Introduction

In the Oil & Gas infrastructure business, which is high risk, procurement officers are usually faced with a “Cost Wall” when the project specification demands pipe diameters beyond 20 inches (508 mm).Although seamless is the default choice for small diameter due to the perception that it is safer, extending this preference to large diameter API 5L pipe introduces a huge problem: Budget Blowout and Delivery Slips.If you’re having trouble locating a supplier for “24-inch Seamless X60 Pipe” at a reasonable price, this is the guide for you.​We’ll discuss the price gap between welded and seamless pipe and also show you why going with LSAW (Longitudinal Submerged Arc Welded) / SSAW (Spiral Submerged Arc Welded) isn’t merely a cost-saving step, but is actually the best practice when it comes to high volume transmissi.

What classifies as Large Diameter API 5L Pipe?

In general, API 5L pipes are large diameter if the pipe OD is greater than 20 inches(508 mm). Seamless pipes are also available in these sizes, but they are very scarce, costly, and hard to make.Therefore LSAW and SSAW production is a standard in the industry for large diameter pipelines, providing equal performance at a small fraction of the cost.

stacked large diameter api 5l pipes at sunset.

 

Why Avoid SMLS for Large Diameters?

Many engineers write “Seamless Only” as a matter of course. Yet, when it comes to large diameter pipe production, seamless process is subjected to both physical and economic constraints.

The Manufacturing Bottleneck

Seamless pipes are made by piercing a solid round steel billet.

  • The Physics: Making a hole in a solid bar becomes an order of magnitude harder as the diameter gets larger. The force to punch out a 24-in. pipe billet is enormous.
  • The “Hot Expansion” Issue: For dimension above 20-24 inch, the mills can applying a “Hot Expansion” (expansion of a smaller pipe) process.This can result in uneven wall thickness (eccentricity) and lower mechanical properties with respect to the original cold worked condition.

LSAW vs. SSAW Explained

In order to address the size/cost issue, the industry turned to the High-Frequency and Submerged Arc Welding processes. For large diameters, two particular types rule the market.

1. LSAW (Longitudinal Submerged Arc Welded)

  • Raw Material: Steel Plate (JCOE or UOE process).
  • Structure: The plate is molded into a cylinder and welded with a single straight seam.
  • Best For: High-pressure gas transmission, offshore deep-sea lines, and severe environments.
  • Availability: Reliable LSAW pipe suppliers can easily provide grades like API 5L X52, X60, and X70 in diameters up to 56 inches.

2. SSAW (Spiral Submerged Arc Welded)

  • Raw Material: Hot Rolled Steel Coil.
  • Structure: The coil is unrolled and welded spirally (like a paper towel roll core).
  • Best For: Long-distance onshore pipelines, water transmission, and piling.
  • Advantage: This is the most economical method to produce giant pipes (up to 100 inches) because the diameter is not limited by the width of a steel plate.

Critical Cost Analysis (The Decision Matrix)

This is the most important section for your project budget. Below is a direct comparison to help you make the right procurement decision.

Factor Seamless (SMLS) LSAW (JCOE) SSAW (Spiral) Allland’s Recommendation
Size Limitation Max ~26″ (Rare & Expensive) Up to 56″ (1422mm) Up to 100″+ (2540mm) Use Welded for >20″
Cost Index High ($$$$$) Medium ($$$) Low ($) SSAW is Best Value
Raw Material Round Billet Steel Plate Steel Coil Coil is cheapest feedstock.
Lead Time Long (Months) Medium Fast Welded offers faster delivery.
Wall Thickness Heavy Wall Specialist Up to 50mm+ Up to 25mm (Typical) LSAW for Heavy Wall.
Application Deep Sea / Critical Gas Mainline / High Pressure Oil/Water / Long Distance Match pipe to pressure.

The Financial Reality

  • Seamless: Costs grow exponentially after 16 inches.
  • LSAW: Costs are stable. Typically 30-40% cheaper than large seamless.
  • SSAW: The budget champion. Typically 15-20% cheaper than LSAW due to coil pricing and continuous production efficiency.

Commercial Intent: If you are looking to buy API 5L X52/X60 pipe for a 50km land pipeline, choosing SSAW over Seamless could save you millions of dollars in material costs alone.

Is Welded Pipe Safe for API 5L Projects?

This is the “Trust Issue” that keeps engineers awake at night. Is the weld seam safe?

The answer lies in the API 5L PSL2 welded pipe specification.

Modern welded pipes are not the “weak link” they were 50 years ago.

1. 100% NDT (Non-Destructive Testing)

According to API 5L standards, every single inch of the weld seam in LSAW and SSAW pipes must undergo Ultrasonic Testing (UT): To detect internal laminations or cracks.Radiographic Testing (RT/X-Ray): To visualize the weld integrity.

2. Joint Efficiency

At Allland, our welded pipes undergo Hydrostatic Testing (water pressure test) that stresses the pipe to 100% of the specified yield strength. The weld is designed to be as strong as the base metal.

3. Heat Treatment

The mechanical expansion and heat treatment of the premium quality LSAW pipes are carried out to relieve the internal strain and to make physical properties (tensile strength, impact toughness) consistent for the whole pipe.

Conclusion

In large diameter API 5L pipe, the blind economic chasing of seamless pipe and pipe must need is not practically required. If you want high pressure reliability, heavy wall thickness and offshore-grade safety, choose LSAW.Choose SSAW to get the best cost per meter for long distance on-shore transmission of oil, gas or water.Both products deliver a safe, certified and cost-effective solution to the shortage of large seamless pipes.

Don’t let “Seamless” specifications drain your budget. Contact Allland today. We analyze your pressure requirements and provide a competitive quote on API 5L LSAW & SSAW pipes tailored to your project’s needs.

FAQs on Buying Large Diameter API 5L Pipe

Q: At what size should I switch from Seamless to LSAW?

A: We usually recommend 18″ or 20″ as the cut-off. Seamless is competitive under 18″. Above 20″ LSAW or SSAW provide a massive cost and availability advantage.

Q: Is SSAW allowed for API 5L gas pipelines?

A: Yes, absolutely. The SSAW is commonly used onshore gas pipelines all over the world as long as it satisfies the requirements of API 5L PSL2.However, for ultra high-pressure Class 4 locations or offshore risers, engineers generally select LSAW because of the shorter weld length.

Q: What is the price difference between LSAW and SSAW?

A:The SSAW is normally 15-20% lower price than LSAW. This is due to Hot Rolled Coil (raw material of SSAW) is cheaper to make than Steel Plate (raw material of LSAW), and the spiral manufacturing procedure is continuous and more productive.