Difference Between Alloy Steel Flanges v/s Carbon Steel Flanges

Carbon steel and alloy steel are different kinds of material grades for flanges, although both are extremely common. Alloy steel comes with a variety of elements depending upon future applications.

Carbon steel is also known as iron-carbon alloy contains less than 2% carbon WC. It usually contains small amounts of carbon, phosphorus, sulfur, manganese, and silicon in the mix.

In the case of alloy steel, elements like molybdenum, manganese, chromium, nickel, vanadium, silicon, and boron are used to form a different chemical composition. Generally, alloy steels are of the higher nickel variety and the term is used to distinguish them from regular stainless or low chrome materials.

Alloy steel

Alloying improves the mechanical properties of steel. The variety of elements used helps to improve future applications. Every steel is an alloy but not all steel is referred to alloy steel.

However, the term alloy steel is the standard term that refers to steel with other elements added deliberately in addition to vanadium, silicon, boron, molybdenum, manganese, chromium, nickel, and other elements.

The less common alloy elements include aluminum, cobalt, copper, cerium, niobium, titanium, tungsten, tin, zinc, lead, and zirconium, etc. The alloyed steels have improved properties, like strength, hardness, toughness, wear resistance, corrosion resistance, hot hardness, and hardenability.

Uses and application of Alloy steel

Alloy steels flanges come in a broad range of applications.  Low alloy steel has applications in a wide range of industries due to its cost-effectiveness. It has applications in military vehicles, construction equipment, ships, pipelines, pressure vessels, and oil drilling platforms.

High alloy steels are widely applied in various applications due to their structural components, automotive applications, chemical processing equipment, corrosion resistance, and superior hardness.

Advantages of Alloy steel

Here are some advantages of alloy steel

1. Corrosion resistance

2. Powerful parts

3. Efficient at high temperature

4. Heat dissipation properties

5. Durable

6. Tough

7. Lightweight

8. High tensile strength

Carbon steel

Carbon steel is a special type of steel with a higher concentration of carbon compared to regular iron. Carbon steel with carbon components less than 0.30% is categorized as low or mild carbon steel, carbon steel with carbon components between 0.30% to 0.60% is considered medium carbon steel, and carbon steel with high carbon components more than 0.60% is known as high carbon steel.

The use of high-carbon steel is usually for tools and knives. Though low carbon steel is more common compared to high-carbon steel because of its greater ductility, easy use, and low production cost.

Uses and application of Carbon steel

Carbon steel flanges are one of the most preferable materials used in fields where higher strength is required. Many types of carbon steel pipes come with a wide range of applications in various industries. Low-carbon steel has applications like automobile components, pipes, construction components, bridge components, containers/cans, etc.

Medium carbon steel is usually useful in machinery parts, gears, railway tracks, train wheels, and crankshafts that require higher strength and toughness. High carbon steel has applications in shear blades, cold setts, punches, rock drills, hand tools, cold chisels, band saws, anvil faces, hammers, wrenches, car bumpers, small forgings, cable wire, large dies for cold presses, cutting tools, high strength wires, and springs.

Advantages of carbon steel

Here are some advantages of carbon steel

1. Good strength

2. Good ductility

3. Durable

4. Safe to process

5. Economical / Budget friendly

6. Healthy and long-lasting for cookware

7. Environment friendly


There are many types of steel within the groups of alloy steel and carbon steel. As the name shows, alloy steel is the category of steel formed by adding various other elements to the steel through metallurgy and heat treatment. On the other hand, carbon steel is steel with carbon as the accompanying component. It also usually does not require any minimum percentage of other elements.

Carbon steel is the type of steel predominantly used in the US for most basic applications when compared to alloy steel, which is found in more chemically sensitive and temperature-elevated services.

In the above comparison, we hope you’ve understood the difference between carbon steel and alloy steel and their uses. This guide will help you identify the key things if you are stuck between selecting the two flanges. To learn more about flange basics, visit https://www.texasflange.com/flange-basics/

Socket Weld Fittings Types and Applications

We are already aware of the four connecting types for the pipe fittings: Slip on flanges, Threaded flanges, Socket Weld (counter bore), and Butt Weld Neck. In terms of the steel pipe fittings that you would use for your pipeline projects, you will find two of them to be quite popular: butt weld fittings and socket weld fittings.

Since both of them seem to have their share of advantages and disadvantages, you may be confused about which one is the best for your particular purpose.

To learn more about socket weld fittings, read on below.

Meaning of socket weld pipe fittings

A socket weld flange fitting is a pipe attachment detail with a socket and counter bore. In this case, you can insert the pipe into a recessed area of flange or fitting. To join the valves or pipes to the other sections of the pipe, seal welds of fillet type together. In several cases, socket weld fittings are a good choice. The benefits of high leakage integrity and great structural strength would be quite an essential factor that needs to be taken into consideration when designing your pipeline project.

Socket Weld Fittings Types and Applications

Usage of socket weld fittings

Socket weld fittings are termed to be used for low to medium pressure in confined spaces, and could easily be used in a diverse range of industrial processes.

Applied in the places where pipework has been deemed to be permanent. In addition, they have also been designed in a manner that provides characteristics of good flow.

Used in conjunction with ASME pipe and for to change to different dimensions.

Socket weld pipe fittings like reducers, tees, elbows, etc can be used at pipelines for conveying expensive, flammable, or toxic materials where there would be no scope of leakage.

Manufactured under ASTM standards and also according to ASME B16.5 /16.11

Types of Socket weld pipe fittings

Like the butt weld fittings, based on material types, socket weld fittings also include a variety of materials as stainless steel pipe fittings, alloy steel flanges, and carbon steel flanges. Based on the applications, it includes flanges, couplings, reducers, reducing tee, socket weld inserts, and socket weld elbows, etc.

Advantages and Disadvantages of Socket Weld

Below are some advantages and disadvantages of the socket weld:


The pipe often does not need to be end finished properly for the preparation of an insert weld.

Temporary tack welding usually doesn’t need alignment. It is because the principle in fitting would help to make sure that it has a proper alignment.

The socket weld insert will not be able to penetrate the bore of the pipe.

Costs of construction are sometimes lower than butt-welded joints. Due to the elimination of special machines, it lacks the exact fit-up bevel requirements.


The welder must make sure that the expansion gap between the pipe and the shoulder of the socket must be of a certain distance, often approaching 1.6mm.

The expansion gap and internal crevices in the socket weld system may promote corrosion with certain media. It would be because of this reason that they have been deemed to be less suitable for corrosive or radioactive applications.

These types of fittings would also be unacceptable for Ultra High Hydrostatic Pressure in food industries. The reason could be the addition to not allow full penetration. It would also leave gaps and crevices that would then become difficult to clean.

Differences between butt weld and socket weld fittings

In the case of socket weld fittings, the referred standard is ASME B16.11. You can insert a pipe in a recessed area of the fitting. You can square cut both the pipe and fitting and do not require any beveled end or preparation other than cleaning the outside. It will ease out the welding processes and installation.

When we talk about butt weld fittings, as pet standard ASME B16.9, the ends being welded onto the pipe end, the thickness would be the same as those of pipes. In this case, the end of the fittings could be beveled to match the application.

Application and installation of socket weld fittings

The socket weld usually has less strength resistance in comparison to butt weld fittings. So, SW fittings are used mainly for the smaller pipeline with diameters NPS 3 or less when available.

In the case of SW fittings, you can find it quite easy to install. Since it often requires around 1/6 inch of the gap at the bottom of the gap to allow the socket access, it also allows thermal expansion. However, the gap could lead to the problems of overstressing that will crack the fillet weld of the fitting. In addition, socket weld has also been found to be problematic in corrosive fluid service as a result of crevice corrosion. The media of the application must be considered.


Socket weld or SW fittings could help you in many ways, and in this blog, we have tried to cover almost all aspects that could help you get a better basic understanding. If you have any inquiries regarding  socket weld fittings and socket weld flanges, contact us today!

How to Get High Quality Flanges?

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)


ASTM B381 Gr. 2 (Titanium)


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


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.


Nominal Designation








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.


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


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


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.

If you want any specific flange information, get in touch with us today!