How to get high quality flanges

How to get high quality flanges

A flange is a method of connecting pipes, valves, pumps and other equipment to form a piping system. It also provides easy access for cleaning, inspection or modification. Flanges are usually welded or screwed. Flanged joints are made by bolting together two flanges with a gasket between them to provide a seal.

The Manufacturing Process of Flange

Our manufacturing process is highly sophisticated and is divided into various departments supervised by experienced industry experts. We use only quality raw materials that are procured from only established and reliable vendors. We have adopted rigorous quality control practices and procedures to ensure the production of only quality products matching industry standards and parameters.

Understanding customers requirement and ensuring to supply as per these requirements is realised with the help of quality assurance at Yaang.com one of the best Flange Manufacturers in China , our product range include all types of flanges such as MS Flange ( Mild Steel ) , Raised face flange , Weld neck flange, Bellow Flange , and Flanges according to custom requirement.

1. Raw Material

• Raw Material Check
• Quantity Check
• Visual & Dimension Check

2. Material Inspection

• Chemical Analysis Check
• Preservation Analysis Certificate

3. Material Cutting

• Weight Measuring
• Cut Surface Check
• Marking

4. Flange forging

• Material Grade Check
• Weight Measuring
• Temperature Control

5. Heat Treatment

• Normalizing
• Tempering, Q.T
• Solution Treatment
• Mechanical Test

6. Forging Rolling

• Material Grade Check
• Weight Measuring
• Temperature Check
• Dimension Check

7. Final Inspection

• Dimension size inspect
• Visual Test
• Nondestructive Test

8. Rust Prevention

• Preserve Check
• Marking on the flange
• Tectyl 506 or Pickling or etc. 

9. Well Packing

• Packing Spec. Check
• Packing Inspection
• Delivery

Requirements are valid for normal situation, in special you have to contact us to introduce.

Our machining and assembly operations have a complete line of metal removal equipment including turning, boring, milling, drilling, grinding, polishing, welding and have testing equipment to manufacture forged steel fittings and valves. This facility also contains all the necessary equipment to support these operations including work holding and cutting tool needs.

Raw Materials:

The usual materials of flanges include stainless steel, carbon steel, aluminum and plastic.

Beginning with this 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 high durability, strength and resistivity to varied non-supporting conditions. Also, checking in each size for chemical and physical properties of these materials at Government approved laboratory.

Flange materials acc. to ASTM

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

The Rust Prevention for Steel Flanges

The normal rust prevention treatment for steel flanges include yellow (Golden) paint Coating, black paint coating or black phosphating treatment, varnish paint coating, varnish antirust oil coating, electro galvanizing coating (Cold), hot dip galvanizing coating etc.

The Packing Works for Steel Flanges  

Steel flanges must be packed with seaworthy packing method then delivery to customers, usually the packing way include wooden box, wooden pallet, iron & steel cage, iron & steel pallet etc. Because of the normal wooden boxes or wooden pallets have to do fumigation treatment, we usually use plywood pallet or plywood case or box to pack steel flanges without fumigation treatment. Whatever plywood or iron & steel packing way, they must be seaworthy, strong, waterproof and easy for loading and unloading.

Marking on the flange

Shipping mark stick to outside of package. Following shall be marked on flange body

• Manufacturer logo: 
• ASTM material code
• Material Grade
• Service rating (Pressure-temperature Class))
• Size
• Thickness (Schedule)
• Heat No
• Special marking if any QT (Quenched and tempered) or W (Repair by welding)

Dispatch:

The final process of dispatch is the most tedious of all , and heavy duty cranes are used for it. With the help of our extensive delivery chain we can ensure time critical deliveries at the behest of our esteemed clients. We are indeed privileged to be able to serve and live upto their expectations and occupy unparalleled postion of Flange makers in China.

Production process of forged flange

Forging flange is a flange in mechanical performance is one of the best products, its raw material is commonly tube billet, and then after cutting to constantly pounding, to eliminate the segregation of steel ingot defects, osteoporosis, etc.

The production process flow of forging flange:

the process of forging process is composed of the following procedure, which is to select the high quality steel billet, heat, shape and forge to cool down. The forging process has a free forging, die forging, and tire forging.

In the production, press the mass of the forging parts, the quantity of the batch of different forging methods. Free forging productivity is low, processing surplus is large, but the tool is simple, universality is large, so it is widely…

Forging flange is a flange in mechanical performance is one of the best products, its raw material is commonly tube billet, and then after cutting to constantly pounding, to eliminate the segregation of steel ingot defects, osteoporosis, etc. Price and mechanical properties are higher than normal casting flanges. The flange is the part that connects the pipe to the pipe and the valve. It is also useful for flanges in the import and export of the equipment, which is used to connect the pipe to the pipe by connecting the pipe to the pipe. It’s an accessory accessory for the pipe. The forging flange is mainly made of carbon steel, alloy steel, stainless steel. The main criteria are national, electric, American, German, and Japanese. The main anticorrosion treatment is oily and galvanized.

Production Process of Forged Flange

The forging process is usually composed of the following processes, namely, the selection of quality steel billet, heating, forming and cooling. The forging process has a free forging, die forging, and tire forging. In the production, press the mass of the forging parts, the quantity of the batch of different forging methods.

It is widely used in forging simple pieces and small batches of forging parts. The free forging equipment is equipped with pneumatic hammer, steam air hammer and hydraulic press, which are suitable for the production of small and large forgings. High productivity, easy operation, easy mechanization and automation. The size of die forging is high, the machining allowance is small, and the fabric of the forging is more reasonable, which can further improve the service life of the parts.

The basic process of free forging: when forging, the shape of the forging is gradually forged through some basic deformation process. The basic process of forging and forging is upbold, long, piercing, bending and cutting.

Upset upsetting is the operation process that reduces the height of the raw material and increases the cross section. This process is used for forging gear billets and other disc shaped forgings. The heading is divided into full heading and partial forging.

The length of the shaft is increased by the length of the billet, the forging process of the reduction of the section is usually used to produce the spindle such as the lathe spindle, the connecting rod and so on.

·        The forging process of punching holes through holes or holes in the blank.

·        The forging process that bends the blank to a certain Angle or shape.

·        Twist the process of turning a part of the billet into a certain angle.

·        The forging process of cutting down the raw material or cutting head.

·        Second, the die forging

The die forging is known as the forging of the model, which is placed in the forging of the forging machine which is fixed on the die forging equipment.

The basic process of die forging: material, heating, pre-forging, finishing, finishing, cutting, trimming and blasting. The common technique is to upset, pull, bend, punch and form.

The commonly used die forging equipment has die forging hammer, hot die forging press, flat forging machine and friction press.

Generally speaking, the forging flange is of better quality, usually through die forging, the crystal structure is fine, the strength is high, and of course the price is more expensive.

Whether casting flange or forging flange are commonly used in manufacturing methods, see the need to use the strength of the components, if the requirements are not high, you can choose to turn the flange.

Flange standard

There are many different flange standards to be found worldwide. To allow easy functionality and interchangeability, these are designed to have standardised dimensions. Common world standards include ASA/ANSI/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean).

European standard EN 1092: Flanges and Their Joints (Circular Flanges for Pipes, Valves, Fittings and Accessories, PN designated)

• Part 1: Steel flanges, PN 2.5 to PN 400
• Part 2: Cast iron flanges, PN 2.5 to PN 63
• Part 3: Copper alloy flanges, PN 6 to PN 40
• Part 4: Aluminium alloy flanges, PN 10 to PN 63

British standards for flanges

• BS EN 1092-1 (Cast steel flanges) for nominal pressures, see DIN EN 1092-1
• BS EN 1092-2 (Cast iron flanges) for nominal pressures, see DIN EN 1092-2

A further European flange standard is EN 1759. This standard only features ANSI/ASME flanges (ASME B 16.5 1996 edition) with Class and NPS designations.

American standards for flanges

• ASME B 16.1: Gray iron pipe flanges and flanged fittings (cast iron flanges, Classes 25, 125 and 250)
• ASME B 16.5: Pipe flanges and flanged fittings: NPS 1/2 through NPS 24 Metric/Inch Standard; (Cast steel and weld-neck flanges 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 max. applicable pressure in bar at a reference temperature of 20 °C.

Class figure in American flange standards

For cast iron flanges, the figure in the Class designation is equal to the max.
applicable pressure in psi at temperatures ranging from 66 to 232 °C depending on the class.

For steel and cast steel flanges, the figure in the class designation is equal to the max. applicable pressure in psi at temperatures ranging from 350 to 650 °C depending on the material.

At a temperature of 20 °C, the figure for the max. applicable pressure is therefore considerably higher than that designating the class, especially for steel and cast steel flanges.

Although PN designations are not used in American flange standards, they are matched with their equivalent pressure classes in ASME B 16.5-2003.

Flanges to ISO 7005 are internationally standardised. This standard series comprises DIN flanges (PN 2.5; 6; 10; 16; 25 and 40) and ASME flanges. This standard, however, also specifies DN and PN designations for ASME flanges (PN 20; 50; 110; 150; 250 and 420).

Other countries Flanges in the rest of the world are manufactured according to the ISO standards for materials, pressure ratings, etc. to which local standards including DIN, BS…. have been aligned.

TYPES OF FLANGES

The most used flange types in Petro and chemical industry are:

Threaded Flanges

Threaded Flanges are also known as screwed flange, and it is having a thread inside the flange bore which fits on the pipe with matching male thread on the pipe. This type of joint connection is Speedy and simple but not suitable for high presser and temperature applications. Threaded Flanges are mostly used in utility services such as air and water.

Socket-Weld Flanges

Socket-Weld Flanges has a female socket in which pipe is fitted. Fillet welding is done from outside on the pipe. Generally, it is used in small bore piping and only suitable for low pressure and temperature application.

Slip-On Flanges

Slip-On flange has a hole with matching outside diameter of pipe from which pipe can pass. The flange is placed on pipe and fillet welded from both inside and outside. Slip-On Flange is suitable for low pressure and temperature application. This type of flange is available in large size also to connect big bore piping with storage tank nozzles. Normally, these flanges are of forged construction and are provided with the hub. Sometimes, these flanges are fabricated from plates and are not provided with the hub.

Lap Joint Flanges

Lap flange is having two components, a stub end, and a loose backing flange. Stub end is butt welded to the pipe and Backing flange freely move over the pipe. The backing flange can be of different material than stub material and normally of the carbon steel to save the cost. Lap flange is used where frequent dismantling is required, and space is constrained.

Weld Neck Flanges

Weld neck flange are most widely used flanged in process piping. It gives the highest level of joint integrity due to Butt-welded with a pipe. These types of flanges are used in high pressure and temperature application. Weld neck flanges are Bulky & costly with respect to other types of flange.

Blind Flanges

 

The blind flange is a blank disc with bolt hole. These types of flanges are used with another type of flange to isolate the piping system or to terminate the piping as an end. Blind flanges are also used as a manhole cover in the vessel.

SPECIAL FLANGES

Except the most used standard flanges, there are still a number of special flanges such as:

• Orifice Flanges generally come with either Raised Faces or RTJ (Ring Type Joint) facings.
• Long Weld Neck Flange is normally referred to as the high hub flange.
• Expander Flange is using a separate reducer-welding neck flange combination.
• NW Long Weld Neck Flange is a welding neck flange has a very long neck.
• Spectacle Blind Flange consist of a connected ring (spacer) and a plate (spade).
• Reducing Flange is used on projects that require the fitting together of different sized pipes.
• Weldoflange / Nipoflange is a combination of a Welding Neck flange and a supposedly Weldolet or Nipolet.

Flange Materials

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

These ASTM standards, define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by “Grade”.

For example, a carbon steel flange can be identified with Grade F9 or F11, a stainless-steel flange with Grade F316 or Grade F321 etc..

Below you will find as an example a table with chemical requirements for fittings ASTM A403 Grade WP304, WP304L, WP316L and a table with frequent Grades, arranged on pipe and pipe-components, which belong together as a group. As you may be have noted, in the table below, ASTM A105 has no Grade. Sometimes ASTM A105N is described;
“N” stands not for Grade, but for normalized. Normalizing is a type of heat treatment, applicable to ferrous metals only. The purpose of normalizing is to remove the internal stresses induced by heat treating, casting, forming 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 LF3 (low temperature carbon steel)
• ASTM A694 Gr. F42 / F52 / F56 / F60 / F65 (high yield carbon steel flange to match API 5L linepipes)

Alloy Steel

ASTM A182 Gr. F1 / F2 / F5 / F9 / F11 Cl. 2 /  F12 Cl. 2 / F22 Cl. 3 / F91 (alloy steel flanges)

Stainless/ Duplex 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)

Nickel Alloys / Superalloys

• ASTM B166 UNS NO6600 (inconel 600)
• ASTM B564 UNS N06625 (Inconel 625)
• ASTM B425 UNS-NO8800 (Incoloy 800)
• ASTM B564 UNS N08825 (Incoloy 825)
• ASTM B160 UNS N0200 (Nickel 200)
• ASTM B564 UNS N04400 (Monel 400)
• ASTM B564 UNS N10276 (Hastelloy C-276)

Titanium

• ASTM B381 Gr. 2 (Titanium)

ASTM A105 CARBON STEEL FLANGES

CHEMICAL COMPOSITION

Composition, %
Element	C	Mn	P	S	Si	Cu	Ni	Cr	Mo	V
	0.35 max	0.60-1.05	0.035 max	0.040 max	0.10-0.35	0.40 max (1)	0.40 max (1)	0.30 max (1-2)	0.12 max (1-2)	0.08 max

Notes:

1. The total of Cu, Ni, Niobium, Moly and Vanadium shall not exceed 1.00%.

2. The sum of Niobium and Molybdenum shall not exceed 0.32%.

MAX WORKING PRESSURE

(Max working pressure of carbon steel / low alloy steel flanges ASTM A105 / ASTM A350 – by Class, in 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

FLANGE SERVICE BY MATERIAL GRADE

MATERIAL	MATERIAL GROUP	FLANGE SERVICE	CAST GRADE
A105	Carbon Steel	Carbon steel flanges for general service such as oil, oil vapor, gas, steam and water at temperatures -20°F to 1000°F (-28°C to 537°C).	ASTM A216-WCB
A350-LF2 CL1	Low Temperature Carbon Steel	Low temp. carbon steel flanges suitable for temperatures -50°F and not above 650°F (-46°C and not above 343°C).	ASTM A352-LCB
A182-F11 CL2	1 1/4% Cr, 1/2% Mo Alloy Steel	Alloy steel flanges for high temperatures from -20°F to 1100°F to minimize graphitization (-28°C to 593§C).	ASTM A217-WC6
A182-F22 CL3	2 1/4% Cr, 1% Mo Alloy Steel	Alloy steel flanges for services requiring greater strength than F11 at temperatures from -20°F to 1100°F (-28°C to 593°C).	ASTM A217-WC9
A182-F5	5% Cr, 1/2% Mo Alloy Steel	Alloy steel flanges for corrosive/erosive refinery use requiring resistance at temperatures from -20°F to 1100§F (-28°C to 590°C).	ASTM A217-C5
A182-F9	9% Cr, 1% Mo Alloy Steel	Alloy steel flanges for services involving media with higher Sulphur content to combat oxidation to 1100oF (593°C).	ASTM A217-C12

ASTM A182 STAINLESS STEEL FLANGES

CHEMICAL COMPOSITION

Composition, %
Grade	C	Mn	P	S	Si	Ni	Cr	Mo	Nb	Ti	Others
F304(1)	0.08	2.0	0.045	0.030	1.0	8.0-11.0	18.0-20.0
F304H	0.04-0.10	2.0	0.045	0.030	1.0	8.0-11.0	18.0-20.0
F304L(1)	0.030	2.0	0.045	0.030	1.0	8.0-13.0	18.0-20.0
F304N(2)	0.08	2.0	0.045	0.030	1.0	8.0-10.5	18.0-20.0
F304LN(2)	0.030	2.0	0.045	0.030	1.0	8.0-10.5	18.0-20.0
F309H	0.04-0.10	2.0	0.045	0.030	1.0	12.0-15.0	22.0-24.0
F310	0.25	2.0	0.045	0.030	1.0	19.0-22.0	24.0-26.0
F310H	0.04-0.10	2.0	0.045	0.030	1.0	19.0-22.0	24.0-26.0
F310MoLN	0.030	2.0	0.030	0.015	0.40	21.0-23.0	24.0-26.0	2.0-3.0			N 0.10-0.16
F316	0.08	2.0	0.045	0.030	1.0	10.0-14.0	16.0-18.0	2.0-3.0
F316H	0.04-0.10	2.0	0.045	0.030	1.0	10.0-14.0	16.0-18.0	2.0-3.0
F316L(1)	0.030	2.0	0.045	0.030	1.0	10.0-15.0	16.0-18.0	2.0-3.0
F316N(2)	0.08	2.0	0.045	0.030	1.0	11.0-14.0	16.0-18.0	2.0-3.0
F316LN(2)	0.030	2.0	0.045	0.030	1.0	11.0-14.0	16.0-18.0	2.0-3.0
F316Ti	0.08	2.0	0.045	0.030	1.0	10.0-14.0	16.0-18.0	2.0-3.0		(3)	N 0.10 max
F317	0.08	2.0	0.045	0.030	1.0	11.0-15.0	18.0-20.0	3.0-4.0
F317L	0.030	2.0	0.045	0.030	1.0	11.0-15.0	18.0-20.0	3.0-4.0
F321	0.08	2.0	0.045	0.030	1.0	9.0-12.0	17.0-19.0			(4)
F321H	0.04-0.10	2.0	0.045	0.030	1.0	9.0-12.0	17.0-19.0			(5)
F347	0.08	2.0	0.045	0.030	1.0	9.0-13.0	17.0-20.0		(6)
F347H	0.04-0.10	2.0	0.045	0.030	1.0	9.0-13.0	17.0-20.0		(7)
F348	0.08	2.0	0.045	0.030	1.0	9.0-13.0	17.0-20.0		(6)		Co 0.20 Ta 0.10
F348H	0.04-0.10	2.0	0.045	0.030	1.0	9.0-13.0	17.0-20.0		(7)		Co 0.20 Ta 0.10

Notes:

1. Grades F304, F304L, F316, and F316L shall have a maximum Nitrogen of 0.10%.

2. Grades F304N, F316N, F304LN, and F316LN shall have a Nitrogen of 0.10 to 0.16%.

3. Grade F316Ti shall have a Titanium content five times above the Carbon plus Nitrogen and not more than 0.70%.

4. Grade F321 shall have a Titanium content five times above the Carbon and not more than 0.70%.

5. Grade F321H shall have a Titanium content four times above the Carbon and not more than 0.70%.

6. Grades F347 and F348 shall have a Niobium content ten times above the Carbon and not more than 1.10%.

7. Grades F347H and F348H shall have a Niobium content above than eight times the Carbon and not more than 1.10%.

MAX WORKING PRESSURE

(Max working pressure of carbon stainless steel flanges ASTM A182 – by Class, in 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

FLANGE SERVICE BY MATERIAL GRADE

MATERIAL	MATERIAL GROUP	FLANGE SERVICE	CAST GRADE
A182-F304	18% Cr, 8% Ni Stainless Steel	Stainless steel flanges for corrosive services and atmospheres from -450°F to 1000°F (-268°C to 537°C).	ASTM A351-CF8
A182-F316	18% Cr, 8% Ni, 2% Mo Stainless Steel	Stainless steel flanges for superior resistance to corrosion from -450°F to 1000°F (-268°C to 537°C).	ASTM A351-CF8M

PIPING MATERIALS MATCH TABLE

Material Group	Pipes	Wrought Fittings	Flanges	Valves	Bolting Sets
Carbon Steel	A106 Gr A	A234 Gr WPA	A105	A216 Gr WCB	A193 Gr B7 A194 Gr 2H
	A106 Gr B	A234 Gr WPB	A105	A216 Gr WCB
	A106 Gr C	A234 Gr WPC	A105	A216 Gr WCB
Carbon Steel Alloy High-Temp	A335 Gr P1	A234 Gr WP1	A182 Gr F1	A217 Gr WC1	A193 Gr B7 A194 Gr 2H
	A335 Gr P11	A234 Gr WP11	A182 Gr F11	A217 Gr WC6
	A335 Gr P12	A234 Gr WP12	A182 Gr F12	A217 Gr WC6
	A335 Gr P22	A234 Gr WP22	A182 Gr F22	A217 Gr WC9
	A335 Gr P5	A234 Gr WP5	A182 Gr F5	A217 Gr C5
	A335 Gr P9	A234 Gr WP9	A182 Gr F9	A217 Gr C12
Carbon Steel Alloy Low-Temp	A333 Gr 6	A420 Gr WPL6	A350 Gr LF2	A352 Gr LCB	A320 Gr L7 A194 Gr 7
	A333 Gr 3	A420 Gr WPL3	A350 Gr LF3	A352 Gr LC3
Austenitic Stainless Steel	A312 Gr TP304	A403 Gr WP304	A182 Gr F304	A182 Gr F304	A193 Gr B8 A194 Gr 8
	A312 Gr TP316	A403 Gr WP316	A182 Gr F316	A182 Gr F316
	A312 Gr TP321	A403 Gr WP321	A182 Gr F321	A182 Gr F321
	A312 Gr TP347	A403 Gr WP347	A182 Gr F347	A182 Gr F347
Material	Pipes	Fttg	Flg	Valves	Bolts & Nuts

ASTM vs. EN MATERIALS FOR FLANGES

Flanges
Material number	EN	ASTM
Carbon steel flanges
1.0038 RSt 37-2	S235JR	–
1.0570 St 52-3	S355J2 (1.0577)	–
1.0460 C 22.8	P250GH	–
1.0432 C 21	–	A 105
1.0352 –	P245GH	–
– –	–	–
Alloy steel flanges
1.5415 15 Mo 3	16Mo3	A 182 Grade F 1
1.7335 13 CrMo 4 4	13CrMo4-5	A 182 Grade F11, F12
1.7380 10 CrMo 9 10	11CrMo9-10 (1.7383)	A 182 Grade F22
1.7362 12 CrMo 19 5	–	A 182 Grade F5
– –	–	A 182 Grade F9
1.4903 –	X10CrMoVNb9-1	A 182 Grade F91
Low temperature carbon steel flanges
1.5637 10 Ni 14	12Ni14	A 350 Grade LF3
1.0566 TStE 355	P355QH1 (1.0571)	A 350 Grade LF2
– –	–	–
High yield carbon steel flanges
– –	–	–
1.0486 StE 285	–	A 694 Grade F42
1.0562 StE 355	P355N	A 694 Grade F52
1.8902 StE 420	P420N	A 694 Grade F60
1.8905 StE 460	P460N	A 694 Grade F70
High yield steels
– –	–	–
Stainless steel flanges
1.4541 X 6 CrNiTi 18 10	X6CrNiTi18-10	A 182 Grade F321
1.4571 X 6 CrNiMoTi 17 12 2	X6CrNiMoTi17-12-2	A 182 Grade F316Ti
1.4301 X 5 CrNi 18 10	X5CrNi18-10	A 182 Grade F304
1.4306 X 2 CrNi 19 11	–	A 182 Grade F304L
1.4307 –	X2CrNi18-9	A 182 Grade F304L
1.4401 X 5 CrNiMo 17 12 2	X5CrNiMo17-12-2	A 182 Grade F316
1.4404 X 2 CrNiMo 17 13 2	X2CrNiMo17-12-2	A 182 Grade F316L
1.4462 X 2 CrNiMoN 22 5 3	X2CrNiMoN22-5-3	A 182 Grade F51 (Duplex)
1.4529 X 1 NiCrMoCuN 25 20 6	X1NiCrMoCuN25-20-7	UNS N 08926
1.4539 X 1 NiCrMoCuN 25 20 5	X1NiCrMoCu25-20-5	A 182 Grade F904L
1.4547 –	X1CrNiMoCuN20-18-7	UNS S 31254

Flange Facing Types

Based on Flange facing Types, it can be further classified as

1.         Flat Face (FF)

2.         Raised Face (RF)

3.         Ring Joint (RTJ)

4.         Tongue and groove (T&G)

5.         And Male and Female type

Other flange facings covered by these standards include the large and small tongue-and-groove facings, and the ring joint facing specifically for ring joint type metal gaskets.

Raised Face (RF)

Raised Face

The Raised Face flange is the most common type used in process plant applications, and is easily to identify. It is referred to as a raised face because the gasket surfaces are raised above the bolting circle face. This face type allows the use of a wide combination of gasket designs, including flat ring sheet types and metallic composites such as spiral wound and double jacketed types. The purpose of a RF flange is to concentrate more pressure on a smaller gasket area and thereby increase the pressure containment capability of the joint. Diameter and height are in ASME B16.5 defined, by pressure class and diameter. Pressure rating of the flange determines the height of the raised face.
The typical flange face finish for ASME B16.5 RF flanges is 125 to 250 µin Ra (3 to 6 µm Ra).

For the height measures H and B of all described dimensions of flanges on this website, with exception of the Lap Joint flange, it is important to understand and remember the following:
In pressure classes 150 and 300, the height of raised face is approximately 1.6 mm (1/16 inch). In these two pressure classes, almost all suppliers of flanges, show in their catalog or brochure, the H and B dimensions including the raised face height. (Fig. 1) 
In pressure classes 400, 600, 900, 1500 & 2500, the height of raised face is approximately 6.4 mm (1/4 inch). In these pressure classes, most suppliers show the H and B dimensions excluding the raised face height. (Fig. 2)

Flat Face (FF)

The Flat 

Face flange has a gasket surface in the same plane as the bolting circle face. Applications using flat face flanges are frequently those in which the mating flange or flanged fitting is made from a casting.
Flat face flanges are never to be bolted to a raised face flange. ASME B31.1 says that when connecting flat face cast iron flanges to carbon steel flanges, the raised face on the carbon steel flange must be removed, and that a full face gasket is required.
This is to keep the thin, bittle cast iron flange from being sprung into the gap caused by the raised face of the carbon steel flange.

Ring-Type Joint (RTJ)

The Ring Type Joint flanges are typically used in high pressure (Class 600 and higher rating) and/or high temperature services above 800°F (427°C). They have grooves cut into their faces which steel ring gaskets. The flanges seal when tightened bolts compress the gasket between the flanges into the grooves, deforming (or Coining) the gasket to make intimate contact inside the grooves, creating a metal to metal seal.
An RTJ flange may have a raised face with a ring groove machined into it. This raised face does not serve as any part of the sealing means. For RTJ flanges that seal with ring gaskets, the raised faces of the connected and tightened flanges may contact each other. In this case the compressed gasket will not bear additional load beyond the bolt tension, vibration and movement cannot further crush the gasket and lessen the connecting tension.

Ring Type Joint gaskets are metallic sealing rings, suitable for high-pressure and high-temperature applications. They are always applied to special, accompanying flanges which ensure good, reliable sealing with the correct choice of profiles and material.
Ring Type Joint gaskets are designed to seal by “initial line contact” or wedging action between the mating flange and the gasket. By applying pressure on the seal interface through bolt force, the “softer” metal of the gasket flows into the microfine structure of the harder flange material, and creating a very tight and efficient seal.

The most applied rings are:
1. Type R-Oval according to ASME B16.20
The original style of metallic ring joint. Used on round bottomed groove flanges though can also be used on later, flat-bottomed groove flanges. Suitable for ASME B16.5 flanges from Class 150 to 2500.
2. Type R-Octagonal according to ASME B16.20
An improved design over the original Oval design. However these can be used only in flat-bottomed groove flanges. Suitable for ASME B16.5 flanges from Class 150 to 2500.

The octagonal cross section has a higher sealing efficiency than the oval and would be the preferred gasket. However, only the oval cross section can be used in the old type round bottom groove. The newer flat bottom groove design will accept either the oval or the octagonal cross section.
The sealing surfaces on the ring joint grooves must be smoothly finished to 63 Microinches and be free of objectionable ridges, tool or chatter marks. They seal by an initial line contact or a wedging action as the compressive forces are applied. The hardness of the ring should always be less than the hardness of the flanges.
Style R ring type joints are designed to seal pressure up to 6,250 psi in accordance with ASME B16.5 pressure ratings and up to 5,000 psi.

Male-and-Female (M&F)

With this type the flanges also must be matched. One flange face has an area that extends beyond the normal flange face (Male). The other flange or mating flange has a matching depression (Female) machined into it’s face.
The female face is 3/16-inch deep, the male face is1/4-inch high, and both are smooth finished. The outer diameter of the female face acts to locate and retain the gasket. Custom male and female facings are commonly found on the Heat Exchanger shell to channel and cover flanges.
Depth of female (recessed) face normally equal to or less than height of male (raised) face, to prevent metal-to-metal contact during gasket compression Recessed O.D. normally is not more than 1/16″ larger than the O.D. of the male face Joint must be pried apart for disassembly.

Tongue-and-Groove (T&G)

The Tongue and Groove faces of this flanges must be matched. One flange face has a raised ring (Tongue) machined onto the flange face while the mating flange has a matching depression (Groove) machined into it’s face.
Tongue-and-groove facings are standardized in both large and small types. They differ from male-and-female in that the inside diameters of the tongue-and-groove do not extend into the flange base, thus retaining the gasket on its inner and outer diameter. These are commonly found on pump covers and Valve Bonnets.
Tongue-and-groove joints also have an advantage in that they are self-aligning and act as a reservoir for the adhesive. The scarf joint keeps the axis of loading in line with the joint and does not require a major machining operation.
General flange faces such as the RTJ, T&G and the F&M shall never be bolted together. The reason for this is that the contact surfaces do not match and there is no gasket that has one type on one side and another type on the other side.

Groove to Flat

•      One flange face is flat, the other is recessed
•      For applications requiring accurate control of gasket compression
•      Only resilient gaskets are recommended —spiral wound, hollow metal O-ring, pressure-actuated, and metal-jacketed gaskets

Advantages and disadvantages of T&G and M&F flange faces
Advantages:
Better sealing properties, more precise location and exact compression af sealing material, utilization of other, more suitable sealing and spezialized sealing material (O-rings). 

Disadvantages: 
Commercial availabillity and cost. Normal raised faced is far more common and ready available both regarding Valves, flanges and sealing material. Another complexity is that some rigid rules must be applied to the piping design. Do you order Valves to be female end both sides, or on one side maybe, in which case do you point all male ends in the flow direction, or what. Same applies to any flanged joint / vessel connection of course.

What is the difference between a RTJ, FF, and RF flange on seals and thermowells?

The raised face, RF, is the standard process connection on our third party seals and thermowells. Both have options for a RTJ and FF type flange connections. The Raised Face (RF) is the most common type used in process plant applications. 
The gasket surface of the flange is raised above the bolting circle face. A Ring-type Joint (RTJ) can also have a raised gasket face with the difference being the ring groove machined in this face.
This groove will accommodate a steel ring gasket for flange mating. The Flat Face, FF, flange has a gasket surface that is in the same plane as the bolting circle face. 
None of these three flange types are interchangeable between types, i.e. RTJ flange cannot be mated to a RF flange.

Serration on the Flange Face

The flange face has small grooves as you can see in the image. This machining is known as a serration. Flange face can be smooth or serrated type. Which type of face to use is depends on the type of the gasket and service of the fluid.

Smooth finish is used with metallic gasket whereas serrated finish is used with non-metallic gasket. Soft material of gaskets is set in this serration and prevent liquid or gas from passing from flange joint.

Yaang can be spiral or concentric rings as you can see in the slide. Concentric rings type finishing is used when fluid is of very low density. If you use spiral type finish with very low density fluid, it may find leakage path through the spiral cavity.

Serration of flange face is specified in RMS (Root Mean Square) or AARH (Arithmetic Average Rough Height), the most common value of serrated face is 120-250 AARH. Comparator gauge is used to check serration of the flange. In the image, you can see the how gauge is used to verify the value of serration.

The most used Surfaces

A serrated finish, either concentric or spiral, is required with 30 to 55 grooves per inch and a resultant roughness between 125 and 500 microinches.

This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. These grades are often referred to by name e.g. stock finish. The exact definition of each grade may differ between manufacturers, but can be generalised as follows;

Stock Finish
The gasket contact surface is typically formed by a continuous (sometimes called phonographic) spiral groove generated by a 1.6mm radius round-nosed tool at a feed rate of 0.8mm per revolution with a depth of 0.15mm. This will result in a roughness between Ra 3.2 and 12.5 micrometers (125 – 500 microinch).
Smooth Finish
No definite tool marking should be apparent to the naked eye. This is typically achieved by having the gasket contact surface formed by a continuous (sometimes called phonographic) spiral groove generated by a 0.8mm radius round-nosed tool at a feed rate of 0.3mm per revolution with a depth of 0.05mm. This will result in a roughness between Ra 3.2 and 6.3 micrometers (125 – 250 microinch).

Hydrogen Service Finish
The finish for flanges in hydrogen service is very smooth, typically between Ra 2 and 3.2 micrometers (79 – 125 microinch).

Cold Water Finish
The flange face appears as mirror like. This flange finish is usually expected to be used with metal to metal contact, i.e. without a gasket. It is seldom used in the oil, petrochem and related industries.
Measuring Surface Roughness
Flange finish is generally measured by visual and tactile means. Comparing the feel of the machined face with that of a surface finish comparator gauge, occasionally referred to as a Rupert gauge, is considered adequate.
There are two common methods of expressing roughness. They are the Arithmetic Average Roughness Height (AARH) and the Root Mean Square (RMS) Average.
Arithmetic Average Roughness Height- Calculation of the Arithmetic Average Roughness Height involves measuring the distance of the peaks and valleys and performing an arithmetic average of the measurements.
Root Mean Square Average – Calculation of the Root Mean Square Average involves measuring the distance of peaks and valleys, adding the square of these measurements and calculating the square root of the total.
The RMS value is approximately 11% higher than the AARH value.

The type of forged flange and sealing face for flange

Flanges provide the necessary connections to link pipelines. Faces are the mating surface of a flange.

Different types of flange faces are used as the contact surfaces to seat the sealing gasket material.

The type of flange	The type of sealing face	Pressure Class(PN,MPA)
Plate flange(PL)	Raise Face(RF)	0.25-2.5
	Flat Face( FF)	0.25-1.6
Slip on flange(SO)	Raise Face(RF)	0.6-4.0
	Flat Face( FF)	0.6-1.6
	male and female face (MFM)	1.0-4.0
	Tongue and groove face (TG)	1.0-4.0
Welding Neck Flange(WN)	Raise Face(RF)	1.0-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	1.0-1.6
Integral type flange(IF)	Raise Face(RF)	0.6-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	0.6-1.6
Socket Weld Flange(SW)	Raise Face(RF)	1.0-10.0
	male and female face (MFM)	1.0-10.0
	Tongue and groove face (TG)	1.0-10.0
Thread Flange(Th)	Raise Face(RF)	0.6-4.0
	Flat Face( FF)	0.6-1.6
Lap joint Flange(LP)	Raise Face(RF)	0.6-1.6
	male and female face (MFM)	1.0-1.6
	Tongue and groove face (TG)	1.0-1.6
Blind flange(BL)	Raise Face(RF)	0.25-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	0.25-1.6

Other flange facings covered by these standards include the large and small tongue-and-groove facings, and the ring joint facing specifically for ring joint type metal gaskets.

Measure the size of a flange

At some point, with all the possibilities of thread form, diameter, and pitch, you need to send it off to SK Grimes or another machinist.

You could buy the thread pitch gauges and comparator and thread micrometer (to measure minor diameter) to fully define the thread, but that still won’t help you to find a ring.

Flange Inspection

Following to be confirmed during inspection of flange

•       Outer & Inner Diameter of body
•       Bolt Circle & Bolt hole Diameter
•       Hub Diameter & thickness of weld end
•       Length of the Hub
•       Straightness and alignment of the bolt hole

Permissible tolerances are given in B16.5 and B16.47 standard.

Place one end of a tape measure on the inside of the flange. The diameter is used to determine what size pipe a flange can be used with, so you must find this information by using the inside of the flange as opposed to the outside.

Stretch your tape measure across the center of the circular shape of the flange until it touches the other side of the unit. Keep this end of the tape measure on the inside of the flange as well. Because the flange is circular in shape, the tape measure must stretch across the exact center of the flange to provide an accurate measurement.

How to Measure the Diameter of a Flange?

A flange is a circular piece of equipment used to connect two pipes together. Flanges can be made out of stainless steel, copper or any other type of metal. They typically match the metal of the pipes they connect. Flanges help seal the pipes together, preventing water from leaking when it passes from one pipe to another along the way from its origin to its destination.

Place one end of a tape measure on the inside of the flange. The diameter is used to determine what size pipe a flange can be used with, so you must find this information by using the inside of the flange as opposed to the outside.

Stretch your tape measure across the center of the circular shape of the flange until it touches the other side of the unit. Keep this end of the tape measure on the inside of the flange as well. Because the flange is circular in shape, the tape measure must stretch across the exact center of the flange to provide an accurate measurement.

Although the dimension of the flange diameter is just one measurement used when identifying your flange, it is an incredibly crucial one when lining this piece up to your system.

Getting started with measurement — the devil is in the details

There are three separate steps when discussing the measurement of the flange diameter. First, measuring the flange’s inside diameter, then across center of the flange and finally, the outside diameter.

Step 1 – Start by measuring inside the flange by simply measuring the center hole. This diameter lets you know what size pipe should be paired with the flange. If you have documentation that tells you the inside measurement of the flange and pipe, make sure you have the right documentation for the part. Papers can get mixed up easily, so it never hurts to take a quick measurement to verify independently.

Step 2 – Measure across the center of the flange. Make sure you find the exact center of the flange to get an accurate dimension. You’ll notice that the bolt holes around the flanges are distributed evenly. This will help guide you to the center.

Step 3 – Finally, measure around the outside diameter of the flange. If your system is squeezed into a tight space, a flange that is too thick may cause problems and some other pipes may need to be moved. Knowing the outside diameter will help you plan for this.

That’s really about all that needs to be done when measuring the diameter of a flange. However, it’s easy to acquire some false confidence and skip one or more of these steps. Be sure to watch the details, which will ensure a much better installation.

If you’re building a new system, this is an opportunity to buy the pipes and flanges specifically manufactured to fit together according to widely accepted standards. Obviously, this will eliminate chances for error. Beyond the measurement, keep in mind what type of fluid will be passing through the system, the temperature of both the fluid inside, the working conditions outside, and of course, the material used to create the flange.

Some pipe/flange materials will not play nice with the chemicals passing through. Make sure you understand the demands the system will create.

Related: Guide to Properly Measuring Flanges

Pressure Classes of Flanges

The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.

Forged steel flanges, according to ASME B16.5, are made in seven primary Pressure Classes:

150 300 400 600 900 1500 2500

The concept of flange ratings likes clearly. 

A Class 300 flange can handle more pressure than a Class 150 flange, because a Class 300 flange are constructed with more metal and can withstand more pressure. However, there are a number of factors that can impact the pressure capability of a flange.

The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.
For example: 150 Lb or 150 Lbs or 150# or Class 150, all are means the same.

The concept of flange ratings likes clearly. A Class 300 flange can handle more pressure than a Class 150 flange, because a Class 300 flange are constructed with more metal and can withstand more pressure. However, there are a number of factors that can impact the pressure capability of a flange.
The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.
For example: 150 Lb or 150 Lbs or 150# or Class 150, all are means the same.

Example of Pressure Rating

Flanges can withstand different pressures at different temperatures. As temperature increases, the pressure rating of the flange decreases. For example, a Class 150 flange is rated to approximately 270 PSIG at ambient conditions, 180 PSIG at approximately 400°F, 150 PSIG at approximately 600°F, and 75 PSIG at approximately 800°F.
In other words, when the pressure goes down, the temperature goes up and vice versa. Additional factors are that flanges can be constructed from different materials, such as stainless steel, cast and ductile iron, carbon steel etc.. Each material have different pressure ratings.
Below an example of a flange NPS 12 with the several pressure classes. As you can see, inner diameter and diameter of the raised face at all the same; but outside diameter, bolt circle and diameter of bolt holes become larger in each higher pressure class.

The number and diameters (mm) of the bolt holes are:

• CL 150 – 12 x 25.4
• CL 300 – 16 x 28.6
• CL 400 – 16 x 34.9
• CL 600 – 20 x 34.9
• CL 900 – 20 x 38.1 CL
• 1500 – 16 x 54 CL 2500 – 12 x 73

Pressure-Temperature Ratings – Example

Pressure-temperature ratings are maximum allowable working gage pressures in bar units at the temperatures in degrees celsius. For intermediate temperatures, linear interpolation is permitted. Interpolation between class designations is not permitted.
Pressure-temperature ratings apply to flanged joints that conform to the limitations on bolting and on gaskets, which are made up in accordance with good practice for alignment and assembly. Use of these ratings for flanged joints not conforming to these limitations is the responsibility of the user.
The temperature shown for a corresponding pressure rating is the temperature of the pressure-containing shell of the component. In general, this temperature is the same as that of the contained fluid. Use of a pressure rating corresponding to a temperature other than that of the contained fluid is the responsibility of the user, subject to the requirements of applicable codes and regulations. For any temperature below -29°C, the rating shall be no greater than the rating shown for -29°C.
As an example, below you will find two tables with material groups acc. to ASTM, and two other tables
with flange pressure-temperature ratings for those ASTM materials acc. to ASME B16.5.

Requirements are valid for normal situation, in special you have to contact us to introduce.

ASTM GROUP 2-1.1 MATERIALS

Notes:

·                                 (1) Upon prolonged exposure to temperatures above 425°C, the carbide phase of steel may be converted to graphite. Permissible but not recommended for prolonged use above 425°C.

·                                 (2) Do not use over 455°C.

·                                 (3) Do not use over 260°C.

·                                 (4) Do not use over 370°C.

ASTM GROUP 2-2.3 MATERIALS

Note: Do not use over 425°C.

PRESSURE-TEMPERATURE RATINGS FOR ASTM GROUP 2-1.1 MATERIALS

Working pressure by Classes, BAR

PRESSURE-TEMPERATURE RATINGS FOR ASTM GROUP 2-2.3 MATERIALS

Working pressure by Classes, BAR

Related: Pressure Rating ANSI Flange / Class 150-2500 

·   Flange Connections

Flange connection is to two pipes, fittings or equipment before each fixed at a flange on the flange between the two, together with flange pad, fastened together with bolts to complete the connection.

Some of pipe fittings and equipment have been built-flange, also falls within the flange connection. Has flanged pipe and fittings, also belongs to the flange. Flange connections are an important connection for pipeline construction. Flange connections easy to use, able to withstand greater pressure.

Sub-threaded flange connection (wiretapping) flange and welding flange. Low-pressure small-diameter wire access flange, high pressure and low pressure are the use of large-diameter welded flange, different pressure, flange thickness and bolt diameter and the number of connections are different.

Within the family, pipe diameter, and are low-voltage, see flange connection. If produced in a boiler room or scene is full of flanged pipes and fittings.

As iron welded flange, a lot of customers have doubts is the quality is better than the forging of iron welding flange welding flange. Actually iron welding flange of quality and forged of welding flange of quality is as of, but iron welding flange what place cannot has guarantees does, is iron welding flange of material most no guarantees has, because General of process among, iron welding flange of density is no problem of, but in for production of process among, iron welding flange of rough rarely for detection, so for, by production out yahoo, not after detection of iron welding flange of material cannot guarantee.

The different grades based on the pressure, flange pad also has a variety of materials, from the low-pressure asbestos pad, high-pressure pads to the metal pads are asbestos.

Within the family, pipe diameter is small, but also ow-voltage, see flange connection. If a boiler room or a production site, full of flanged pipes and equipment. Flange connection is to two pipes, fittings or equipment before each fixed at a flange on the flange between the two, together with flange pad, fastened together with bolts to complete the connection. Some of pipe fittings and equipment have been built-flange, also falls within the flange connection.

How to select the gasket for Flange Connections?

One of the best all-around seals, the spiral wound gasket offers a low-cost solution that has the ability to handle temperature and pressure fluctuations. Multiple plies of metal and filler in the spiral create a barrier that reduces the possibility of leaks.

Heat Exchanger Gaskets

Garlock manufactures a wide variety of double-jacketed, spiral-wound, metal-clad and solid metal gaskets for heat exchanger applications. GRAPHONIC® and Kammprofile gaskets are also available in heat exchanger configurations.

Temperature and Chemical Considerations

Be certain that the gasket you order is as resistant as possible to the media and temperature involved. Check the chemical compatibility of the metal as well as the filler material for the media to be sealed. As a general rule, the metal used in either the spiral winding or double-jacketed gasket should be similar to the flange material.

The compressibility of flexible graphite makes it an excellent filler material for metallic gaskets. Flexible graphite may be used in services with temperatures up to 950ºF (485ºC), though it should not be used with strong oxidizers such as nitric or sulfuric acid.

PTFE filler material provides excellent chemical resistance at temperatures below 500ºF (260ºC). In accordance with ASME B16.20, an inner ring is required when using conventional PTFE filler materials, in order to protect the winding from radial buckling.

Flange gasket

A flange gasket is a type of gasket made to fit between two sections of pipe that are flared to provide higher surface area.

Flange gaskets come in a variety of sizes and are categorized by their inside diameter and their outside diameter.
There are many standards in gasket for flanges of pipes. The gaskets for flanges can be divided in major 4 different categories:

•       Sheet gaskets
•       Corrugated metal gaskets
•       Ring gaskets
•       Spiral wound gaskets

Sheet gaskets are simple, they are cut to size either with bolt holes or without holes for standard sizes with various thickness and material suitable to media and temperature pressure of pipeline.
Ring gaskets also known as RTJ. They are mostly used in offshore oil- and gas pipelines and are designed to work under extremely high pressure. They are solid rings of metal in different cross sections like oval, round, octagonal etc. Sometimes they come with hole in center for pressure equalization.
Spiral wound gaskets are also used in high pressure pipelines and are made with stainless steel outer and inner rings and a center filled with spirally wound stainless steel tape wound together with graphite and PTFE, formed in V shape. Internal pressure acts upon the faces of the V, forcing the gasket to seal against the flange faces.

Types of flange gaskets

Materials for gaskets can be divided into three main categories:

• Non-Metallic types
• Semi-Metallic types
• Metallic types

Non-Metallic gaskets are usually composite sheet materials are used with flat-face and raised-face flanges in low Pressure Class applications. Non-metallic gaskets are manufactured from arimid fiber, glass fiber, elastomer, Teflon® (PTFE), graphite etc.. Full-face gasket types are suitable for use with flat-face flanges. Flat-ring gasket types are suitable for use with raised face flanges.
ASME B16.21 covers types, sizes, materials, dimensions, dimensional tolerances, and markings for non-metallic flat gaskets.

Bolted Flange connections

A bolted flange connection is a complex combination of many factors (Flange, Bolts, Gaskets, Process, Temperature, Pressure, Medium). All these various elements are interrelated and depend upon one another to achieve a successful result.

TYPICAL BOLTED FLANGE CONNECTION

The reliability of the flanged joint depends critically upon competent control of the joint making process.

Some other disadvantages of flange connections:

• Each flange connection can leak (some people claim that a flange connection is never 100 percent leak proof).
• Flanged pipe systems need much more space (just think of a pipe rack).
• Insulation of flanged pipe systems is more expensive (special flange caps).

Applications of flanges

Flanges are integral parts of many engineering and plumbing projects.

In many applications, engineers need to find a way to close off a chamber or cylinder in a very secure fashion, usually because the substance inside must differ from the substance outside in composition or pressure. They do this by fastening two pieces of metal or other material together with a circle of bolts on a lip. This “lip” is a flange.

Plumbing

You can connect two sections of metal piping by soldering or welding them together, but pipes connected in this way are very susceptible to bursting at high pressures. A way of connecting two sections of pipe more securely is by having flanged ends that you can connect with bolts. This way, even if gases or liquids build up to high pressures inside the pipe, it will often hold with no problem.

Mechanics

In order to connect two sections of a large, enclosed area, it is often best to used flanges and bolts. An example of this is the connection between the engine and the transmission in an automobile. In this case, both the engine and the transmission contain a number of moving parts that can easily get damaged if they get dust or other small objects inside of them. By connecting the outer casings of the engine and transmission in this way, engineers protect the inner workings of both.

Electronics

Flanges have a specific purpose in cameras and other electronic devices. Though flanges in such items do not usually have to sustain high pressures, they do have to hold tight so they can keep out harmful particles. These flanges are usually found connecting two different materials, such as the glass of a lens and the rest of the body of the camera.

Applications of ANSI Long Weld Neck Flanges

Applications involving high pressure and the need for a hub that is long and tapered are what weld neck flanges are most often used for. Specifying the schedule of pipe that it will be utilized for is of utmost importance when ordering. This type of flange is excellent for use in environments involving extreme temperature fluctuations and excessive handling and bending.

Uses for Long Weld Neck Flanges

The uses for long weld neck flanges are predominantly on vessels where an extended neck is required. The uses for long weld neck flanges (LWN) are predominantly on vessels where an extended neck is required. This is deemed to be a specialty flange due to the protruding neck or hub, which acts as a boring extension.

The tapered neck aids in reducing the thickness of the steel and it then seems to be a pipe extension. Steel LWN flanges are chiefly utilized in the chemical and petroleum industries, as well as commercial and residential buildings that experience high levels of stress and temperatures that fluctuate.

Source: China Flanges Manufacturer – Yaang Pipe Industry (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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References:

1. https://en.wikipedia.org/wiki/Flange
2. https://www.pipingonline.com/flanges/flange_facing_type-rf_flange-ff_flange-rtj_flange-raised_face_flange-flat_face_flange-ring_joint_flange
3. http://blog.worldwidemetric.com/problem-solving/guide-to-properly-measuring-flanges/
4. https://www.pipingonline.com/flanges/flange_pressure_rating-flange_class-flange_max_pressure-asme_pressure_rating
5. https://www.yaang.com/stainless-steel-flange-connection-methods.html