GB/T 13793 Longitudinal Electric Resistance Welded Pipe in 10#, 15#, 20#, Q235B and Q345B

GB/T 13793 longitudinal electric resistance welded (ERW) pipe is a straight-seam welded carbon steel pipe for structural service and general fluid conveyance. The standard covers longitudinal electric welded steel pipe up to 711 mm outside diameter, and is commonly selected when buyers need stable dimensional control, efficient production, and a broad material range from low-carbon quality steels such as 10#/15#/20# to structural grades such as Q235B and Q345B. GB/T 13793-2016 is the current GB product standard for this pipe category.

Specifications

Main Features

1. Straight-seam ERW construction for efficient roundness and dimensional consistency. HF-ERW is widely recognized for lower heat input, high productivity, and good dimensional accuracy compared with many other welded pipe routes.
2. Broad strength window from mild structural grade to higher-load structural grade.
   • Q235B: yield strength starts at 235 MPa for thickness ≤16 mm, with tensile strength 370-500 MPa.
   • Q345B: yield strength starts at 345 MPa for thickness ≤16 mm, with tensile strength 470-630 MPa.
3. Good fabrication behavior in the low-carbon grades.
   • 10#: C 0.07-0.13%, good formability and weldability.
   • 15#: C 0.12-0.18%, good weldability with slightly higher strength than 10#.
   • 20#: C 0.17-0.23%, balanced strength and toughness, commonly used for mechanical parts and medium-duty tube service.
4. Usable for both structural and low-pressure general fluid applications. GB/T 13793 explicitly covers structural uses and can also be used for general fluid conveying welded pipe.

Our Advantages

1) How do we control ERW weld seam reliability?

For professional buyers, the weld seam is always the first concern. ERW seam defects such as lack of fusion or hook cracks can reduce pressure or structural reliability, which is why practical quality control must focus on seam integrity. Our advantage is that we treat seam quality as a separate control item: online weld monitoring, dimensional inspection around the seam zone, and optional NDT / hydrostatic verification according to project requirements. Industry sources consistently identify seam integrity assessment, hydrostatic testing, and crack-detection inspection as the key controls for ERW pipe quality.

2) How do we reduce installation problems caused by dimensional variation?

Buyers care about fit-up, especially for fabricated structures, sleeves, and general piping assemblies. Dimensional tolerance directly affects installation accuracy, welding efficiency, and downstream machining. Our advantage is stable forming control on OD, wall, ovality, and straightness, with order-based inspection records and mill certificates tied to each lot. Industry guidance on ERW tolerance selection emphasizes that dimensional precision is one of the main reasons engineers choose ERW products.

3) How do we avoid grade substitution risk across 10#/15#/20#/Q235B/Q345B?

Another common procurement issue is receiving a pipe that meets size requirements but not the intended chemistry or strength class. Our advantage is grade-by-grade traceability from raw strip or coil to finished pipe, with the material standard matched to the steel family: GB/T 699 for 10#/15#/20#, GB/T 700 for Q235B, and legacy GB/T 1591/market practice for Q345B. This is especially important because Q345B is widely known in the market, while the newer GB/T 1591 system uses Q355B as the current replacement route in many structural applications.

Execution Standards

Application Field

Product focus: welded steel pipe for building steel structure columns and bracing members.
This is a practical application for Q235B and Q345B longitudinal ERW pipe where controlled straightness, reliable weld seam quality, and stable dimensional consistency are more important than premium alloying. GB/T 13793 itself is expressly intended for mechanical and construction structural applications.

Chemical Composition

Reference note: 10#, 15#, 20# are based on GB/T 699 grade data; Q235B is based on GB/T 700 data; Q345B shown below follows legacy market/common reference data associated with GB/T 1591-era designation. Q345B is widely mapped in current practice toward Q355B in newer GB/T 1591 editions.

*Q345B is a legacy designation widely used in trade and earlier GB/T 1591 practice; current domestic structural updates often reference Q355B instead.

Mechanical Properties

Reference note: mechanical values below are grade reference values from the associated material standards, not a blanket single-value guarantee for every pipe size; actual pipe acceptance should follow the purchase order, size range, and GB/T 13793 testing provisions.