316L welded pipes are used in many industries for handling liquids, gases, and chemicals. They are made from 316L stainless steel, a low-carbon grade known for its strong corrosion resistance. Welded pipes are more cost-effective than seamless ones, especially in larger sizes. They are easier to produce in bulk and offer good strength for many standard uses. Selecting the proper pipe for every project requires knowledge of pipe size, pressure ratings, and industry standards. This guide provides clear, practical information to help you understand what matters when choosing a 316L welded pipe.
What is 316L Welded Pipe?
Material Overview: 316L Stainless Steel
316L is a low-carbon version of 316 stainless steel. It has excellent corrosion resistance especially in chloride-heavy environments like coastal or chemical areas, because it contains less carbon. 316L avoids carbide precipitation during welding, making it ideal for welded pipe applications.
Manufacturing Process of Welded Pipes
316L welded pipes are made by forming a flat strip or plate into a tube shape and then welding the seam. In some cases, the pipe goes through post-weld heat treatment to improve structure and performance. Surface finishes vary; common options include pickled, polished, or annealed surfaces, depending on the intended use.
Available Dimensions and Sizes of 316L Welded Pipes
Pipe Sizes: There are numerous sizes available for SS 316L welded pipes. Although there are larger sizes available, the most common Nominal Pipe Size (NPS) is between ½ and 24 inches.
In addition to NPS, the outer diameter (OD) and wall thickness are important metrics. Schedule-based wall thickness groups include SCH 5S, SCH 10S, SCH 40 and SCH 80. Higher pressure can be tolerated by thicker schedules.
Standard Lengths & Customization
The most common lengths for 316L welded pipes are 6 meters and 12 meters. Some suppliers offer cut-to-length services for custom requirements.
There are also two production styles: coil-welded pipes and mill-length welded pipes. Coil-welded pipes allow longer lengths with fewer joints, while mill-length pipes are more standard.
International Standards for 316L Welded Pipes
Common Standards
These are the most common standards you’ll see on 316L welded pipes:
ASTM A312 – Covers seamless and welded austenitic stainless steel pipes for general service.
ASTM A358 – Specifies electric-fusion-welded austenitic stainless steel pipe.
ASME B36.19M – Lists the dimensions for stainless steel pipes.
EN 10217-7 – European standard for welded stainless steel pipes used in pressure applications.
Certifications to Look For
When buying 316L welded pipes, always check for:
Mill Test Certificate (MTC) as per EN 10204 3.1 – Confirms the material and quality.
ISO 9001, PED, or NACE MR0175 – These may be needed for certain projects, especially in oil, gas, or export work.
Pressure Ratings of 316L Welded Pipe
How Pressure Ratings Are Calculated
Pressure ratings depend on pipe wall thickness, outer diameter, and operating temperature. The higher the wall thickness and the lower the temperature, the more pressure a pipe can handle. Engineers use ASME B31.3 for design rules and safety margins. Always check actual project specs and certified standards before making a final decision.
Sample Pressure Ratings (Indicative)
1″ NPS, SCH 10S: 2.77 mm wall thickness, handles up to 55 bar at 100°C
2″ NPS, SCH 40: 3.91 mm wall thickness, handles up to 45 bar at 100°C
4″ NPS, SCH 10S: 3.05 mm wall thickness, handles up to 30 bar at 100°C
Tolerances and Surface Finishes
Dimensional Tolerances
316L welded pipes must follow set tolerances for outer diameter, wall thickness, and length. These are defined in ASTM and ASME standards. Special tolerances are available for critical or high-precision applications.
Surface Finishes
Common surface types include:
Pickled – Acid-cleaned to remove scale
Bright Annealed (BA) – Smooth, shiny finish
Mechanically Polished (MP) – Clean, uniform surface
In applications where fluid flow, corrosion resistance, or hygiene are crucial, such as in the food or pharmaceutical sectors, surface finish matters.
Applications of 316L Welded Pipes by Industry
Food & Beverage: It is used in processing lines for transporting liquids, steam, and cleaning agents. The corrosion resistance and smooth finish of 316L help maintain hygiene standards, ensuring no buildup or contamination. It also supports easy cleaning and sterilization, reducing downtime and meeting health codes.
Pharmaceutical: 316L welded pipe is essential in systems requiring sterile conditions like high-purity water distribution and clean-in-place operations. The low carbon content and clean welds reduce contamination risk and ensure regulatory compliance. These pipes are preferred for their non-reactive surfaces, vital in controlled environments.
Oil & Gas: They are used in pipelines that transport water, gas and other fluids for exploration and refinement operations. The material is appropriate for both onshore and offshore situations due to its durability and resistance to corrosion caused by chloride. It performs reliably under high pressure and in corrosive drilling zones.
Marine: Installed in ballast systems, exhaust systems, and seawater cooling lines. The alloy’s ability to resist saltwater corrosion extends service life and reduces the need for frequent maintenance in marine structures. It’s a dependable choice for shipbuilding, offshore rigs, and desalination systems.
Chemical Processing: They are used in transporting aggressive chemicals such as acids, alkalis, and solvents. The high resistance to corrosion and chemical attack, combined with ease of fabrication, makes 316L reliable in continuous processing plants. Welded pipes handle both low and high-temperature flows without degradation.
Conclusion
Choosing the appropriate 316L welded pipe for every task requires an understanding of its dimensions, pressure ratings and standards. These pipes provide a dependable combination of price, strength, and resistance to corrosion. With sizes from ½” to 24″ and support for various schedules and finishes, they fit many industrial needs. For food processing, marine systems, or chemical transport, 316L welded pipe is a trusted solution. Need help in selecting the right 316L welded pipe size or pressure class? Contact our technical team for expert guidance and certified supply.
