Choosing Seamless, Welded or Forged Pipe

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When you are first looking to source a stainless steel pipe, whether it&#;s for a desalination plant, an oil rig or even a nuclear power station, one of the first questions you need to ask yourself is &#;do I need a seamless, welded or forged pipe&#;? The three types all have different advantages and are therefore suited to different applications and environments. An abundance of factors should be taken into consideration when choosing what is right for a particular project.

Engineers will more than likely instinctively know the answer to that question, but let&#;s spend some time exploring these seamless, welded and forged pipes and their various properties.

Let&#;s start with seamless pipe. As the name suggested, a seamless pipe is one without any seam or weld-joint.

Manufacturing and applications:

Seamless pipes can be manufactured using various different methods, which is very much dependent on the diameter required, or the ratio of the diameter to the thickness of the wall. In general, the manufacturing process of seamless pipe starts with raw steel being cast into a more workable format &#; a hot solid billet. This is then stretched out and pushed or pulled over a form. This hollow pipe then undergoes an extrusion process whereby it is forced through a die and mandrel. This works to increase the inside diameter and reduce the outside diameter.

Seamless steel pipe is regularly used in the transportation of fluids such as water, natural gas, waste and air. It is also regularly required in many high-pressure, high-corrosive environments such as in the oil & gas, power generation and pharmaceutical industries.

Advantages:

1. Strength: Seamless pipes come with the obvious advantage of having no seam and therefore no chance of a weak seam. This means that typically, seamless pipe can withstand 20% more working pressure than welded ones of the same material grade and size.
2. Resistance: The lack of seam means that seamless pipe can offer higher resistance to corrosion because there is less opportunity for things like impurities and defects that can more commonly occur along a weld.
3. Less Testing: It goes without saying that seamless pipes don&#;t require testing for weld integrity &#; no weld means no test!

Welded pipe comes in three forms: welded on the outside diameter, welded on the inside diameter or welded on both sides. The commonality is that they all have a seam!

Manufacturing and applications:

The manufacturing process of welded pipe starts by rolling out a steel coil to the desired thickness to form a flat strip or plate. This is then rolled, and the seam of the resultant tube is welded in a chemically neutral environment.

In regard to what type of steel is weldable, austenitic steels are generally the most weldable whereas ferritic steels are weldable in thin sections. Duplex steels are now regarded as fully weldable, but they do require more care than austenitic steels.

Welded pipe manufacturing techniques are thought to have greatly improved over the past few years. Arguably the most significant advancement being the development of using high-frequency electric currents as a welding technique. This has greatly improved the ability of welded pipe to avoid corrosion and seam failure.

While it is correct that the seam in a welded pipe makes it theoretically weaker, manufacturing methods and quality assurance procedures are far more superior these days. This means that as long as a welded pipe&#;s specified tolerances for temperature and pressure aren&#;t surpassed, there is no reason why is shouldn&#;t perform just as well as a seamless pipe in a wide array of industries.

Advantages:

1. Cost: A big advantage of welded pipe is that it is the least expensive of all pipe types and it is much more readily available.
2. Consistency: It is generally accepted that the wall thickness of welded pipes is much more consistent than that of seamless pipes. This is because the manufacturing process starts with a flat sheet of steel.
3. Surface quality: The avoidance of the extrusion process also means that the surface of a welded pipe can be much smoother than a seamless pipe as well.
4. Speed: Shorter procurement lead time is required for welded pipe due to the manufacturing process being simpler.

Forging steel is a metal forming process that shapes metal using compressive force and extreme heat and pressure.

Manufacturing and applications:

The manufacturing of a forged pipe starts with a piece of steel (whether that&#;s 6% Moly, Super Duplex, Duplex, Stainless Still, Nickel Alloy) being placed between an upper and lower die. Heat and pressure mould the steel into the desired shape and it is put through a machining process where it is finished to meet all of the required specifications.

This complex manufacturing process does result in higher cost implications for forged pipe.

The many advantages of forged pipe mean that it has a number of different applications in a diverse range of sectors such as oil, gas, hydraulic machinery, fertilisation and chemical. The fact that forged steel has no seam or welding point allows it to successfully contain potentially harmful or corrosive substances and their fumes. Therefore, it can be used in many heavy industries.

Advantages:

1. Strength: Forging pipe usually results in a strong and very reliable end-product because forging causes the grain flows of the steel to alter and align. In other words, the steel becomes more refined and the pipe&#;s structure is changed unequivocally resulting in sheer strength and high impact resistance.
2. Longevity: Forging excludes the potential for porosity, shrinkage, cavities and cold pour issues.
3. Economical: It is generally accepted that the process of forging is very economical as no material is wasted.
4. Flexibility: The steel forging process is very flexible and can produce many different pipes of varying sizes.

Whatever variety of seamless, welded or forged pipe you require, rest assured that Special Piping Materials is able to source and supply all sizes of seamless pipe, welded pipe and forged pipe. Our vast global network will be able to find and stock whichever type you need, in whatever material grade &#; be it super duplex, duplex, nickel alloy, 6% Moly or stainless steel. The trusted mills that we work with are highly efficient and specialists in their respective fields, ensuring that your products are exactly how you need them.

Although the names say it all, you may be wondering what&#;s the difference between seamless and welded pipes. Can&#;t you use both for any application or industry? Is one weaker than the other? And what&#;s the different price point between the two?

Before we answer these questions, you need to know the difference between the two pipes.

Welded Pipes

Welded pipes begin their lives as a flat piece of steel called a skelp. It&#;s cut to a specific length then fed through a rolling machine, curling the longer sides of the sheet toward each other to form a cylinder. Once bent, the pipe is then welded with or without filler material. The welding causes the edges to melt and fuse, creating a seam.

Because the seam can affect the overall performance of the pipe, welded pipes are considered the weaker of the two pipes. Many industries today require seamless piping to be used for any high-pressure or high-temperature applications.

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However, welded pipes are less expensive than seamless pipes and are quicker to produce. This allows the welded pipe to be more versatile than seamless pipes and can be used in many industries for low and medium-pressure applications.

Seamless Pipes

Seamless piping begins as a cylindrical-shaped piece of steel called a billet. The billet is heated up then pierced through the center with a piercing to create a hollow tube. Like welded pipes, seamless piping is rolled and stretched out to meet a specific length, diameter, and wall thickness depending on the order.

Since they do not have a welded seam, seamless pipes are generally stronger and have better pressure capacity than a welded pipe, making them perfect for high-pressure applications, such as power generation, oil and gas production, and pharmaceutical manufacturing.

And yet, there are some downfalls to the seamless pipe. Many say the rolling and stretching process can produce an inconsistent wall thickness as compared to the welded pipe. And since the manufacturing process takes much longer and is more labor-intensive, seamless piping tends to be more expensive than welding piping.

Understanding Welded Pipe: Applications, Advantages, and Manufacturing Process

Welded pipes are a fundamental component in various industries, known for their versatility and cost-effectiveness. Understanding the intricacies of welded pipes, including their applications, advantages, and manufacturing process, is crucial for professionals in fields ranging from construction to manufacturing.

1. Introduction to Welded Pipes Welded pipes begin as flat steel sheets, known as skelps, which are molded into cylindrical shapes and then welded. This process differs significantly from the manufacturing of seamless pipes, which involves piercing and stretching a solid billet of steel.
2. The Manufacturing Process of Welded Pipes The journey of a welded pipe starts with the skelp. This steel sheet is carefully rolled and bent until its edges meet, forming a cylinder. The edges are then welded together, either with or without filler material. The welding process is critical as it determines the strength and integrity of the pipe. Advanced welding techniques have significantly improved the quality and reliability of welded pipes over the years.
3. Applications of Welded Pipes Welded pipes are extensively used in various industries due to their versatility. They are commonly found in:

• Plumbing systems for residential and commercial buildings.
• Oil and gas industries, particularly for transporting fluids over long distances.
• Automotive industry, for exhaust systems and structural components.
• Construction, especially in structural supports and scaffolding.

4. Advantages of Welded Pipes One of the primary advantages of welded pipes is their cost-effectiveness. They are generally less expensive to produce than seamless pipes, making them a popular choice for budget-conscious projects. Additionally, welded pipes offer:

• Versatility in size and shape, accommodating a wide range of applications.
• Faster production times, ensuring quicker availability for projects.
• Sufficient strength for low to medium-pressure applications.

5. Quality and Performance Considerations While welded pipes are often viewed as less robust than seamless pipes, advancements in welding technology have significantly narrowed this gap. Modern welded pipes boast high-quality seams that can withstand considerable stress, making them suitable for a variety of applications, including some high-pressure scenarios.

5. Choosing Between Welded and Seamless Pipes The choice between welded and seamless pipes depends on several factors, including the application&#;s pressure requirements, budget constraints, and specific industry standards. Welded pipes are often the go-to choice for projects that do not require the high-pressure resilience of seamless pipes.

5. Welded Pipes in High-Pressure Applications Although seamless pipes are typically preferred for high-pressure applications, certain types of welded pipes are also suitable for such conditions. Advances in welding technology have enabled the production of welded pipes that can handle higher pressures, expanding their usability in industries like power generation and certain chemical processes.

5. Environmental Impact and Sustainability Welded pipes also contribute to environmental sustainability. The efficiency of their manufacturing process results in less waste and energy consumption compared to seamless pipes. This aspect is increasingly important in industries striving to reduce their environmental footprint.

5. Future Trends in Welded Pipe Manufacturing The welded pipe industry continues to evolve, with ongoing research and development focusing on enhancing the strength, durability, and versatility of these pipes. Innovations in welding techniques and materials are expected to further expand the applications of welded pipes.

Connecting Seamless Pipes and Exploring Their Types

Seamless pipes, known for their strength and uniformity, are a crucial component in various industrial applications. Understanding how to connect these pipes and the different types available is essential for professionals in industries like oil and gas, power generation, and construction.

1. How to Connect Seamless Pipes Connecting seamless pipes involves several methods, each suited to specific requirements and applications. The most common methods include:

• Welding: The most durable and permanent method, welding is often used for high-pressure applications. It involves fusing the pipe ends together using high heat and, sometimes, filler material. This method is ideal for large-scale industrial applications.
• Flanging: Flanges are external rims installed at the end of pipes, allowing them to be bolted together. This method is preferred for systems that require regular disassembly for maintenance or inspection.
• Threading: In this method, threads are cut into the ends of the pipes, allowing them to be screwed together. Threaded connections are common in low-pressure applications and smaller pipe diameters.
• Compression Fittings: These fittings use a nut and ferrule to compress and seal the pipe connection. They are typically used in applications where welding is not feasible or for temporary connections.

Each connection method has its own set of advantages and is chosen based on factors like pressure requirements, the nature of the fluid being transported, and maintenance needs.

2. Types of Seamless Pipes Seamless pipes come in various types, each designed for specific applications and environments. The most common types include:

• Standard Pipes: Used in low to medium-pressure applications, such as water transportation and HVAC systems.
• Line Pipes: Designed for transporting oil, gas, and water from the field to refineries or storage facilities. These pipes are made to withstand the harsh conditions of underground or underwater environments.
• Boiler Pipes: Manufactured to withstand high pressure and temperature, these pipes are used in boilers, heat exchangers, and superheaters.

3. What is the maximum thickness of a seamless pipe?

• Maximum Thickness: For industrial and commercial applications, seamless pipes can have a very high thickness to withstand high pressures. For instance, seamless steel pipes can have a wall thickness up to several inches. The exact maximum thickness would depend on the manufacturer&#;s capabilities and the specific standards they adhere to, such as ASTM, ASME, or API standards.

Thickness of a 4-inch Seamless Pipe: The thickness of a 4-inch seamless pipe is not a fixed value and depends on the pipe&#;s schedule number. Common schedules include Schedule 40, Schedule 80, Schedule 160, and others. For example, a 4-inch Schedule 40 pipe typically has a wall thickness of 0.237 inches (6.02 mm), while a 4-inch Schedule 80 pipe has a wall thickness of 0.337 inches (8.56 mm). These values can vary slightly depending on the specific standards and material.

Which Pipe is Right For Your Application?

If you&#;re still not sure which pipe is right for your project, the experts at James Duva, Inc. can help! We have an extensive inventory of both welded and seamless pipes and can quickly deliver your orders, no matter how large or how small. We&#;re committed to solving our client&#;s piping issues and we&#;ll deliver high-quality products to you on time, every time!

If you&#;re looking for a new supplier for stainless steel and high-nickel alloy industrial products, look no further. Contact James Duva, Inc. today to learn more about our products.