ASTM A252, API 5L, GB/T3091 Longitudinal Submerged Arc Welded (LSAW) Pipe is a type of steel pipe manufactured by rolling steel plates into a cylindrical shape and welding a single straight seam along its length. The core technology is Submerged Arc Welding (SAW), where the welding arc is shielded by a layer of flux, ensuring high weld quality and stable formation. Key advantages of this process include:
Superior Weld Quality: The flux protection prevents air exposure, effectively reducing defects such as porosity and cracks.
High Production Efficiency: Ideal for large-scale manufacturing, with welding speeds reaching 1–2 meters per minute.
Thick-Wall Capability: Capable of welding pipes with wall thicknesses ranging from 6–100 mm (e.g., per API 5L standards), making them widely used in high-pressure pipeline applications.
Specification
Standard: ASTM A252, API 5L, GB/T3091, EN10219, EN10210, EN10217 etc.
Diameter Range: Typically Φ219mm–Φ3000mm, with customized special sizes available based on engineering requirements.
Wall Thickness: Standard range of 6mm–100mm, with specific thickness requirements varying by application.
Length Standards: Generally 6m–12.5m, with non-standard lengths customizable per customer needs.
Non-Destructive Testing (NDT): 100% inspected via X-ray or ultrasonic testing to ensure defect-free welds.
Anti-Corrosion Treatment: Options include internal/external epoxy coating and galvanizing for corrosion protection.
Process
- Plate Inspection: At the start of the production line, steel plates for manufacturing large-diameter LSAW pipes undergo 100% full-plate ultrasonic testing to ensure quality before entering production.
- Milling: Based on pipe diameter requirements, the edges of the steel plate are double-sided milled by a milling machine to achieve the desired plate width, edge parallelism, and groove profile.
- Pre-Bending: Using a pre-bending machine, the edges of the steel plate are pre-bent to achieve a specific curvature, meeting subsequent forming requirements.
- Forming: On a JCO forming machine, the pre-bent steel plate undergoes progressive stamping-half is pressed into a "J" shape, while the other half is bent into a "C" shape, ultimately forming an open "O" structure.
- Pre-Welding: After forming, the LSAW pipe undergoes seam alignment followed by continuous MAG (Metal Active Gas) welding to ensure weld integrity.
- Internal Welding: Inside the pipe, longitudinal multi-wire submerged arc welding (up to 4 wires) is applied to enhance strength and sealing.
- External Welding: The exterior of the LSAW pipe undergoes precise multi-wire submerged arc welding to ensure structural integrity and sealing.
- Ultrasonic Testing I: 100% ultrasonic inspection is performed on both internal and external welds, as well as the base metal on either side of the weld, leaving no defects undetected.
- X-ray Inspection I: 100% X-ray industrial television testing is conducted on both internal and external welds, supported by image processing systems to ensure detection accuracy.
GNEE LSAW pipe for sale
