A flange is the protruding rim that enable pipes, valves and other equipment to form a connection. Flanges also increase strength at the joint. They enable you to create a piping system while also allowing for fast disassembly. By providing access points, inspections or modifications can be carried out with relative ease.
How you make a pipe-flange connection varies. It depends on the type and the requirements of your piping system. Some are weld-on pipe flange, while others can be screwed on. The type of flange you choose will also depend on issues such as pressure capacity and application. But first, let’s look at Common Flange types.
While specialty pipe flanges are available, there are six main types. Here they are, along with how to secure the flange on a pipe.
They’re used in low-pressure systems on smaller pipes with thick walls. They also make it easy to connect and disconnect pipe systems without disrupting the entire system for maintenance or to make adjustments. To attach the flange on a pipe, the bore’s female thread is screwed onto the pipe’s external threads. These flanges are not welded on.
Typical use:
Flammable, hazardous or explosive applications where welding is dangerous
Ideal in restricted spaces where welding flange to pipe can’t be carried out
The simple design is intended for small-size and high-pressure piping that do not transfer highly corrosive fluids. Socket weld flanges are attached by inserting the pipe into the socket and applying one fillet weld around the outside of the flange. First, the pipe is inserted in the socket of the flange. When it reaches the
bottom of the flange, the pipe is lifted out slightly by 1/16" (1.5mm) and welded. This gap allows for thermal expansion created by welding, minimizing the probability that the weld will crack. Not suitable for highly erosive or corrosive applications, as the gap is vulnerable to corrosion between the pipe end and the socket’s shoulder.
Typical use:
Hydraulic pipes
Slides over the pipe and used with a stub end. Also known as loose-ring flanges, and back-up flanges. These flanges are used on piping fitted with lapped pipe or with lap joint stub ends. With the stub end, the lap joint flange is typically used in systems requiring frequent dismantling for inspection and cleaning. Another advantage is its ability to swivel and align with bolt holes. As the flange never comes into contact with the fluid, the flange is highly durable and can be re-used.
Not recommended in extreme or high-pressure temperature applications.
Typical use:
Low-pressure applications
When flange needs frequent dismantling for maintenance
These low-pressure flanges are thinner than most other flanges. With an inside diameter slightly larger than the pipe’s outside diameter, the flange slips onto the pipe. A fillet weld is applied at the top of the flange and at the bottom. The welds enhance strength and prevent leakage. Also known as hubbed flanges. Installation of slip-on pipe flanges is easy and therefore low cost.
The speed at placing the flange on the pipe saves costs, but those savings are reduced with the additional costs of two fillet welds which are needed for proper installation.
Typical use:
Cooling and firefighting water lines
Process lines for oil, gas and steam
The lack of an inner hole enables blind flanges to seal off the end of pipe systems, preventing flow. This makes it easier and more cost efficient to carry out pressure tests. The blind flange connection is also an ideal pipeline flange. You can stop the flow of fluid and safely add new pipes or new lines to the pipeline.
Without blind flanges, shutdowns and repairs would be incredibly difficult to handle. While shutoff valves solve the problem of stopping flow, the location of the valve can be a problem. For example, if the valves are a mile or two away, then you’re looking at a significant amount of wasted fluid.
Blind flanges are installed with bolts, so they’re also easy to remove.
Typical use:
Testing pipe pressure
Creating access points to piping systems
Seal a piping system temporarily to make repairs, or permanently
Also known as weld bend flanges. Their long necks are butt welded to a pipe. The flange’s bore matches that of the pipe, reducing turbulence and erosion. This flanged connection relocates stress to the pipes, ensuring a decrease in high-stress concentration at the bottom of the flange. When installing, weld neck pipe flanges must be positioned parallel at the time of fitting. Flanges at opposite ends of a pipe should typically have the same bolt-hole direction too.
Typical use:
Piping systems with repeating bends
In conditions with wide fluctuations in temperature and pressure
Volatile and hazardous fluids
Type
Pressure capacity
Pipe sizes
Use for
Threaded
Low
Small
Attaching without welding
Lap joint
Low
All
Systems that need frequent disassembly
Slip on
Low
All
Low installation cost; easy assembly
Blind
Very high
All
Flow pressure testing; closing pipes
Welded neck
High
All
High-pressure systems; extreme temperatures
The flange face is the area on the head where your gasket will go. The three most common types are:
Raised face (RF)
Ring type joint (RTJ)
Flat face (FF)
Flanges with different faces should not be mated. For example, a raised face to flat-face flange connection will result in leakage from the joint, per ASME code B31.3.
The Most Common type is the raised face flange. Its name comes from the raised gasket surface, above the bolting circle face. The raised face concentrates more pressure on a smaller gasket area. In turn, this increases the joint’s pressure containment capability.
The height of the raised face is determined by the flange’s pressure rating. Likewise, the higher the pressure rating, the bigger the flange diameter, the more bolts needed and the thicker the flange.
Raised face vs. flat face flange, also called full face flange, isn’t an issue. They play different roles. Instead of a raised face, this is a flat surface. Consequently, the gasket surface is the same plane as the bolt frame, covering the flange from its inside diameter to outside diameter.
Full face is designed to avoid the bending that flanges undergo as bolts are torqued.
Cast iron can break during this process, which is why this material is often used to make flat face flanges. The design prevents this problem from happening.
High temperature, high-pressure flanges or rather, flanges used in extreme environments, utilize a ring-type-joint face. These flanges often have a raised face with a ring groove machined into it. They can also have grooves cut into their faces with steel ring gaskets. The flanges seal when the bolts are torqued, compressing the gasket between the flanges into the grooves.
The purpose behind a raised face flange is to concentrate more pressure on a smaller gasket area, increasing the joint’s ability to contain the pressure. Ring-type-joint face flanges don’t use gaskets. The groove within the flange enables the ring to center itself when the bolts are torqued. As the process pressure increases, so, too, does the sealing pressure.
Typically used:
Raised face flange
Flat face flange
Ring-type- joint face
Process plants (chemical, etc.)
Oil & gas
Valves
Cast-iron equipment
Low-pressure water pipe systems
Severe applications: high pressure and high temperature (up to 1,382⁰F/ 750⁰C)
The pipe flange face is vulnerable to damage during handling and transport, so you need to think about flange covers. This flange cover shown here is made of durable and flexible polyethylene. It protects both raised and flat face flanges, along with full-face gaskets.
Flange protectors are also critical. The studded full face flange protector here is also made of polyethylene and provides full coverage by inserting the lugs firmly into the bolt holes.
Understand more about flange covers in our guide, Why Flange Covers are Essential.
The raised face flange protector shown here has an adhesive backing for fast application.
You can learn more about flange protection in Pipe & flange protection: a quick buyer’s guide.
Whether steel pipe flanges or a plastic flange, you should base the material you choose on its application. Typically, the materials should match your pipe material, but again, it depends on your application. For example, if your piping system is used for air or other non-corrosive applications, then your flanges and pipes may not need to be of the same corrosion-resistant material as acidic or caustic liquids.
Otherwise, if you’re interested in say, carbon steel slip-on flanges, you need to match the grade steel you choose to the pipe. Common flange materials include:
Carbon-steel flanges are alloyed primarily with carbon. Carbon steel has a high hardness and strength that increases with carbon content but lowers ductility and melting point. Carbon steels range from mild and low, with 0.16—0.29% carbon to ultra-high carbon steel, with around 1–2% carbon. Steels with carbon content above 2% are considered cast iron.
Just as you can enhance properties in plastics with additives, you can alloy steels with other elements to enhance the properties of your chose steel. Common alloys include molybdenum and chromium. Through different elements, you can increase a steel’s strength, ductility, corrosion resistance, and machinability.
Stainless steel is alloyed with chromium in amounts above 10%. It’s chromium that gives stainless steel a higher corrosion resistance than carbon steel, which easily oxidizes from air and moisture exposure. Stainless steel is ideal for corrosive applications that also require high strength. Different grades of stainless steels yield different outcomes. You can learn more in our guide, Understanding stainless-steel grades.
When iron is alloyed with carbon, silicon, and other alloyants, the result is cast iron. Cast irons have good fluidity, castability, machinability, and wear resistance. They tend to be brittle to a degree with low melting points.
This is a low-density metal with medium strength. Malleable and ductile, it’s more corrosion resistant than typical carbon and alloy steels. Aluminum is suitable for flanges that need both strength and low weight, such as for irrigation applications.
A PVC flange is low cost and durable. PVC pipe flanges also have the advantage of being both chemical and corrosion resistant. Additives can make PVC more flexible and softer. PVC flange connections can provide extra protection to underlying pipes. They’re also popular for water-treatment processes, favored by the agricultural industry and used in domestic plumbing. Lightweight and easy to install, PVC flanges are perfect for PVC pipe systems.
For all flange types excluding ring-type-joint faces, you’ll need gaskets. Choose them based on factors such as operating temperature, the fluid being conveyed by the pipeline, flange type, size, pressure class or rating and other specifications. First, however, you need to know material properties, which can be enhanced with additives.
Suitable for
EPDM
Natural rubber/SBR
Neoprene
Nitrile
Butyl
Silicone
Flange dimensions are determined by the nominal pipe size (NPS) and the pressure class that your application requires. The higher the pressure rating of the class, the higher the size and dimensions of the flange. Typically, a 1/2" pipe flange will belong to the 150-pound pressure class. For threaded flange, a 4" pipe flange is the largest size available.
Large diameter flanges are in higher pressure classes. Below are the different classes:
150 lbs
300 lbs
400 lbs
600 lbs
900 lbs
lbs
lbs
Flange types and sizes vary, but they’re manufactured according to the standards set by organizations. For example, a long weld neck flange ASME B16.5 conforms to ASME standards, and might differ slightly from another standard. ASME B16.5 swivel flange dimensions – a type of weld neck flange – have equivalents in EN and MSS standards.
(If you see, for example, ANSI 150 swivel flange dimensions, this is incorrect. ANSI at one time published standards and started working with ASME in . At the time standards appeared as ANSI/ASME, but by , ASME had taken over standards.)
So your first task is determining the standard you’ll work to, which will likely follow what’s commonly used in your area.
Size standards are set according for each pressure class.
The example here is a threaded flange, both raised face and flat face, according to ASME B16.5. The pressure class is 150.
Sizes: inches
Flange NPS
I.D.
O.D.
Bolt circle (BC)
Raised face (R)
Raised face (RF)
H
Raised face thickness (T)
T1
Flat face thickness (T2)
Bolt hole (B)
No. of bolt holes
½
0.93
3.50
2.38
1.38
.063
1.19
.62
.38
.56
.62
4
¾
1.14
3.88
2.75
1.69
.063
1.50
.62
.44
.56
.62
4
1
1.41
4.25
3.12
2.00
.063
1.94
.69
.50
.63
.62
4
1 ¼
1.75
4.62
3.50
2.50
.063
2.31
.81
.56
.75
.62
4
1 ½
1.99
5.00
3.88
2.88
0.63
2.56
.88
.62
.82
.62
4
2
2.50
6.00
4.75
3.62
0.63
3.06
1.00
.69
.94
.75
4
2 ½
3.00
7.00
5.50
4.12
0.63
3.56
1.12
.82
1.06
.75
4
3
3.63
7.50
6.00
5.00
0.63
4.25
1.19
.88
1.13
.75
4
3 ½
4.13
8.50
7.00
5.50
0.63
4.81
1.25
.88
1.19
.75
8
4
4.63
9.00
7.50
6.19
0.63
5.31
1.31
.88
1.25
.75
8
5
5.69
10.00
8.50
7.31
0.63
6.44
1.44
.88
1.38
.88
8
6
6.75
11.00
9.50
8.50
0.63
7.56
1.56
.94
1.50
.88
8
8
8.75
13.50
11.75
10.62
0.63
9.69
1.75
1.06
1.69
.88
8
10
10.88
16.00
14.25
12.75
0.63
12.00
1.94
1.13
1.88
1.00
12
12
12.94
19.00
17.00
15.00
0.63
14.38
2.19
1.19
2.13
1.00
12
14
14.19
21.00
18.75
16.25
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0.63
15.75
2.25
1.32
2.19
1.12
12
16
16.19
23.50
21.25
18.50
0.63
18.00
2.50
1.38
2.44
1.12
16
18
18.19
25.00
22.75
21.00
0.63
19.88
2.69
1.50
2.63
1.25
16
20
20.19
27.50
25.00
23.00
0.63
22.00
2.88
1.63
2.83
1.25
20
22
22.19
29.50
27.25
25.25
0.63
24.25
3.13
1.75
3.07
1.38
20
24
24.19
32.00
29.50
27.25
0.63
26.12
3.25
1.82
3.19
1.38
20
EN sizes: millimetres
DN
D
(diameter)
k
(PCD)
b
(thickness)
d2
(diameter of bolt hole)
Bolt size
No. of holes
Weight (kg)
10
90
60
16
14
M12
4
0.72
15
95
65
16
14
M12
4
0.81
20
105
75
18
14
M12
4
1.14
25
115
85
18
14
M12
4
1.38
32
140
100
18
18
M16
4
2.03
40
150
110
18
18
M16
4
2.35
50
165
125
18
18
M16
4
2.88
65
185
145
18
18
M16
8
3.51
80
200
160
20
18
M16
8
4.61
100
220
180
20
18
M16
8
5.65
125
250
210
22
18
M16
8
8.13
150
285
240
22
22
M20
8
10.5
200
340
295
24
22
M20
8
16.5
250
395
350
26
22
M20
12
24.1
300
445
400
26
22
M20
12
30.8
350
505
460
26
22
M20
16
39.6
400
565
515
26
26
M24
16
49.4
450
615
565
26
26
M24
20
63.0
500
670
620
28
26
M24
20
75.2
600
780
725
34
30
M27
20
124
700
895
840
38
30
M27
24
183
800
950
42
33
M30
24
29.7
900
46
33
M30
28
374
52
36
M33
28
492
60
39
M36
32
842
Free CADs are available for most solutions, which you can download. You can also request free samples to make sure you’ve chosen the right product for what you need.
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A flange casting is typically a cast ring designed to connect the sections of a pipe or other machinery which requires a connecting joint.
Most cast options are outdated and flanges provided to modern specifications are made from plate or forged carbon steel or stainless steel. Before you buy flanges, it is crucial to note that these flanges come in different measurements, diameters, sizes, types/forms, and materials.
Several types of flanges are available for different types of applications. Therefore, all you have to do is choose your product on a per-project basis. When we talk about the materials to use in your applications, a variety of factors come into play. Therefore, some crucial aspects that are required to be considered while buying stainless steel flanges are discussed in this blog:
It is crucial to note the diameter of the pipes to which the flange needs to be connected. Also, you must understand that these pipe connections could be ERW, welded, seamless, etc., and would help you choose the required flanges.
Stainless steel pipe flanges, rings, and discs attach to the pipe to increase the strength or support based on the existing connection type from the pipe, which are usually welded or screwed to the pipe end. These pipe flanges are designed per the specifications and are easy to customize by established manufacturers.
SS Flanges are accessible in numerous grades. The client’s selection of products needs to rely on the budget and project you need. However, top-quality products need to be costly and need to be sturdy.
Both SS 316L Flanges and SS 304L Flanges are corrosion resistant alloys with a high, 95% alloy composition. SS 316 and SS 304 belong to the chromium-nickel category and are grades that withstand standard corrosion. It needs to be durable, resists most basic chemicals, and hold more excellent resistance to numerous types of deterioration.
Here’s how you can select the SS flange types available around the market:
The bore size of the slip-on flange as a standard is slightly larger compared to the outside diameter of the connecting pipe, as the pipe has to slide inside the flange then needs to be connected by the execution of the fillet weld around the perimeter.
SS Weld neck flanges are helpful in high/low-temperature applications and high-pressures that require an unrestricted fluid flow conveyed by the piping system. These butt-weld end connection flanges are most common in industrial applications to ensure a high strength connection between assemblies.
Most piping systems require regular inspection and blind/blank flanges are common inspection point. This type of flange, when selected according to the proper pressure class, can easily handle the stress caused by the liquid’s operating pressure and pressure flowing through the pipe. They are helpful to ‘blank off’ valves, pipelines, etc… in almost all applications.
You can assemble the flange without welding, and hence it is easy to remove. You do not have to use it for applications where bending stresses involve high pressure or temperatures. A seal weld is useful in conjunctions with times.
It is a type of slip-on flange but made for connecting to a stub end for rotation. Lap joints are helpful to maintain carbon/low alloy steel pipes with additional mechanical properties. These flanges are similar to slip-on flanges but are characterized by the radius-rounded interior edge of the flange face and generally come with a taller hub.
Smaller diameter socket weld and counter bore flanges handle the applications with high pressures like steam lines but with limited spacing. You must ensure durability possess internal welds—the bore of the pipe and flange match provides a good flow connection.
If you want to combine two pipeline components in assemblies for which you need easy access to modify, inspect, and clean, orifice sets are commonly recommended. Types need to vary as per the use and maintain high-pressure applications, and line blanks are also usually installed for maintenance or operating differentials.
Even if you find a range of flanges in the market, we offer you the best quality for your establishment. Nothing can beat stainless steel flanges in most lighter corrosion applications. The above blog signifies the buying guide of stainless steel flanges above; we hope you’ve now good knowledge about various steel flanges and whether they are the best option for you or not.
If you want any specific information, then contact Texas Flange today!
A breast pump flange, also known as a breast shield, is a plastic or silicone piece that fits directly over your nipple to form a seal. When you begin to pump, this creates a vacuum seal that should only draw your nipple into the flange tunnel for maximum milk extraction. Many pumps come with 24mm flanges, but you may need to select smaller or larger flanges based on your measurement and experience when pumping.
Having the wrong flange size can affect milk supply, cause nipple pain and damage, and can even lead to clogged milk ducts (ductal narrowing) and mastitis. Having the correct flange size is also key for allowing adequate pump suction and milk removal.
For first-time pumps, seeing a lactation specialist can be helpful in determining the correct flange size for your nipple size as well as areola density and fullness, and can make a big difference in your pumping experience.
A flange can be characterized and classified in various ways such as:
-Types of Connection
-Flange facing Types
-Pressure Temperature Ratings
-Material Types
The standard type of steel flanges mostly used are:
In addition to the most used standard flanges, there are still a number of special steel flanges such as:
We are manufacturer of high quality steel flanges and supply high quality flanges in both large and small quantities worldwide and offer you the best prices in the market.
A flange is produced either by forging, casting, cutting, or rolling. We produce flanges mainly by forging, cutting, and rolling process.
The forging process is usually composed of the following processes, namely, the selection of quality steel billet, heating, forming and cooling.
Are you interested in learning more about Ss304 Long Weld Neck Flange? Contact us today to secure an expert consultation!