Choosing between the different stainless steel pipe types for your project can be difficult. With so many choices, how will you decide which type covers your need? This detailed guide will discuss 4 major classifications of stainless steel pipes.
We will discuss each classification and its pipe types one by one which will help you to make an informed choice for your needs.
Pipes Types Classified By Production Method
Stainless pipes are manufactured using different production methods. Each type has different properties which makes them appropriate for different operations in industries.
Seamless Stainless Steel Pipes
Seamless pipes are made through a complex high-temperature metal shaping process. It starts with a solid steel block heated to extreme temperatures. A rod is then used to pierce this block which produces a hollow center. The resulting shape goes through rolling and drawing processes to acquire the desired dimensions. This method makes hollow pipe without any welded seams.
This type provides better corrosion resistance and strength and are mostly used in high-pressure situations in oil/gas, chemical processing, and nuclear industries.
Welded Stainless Steel Pipes
The process involved in the production of these pipes is by rolling flat steel sheets into round or cylindrical shapes. After that, different welding methods like electric resistance welding (ERW) or tungsten inert gas (TIG) welding are used to join the edges to form a lengthwise seam. Strict non-destructive testing and heat treatment after welding guarantee the quality and structural strength of pipe.
Welded pipes are a cost-effective choice for low to medium-pressure uses. They are broadly used in industrial piping systems, construction and water treatment plants.
Longitudinally Submerged Arc Welded (LSAW) Pipes
LSAW pipes are produced by using a particular welding technique. It starts by forming steel plates into cylindrical tubes. A submerged arc welding process is then used to connect the edges. This method uses a continuously fed electrode and flux layer that protects the weld area from contamination and also helps in shaping weld bead.
Typically, LSAW pipes are used in high-pressure applications like large diameter water lines, oil and gas pipelines and offshore platforms.
Cold-Drawn Stainless Steel Pipes
Cold drawing process is commonly used to produce these pipes. It involves pulling a larger diameter pipe through a series of dies with progressively smaller holes. The process also decreases the pipe’s diameter and wall thickness while increasing its length. This results in a pipe with better mechanical properties and accurate dimensions.
They also provide better surface finish and tight tolerances which makes these pipes appropriate for accurate instruments, pneumatic and hydraulic systems.
Extruded Stainless Steel Pipes
They are usually produced through a high-pressure process. It involves forcing heated stainless steel billets through a die to create pipes with required cross sectional shape. The hot or cold extrusion process can be used according to the specific alloy and required properties.
These extruded pipes broadly used in chemical processing industries, automotive and aerospace. As they provide uniform wall thickness and outstanding corrosion resistance.
| Production Method | Wall Thickness Uniformity | Pressure Resistance | Cost-Effectiveness | Typical Applications |
| Seamless | Excellent | High | Moderate | Oil & Gas, Chemical Processing |
| Welded | Good | Medium | High | Water Treatment, HVAC |
| LSAW | Very Good | Very High | Moderate | Oil & Gas Transmission, Offshore |
| Cold-Drawn | Excellent | High | Low | Precision Engineering, Hydraulics |
| Extruded | Very Good | Medium | Moderate | Heat Exchangers, Aerospace |
Pipe Types Grouped by Different Shapes
Stainless pipes have different forms to cover different industry requirements. Each shape has different properties and benefits for particular uses. Let’s discuss the different shape types.
Round Pipes:
Round-shaped Pipes are cylindrical conduits with a circular cross section. Their circular cross-section gives constant wall thickness and uniform stress distribution. They have ability to withstand high pressure due to their symmetry. These pipes are mostly used in heat exchangers, fluid systems and structural operations.
Square Pipes:
These pipes provide many benefits. They have a uniform square cross section with equal sides and 90-degree angles. They show resistance to bending and high torsional strength. Builders and designers frequently used these pipes for machinery parts, structural frames and architectural elements.
Rectangular Pipes:
This type has a cross section with two parallel sides where length is greater than the width. Their elongated cross-section offers high moments of inertia along the major axis. Due to this reason, they are an appropriate choice for equipment fabrication, structural frames and architectural designs.
Oval Pipes:
Oval Pipes feature an elliptical cross section with two axes of symmetry. They have the properties of both round and rectangular pipes. Their elliptical cross-section offers better flow dynamics than rectangular pipes. They are used in architectural designs, automotive exhaust systems and fluid handling systems.
Custom-Shaped Pipes:
Sometimes, the usual pipe shapes do not cover the project needs, so custom stainless steel pipes are used. These pipes provide different cross-sectional geometries to meet the particular needs. These pipes are mostly used in complicated fluid handling systems, architecture and industrial equipment.
The following table compares key characteristics these pipes classified by different shapes:
| Shape | Cross-Section | Strength | Flow Dynamics | Common Applications |
| Round | Circular | High pressure resistance, uniform stress distribution | Excellent, minimal turbulence | Fluid transport, heat exchangers, structural supports |
| Square | Equal sides, right angles | High torsional strength, good load-bearing | Moderate, some turbulence at corners | Structural frameworks, architectural elements |
| Rectangular | Unequal sides, right angles | High moment of inertia along major axis | Fair, increased turbulence | Architectural elements, equipment fabrication, |
| Oval | Elliptical | Balanced strength-to-weight ratio | Good, improved over rectangular | Specialized fluid systems, automotive exhausts, furniture design |
| Custom | Varies | Tailored to specific requirements | Depends on design | Unique industrial equipment, complex systems, specialized machinery |
Pipe Types Classified by Different Alloy Grades
Stainless pipes come in different alloy grades. Each alloy grade has different characteristics. This section will discuss five major categories: austenitic, ferritic, martensitic, duplex, and precipitation hardening pipes.
Austenitic Stainless Steel Pipes
Austenitic pipes are known for outstanding corrosion resistance. It has different grades like 304, 316, 321, and 347. Grade 304 which is also called 18/8 stainless. It has 18% chromium and 8% nickel which makes it appropriate for architectural elements, food equipment and chemical tanks.
Ferritic Stainless Steel Pipes
Ferritic pipes are an affordable option than austenitic stainless steel pipes due to less nickel content. They have different alloy grades like 409, 430 and 444. Grade 409 has 10.5% chromium which is very useful in car exhaust systems. This grade also provides good corrosion resistance and high temperature tolerance.
Martensitic Stainless Steel Pipes
These magnetic pipes have 11.5-18% chromium and 0-1.2% carbon. The most common grades of martensitic pipes are 410, 420, and 440. Grade 420 has a higher carbon content (0.15-0.40%) which gives outstanding wear resistance and hardness. These characteristics make this pipe an appropriate choice for valve components and surgical tools.
Duplex Stainless Steel Pipes
These pipes combine ferritic and austenitic structures. They also provide a balance of strength and outstanding corrosion resistance. Common alloy grades are 2205, 2304, and 2507. Grade 2205 has 22% chromium and 5% nickel.
Duplex are broadly used in demanding conditions like desalination plants, offshore oil and gas facilities and chemical plants.
Precipitation Hardening Stainless Steel Pipes
This type covers different alloy grades like 17-4PH, 15-5PH, and 13-8Mo. The most common grade is 17-4PH which has about 17% chromium, 4% nickel, 4% copper, and 0.3% niobium. These pipes acquire high strength through heat treatment which makes fine precipitates inside the microstructure. They are mostly used in high pressure systems, aerospace and nuclear reactors.
The following table provides a comprehensive comparison of stainless pipes classified by various alloy grades:
| Grade Type | Common Grades | Chromium Content | Nickel Content | Key Properties | Typical Applications |
| Austenitic | 304, 316, 321 | 16-26% | 6-22% | High corrosion resistance, non-magnetic, excellent ductility | Food processing, chemical tanks, marine environments |
| Ferritic | 409, 430, 444 | 10.5-27% | 0-2% | Magnetic, good corrosion resistance, lower cost | Automotive exhaust, heat exchangers, kitchen equipment |
| Martensitic | 410, 420, 440 | 11.5-18% | 0-2% | High strength, moderate corrosion resistance, heat-treatable | Turbine blades, surgical instruments, valve components |
| Duplex | 2205, 2304, 2507 | 21-25% | 3-7% | High strength, excellent corrosion resistance, good ductility | Offshore oil & gas, desalination plants, chemical processing |
| Precipitation Hardening | 17-4PH, 15-5PH, 13-8Mo | 11-18% | 3-8% | Very high strength, good corrosion resistance, heat-treatable | Aerospace, nuclear reactors, high-pressure systems |
Pipe Types Classified by Application Areas
Steel Pipes perform an important role in different areas. Now, we will discuss some pipe types designed for particular operations because of their properties.
Sanitary Stainless Steel Pipes
Sanitary pipes are very important and broadly used in clean steam distribution, bioreactors and pasteurization systems and fermentation processes. Their smooth inside surfaces (with Ra of 0.8μm) and design helps in preventing bacterial growth and contamination. Manufacturers often use high-grade austenitic stainless steel like 316L in these pipes for better corrosion resistance.
Polished Stainless Steel Pipes
They are largely used in facade elements, modern furniture and architecture handrails. In pharmaceuticals, polished pipes are also very important for sterilization processes, clean piping systems and cleanroom tools. Architects and designers also use these pipes into decorative plumbing fixtures, handrails and interior design. Their smooth finish provides a sleek surface, increased flow characteristics and easy cleaning.
Mechanical Stainless Steel Pipes
These are mostly used in industrial pneumatic lines, hydraulic cylinders and car fuel injection systems. They also find many uses in refinery processes, oil rig wellheads and aerospace equipment. Their durability in extreme conditions makes them appropriate for different industry uses.
Nuclear-Grade Pipes
Nuclear power plants heavily depend on special stainless pipes. These N-grade pipes can withstand high radiation exposure, temperatures and pressure. They also follow strict standards which guarantee reliability and safety in fuel handling equipment, coolant systems and reactor parts.
Electric Fusion Welded Pipes
These pipes are usually used in structural operations, water distribution lines and oil and gas pipelines. They also provide high strength and outstanding weld quality. Their ability to handle high pressures and cost-effectiveness make them appropriate for long distance fluid transportation.
Comparison Table of Steel Pipes classified by Application areas
| Type | Primary Industries | Key Features | Typical Grades |
| Sanitary | Food, Pharma, Biotech | Smooth interior, Hygienic fittings | 304, 316L |
| Polished | Architecture, Decor | Aesthetic finish, Enhanced corrosion resistance | 304, 316 |
| Mechanical | Oil & Gas, Chemical | High strength, Temperature resistance | 304/L, 316/L, 321 |
| Nuclear-Grade | Nuclear Power | Ultra-low impurities, Strict quality control | 304, 316, 347 |
| EFW | Oil & Gas, Construction | Uniform wall thickness, Cost-effective | API 5L grades |
Conclusion
Stainless pipes provide different solutions across industries. How they’re classified on the basis of production method, different shapes and alloy grades and truly shows their flexibility.
Learning about these types can help manufacturers and engineers to choose the best pipe for their particular needs.
KDM Fabrication specializes in custom stainless steel pipe fabrication. Our expert team can help you in selecting the appropriate pipe type for your project needs. Contact us today for consultation services.
FAQs
What are the advantages of using stainless steel pipes?
Stainless pipes provide high strength to weight ratio, durability and corrosion resistance. They also keep structural integrity under extreme pressures and temperatures. These pipes are also easy to clean, recyclable, cost effective and hygienic for different industrial uses.
What factors you should consider when choosing a stainless pipe type?
When choosing a stainless pipe, consider the temperature range, pressure requirements and operating environment. Also, know about the pipes mechanical properties, corrosion resistance and chemical composition. Finally, check the pipe’s compliance with industry standards and cost-effectiveness for the particular application.
