	M10	11
	PN10	95	65	4	M12	14
	PN16	95	65	4	M12	14
	PN20	90	60.5	4	M14	16
	PN25	95	65	4	M12	14
	PN40	95	65	4	M12	14

Gost 12821 Flanges Dimension Table

Conditional passage Dy	Py  1.0 MPa (10 kgf/cm2)
	d n	d in	b	Mass, kg
				with a connecting projection	with a ledge	with a depression
10	14	15	10	0,46	0,46	0,44
15	18	19		0,51	0,51	0,49
20	25	26	12	0,74	0,75	0,71
25	32	33		0,89	0,89	0,84
32	38	39	14	1,40	1,39	1,34
40	45	46	15	1,71	1,72	1,67
50	57	59		2,06	2,03	1,99
65	76	78	17	2,80	2,77	2,69
80	89	91		3,19	3,13	3,08
100	108 (A)	110	19	3,96	3,94	3,76
	114 (B)	116		3,81	3,76	3,61
125	133 (A)	135	21	5,40	5,38	5,18
	140 (B)	142		5,15	5,08	4,93
150	152 (A)	154		6,92	6,97	6,62
	159 (B)	161		6,62	6,62	6,33
	168 (B)	170		6,24	6,17	5,95
(175)	194	196		7,32	7,31	7,02
200	219	222		8,05	8,04	7,71
(225)	245	245		9,30	9,30	9,05
250	273	273	23	10,65	10,66	10,22
300	325	325	24	12.90	12,89	12,21
350	377	377		15,85	15,79	14,96
400	426	426	26	21,56	21,51	20,49
(450)	480	480		22,76	22,68	21,67
500	530	530	28	22,70	28,02	26,86
600	630	630	31	39,40	39,26	37,48
(700)	720	720	34	59,46	58,58	56,45
800	820	820	37	79,16	77,89	76,08
(900)	920	920	40	94,13	-	-
1000	1020	1020	43	118,43
1200	1220	1222	51	197,44
1400	1420	1420	60	278,92
1600	1620	1620	70	422,65

GOST 12821-80 Threaded Flanges Dimension Chart

Pressure PN = 1.6 MPa (16 kgf/s m²)
Name	D, mm	D1, mm	dv, mm	b, mm	d, mm	resp., pcs.	Mass, kg
1-15-16 st.3 (20)	95	65	19	12	14	4	0,61
1-20-16 st.3 (20)	105	75	26	14			0,86
1-25-16 st.3 (20)	115	85	33	16			1,17
1-32-16 st.3 (20)	135	100	39	16	18		1,58
1-40-16 st.3 (20)	145	110	46	17			1,96
1-50-16 st.3 (20)	160	125	59	19			2,58
1-65-16 st.3 (20)	180	145	78	21			3,42
1-80-16 st.3 (20)	195	160	91	21			3,71
1-100-16 st.3 (20)	215	180	110	23		8	4,73
1-125-16 st.3 (20)	245	210	135	25			6,38
1-150-16 st.3 (20)	280	240	161	25	22		7,81
1-200-16 st.3 (20)	335	295	222	27		12	10,1
1-250-16 st.3 (20)	405	355	273	28	26		14,49
1-300-16 st.3 (20)	460	410	325	28			17,78
1-350-16 st.3 (20)	520	470	377	30		16	22,88
1-400-16 st.3 (20)	580	525	426	34	30		31
1-500-16 st.3 (20)	710	650	530	44	33	20	57,01
1-600-16 st.3 (20)	840	770	630	45	39		80,03
1-800-16 st.3 (20)	1020	950	820	49		24	104,41
1-1000-16 st.3 (20)	1255	1170	1020	58	45	28	179,37
1-1200-16 st.3 (20)	1485	1390	1220	71	52	32	297,78