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longitudinal welded pipe

More cost-effective for medium diameters (2"-24") vs. seamless pipes.

$1080 
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1. Definition & Manufacturing Process

Longitudinal Welded Pipe (LWP) is produced by:

  1. Roll-forming steel plates/coils into cylindrical shape

  2. Welding the longitudinal seam using:

    • Submerged Arc Welding (SAW) for thick walls

    • High-Frequency Induction (HFI) Welding for thin walls

  3. Sizing & Testing to meet dimensional/mechanical requirements

Key Advantage: More cost-effective for medium diameters (2"-24") vs. seamless pipes.

2. Technical Specifications

ParameterStandard RangeSpecial Grades
Diameter (OD)2" - 24" (50 - 600mm)Up to 80" for special orders
Wall Thickness0.1" - 1.5" (2.5-38mm)X80/X100 high-strength steel
Length20' - 40' (6-12m)Double random lengths up to 80'
Pressure Rating300 - 3,000 psiAPI 5L PSL2 compliant
Tolerances±0.5% OD, ±10% WTAerospace-grade ±0.1% OD

3. Material Grades

StandardCommon GradesYield StrengthKey Applications
API 5LB, X42, X52, X6535,000-80,000 psiOil/gas pipelines
ASTM A53A, B30,000-35,000 psiStructural, plumbing
ASTM A252Gr.1-345,000-60,000 psiPiling foundations
EN 10219S235-S460235-460 MPaConstruction in EU

4. Welding Methods Comparison

MethodThickness RangeAdvantagesDisadvantages
SAW0.25"-2.5"High deposition ratesLimited to straight seams
HFI Welding0.1"-0.5"No filler metal requiredOnly for carbon steels
Laser Welding0.04"-0.5"Ultra-precise, minimal HAZHigh equipment cost

5. Quality Control Tests

  • Non-Destructive Testing (NDT):

    • 100% X-ray inspection of weld seam

    • Ultrasonic testing (UT) for laminations

    • Hydrostatic test at 1.5x working pressure

  • Mechanical Tests:

    • Transverse tensile test

    • Charpy V-notch impact test (-60°F capability)

    • Hardness survey across weld zone

6. Applications

IndustryUsage ExamplesSpecial Requirements
Oil & GasGathering pipelines, pilingHIC/SSC resistant coatings
ConstructionScaffolding, structural supportsGalvanized (ASTM A123)
Water TransportMunicipal water mainsCement mortar lining
MechanicalConveyor systems, hydraulic cylindersPrecision-ground OD

7. Advantages vs. Seamless Pipe

FactorLWPSeamless
Cost30-50% lowerHigher raw material cost
Lead TimeShorter (weeks vs. months)Longer for specialty grades
Size AvailabilityBetter for large diametersLimited above 24"
Weld ReliabilityRequires rigorous NDTNo seam weaknesses