The Benefits of Using forging Overhead Line Fittings

Hydraulic and instrumentation fittings must have the necessary strength to withstand the often high pressures and temperatures of the system. The fittings must also resist the potential of corrosion and rust from the different media inside the system and the outside environmental conditions. Generally, metal fittings are used in most hydraulic and instrumentation systems due to their high pressure requirements or corrosive conditions. Though plastics typically have a higher resistance to corrosion than metals, their comparatively low strength and durability make them less suitable for hydraulic systems and the majority of instrumentation applications.

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Metal fittings are primarily made of carbon steel, stainless steel, other exotic alloys (i.e. Hastelloy®, Inconel® & Monel®) or sometimes brass. For the purposes of this paper we are focusing on carbon
and stainless.

These metals are strong and durable, and can withstand high pressures and have exceptional heat resistance. Carbon steel fittings can withstand temperatures from -54°C (-65.2°F) to 260°C (500°F) and are an alloy of iron, carbon other metals for high strength and durability.

Stainless steel has superior resistance to chemicals and corrosive environments. Stainless steel fittings withstand a typical temperature range from -254°C (-425.2°F) to 649°C (.2°F) and possess excellent corrosion resistance properties. Therefore, the characteristics of stainless make it a highly suitable fitting material for applications where the internal fluid or external environment is subjected to extreme heat and/or corrosive conditions.

It is also the necessary choice for high pressures, as stainless steel fittings are typically rated to 10,000 PSI and specially developed stainless fittings can withstand pressures up to as much as 20,000 PSI.

Forged fittings are far superior to other processes in the majority of applications. The forging process provides consistency in the structure and composition of the materials, and the metallurgical recrystalisation and grain refinement strengthens steel products, particularly for shear, impact and strength.

Forged steel is stronger and more reliable than brazing, casting and plate steel because the grain structure of the steel is altered, conforming to the shape of the part.

SOME OF THE LEADING ADVANTAGES OF FORGED FITTINGS INCLUDE:

•  The tight grain structure makes them mechanically stronger than alternative methods
•  Low cost due to less waste of excess flashing and ability to produce near-net shapes
•  Exclusion of porosity, cavities, shrinkage and cold pour issues
•  Less need for expensive alloys to manufacture high strength components
•  Greater wear resistance and longer service life of the fitting
•  Does not require a special skilled operator to produce
•  Wider variety of solid body shapes can be produced
•  Superior ability to withstand impact over brazed or casted fittings

FORGED FITTINGS VERSUS CASTING
A cast fitting is made by pouring molten metal into a mold of the desired shape. Forged steel is stronger and more reliable than castings because the grain flow of the solid steel piece is altered to conform to the shape of the part in the die. Because of this, forging provides a uniformity of the structure and composition of the finished part. The refinement that occurs is due to the thermal cycle and deformation process which is what strengthens the final part in respect to internal working pressure, and external impact and shear strength.

ADVANTAGES OF FORGING OVER CASTING
• Due to the tight grain structure, a forging is mechanically stronger than a casting
• Unlike castings, forgings are not susceptible to cavities, cold pour problems, porosity or shrinkage
• Castings typically require more expensive alloys to achieve the high strength required for most fittings
• The tight grain structure of forgings provides more wear resistance and is not so hard as to be more likely to become brittle in comparison to castings, allowing the forged fitting to withstand higher pressures, more extreme conditions and experience a longer service life than a casted fitting.

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Testing performed on a blank HRC 38-42 forged grinder insert wear/wash is about the same as on a high alloy HRC 46-50 cast grinder insert, however a HRC 46-50 casting does not have the ductility to handle high impact grinding. This testing illustrates how forged fittings will withstand higher impacts, pressures and wear resistance than casted fittings. In short, forged metal fittings have a longer and more reliable service life than castings, and are typically less expensive in the identical application.

The structural integrity of the forging process provides the highest strength possible to a part. It produces a solid structure that is free of internal defects which can reduce the durability and strength of the metal. The forging process provides the highest strength to weight ratio of any metal forming process. Forged fittings are the best choice for critical applications that require high pressure, high temperature, exceptional wear resistance and internal toughness.

Forged fittings are made in what is called a closed die process (a.k.a. hot drop forging), also known as impression die forging. This process is commonly used in the manufacturing of small or medium metal components using a plastic deformation method. Unlike in the open die forging, the material is forced to flow in a pre-machined closed die of the specified shape. Close die forging provides near-net shapes to attain more complex geometries that are very close to the dimensions of the finished part. The plastic deformation is a process of rapid shots which forces the material to fill the shape of the die. The final product is considered a flashless forging that chucks on the OD of the part without having to worry about a parting/trim line. The result is less waste, stronger part integrity and a more concentric finished part.

In industries such as oil and gas, petrochemicals, and construction, the selection between pipe fittings and forged fittings is critical for ensuring the safety, efficiency, and longevity of piping systems. Both types of fittings are essential components, but they differ significantly in terms of manufacturing processes, applications, and costs. This blog provides an in-depth comparison between pipe fittings and forged fittings, complete with pricing information in India to help you make an informed decision.

What are pipe fittings?

Pipe fittings are components used to connect, control, or change the direction of the flow within a piping system. These fittings come in various shapes, sizes, and materials, and they are essential for creating a reliable and functional piping network.

Common Types of Pipe Fittings and Their Applications:

1. Elbows:
   • Function: Change the direction of flow between two pipes, typically by 45° or 90°.
   • Applications: Commonly used in plumbing, HVAC systems, and process piping.
   • Price in India: ₹50 – ₹500 per piece, depending on material and size.
2. Tees:
   • Function: Allow the splitting or combining of flow from different directions.
   • Applications: Widely used in fluid distribution systems and branching pipelines.
   • Price in India: ₹60 – ₹600 per piece.
3. Reducers:
   • Function: Connect pipes of different diameters, facilitating a smooth transition between sizes.
   • Applications: Used in piping systems to accommodate changes in flow rate.
   • Price in India: ₹70 – ₹700 per piece.
4. Couplings:
   • Function: Join two pipes together, ensuring a secure connection.
   • Applications: Found in plumbing systems, gas pipelines, and chemical processing plants.
   • Price in India: ₹40 – ₹400 per piece.
5. Caps and Plugs:
   • Function: Close the end of a pipe, preventing fluid or gas from escaping.
   • Applications: Used to seal off unused pipe ends or for future expansion.
   • Price in India: ₹30 – ₹300 per piece.

Manufacturing Process:

Pipe fittings are typically manufactured through casting or welding. In the casting process, molten metal is poured into molds, which allows for complex shapes and sizes. Welding involves fusing metal pieces together at high temperatures. While these methods are cost-effective and versatile, they can result in lower strength and durability compared to forged fittings, especially under high-pressure conditions.

What are forged fittings?

Forged fittings are manufactured using a forging process, where metal is heated and then shaped under extreme pressure. This method results in a denser and more uniform material structure, making forged fittings stronger and more durable than their cast or welded counterparts.

Common Types of Forged Fittings and Their Applications:

1. Elbows:
   • Function: Provide a robust solution for changing the direction of flow in high-pressure systems.
   • Applications: Used in industries like oil and gas, power generation, and chemical processing.
   • Price in India: ₹150 – ₹1,500 per piece.
2. Tees:
   • Function: Split or combine flow in systems where reliability is crucial.
   • Applications: Essential in high-stress environments like refineries and industrial plants.
   • Price in India: ₹200 – ₹2,000 per piece.
3. Couplings:
   • Function: Join pipes in systems where safety and durability are non-negotiable.
   • Applications: Found in heavy-duty applications such as hydraulic systems and offshore drilling.
   • Price in India: ₹120 – ₹1,200 per piece.
4. Unions:
   • Function: Allow for easy disconnection of pipes for maintenance or repair without cutting.
   • Applications: Used in situations where frequent disassembly is required, such as in processing plants.
   • Price in India: ₹180 – ₹1,800 per piece.
5. Swage Nipples:
   • Function: Connect pipes of different diameters, with superior strength and durability.
   • Applications: Ideal for high-pressure and high-temperature applications, such as steam lines and chemical plants.
   • Price in India: ₹250 – ₹2,500 per piece.

Manufacturing Process:

Forged fittings are produced by heating a billet of raw metal and then applying high-pressure machinery to shape it into the desired form. This process aligns the metal’s grain structure, resulting in fittings with excellent mechanical properties, including higher tensile strength, greater fatigue resistance, and improved toughness. Forged fittings are less likely to crack, leak, or fail under extreme conditions, making them ideal for demanding environments.

Key Differences Between Pipe Fittings and Forged Fittings

1. Strength and Durability:
   • Pipe Fittings: Suitable for low to medium pressure applications. The casting and welding processes may introduce internal defects, such as porosity or weak joints, reducing their overall strength.
   • Forged Fittings: Designed for high-pressure and high-temperature environments. The forging process ensures a more uniform and defect-free structure, leading to superior strength and durability.
2. Manufacturing Process:
   • Pipe Fittings: Made by casting or welding, which can result in variations in grain structure and potential weak points.
   • Forged Fittings: Manufactured through forging, which creates a consistent grain structure and reduces the risk of defects.
3. Applications:
   • Pipe Fittings: Commonly used in residential plumbing, low-pressure systems, and applications where extreme conditions are not a concern.
   • Forged Fittings: Preferred in industries where safety, reliability, and performance are critical, such as oil and gas, petrochemical, and heavy machinery.
4. Cost:
   • Pipe Fittings: Generally less expensive due to simpler manufacturing processes, making them a cost-effective choice for less demanding applications.
   • Forged Fittings: More costly, reflecting their superior material properties and manufacturing complexity, but offering better long-term value due to their durability.
5. Installation and Maintenance:
   • Pipe Fittings: Easier to install and replace, which is advantageous in systems where frequent maintenance is expected.
   • Forged Fittings: Require more expertise during installation due to their robustness, but they provide a more secure and lasting connection, reducing the need for frequent maintenance.

Price Comparison in India

• Pipe Fittings: Prices typically range from ₹50 to ₹700 per piece, depending on the type, size, and material. These fittings are affordable and accessible, making them suitable for general applications.
• Forged Fittings: Prices range from ₹150 to ₹2,500 per piece, reflecting the higher cost of manufacturing and the superior quality of the fittings. Although more expensive upfront, forged fittings offer better long-term value due to their strength and reliability.

Conclusion: Which One Should You Choose?

The decision between pipe fittings and forged fittings should be based on the specific requirements of your project. For applications that involve high pressure, extreme temperatures, or where the risk of failure is unacceptable, forged fittings are the clear choice despite their higher cost. On the other hand, if your system operates under less demanding conditions and budget constraints are a priority, pipe fittings offer a more economical solution.

By carefully considering the differences in strength, durability, and cost, you can select the right type of fitting to ensure your piping system operates safely and efficiently for years to come. Whether you opt for the cost-effectiveness of pipe fittings or the robustness of forged fittings, making an informed choice will lead to better performance and reliability in your projects.

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