Seamless vs Welded tubing

Seamless vs Welded Tubing
When choosing between different types of tubing, several factors must be considered. The table below will help you understand the differences between welded and seamless tubing.

Table of contents

  • What is Seamless Tube
  • What is Welded Tubes
  • Pressure Capacity of Seamless And Welded Tubing
  • Seamless vs Welded Tubing
  • Difference Between ERW and Seamless Tube Price
  • Advantages and Disadvantages of seamless and welded tube
  • Seamless Tubing Sizes
  • Seamless Steel Tubes Manufacturing Process
  • Welded Steel Tube Manufacturing Process
  • Seamless Tubing vs DOM Tubing
  • Seamless Steel Tube Uses
  • Application for Welded Round Tubing
  • Mechanical Properties of ERW vs Seamless Tube
  • Finish for Welded and Seamless Tubes
  • Seamless Tube Weight Chart
  • SMLS Tube Extrusion Process
  • Welded Tube Types

What is Seamless Tube

Seamless tube meaning A seamless, weld-free metal tube manufactured by heating a solid billet into the desired shape and form.
Seamless Tube Production Process
  • Billet Heating
  • Piercing
  • Elongation
  • Sizing
  • Heat Treatment
  • Testing & Inspection
Characteristics
  • Uniform Structure
  • High Strength.
  • Durability
  • Surface Finish

What is Welded Tubes

Definition A metal tube created by joining the edges of a metal plate or strip to create a tube structure.
Production Process
  • Metal Strip Formation
  • Tube Formation
  • Welding
  • PostWeld Processing
Characteristics
  • Weld Seam
  • Strength
  • Surface Finish
  • Dimensional Accuracy

Seamless tubes can handle higher pressure compared to welded tubing

Due to the absence of a weld, seamless tubes have no weak points. This makes them more suitable for high-pressure applications. Below are detailed pressure ratings for both types of tubes.

Pressure Capacity of Seamless And Welded Tubing

Pressure Capacity of Seamless And Welded Tubing

Welded tubes often have larger diameters and thinner walls

This feature makes them ideal for architectural and construction projects where precise dimensions are required. Because they can be produced faster, they offer more flexibility for custom designs. Thus, you can achieve larger diameters and thinner walls for specific applications.

Seamless vs Welded Tubing

Description Seamless Tubing Welded Tubing
Manufacturing Process Seamless tubes are made from a solid billet that is heated and extruded to form a tube without any weld seam. Formed from flat strips of metal that are rolled and welded along the length.
Length Shorter in length Long continuous lengths
Strength Stronger Lower compared to seamless
Uniformity More uniform wall thickness Wall thickness may vary slightly
Applications Used for high-pressure applications and critical structural components. Commonly used in less critical applications
Corrosion Resistance More corrosion-resistant. Less corrosion resistance.
Cost More expensive Less expensive
Manufacturing Flexibility Less flexible More flexible
Surface Quality Rough because of extrusion process Smooth high-quality surface
Surface Finish Smoother finish and few surface defects. Surface finish can be less consistent due to the welding process
Ovality Provide better ovality and roundness  Poor ovality and roundness
Inspection & Testing Requires more rigorous testing to ensure quality and strength. May require less rigorous testing
Internal surface check Not possible Checked before manufacturing
Size Range Available in a more limited range of sizes than welded tubing. Can be produced in a large range of sizes and lengths.

Welded tubing is generally less expensive than seamless tubing

Since welded tubes can be manufactured quickly, they are more adaptable than seamless pipes. This means more welded tubes can be produced in a given time, reducing labor costs. It is ideal for industries requiring low to medium pressure applications.

Difference Between ERW and Seamless Tube Price

Seamless Tube ERW Steel Tube
More expensive: 1.5 to 3 times the cost of welded tubes Less expensive: 30% to 60% cheaper than seamless tubes
Factors affecting: Manufacturing Process, Quality, Production Costs, Demand

Advantages and Disadvantages of seamless and welded tube

Pros and Cons of Hot Finished Seamless Type Tubes

Pros Cons
Excellent corrosion resistance Expensive
Good Durability Difficult to manufacture
High pressure rating Not ideal for thin wall large diameter tubes
Good Purity Longer lead times
Ideal for critical applications  

Pros and Cons of Welded Tubes

Pros Cons
Better lead times Suitable for Heavy wall applications
Less Expensive Less corrosion resistant
Available in long lengths Slight impurities
Thinner wall Stress concentration
More consistent concentricity  
Tighter tolerances  

Seamless Tubing Sizes

NPS Schedule DN OD Wall thck Weight
[inch] [inch] [lbs/ft]
1/8 10 6 .405 .049 .19
  40     .068 .24
  80     .095 .31
1/4 10 8 .54 .065 .33
  40     .088 .42
  80     .119 .54
3/8 10 10 .675 .065 .42
  40     .091 .57
  80     .126 .74
1/2 5 15 .84 .065 .54
  30     .095 .76
  40     .109 .85
  160     .188 1.31
3/4 5 20 1.05 .065 .69
  30     .095 .97
  80     .154 1.47
  160     .219 1.94
1 5 25 1.315 .065 .87
  10     .109 1.41
  40     .133 1.68
  160     .25 2.84
1 1/4 5 32 1.66 .065 1.11
  30     .117 1.93
  80     .191 3
  160     .25 3.76
1 1/2 5 40 1.9 .065 1.28
  10     .109 2.09
  40     .145 2.72
  80     .2 3.63
  160     .281 4.86
2 5 50 2.375 .065 1.61
        .109 2.64
        .141 3.36
  40     .154 3.65
        .188 4.39
  80     .218 5.02
        .281 6.28
  160     .344 7.46
2 1/2 5 65 2.875 .038 2.47
  10     .12 3,53
        .125 3.67
        .156 4.53
        .188 5.4
  40     .203 5.79
  80     .276 7.66
  160     .375 1 .01
3   80 3.5 .083 3.03
  10     .12 4,34
        .141 5.06
        .172 6.11
  40     .216 7.58
        .281 9.66
  80     .3 1 .25
  160     .438 14.32
3 1/2 5 90 4 .083 3.48
  10     .12 4.98
        .141 5.81
        .172 7.03
  40     .226 9.11
        .281 11.16
  80     .318 12.5
4 5 100 4.5 .083 3.92
  10     .12 5.62
        .141 6.56
        .172 7.95
        .203 9.32
  40     .237 1 .79
        .281 12.66
  80     .337 14.98
  160     .531 22.51
Seamless steel tube is extruded and drawn from a billet while welded tube is manufactured from a strip

The difference between the two tubes lies in their manufacturing process. Seamless tubes do not have any weld seams, which gives them higher strength, making them suitable for high-pressure conditions.

On the other hand, welded tubes have welds, which make them lower in strength and more suitable for applications with medium to low pressure conditions.

Seamless Steel Tubes Manufacturing Process

Seamless Steel Tubes Manufacturing Process

Welded Steel Tube Manufacturing Process

Welded Steel Tube Manufacturing Process

Seamless Tubing vs DOM Tubing

Description Seamless Tube DOM Tubing
Manufacturing Process Made from a solid billet Starts as a welded tube, then drawn over a mandrel
Advantages High strength and durability Good dimensional accuracy
Strength Higher Improved strength compared to standard welded tubes, but not as strong as seamless tubing
Weld Seams No weld seams Originally welded, but weld seam is removed during the mandrel process
Dimensional Accuracy High Very high
Surface Finish Varies Smooth and uniform after mandrel drawing
Cost More Less

Seamless Steel Tube Uses

  • Aerospace
  • Oil and gas
  • Structural components in demanding environments
  • High-pressure hydraulic systems
Seamless Steel Tube Uses
Seamless annealed tubing is more expensive than welded round tubing

Seamless annealed tubing goes through several processes, which makes it costlier. The longer manufacturing process increases labor and machining costs, leading to a higher price.

Application for Welded Round Tubing

Application for Welded Round Tubing
  • General structural applications
  • Piping and tubing in less demanding environments
  • Automotive components
  • Furniture and general manufacturing

Mechanical Properties of ERW vs Seamless Tube

Property Seamless Tubes ERW Steel Tubes
Tensile Strength Higher than welded Lower than seamless
Yield Strength Consistent across the entire tube May vary
Elongation Better Can be reduced at the weld seam and heat-affected zones – HAZ
Impact Toughness Higher Lower
Fatigue Resistance Higher Lower
Hardness Typically more consistent throughout the tube. Show variation
Weld Integrity N/A Quality of the weld can impact overall mechanical properties

Finish for Welded and Seamless Tubes

Seamless tubing

  • Cold Drawn Finish
  • Hot Finished
  • Polishing
  • Passivation
  • Coating

Welded tubing

  • Heat Treatment
  • Descaling
  • Polishing
  • Coating
  • Anodizing

Seamless Tube Weight Chart

Nominal Tube Size inch 1/8 1/4 3/8 1/2 3/4 1 1.1/4 1.1/2 2 2.1/2 3 4 5 6 8 10 12
mm 3 6 10 15 20 25 32 40 50 65 80 100 125 150 200 250 300
Outside Diameter mm 10.3 13.7 17.1 21.3 26.7 33.4 42.2 48.3 60.3 73 88.9 114.3 141.3 168.3 219.1 273.1 323.8
Sched 5 S Weight in kgm 0.2 0.37 0.47 0.8 1.03 1.3 1.65 1.91 2.4 3.69 4.51 5.84 9.47 11.32 14.79 22.63 31.25
WT in mm 1.2 1.2 1.2 1.65 1.65 1.65 1.65 1.65 1.65 2.11 2.11 2.11 2.77 2.77 2.77 3.4 3.96
Sched 10 S Weight in kgm 0.28 0.49 0.63 1 1.28 2.09 2.7 3.11 3.93 5.26 6.45 8.36 11.57 13.84 19.96 27.78 36
WT in mm 1.24 1.65 1.65 2.11 2.11 2.77 2.77 2.77 2.77 3.05 3.05 3.05 3.4 3.4 3.

Refined Application Of Thermal Oil

Thermal oil is used in high-temperature industrial processes, such as heat transfer systems, for efficient temperature control.
It's favored for its stability at high temperatures, low vapor pressure, and long operational life, making it ideal for applications requiring consistent, precise heating or cooling solutions.

thermic fluid，dowfrost，therminol 55

Heat Transfer Fluids , https://www.armcoltherm.com