Seamless Stainless Steel Pipe: Everything You Need To Know 

In the field of construction applications, barely any material get as much love and adoption as stainless steel. The alloy contains multiple materials, providing optimal resistance to things like corrosion and rust while also being very strong and holding its own in times of high temperature. 

However, like many other material types, stainless steel comes in different forms. And, in terms of manufacturing, rarely does any variation strike you like welded and seamless stainless steel. Both are similar in several ways, but the lines of distinction also stand quite well. 

This article will explore seamless stainless steel pipes – from their benefits and manufacturing processes to their applications. 

What is a Seamless Stainless Steel Pipe? 

Steel manufacturers generally split their development process into two – welding and non-welding. Seamless stainless steel pipes are manufactured using the latter method, essentially coming without the presence of any welded seams. 

As you’d expect, that absence is the primary differentiating factor between these pipes and the welded stainless steel pipes. 

This characteristic means that stainless seamless steel pipes have cross sections that are uniform – thus providing a more consistent look and feel. 

In the manufacturing process of a stainless steel seamless pipe, a solid stainless steel billet or ingot is heated to a significantly high temperature and then pierced. This piercing essentially creates a hollow tube, which is then elongated further and shaped using different processes. As you’d expect, the goal here is to provide the right shape for the pipe according to your specifications. 

With its unique shape, a seamless stainless steel pipe provides benefits such as a uniform structure across its entire length. This provides additional strength and durability, thus ensuring that the pipe is significantly more reliable. With optimal corrosion resistance and the absence of welded points, these pipes make it very easy for fluids to flow through them without losing their potency or encountering much friction.

All in all, seamless stainless steel pipes come with several significant functionalities. They are used across multiple industries, from oil and gas to pharmaceuticals and food processing.  Their ability to withstand tough conditions makes them especially adept and suitable for demanding environments. 

The Manufacturing Process Of Seamless Stainless Steel Pipe 

So, how are seamless stainless steel pipes made? 

Billet (Or Ingot) Building

Generally, the first step in the stainless steel seamless pipe manufacturing process will be to prepare a solid cylindrical billet or ingot. As you’d expect, this billet or ingot will be made of stainless steel, and manufacturers need to properly inspect it for any possible surface defects. 

Manufacturers also need to carry out initial checks to ensure that the product meets the manufacturer’s specifications, so it is important to be especially careful here.

Heating & Piercing

Once the inspection is done, the billet is heated to a high temperature. This makes it easy for the steel manufacturers to create any shape they’d like with the pipe. 

The heated billet is then pierced with a piercing plug or a mandrel, thus creating a hollow tube that runs through the entire shape. Normally, manufacturers can also use rotary piercing mills or cross-roll piercing mills to achieve perfection and accuracy in their piercings. 

It is also worth noting that the initial piercing is what forms the rough shape of the pipe – not necessarily its final form.

Product Elongation 

Once the billet has been pierced, it is then elongated and constrained in size using a myriad of processes -including and especially Pilger and plug mills. These mills essentially stretch the billet gradually, thus cutting its diameter and making it much longer. 

Besides stretching, the elongation process also provides a more refined grain structure for the billet, while also enhancing the pipe’s overall mechanical properties – which we will examine in a later section. 

Product Sizing 

The elongation process is followed by a sizing procedure that allows manufacturers to achieve the desired product dimensions. With different stainless steel pipe sizes, this is also very critical to the overall manufacturing process.

This process is usually completed by passing the pipe through a sizing or reducing mill. As you’d expect, the pipe sizing mill reduces the pipe’s diameter even further, while helping to adjust the pipe’s overall thickness.  

Heat Treatment 

Depending on the manufacturer’s requirements, the pipe could also undergo a quick heat treatment process. This could be tempering, annealing, or any of the other options available. 

The function of the heat treatment process is to relieve any internal stress. It also helps to bolster the pipe’s properties and improve its ability to withstand corrosion.

Product Finishing

Once the heat treatment is done, the pipe can also undergo any additional finishing operations the manufacturer sees fit. These operations could include cutting, straightening, or even surface treatment. Whatever is required to achieve the final desired specs, it can be done. 

In many cases, the pipe’s ends are beveled for welding or threaded for connections. 

You should keep in mind that the exact manufacturing process could vary depending on the specific pipe dimensions, stainless steel grade, and industry standards. However, the general steps mentioned above provide a broad understanding of how we at Tuolian Metal manufacture seamless stainless steel pipes. 

Need any pipes or consultations? Please get in touch with us.

Seamless Stainless Steel Pipes: Material Variants

Over the years, stainless steel has become notable for its impressive versatility. Manufacturers and users have different grades of material that can be applied in producing stainless seamless steel pipes. 

These grades vary based on several factors, including but not limited to corrosion resistance, mechanical attributes, and suitability in different environments and uses. However, the most popular of these variants include:

Grade 304 (UNS S30400): 

For many, 304 is the most prominent stainless steel grade. Known for its formability and corrosion resistance, a 304 seamless stainless steel pipe easily stands out among the pack.

A 304 seamless stainless steel pipe is used for different functionalities, ranging from food processing to developing kitchen appliances and more. 

Grade 316 (UNS S31600): 

Next on the popularity chart is 316 stainless steel. The material provides impressive corrosion resistance, which will come in handy in environments where acidity and chloride are prominent. 

A 316 seamless stainless steel pipe will be best applied in fields such as marine applications, chemical processing, pharmaceutical equipment, and coastal structures.

Grade 430 (UNS S43000): 

Like many others in its class, 430 stainless steel offers impressive corrosion resistance. Just as well, it holds its own against high temperatures and doesn’t oxidize easily.

You can use a 430 seamless stainless steel pipe in applications that require premium resistance to atmospheric conditions. 

Grade 201 (UNS S20100): 

Grade 201 is especially popular for its cost efficiency – especially relative to many other stainless steel grades. It offers many similar properties to 304 steel, although its mechanical properties are a bit lower than its higher-end counterpart. 

201 seamless stainless steel pipe is commonly used in developing household appliances, restaurant equipment, and other related functionalities. Similar pipe variants include the 202 seamless stainless steel pipe and the 2205 seamless stainless steel pipe.

Grade 316L (UNS S31603): 

Similar to 316, grade 316L is a low-carbon stainless steel version that offers enhanced weldability and resistance to sensitization. 

You can use the 316L stainless steel seamless pipe in different industries, ranging from chemical processing and pharmaceuticals to medical devices.

Grade 321 (UNS S32100): 

Grade 321 is a stabilized stainless steel grade that comes with an added titanium component. It is notable for its resistance to intergranular corrosion and its ability to operate in high-temperature environments. 

A 321 seamless stainless steel pipe is commonly used in heat exchangers, aircraft components, and exhaust systems.

You should note that these are just the tip of the iceberg when it comes to stainless steel grades that can be used to make stainless steel seamless pipes. 

Other grades of stainless steel, such as 316Ti, 309, 410, and 2205 (Duplex stainless steel), also come with their specific applications and are notable for their unique characteristics. Based on these unique properties, you can make a decision on which steel grade or variant you’d like to work with. However, your selection should be based on factors such as: 

• Application requirements
• Corrosion resistance
• Temperature resistance
• Physical properties
• Price and cost consideration

Seamless vs Welded Stainless Steel Pipes 

As explained earlier, the major distinctions when it comes to stainless steel pipes are the welded and seamless options. Both are incredibly similar, but as you’d expect, they also vary significantly across multiple factors. 

So, what are the lines of distinction in the seamless vs welded stainless steel pipe debate? Below are some of their most significant differences:  

Manufacturing Processes: 

To begin the comparison, let’s examine the different manufacturing processes: 

Seamless Stainless Steel Pipes: 

These pipes are primarily products from an ingot or billet made of stainless steel. The material is heated and pierced to create a hollow tube, which is then stretched and formed into the right shape and dimensions that the manufacturers would love. This manufacturing process chiefly doesn’t include any welding, so seams are absent. 

Due to this, seamless stainless steel pipes come with a uniform and consistent structures that run along their entire length. 

Welded Stainless Steel Pipes: 

To create welded pipes, manufacturers need to join at least two steel sheets by welding them together. Manufacturers form stainless steel strips or sheets into cylindrical shapes, then welded along seams using different welding techniques – whether its electric resistance welding (ERW), submerged arc welding (SAW), or TIG welding

As you’d expect, the welding process is what primarily makes the difference here. It introduces a visible seam along the length of the pipe, marking a significant distinction in the welded vs. seamless stainless steel pipe comparison. 

Strength and Integrity:

Seamless Stainless Steel Pipes: 

These pipes are generally stronger than their welded counterparts. Thanks to the absence of a seam, there is no possible weak point that could be exploited by structural failure or even material corrosion. 

Essentially, seamless pipes work much better in high-pressure situations and for critical industrial manufacturing processes, and any other environment where you prioritize structural reliability. 

Welded Stainless Steel Pipes: 

As explained earlier, welded pipes come with welded seams. While these do serve their purposes, they also create a possible point of weakness for the pipes. 

It is worth noting, however, that several modern welding techniques and top-of-the-line quality control measures can be used to ensure that welded pipes meet the required reliability and durability standards. 

Still, with these pipes boasting lower strength metrics, their application is best in situations where the demand for strength isn’t so high – from regular plumbing to structural framework development and more. 

Size and Availability:

Seamless Stainless Steel Pipes: 

You can find seamless stainless steel pipes in different dimensions and sizes – especially compared to the welded versions. They can also be manufactured in larger diameters and tucker surfaces, making them especially more suitable for situations where large pipe sizes and configurations are required. 

Welded Stainless Steel Pipes: 

As you’d expect, these pipes are more readily available in smaller sizes and dimensions. With their thinner walls and smaller diameters, they are better suited for lighter applications. 

Surface Finish:

Seamless Stainless Steel Pipes: 

Seamless pipes come with smoother and more uniform surface finishes – whether internally or externally. This makes them suitable for proper fluid transportation and management, while also cutting the accumulation of particles and debris. 

Welded Stainless Steel Pipes: 

These pipes show a visible weld that is built along each seam. This results in a bit of a rougher surface compared to the seamless pipes, which can manipulate fluid flow a bit. 

It is worth noting, however, that manufacturers tend to use different post-weld treatments and polishing procedures that can improve the surface finish of welded pipes. 

Price: 

Seamless Stainless Steel Pipes: 

As explained earlier, the process of manufacturing seamless stainless steel pipes is more complex and time-consuming. With additional processes and equipment involved, it should come as no surprise that these pipes tend to be more expensive.

Welded Stainless Steel Pipes: 

Welded pipes go through a simpler and more straightforward manufacturing procedure, making them more cost-effective compared to their seamless counterparts.

All in all, both seamless and welded stainless steel pipes come with their benefits and drawbacks. Eventually, your selection will most likely be based on factors such as your intended use and budget. 

Physical Characteristics Of Seamless Stainless Steel Pipes 

If you check a seamless stainless steel pipe chart, you should find the following physical properties: 

• Density: The density of this material is quite high. It usually ranges from 7.9 to 8.0 grams per cubic centimeter (g/cm³), although you should remember that the grade or alloy of stainless steel being used will most likely determine the actual figures. 
• Melting Point: As we all know, stainless steel has a much higher melting point compared to many other materials. The melting point usually varies between 1370°C and 1400°C (that is, 2500°F to 2550°F), all varying based on the composition of the stainless steel material. 
• Thermal Conductivity: Stainless steel doesn’t necessarily do well when conducting electricity – pretty surprising, since its metallic nature. While it can conduct electricity to some extent, this might be a significant impediment to its use in situations where electrical conductivity is required. 
• Thermal Conductivity: As you’d expect, stainless steel also comes with a lower thermal conductivity profile compared to many other metals. The stainless steel thermal conductivity is moderate enough to handle some light tasks, however. 
• Pressure Rating: The seamless stainless steel pipe pressure rating will depend primarily on factors such as wall thickness, temperature, and stainless steel grade. 
• Magnetic Properties: Depending on the composition of materials and alloys, stainless steel can exhibit some magnetism. For instance, 304 and 316 stainless steel – the most popular stainless steel grades that are used for manufacturing seamless stainless steel pipes – are non-magnetic when in their annealed condition. However, when you apply some cold working or heat treatment, they tend to develop mild magnetic capabilities. 
• Expansion and Contraction: Stainless steel has a relatively low coefficient of thermal expansion, which means it expands and contracts less with temperature changes compared to other materials. This property makes stainless steel pipes less susceptible to thermal stress and distortion.
• Surface Finish: Seamless stainless steel pipes can have different surface finishes depending on the manufacturing process and intended application. Common surface finishes include smooth, polished, brushed, or mill-finished surfaces.

It’s important to note that the specific physical properties of seamless stainless steel pipes can vary depending on the grade, alloy, and manufacturing process. Additionally, stainless steel can exhibit different properties in different temperature ranges and conditions.

What Are Seamless Stainless Steel Pipes Used For?

Over the years, there have been different applications of these pipes across multiple industries. Their physical properties make themes especially versatile, and they have so far found use in the following spaces: 

Oil & Gas Transportation

For most oil and gas companies, finding the right way to effectively transport fluids can be a challenge. The finicky nature of these fluids makes them incredibly difficult to deal with, and there is a significant need to ensure that they are moved right. 

With seamless stainless steel pipes, this is possible. Their lack of welds and seams means that they make it easy to transport fluids from one end to the other, whether onshore or offshore. And, their ability to resist rust means that they help to transport different types of fluid materials – from gases to hydrocarbons and more. 

Chemical Industry Applications: 

In the chemical industry, these pipes also help to transport all forms of corrosive materials – from acids to chemicals and more. Their properties ensure that there is no compromise to their strength – as well as the materials they are transporting – across the moving process. 

Food and Beverage Manufacturing: 

As many of us probably know, stainless steel is also renowned for being clean. This, along with the material’s ability to resist rust, means that it can work across multiple functionalities in the food and beverage space. Stainless steel does well with food-grade substances, so manufacturers utilize it in different roles. 

Drug Manufacturing: 

Like it is in the oil and gas industry, seamless stainless steel pipes also help to transport pharmaceutical products from end to end. 

Pharma products are known to have some of the most stringent and extensive purity and cleanliness requirements in the world, and seamless stainless steel pipes ensure that the health of these products is never compromised. 

Utilities: 

You can find seamless stainless steel pipes in power plants, where they are used to transport steam, water, and other fluids in high-pressure environments and extreme heat. With their long-lasting performance and ability to withstand significant pressure, these pipes are especially ideal for material transportation.

Petrochemical Industry: 

In the petrochemical industry, companies use seamless stainless steel pipes to handle several processes – from petroleum processing to refining and, of course, transportation. 

Automotive and Aerospace: 

For automotive and aerospace applications, seamless stainless steel pipes help in manufacturing exhaust systems, fluid transfer conduits, and other structural components. Their strength, corrosion resistance, and lightweight capabilities make them very versatile in their application. 

Construction and Infrastructure: 

Seamless stainless steel pipe fittings are utilized in construction and infrastructure projects for plumbing, water supply, HVAC systems, and other important structural applications.

Desalination Plants: 

Seamless stainless steel pipes are commonly employed in desalination plants, where water is collected and treated before being distributed across different channels. They especially help in transporting brine and seawater, with their resistance to salt and alkalinity making them especially ideal.

As you would expect, the specific application of seamless stainless steel pipes can vary depending on the industry and requirements. Knowing what you need the steel for will also help to determine the grade and other features to look out for.

How Do I Get Seamless Stainless Steel Pipes?

When you do decide that you’d like to get a seamless stainless steel pipe, your best bet would be to find a supplier that is willing and able to help you out. 

Considering the many intricacies of these pipes, understanding what you need is undoubtedly important. However, finding a supplier that is knowledgeable and that can get you precisely what you need is equally critical. 

Choosing A Pipe Supplier

When choosing a seamless stainless steel supplier, here are some of the characteristics you want to keep in mind: 

• Product Quality: Always look for a supplier that provides high-quality pipes that are recognized by industry standards, such as the American Society for Testing and Materials (ASTM), American Society of Mechanical Engineers (ASME), and the International Organization for Standardization (ISO)
• Product Range: You also need to evaluate the supplier’s product range to ensure that they have enough steel grades, sizes, and specifications. 
• Experience & Reputation: Always consider a supplier’s experience in the industry. When they have a track record of serving satisfied customers, they have a better chance of meeting your needs. 
• Technical Expertise: A supplier with the right expertise and technical knowledge will be able to provide guidance on the right stainless steel grade specifications for your application. They should be able to address all technical questions, provide accurate details, and offer support. 
• Pricing and Value: The right supplier should be able to offer affordable products without necessarily compromising quality. 

Determining Your Pipe Specifications 

Besides getting the right supplier, you also need to be able to determine the specifications of your stainless seamless steel pipe. These specifications will essentially determine what you’d like your pipe to be, and they will be critical in helping you to make your final decision. 

Share these specifications with the supplier, and they should be able to help get you what you need. 

Conclusion 

Stainless seamless steel pipes are highly versatile tools in the market. With their impressive physical properties, the pipes help provide significant operational versatility. 

Need to get your hands on a seamless stainless steel pipe? Contact us at Tuolian Metal and let’s help you out. 

Frequently Asked Questions 

How do seamless stainless steel pipes help my construction? 

Seamless stainless steel pipes are very useful in construction projects. However, among their many uses, they especially help to optimize fluid movement. With their clean and clear surface finishings, these pipes ensure that fluid movement is as seamless as possible, while also ensuring that the fluids themselves aren’t contaminated. 

What are the most popular stainless steel grades for making seamless pipes? 

Generally, 304 stainless steel and 316 stainless steel are the most popular options for making seamless stainless steel pipes. 

However, while the 316l stainless steel seamless pipe is easy to get, you also need to keep in mind that 304 stainless steel is still quite versatile. For instance, you might have to choose between 304l seamless stainless steel pipes, 304H, 304N, and much more. 

Other stainless steel grades include 201 stainless seamless steel pipes, 403 stainless seamless steel pipes, and much more. 

What is the pricing basis for a seamless stainless steel pipe?

Generally, the seamless stainless steel pipe price will depend on the manufacturer. This is why we recommend finding manufacturers with competitive pricing structures. However, note that competitive pricing shouldn’t necessarily come at the expense of quality.