GOST - ISO 3183-2007 Straight Seam Pipe API 5L X70 PSL2 LSAW TGAZ Project

API 5L X70 PSL2 LSAW Piperefers to longitudinally submerged arc welded steel pipes manufactured in compliance withAPI 5L Specification

LSAW (Longitudinally Submerged Arc Welding): The manufacturing method-longitudinal seam, double-sided submerged arc welding.

API 5L X70 PSL2 LSAWPipe is a premiumhigh-strength, large-diameter line pipethat delivers exceptional mechanical performance, low-temperature toughness, and weld integrity. It is the industry-standard solution for the most demandingoil and gas pipeline projectsworldwide, where safety, reliability, and long-term service life are non-negotiable

 

Typical Size Range:

Outer Diameter (OD): 8"to 72" (219mm - 1820 mm)
Wall Thickness(WT): 6mm to 60 mm(0.250″ - 2.362″).
Length:6 m, 12 m (single random length), or up to 18 m (double random).
End Finish:Beveled Ends (BE) for on-site welding; Plain Ends (PE) available.

Surface:Natural, varnished, black painting, anti-rust oil

Protection:Plastic caps or iron protectors on pipe ends

Packing:Bare, bundled, or PVC packing

LSAW Manufacturing Process

LSAW pipes are produced from single hot-rolled steel plates (not coils), offering superior dimensional accuracy and structural integrity.

1.Plate Preparation:Raw steel plate is cut, edged, and pre-bent.
2.Pipe Forming:The plate is cold-formed into a cylindrical shell via methods likeUOE, JCOE, or HME.
UOE:U-ing → O-ing → Expanding (most common for large-diameter pipes).
JCOE: J-bending → C- bending → O-forming → Expanding.

Method	Description	Advantages	Typical Application
UOE	Plate pressed into U-shape, then O-shape, seam-welded and mechanically expanded	Highest dimensional accuracy, excellent roundness and straightness, high throughput	High-grade pipeline pipe (X65-X80) large-volume production
JCOE	Incremental J-press forming (edges first, then center) welded, and expanded	Lower capital investment, flexible production balanced stress distribution	Small to medium production capacities challenging dimensions
Roll-Bend	Plate progressively rolled into a cylinder	Suitable for thicker walls, smaller production runs	Thick-wall applications, specialty orders

3.Welding:Double-sided submerged arc welding (internal & external). The arc is buried under granular flux, ensuring deep penetration, high quality, and minimal defects.
4.Expansion & Sizing: Mechanical cold expansion to achieve precise roundness, dimensional tolerance, and to relieve internal stresses.
5.Heat Treatment:Often normalized (N) or quenched & tempered (Q&T) to meet PSL2 mechanical properties.
6.Inspection & Testing:Full-body Non-Destructive Testing (UT, RT, MT), hydrostatic test, final inspection, and marking.

 

 

Technical Data

1.Chemical Composition (PSL2, Max Limits)

Element	Max. % (Wt)	Key Function
Carbon (C)	0.22	Controls strength & hardness; limited for weldability
Manganese (Mn)	1.65	Enhances strength & toughness; deoxidizer
Silicon (Si)	0.45	Deoxidation; improves strength
Phosphorus (P)	0.025	Reduced to prevent brittleness
Sulfur (S)	0.015	Minimized to avoid hot cracking & improve toughness
Niobium (Nb) + Vanadium (V) + Titanium (Ti)	0.15	Microalloying; grain refinement & precipitation hardening
Carbon Equivalent (CEV)	Strictly controlled	Ensures excellent field weldability

2.Mechanical Properties (PSL2)
PSL2 requires mandatory Charpy V-Notch (CVN) impact testing, which PSL1 does not.

Property	Requirement
Yield Strength (YS)	≥ 485 MPa (70,300 psi)
Tensile Strength (TS)	570 - 760 MPa (82,665 - 110,200 psi)
Elongation	≥ 21% (depends on wall thickness)
Hardness	Typically ≤ 248 HB; controlled for sour service resistance
Charpy Impact Toughness (PSL2 Mandatory)	Min. 27 J (20 ft-lb) at 0°C or lower (e.g., -20°C/-40°C) for pipe body & weld seam

3.PSL2 vs. PSL1: Critical Differences (X70)

Parameter	API 5L X70 PSL1	API 5L X70 PSL2
Quality Level	Basic	Advanced/Enhanced
Sulfur (S) Max	0.0003	0.00015
Phosphorus (P) Max	0.0003	0.00025
Impact Test	Not mandatory	Mandatory CVN (e.g., 27J @ -20°C)
NDT Requirement	Basic	Full-body UT + Seam RT/UT
Traceability	Limited	Full material & process traceability
Hardness Control	Loose	Strictly controlled (for HIC/SSC resistance)
Application	General service	Critical, high-pressure, sour, low-temp

4.Quality Control and Testing for LSAW Pipes:

All LSAW pipes undergo rigorous inspection procedures, including:

"Chemical composition analysis

"Mechanical properties testing (tensile, yield, elongation)

"Technical property evaluations (flattening test, bending test, impact test)

"Exterior size and dimensional inspection

"Hydrostatic test (mandatory - nondestructive substitution not allowed)

X-ray examination (100% of the weld seam)

"Ultrasonic testing (UT) for each steel grade

Hardness testing (pipe body, weld, and HAZ)

"Drop Weight Tear Test (DWTT) for fracture resistance evaluation

 

Certificate:EN 10204 Type 3.1 (manufacturer's inspection) or Type 3.2 (independent third-party inspection), with third-party inspection services available through TUV, DNV, SGS, Lloyds, and other recognized bodies.

LSAW vs. SSAW Comparison

Feature	LSAW (Longitudinal SAW)	SSAW (Spiral SAW)
Weld Seam	Single straight longitudinal seam	Continuous helical (spiral) seam
Residual Stress	Lower	Higher
Weld Length	Shorter (pipe length)	Longer (multiple times pipe length)
Geometric Accuracy	Higher	Lower
Diameter Range	8 ″-72 ″ (219mm-1820mm)	8″-100″ (219mm-2540 mm)
Preferred	High-pressure transmission pipelines	Large-diameter, lower-pressure applications

LSAW pipes demonstrate better performance than SSAW pipes due to their lower residual stress, uniform expansion process, fewer welding lines, and higher geometrical accuracy

Coating Options for Corrosion Protection

For buried or offshore pipelines, external anti-corrosion coatings are essential. The most common coating systems for API 5L X70 LSAW pipes include

Coating Type	Description	Application	Temperature Range
FBE (Fusion Bonded Epoxy)	Single-layer epoxy powder coating	Onshore pipelines, moderate corrosion environments	-30°C to 100°C
2FBE (Dual-Layer FBE)	Double-layer epoxy system	Enhanced corrosion protection for aggressive soils	-30°C to 100°C
3LPE (Three-Layer Polyethylene)	FBE + copolymer adhesive + polyethylene	Underground projects, mechanical damage risk	Up to 80-85°C
3LPP (Three-Layer Polypropylene)	FBE + copolymer adhesive + polypropylene	High-temperature pipelines, harsh terrains, HDD	Up to 110°C+
CWC (Concrete Weight Coating)	Concrete coating over anti-corrosion layer	Submarine pipelines (negative buoyancy control)	N/A

Application

API 5L X70 PSL2 LSAW pipes are engineeredmission-critical pipeline infrastructure:

1.Cross-country oil and gas transmission pipelines- Long-distance, high-pressure transportation

2.Offshore and subsea pipelines- High-strength requirements for deepwater conditions

3.Gas distribution networks- High-pressure natural gas transmission

4.Water transmission mains- Large-diameter water supply systems

5.Offshore platform structural members- Jacket legs and pile foundations

6.Sour service pipelines- H₂S-containing environments (with Annex H requirements)

7.High-pressure and high-temperature environments

8.Piling pipes for large-diameter foundations

9.Long-Distance Oil & Gas Transmission Pipelines(Cross-country, high-pressure).

10Offshore & Subsea Pipelines(Deepwater projects >500m).

11.Sour Service Pipelines(H₂S/CO₂ corrosive gas fields).

12.Arctic/Cold Region Pipelines(Low-temperature service).

13.Urban Gas Distribution Networks(High-density population areas).

14.Large-Diameter Water Transmission& Structural Piling.

LSAW pipes are preferred due to their superior strength, corrosion resistance, and weldability, making them well-suited for offshore, deepwater, and extreme-condition applications.