Alloy Steel A182 F91 Flanges | UNS K90901 | DIN 1.4903

Alloy steel A182 F91flanges are high-performance pipe fittings built for demanding high-temperature and high-pressure service. You will find them across power generation, petrochemical, oil and gas, and industrial processing plants. They are made to ASTM A182, and the F91 grade is a chromium-molybdenum-vanadium alloy steel engineered for better creep strength, thermal stability, and resistance to temper embrittlement than standard carbon steels. That makes F91 a sound pick for steam lines, headers, boilers, and pressure vessels running at temperatures up to about 600-650°C. PM Industries supplies and stocks these flanges in a full range of types, sizes, and pressure classes.

After proper heat treatment (normalizing and tempering), A182 F91 flanges carry high tensile and yield strength, with even hardness that supports reliable bolted joints and long service under cyclic thermal load. Fabrication and welding call for controlled preheat and post-weld heat treatment to avoid cracking and to restore the alloy's designed microstructure, and suppliers and fabricators have to follow that guidance to keep toughness and creep resistance intact. Corrosion resistance is moderate. F91 handles high-temperature oxidation better than many low-alloy steels, but it is not stainless, so it usually needs protective coatings or careful material selection where corrosive media are present.

We produce A182 F91 flanges in a spread of face types, including raised face (RF), ring-type joint (RTJ), slip-on (SO), weld neck (WN), blind, and threaded. They come in standard pressure classes to match the piping system, in forged or finished-machined forms held to tight tolerances. Quality control covers chemical analysis, mechanical testing, NDT such as PT and UT, and full documentation (MTC) to meet ASTM and purchaser requirements.

When picking F91, engineers weigh the high-temperature strength against cost and weldability, and they reach for it where long-term creep performance and structural integrity at temperature are critical to safety and service life. PM Industries holds stock ready to ship, with certification and test documentation on every order. Tell us your flange type, size, class, and face, and we will quote it.

Specification Alloy Steel A182 F91 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

Equivalent Grade

STANDARD	UNS	WERKSTOFF NR.	Trade Name
Alloy Steel F91	K90901	1.4903	9Cr-1Mo-V

Chemical Properties

Grade	C	Mn	Si	P	S	Cr	Mo
Alloy Steel F91	0.08 - 0.12	0.3 - 0.6	0.5	0.01	0.02	8.5 - 9.5	0.85 - 1.05

Mechanical Properties

Grade	Tensile Strength (MPa) min	Yield Strength 0.2% Proof (MPa) min	Elongation (% in 50mm) min
Alloy Steel F91	415	585	20

AS F91 Flanges Dimensions Class-150

Nominal Pipe Size NPS (inches)	Class 150
	Diameter of Flange (inches)	No. of Bolts	Diameter of Bolts (inches)	Diameter of Bolt Holes (inches)	Bolt Circle (inches)
1/4	3-3/8	4	1/2	0.62	2-1/4
1/2	3-1/2	4	1/2	0.62	2-3/8
3/4	3-7/8	4	1/2	0.62	2-3/4
1	4-1/4	4	1/2	0.62	3-1/8
1-1/4	4-5/8	4	1/2	0.62	3-1/2
1-1/2	5	4	1/2	0.62	3-7/8
2	6	4	5/8	0.75	4-3/4
2-1/2	7	4	5/8	0.75	5-1/2
3	7-1/2	4	5/8	0.75	6
3-1/2	8-1/2	8	5/8	0.75	7
4	9	8	5/8	0.75	7-1/2
5	10	8	3/4	0.88	8-1/2
6	11	8	3/4	0.88	9-1/2
8	13-1/2	8	3/4	0.88	11-3/4
10	16	12	7/8	1	14-1/4
12	19	12	7/8	1	17
14	21	12	1	1.12	18-3/4
16	23-1/2	16	1	1.12	21-1/4
18	25	16	1-1/8	1.25	22-3/4
20	27-1/2	20	1-1/8	1.25	25
24	32	20	1-1/4	1.38	29-1/2

SA 182 Gr F91 Flanges Dimension

NPS	O.D. of Flange	Flanges Thickness	Diameter of RF	Diameter of Hub at Base	Length Thru Hub			Bore or Diameter		Dia. of Hub at Bevel	Radius of Fillet	Deptd of Socket
					Welding (WN) Neck	Slip-On (SORF) Threaded (NPT) Socket (SWRF)	Lap Joint (Loose)	Slip-on (SORF) Socket (SWRF)	Lap Joint (Loose)
	O	Q	R	X	Y	Y	Y	W	B	H	r	Z
1/2	3-1/2	7/16	1-3/8	1-3/16	1-7/8	5/8	5/8	.88	.90	.84	1/8	3/8
3/4	3-7/8	1/2	1-11/16	1-1/2	2-1/16	5/8	5/8	1.09	1.11	1.05	1/8	7/16
1	4-1/4	9/16	2	1-15/16	2-3/16	11/16	11/16	1.36	1.38	1.32	1/8	1/2
1-1/4	4-5/8	5/8	2-1/2	2-5/16	2-1/4	13/16	13/16	1.70	1.72	1.66	3/16	9/16
1-1/2	5	11/16	2-7/8	2-9/16	2-7/16	7/8	7/8	1.95	1.97	1.90	1/4	5/8
2	6	3/4	3-5/8	3-1/16	2-1/2	1	1	2.44	2.46	2.38	5/16	11/16
2-1/2	7	7/8	4-1/8	3-9/16	2-3/4	1-1/8	1-1/8	2.94	2.97	2.88	5/16	3/4
3	7-1/2	15/16	5	4-1/4	2-3/4	1-3/16	1-3/16	3.57	3.60	3.50	3/8	13/16
3-1/2	8-1/2	15/16	5-1/2	4-13/16	2-13/16	1-1/4	1-1/4	4.07	4.10	4.00	3/8	7/8
4	9	15/16	6-3/16	5-5/16	3	1-5/16	1-5/16	4.57	4.60	4.50	7/16	15/16
5	10	15/16	7.5/16	6-7/16	3-1/2	1-7/16	1-7/16	5.66	5.69	5.56	7/16	15/16
6	11	1	8-1/2	7-9/16	3-1/2	1-9/16	1-9/16	6.72	6.75	6.63	1/2	1-1/16
8	13-1/2	1-1/8	10-5/8	9-11/16	4	1-3/4	1-3/4	8.72	8.75	8.63	1/2	1-1/4
10	16	1-3/16	12-3/4	12	4	1-15/16	1-15/16	10.88	10.92	10.75	1/2	1-5/16
12	19	1-1/4	15	14-3/8	4-1/2	2-3/16	2-3/16	12.88	12.92	12.75	1/2	1-9/16
14	21	1-3/8	16-1/4	15-3/4	5	2-1/4	3-1/8	14.14	14.18	14.00	1/2	1-5/8
16	23-1/2	1-7/16	18-1/2	18	5	2-1/2	3-7/16	16.16	16.19	16.00	1/2	1-3/4
18	25	1-9/16	21	19-7/8	5-1/2	2-11/16	3-13/16	18.18	18.20	18.00	1/2	1-15/16
20	27-1/2	1-11/16	23	22	5-11/16	2-7/8	4-1/16	20.20	20.25	20.00	1/2	2-1/8
24	32	1-7/8	27-1/4	26-1/8	6	3-1/4	4-3/8	24.25	24.25	24.00	1/2	2-1/2

Pressure Class/ 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

ASTM A182 F91 Type 1 Flanges Thickness Tolerance

ASTM A182 F91 Flanges Wall Thickness
NPS (Normal Pipe Sizes)	Outside Daimeter (O.D.)	Schedule 10	Schedule 20	Schedule 30	STD Wall	Schedule 40	Schedule 60	EXT Hvy	Schedule 80	Schedule 100	Schedule 120	Schedule 140	Schedule 160	XX Hvy
½	0.84	0.083	...	...	0.109	0.109	...	0.147	0.147	...	...	...	0.188	0.294
¾	1.05	0.083	...	...	0.113	0.113	...	0.154	0.154	...	...	...	0.219	0.308
1	1.315	0.109	...	...	0.133	0.133	...	0.179	0.179	...	...	...	0.25	0.358
1 ¼	1.66	0.109	...	...	0.14	0.14	...	0.191	0.191	...	...	...	0.25	0.382
1 ½	1.9	0.109	...	...	0.145	0.145	...	0.2	0.2	...	...	...	0.281	0.4
2	2.375	0.109	...	...	0.154	0.154	...	0.218	0.218	...	...	...	0.344	0.436
2 ½	2.875	0.12	...	...	0.203	0.203	...	0.276	0.276	...	...	...	0.375	0.552
3	3.5	0.12	...	...	0.216	0.216	...	0.3	0.3	...	...	...	0.438	0.6
3 ½	4	0.12	...	...	0.226	0.226	...	0.318	0.318	...	...	...	...	0.636
4	4.5	0.12	...	...	0.237	0.237	...	0.337	0.337	...	0.438	...	0.531	0.674
5	5.563	0.134	...	...	0.258	0.258	...	0.375	0.375	...	0.5	...	0.625	0.75
6	6.625	0.134	...	...	0.28	0.28	...	0.432	0.432	...	0.562	...	0.719	0.864
8	8.625	0.148	0.25	0.277	0.322	0.322	0.406	0.5	0.5	0.594	0.719	0.812	0.906	0.875
10	10.75	0.165	0.25	0.307	0.365	0.365	0.5	0.5	0.594	0.719	0.844	1	1.125	1
12	12.75	0.18	0.25	0.33	0.375	0.406	0.562	0.5	0.688	0.844	1	1.125	1.312	1
14	14	0.25	0.312	0.375	0.375	0.438	0.594	0.5	0.75	0.938	1.094	1.25	1.406	...
16	16	0.25	0.312	0.375	0.375	0.5	0.656	0.5	0.844	1.031	1.219	1.438	1.594	...
18	18	0.25	0.312	0.438	0.375	0.562	0.75	0.5	0.938	1.156	1.375	1.562	1.781	...
20	20	0.25	0.375	0.5	0.375	0.594	0.812	0.5	1.031	1.281	1.5	1.75	1.969	...
22	22	0.25	...	...	0.375	...	...	0.5	...	...	....	....	....	....
24	24	0.25	0.375	0.562	0.375	0.688	0.969	0.5	1.219	1.531	1.812	2.062	2.344	....
26	26	....	....	....	0.375	....	....	0.5	....	....	....	....	....	....
30	30	0.312	0.5	0.625	0.375	....	....	0.5	....	....	....	....	....	....
36	36	0.312	0.5	0.625	0.375	0.75	....	0.5	....	....	....	....	....	....
40	40	....	....	....	0.375	....	....	0.5	....	....	....	....	....	....
42	42	……..	……..	……..	0.375	……..	……..	0.5	……..	……..	……..	……..	……..	……..
48	48	……..	……..	……..	0.375	……..	……..	0.5	……..	……..	……..	……..	……..	……..

A182 F91 Type 2 Flanges Bolt Pattern

	Class 150 Flanges				Class 300 Flanges				Class 600 Flanges
NPS	# Bolts And Studs	Diameter of Bolts And Studs	Stud Length		# Bolts And Studs	Diameter of Bolts And Studs	Stud Length		# Bolts And Studs	Diameter of Bolts And Studs	Stud Length
			1/16 RF	RTJ			1/16 RF	RTJ			1/4 RF	RTJ
1/2	4	0.50	2-1/4	–	4	0.50	2-1/2	3	4	0.50	3	3
3/4	4	0.50	2-1/2	–	4	0.63	3	3-1/2	4	0.63	3-1/2	3-1/2
1	4	0.50	2-1/2	3	4	0.63	3	3-1/2	4	0.63	3-1/2	3-1/2
1-1/4	4	0.50	2-3/4	3-1/4	4	0.63	3-1/4	3-3/4	4	0.63	3-3/4	3-3/4
1-1/2	4	0.50	2-3/4	3-1/4	4	0.75	3-1/2	4	4	0.75	4-1/4	4-1/4
2	4	0.63	3-1/4	3-3/4	8	0.63	3-1/2	4	8	0.63	4-1/4	4-1/4
2-1/2	4	0.63	3-1/2	4	8	0.75	4	4-1/2	8	0.75	4-3/4	4-3/4
3	4	0.63	3-1/2	4	8	0.75	4-1/4	4-3/4	8	0.75	5	5
3-1/2	8	0.63	3-1/2	4	8	0.75	4-1/4	5	8	0.88	5-1/2	5-1/2
4	8	0.63	3-1/2	4	8	0.75	4-1/2	5	8	0.88	5-3/4	5-3/4
5	8	0.75	3-3/4	4-1/4	8	0.75	4-3/4	5-1/4	8	1.00	6-1/2	6-1/2
6	8	0.75	4	4-1/2	12	0.75	4-3/4	5-1/2	12	1.00	6-3/4	6-3/4
8	8	0.75	4-1/4	4-3/4	12	0.88	5-1/2	6	12	1.13	7-1/2	7-3/4
10	12	0.88	4-1/2	5	16	1.00	6-1/4	6-3/4	16	1.25	8-1/2	8-1/2
12	12	0.88	4-3/4	5-1/4	16	1.13	6-3/4	7-1/4	20	1.25	8-3/4	8-3/4
14	12	1.00	5-1/4	5-3/4	20	1.13	7	7-1/2	20	1.38	9-1/4	9-1/4
16	16	1.00	5-1/4	5-3/4	20	1.25	7-1/2	8	20	1.50	10	10
18	16	1.13	5-3/4	6-1/4	24	1.25	7-3/4	8-1/4	20	1.63	10-3/4	10-3/4
20	20	1.13	6-1/4	6-3/4	24	1.25	8	8-3/4	24	1.63	11-1/4	11-1/2
24	20	1.25	6-3/4	7-1/4	24	1.50	9	10	24	1.88	13	13-1/4

Weight Chart Of A182 F91 Type 1 Flanges

Nominal Pipe Sizes (NPS)	Slip On (SORF)	Threaded (NPT)	Socket Weld (SWRF)	Lap Joint (Loose)	Blind (BLRF)	Weld Neck (WRNR)
½	1	1	2	1	2	2
¾	2	2	2	2	2	2
1	2	2	2	2	2	3
1¼	3	3	3	3	3	3
1½	3	3	3	3	4	4
2	5	5	5	5	5	6
2½	8	8	8	8	7	10
3	9	9	9	9	9	11.5
3½	11	12	11	11	13	12
4	13	13	13	13	17	16.5
5	15	15	15	15	20	21
6	19	19	19	19	27	26
8	30	30	30	30	47	42
10	43	43	43	43	70	54
12	64	64	64	64	123	88
14	90	90	90	105	140	114
16	106	98	98	140	180	140
18	130	130	130	160	220	165
20	165	165	165	195	285	197
22	185	185	185	245	355	225
24	220	220	220	275	430	268