A flange is a tool to connect pumps, valves, pipes, and other equipment to form a piping system. It also provides easy access to modify, inspect, and clean. Flanges are usually screwed on or welded. Flanged joints are made by bolting two flanges together with a gasket that provides a seal.

Flange manufacturing process

The manufacturing process of the flange is highly sophisticated and divided into many departments supervised by experienced industry experts. Quality raw materials can be procured from only reliable and established vendors. Rigorous quality control procedures and practices ensure the production of only quality products matching parameters and standards.

Raw materials

The usual materials of flanges include plastic/polymer, nickel alloys, aluminum, carbon steel, and stainless steel. Beginning with the process, the system controls the quality of all incoming materials as per the raw material test certificate of the material. Mild Steel Flanges (MS) are of premium quality that ensures resistivity, strength, and high durability to varied non-supporting conditions.

Flange Standard

You can find a variety of flange standards worldwide. It allows easy interchangeability and functionality and are designed to have standardized dimensions. Common world standards include ASA/ANSI/ASME (USA), JIS/KS (Japanese/Korean), BS10 (British/Australian), and PN/DIN (European metric).

American standards for flanges

ASME B16.1: Flanged fittings and gray iron pipe flanges (cast iron flanges, Classes 25, 125, and 250) which are commonly made today in carbon steel instead of cast

ASME B16.5: Flanged fittings and pipe flanges: NPS ½ through NPS 24 Metric/Inch Standard; (Weld-neck and alternate connection flanges in classes 150, 300, 400, 600, 900, 1500 and 2500)

In the EN 1092 standard, the numerical value in the PN designation is equal to the maximum applicable pressure in the bar at a reference temperature of 20°C.

Flange materials

Dimensions from stainless steel and carbon steel flanges are defined in the ASME B16.5 standard. The material qualities for these flanges are defined in the ASTM standards for the corresponding grades.

The ASTM standards, define the specific manufacturing process of the materials and determine the exact chemical composition of flanges, fittings, and pipes through percentages of the permitted quantities of nickel, magnesium, carbon, etc., and are indicated by ‘Grade’.

You can identify the low chrome steel flange with Grade F11 or F9, a stainless-steel flange with Grade F321 or F316, etc.

The most common materials for flanges are:

Carbon steel

ASTM A 105 / A 266 Gr. 2 (high-temperature carbon steel)

ASTM A350 LF1 to LF6 (low-temperature carbon steel)

ASTM A694 Gr. F42/ F52/ F56/ F60/ F65 (high yield carbon steel flange to match API 5L line pipes)

Alloy Steel

ASTM A182 Gr. F5 / F9 / F11 Cl. 2 / F12 Cl. 2 / F22 Cl. 3 / F91 (alloy steel flanges)

Duplex/Stainless steel

ASTM A182 F 304/304L, 316/316L, 321, 347, 348 (stainless steel flanges), 904/904L

ASTM A182 F51 (duplex stainless steel flanges) / F53-F55 (super duplex stainless steel flanges)

Superalloys / Nickel Alloys

ASTM B564 UNS N10276 (Hastelloy C-276)

ASTM B564 UNS N04400 (Monel 400)

ASTM B160 UNS N0200 (Nickel 200)

ASTM B564 UNS N08825 (Incoloy 825)

ASTM B425 UNS-NO8800 (Incoloy 800)

ASTM B564 UNS N06625 (Inconel 625)

ASTM B166 UNS NO6600 (inconel 600)

Titanium

ASTM B381 Gr. 2 (Titanium)

ASTM GROUP 2-1.1 MATERIALS

Nominal Designation	Forgings	Castings	Plates
C-Si	A105(1)	A216 Gr.WCB (1)	A515 Gr.70 (1)
C Mn Si	A350 Gr.LF2 (1)	…	A516 Gr.70 (1),(2)
C Mn Si V	A350 Gr.LF6 Cl 1(3)	…	A537 Cl.1 (4)
3.1/2Ni	A350 Gr.LF3	…	…

Notes:

If it gets exposed to a temperature above 425°C for a long time, the carbide phase of steel may convert into graphite.

Do not use over 370°C.

Do not use over 260°C.

Do not use over 455°C.

ASTM GROUP 2-2.3 MATERIALS

Nominal Designation	Forgings	Cast	Plates
16Cr 12Ni 2Mo	A182 Gr.F316L	…	A240 Gr.316L
18Cr 13Ni 3Mo	A182 Gr.F317L	…	…
18Cr 8Ni	A182 Gr.F304L (1)	…	A240 Gr.304L (1)

Note: Do not use over 425°C.

PRESSURE-TEMPERATURE RATINGS FOR ASTM GROUP 2-1.1 MATERIALS

Working pressure by Classes, BAR

TEMP(°C)	150	300	400	600	900	1500	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
TEMP (°C)	150	300	400	600	900	1500	2500

PRESSURE-TEMPERATURE RATINGS FOR ASTM GROUP 2-2.3 MATERIALS

Working pressure by Classes, BAR

TEMP(°C)	150	300	400	600	900	1500	2500
-29 TO 38	15.9	41.4	55.2	82.7	124.1	206.8	344.7
50	15.3	40	53.4	80	120.1	200.1	333.5
100	13.3	34.8	46.4	69.6	104.4	173.9	289.9
150	12	31.4	41.9	62.8	94.2	157	261.6
200	11.2	29.2	38.9	58.3	87.5	145.8	243
250	10.5	27.5	36.6	54.9	82.4	137.3	228.9
300	10	26.1	34.8	52.1	78.2	130.3	217.2
325	9.3	25.5	34	51	76.4	127.4	212.3
350	8.4	25.1	33.4	50.1	75.2	125.4	208.9
375	7.4	24.8	33	49.5	74.3	123.8	206.3
400	6.5	24.3	32.4	48.6	72.9	121.5	202.5
425	5.5	23.9	31.8	47.7	71.6	119.3	198.8
450	4.6	23.4	31.2	46.8	70.2	117.1	195.1
TEMP(°C)	150	300	400	600	900	1500	2500

Conclusion

It is always better to get in-depth knowledge about the product you need to buy. You can find the best and high-quality flanges with the help of the points given above. The guide will help to select the right one as per the requirements of your application.

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