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About us
Tianjin lefin Industrial
TIANJIN LEFIN STEEL GROUP containing Tianjin lefin Industrial Co.,Ltd. 、Tianjin lefin steel import & export Co.,Ltd and Tianjin Shengqifeng International Trading Co., Ltd. -
Products
Steel Pipe Processing
Our main products include 1/2inch to 16 inch ERW PIPE/GI PIPE which has been produced according to BS1387/ASTM A53/EN10219/EN10255/EN10217 Standard -
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Service Capability
Guarantee Quality
Our steel pipes are suitable for oil, natural gas, shipbuilding, chemical industry, water conservancy, electrical, steel structure, construction and other related fields.
Our main products include 1/2inch to 16 inch ERW PIPE/GI PIPE which has been produced according to BS1387/ASTM A53/EN10219/EN10255/EN10217 Standard
Our main products include 1/2inch to 16 inch ERW PIPE/GI PIPE which has been produced according to BS1387/ASTM A53/EN10219/EN10255/EN10217 Standard
Has rich experience in steel pipe processing, can be customized according to customer requirements according to the drawing and sample processing, assist in the development of new products.
Product Description
DSAW LINE PIPE (Double Submerged Arc Welded Line Pipe) is a kind of welded steel pipe made of double submerged arc welding process, which is widely used in long-distance pipeline systems such as oil and natural gas.
Products Description
1. Material preparation
• The use of high-strength steel plates (such as API 5L X42 to X80 grades) as raw materials, subject to strict chemical composition and mechanical properties standards.
2. Forming and welding
• Pre-bending and forming:
After pre-bending, the steel plate is gradually bent into a cylindrical shape by the forming machine (JCOE/UOE process).
• Internal and external welding:
◦ The inner and outer walls of the steel pipe are submerged arc technology, and the arc is covered by flux during welding to prevent oxidation and ensure penetration and uniformity.
◦ The inner welding is done on the inside of the tube and the outer welding is done on the outside, creating a high quality weld on both sides (more reliable than single side welding).
3. Post-processing
• Expanding: Hydraulic or mechanical expanding processes eliminate residual stress and ensure roundness and dimensional accuracy.
• Non-destructive testing (NDT) : Using ultrasonic (UT), radiographic (RT) or magnetic particle testing (MT) to check for weld defects.
• Coating and anti-corrosion: Coating epoxy resin (FBE), three layers of polyethylene (3PE) and other anti-corrosion layers according to requirements.
Key characteristics
1. High strength and toughness
• Suitable for high pressure conveying (can withstand more than 10MPa pressure), material grade up to X80 (yield strength above 550MPa).
2. Large caliber and thick wall
• Typical specifications: Outer diameter 406-1600mm, wall thickness 6-40mm, length 6-18m.
• Suitable for laying the main line of long distance oil/gas pipelines.
3. High welding quality
• Double-sided submerged arc welding has large penetration depth, few defects, and weld strength is close to the base material.
4. Strong environmental adaptability
• Suitable for low temperature, high pressure, high corrosion (such as submarine pipeline) and other harsh conditions.
Application fields
• Oil and gas transportation: land and subsea long-distance pipelines (such as west-east gas transmission, cross-border pipelines).
• Chemicals and energy: Transportation of liquefied natural gas (LNG), carbon dioxide, hydrogen, etc.
• Infrastructure: water conservancy projects, nuclear power cooling systems and other high-pressure and durable scenarios.
Standards and Certification
• International standards: API 5L (American Petroleum Institute), ISO 3183, DNV (Norske Veritas), etc.
• Environmental requirements: HIC (resistance to hydrogen cracking) and SSC (sulfide stress corrosion) tests are required.
Advantages and limitations
Advantages:
• Stable weld quality, suitable for high pressure, large flow conveying;
• Preferred solution for large diameter pipes with long service life (up to more than 50 years).
Disadvantages:
• Long production cycle and high cost;
• Small diameter pipelines are less economical than ERW.
Address: Hengtai Road,Daqiuzhuang Town,Jinghai County,Tianjin,China
Mob: +8615122229899(whatspp)
Phone: +86 22 58171905
Fax: +86 22 58171902
E-mail:info@lefinsteel.com
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