A350 LF2 Flanges | ASTM A350 | UNS K03011

PM Industries manufactures, supplies, and stocks A350 LF2 Flanges across all standard flange types, pressure classes, and pipe sizes. ASTM A350 is the specification covering carbon and low-alloy steel forgings for piping components intended for low-temperature service. LF2 is the most commonly specified grade within that standard, a carbon-manganese steel with silicon addition that provides the combination of strength and low-temperature toughness required for cold service piping systems.

The key requirement that separates A350 LF2 from standard carbon steel flange material like A105 is mandatory Charpy impact testing. A350 LF2 flanges are tested per ASTM A350 at a minimum temperature of -46°C (-50°F), verifying that the material maintains adequate toughness at that temperature rather than transitioning to brittle behavior. Standard A105 carbon steel forgings are not impact tested and are not reliable below approximately -29°C (-20°F). In any piping system where the design temperature goes below that threshold, A350 LF2 is the correct carbon steel specification.

Low-temperature service in oil and gas is the primary driver for A350 LF2 specifications. Offshore platforms in arctic and sub-arctic locations, LNG facilities, cryogenic gas processing plants, and cold climate pipeline systems all have process and design temperatures that fall below the limit where standard carbon steel provides reliable toughness. A350 LF2 covers those applications within the carbon steel cost range, without requiring the step to more expensive low-alloy grades like A350 LF3 or austenitic stainless steels.

Impact testing certification is the documentation deliverable that A350 LF2 provides beyond standard A105. The test results must be reported on the material test report, along with the test temperature and the specific impact energy values for each test piece. In projects where the piping specification requires traceable low-temperature impact certification for all pressure-containing flanges in the cold service piping class, A350 LF2 flanges with properly documented test reports satisfy that requirement. Procurement teams should confirm that test reports include actual impact values, not just a statement that testing was performed.

Class and grade selection within A350 deserves attention. A350 LF2 Class 1 is the standard delivery condition, produced to fine-grain practice with normalized or normalized-and-tempered heat treatment. A350 LF2 Class 2 allows a lower minimum impact value. Most project specifications default to Class 1. Confirming which class the project piping specification requires before placing the order avoids certification discrepancies at inspection.

A350 LF2 flanges are available with full material certification including Charpy impact test results to ASTM A350 and applicable specifications. Contact PM Industries for flange type, pressure class, pipe size, face type, and pricing.

Specification A350 LF2 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

Group Of Material	Common Name Of Material	Type Of Material	UNS	Forging Spec.	Casting Spec. Equivalent	DIN	DIN W. No	Application
Carbon Steel (CS)	CS	C-Si	K03504	A105	A216-WCB	C22.8 DIN 17243	1.0460	General non-corrosive service from -29ºC (-20ºF) to 425ºC (800ºF)
Low Temperature Carbon Steel (LTCS)	LTCS	C-Mn-Fe	K03011	A350-LF2	A352-LCB A352-LCC	TSTE 355 DIN 18103	1.0566	General non-corrosive service from -46ºC (-50ºF) to 340ºC (650ºF), LF2 -46ºC ~ 425ºC
Low Temperature Alloy Steel (LTAS)	Nickel Steel	3.1/2Ni	K32025	A350-LF3	A352-LC3	10Ni14	1.5637	-101ºC (150ºF) to 340ºC (650ºF)

Chemical and Mechanical Properties

Chemical Composition		Mechanical Properties
C 0.30 Maximum	TS Min psi (Mpa)	70,000 (485)
Mn 0.60 – 1.35	YS Min psi (Mpa)	36,000 (250)
Si 0.15 – 0.30	EL (2″ Min)	22%
P 0.035 Maximum	RA Min	30%
S 0.040 Maximum	Hardness, Bhn	Maximum 197
Cr 0.30 Maximum	-50ºF Charpy	Min Impact
Ni 0.40 Maximum	Energy F t/Lb (J):-
Mo 0.12 Maximum	Set of 3 Specimen*	15 (20)
V 0.08 Maximum	For One Specimen	12 (16)
Cb 0.02 Maximum
Cu 0.04 Maximum
Pb 0.02 Maximum
Total Residuals = 0.50

LTCS A350 LF2 Flanges Thickness Calculation

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	……..	……..	……..	……..	……..	……..

ASME SA 350 GR LF2 Bolt Chart

	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

Low Temperature Carbon Steel Gasket Size Chart

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

A350 Lf2 Pressure-Temperature Rating

TEMP °C	Class 150	Class 300	Class 400	Class 600	Class 900	Class 1500	Class 2500
-29 TO 38	19.6	51.1	68.1	102.1	153.2	255.3	425.5
50	19.2	50.1	66.8	100.2	150.4	250.6	417.7
100	17.7	46.6	62.1	93.2	139.8	233	388.3
150	15.8	45.1	60.1	90.2	135.2	225.4	375.6
200	13.8	43.8	58.4	87.6	131.4	219	365
250	12.1	41.9	55.9	83.9	125.8	209.7	349.5
300	10.2	39.8	53.1	79.6	119.5	199.1	331.8
325	9.3	38.7	51.6	77.4	116.1	193.6	322.6
350	8.4	37.6	50.1	75.1	112.7	187.8	313
375	7.4	36.4	48.5	72.7	109.1	181.8	303.1
400	6.5	34.7	46.3	69.4	104.2	173.6	289.3
425	5.5	28.8	38.4	57.5	86.3	143.8	239.7
450	4.6	23	30.7	46	69	115	191.7
475	3.7	17.4	23.2	34.9	52.3	87.2	145.3
500	2.8	11.8	15.7	23.5	35.3	58.8	97.9
538	1.4	5.9	7.9	11.8	17.7	29.5	49.2

Flanges Dimensions Class-900

Nominal Pipe Size NPS (inches)	Class 900
	Diameter of Flange (inches)	No. of Bolts	Diameter of Bolts (inches)	Diameter of Bolt Holes (inches)	Bolt Circle (inches)
1/2	4-3/4	4	3/4	0.88	3-1/4
3/4	5-1/8	4	3/4	0.88	3-1/2
1	5-7/8	4	7/8	1	4
1-1/4	6-1/4	4	7/8	1	4-3/8
1-1/2	7	4	1	1.12	4-7/8
2	8-1/2	8	7/8	1	6-1/2
2-1/2	9-5/8	8	1	1.12	7-1/2
3	9-1/2	8	7/8	1	7-1/2
4	11-1/2	8	1-1/8	1.25	9-1/4
5	13-3/4	8	1-1/4	1.38	11
6	15	12	1-1/8	1.25	12-1/2
8	18-1/2	12	1-3/8	1.5	15-1/2
10	21-1/2	16	1-3/8	1.5	18-1/2
12	24	20	1-3/8	1.5	21
14	25-1/4	20	1-1/2	1.62	22
16	27-3/4	20	1-5/8	1.75	24-1/2
18	31	20	1-7/8	2	27
20	33-3/4	20	2	2.12	29-1/2
24	41	20	2-1/2	2.62	35-1/2

ANSI B16.5 A350 Gr Lf2 Flanges Dimensions Class-2500

Nominal Pipe Size NPS (inches)	Class 2500
	Diameter of Flange (inches)	No. of Bolts	Diameter of Bolts (inches)	Diameter of Bolt Holes (inches)	Bolt Circle (inches)
1/2	5-1/4	4	3/4	0.88	3-1/2
3/4	5-1/2	4	3/4	0.88	3-3/4
1	6-1/4	4	7/8	1	4-1/4
1-1/4	7-1/4	4	1	1.12	5-1/8
1-1/2	8	4	1-1/8	1.25	5-3/4
2	9-1/4	8	1	1.12	6-3/4
2-1/2	10-1/2	8	1-1/8	1.25	7-3/4
3	12	8	1-1/4	1.38	9
4	14	8	1-1/2	1.62	10-3/4
5	16-1/2	8	1-3/4	1.88	12-3/4
6	19	8	2	2.12	14-1/2
8	21-3/4	12	2	2.12	17-1/4
10	26-1/2	12	2-1/2	2.62	21-1/4
12	30	12	2-3/4	2.88	24-3/8