1. Scope
This standard defines the classification, ordering information, dimensions, shapes, weight, allowable deviations, technical requirements, test methods, inspection rules, marking, packaging, and quality certificates for longitudinal electric (resistance) welded steel pipes.
It applies to steel pipes with an outer diameter not exceeding 711 mm, primarily used for mechanical and structural purposes in industries such as construction. These pipes are also suitable for general fluid transportation applications.
2. Key Requirements
2.1 Classification and Codes
By Outer Diameter Precision:
Ordinary Precision (PD.A)
High Precision (PD.C)
By Wall Thickness Precision:
Ordinary Precision (PT.A)
Higher Precision (PT.B)
High Precision (PT.C)
By Bending Precision:
Ordinary Precision (PS.A)
Higher Precision (PS.B)
2.2 Ordering Information
Orders should include at least the following details:
Standard number (GB/T 13793-2016)
Product name
Steel grade (quality level)
Quantity (total weight or length)
Manufacturing method
Dimensions and specifications
Intended use
Additional special requirements (e.g., hydraulic testing, manufacturing precision, end conditions, internal burr removal) can be specified through mutual agreement between the buyer and supplier.
2.3 Dimensions, Shapes, Weight, and Allowable Deviations
Outer Diameter and Wall Thickness:
Allowable deviations are specified in tables based on precision levels.
For pipes not covered by standard dimensions, deviations can be agreed upon between the buyer and supplier.
Length:
Usual lengths range from 4,000 mm to 12,000 mm, depending on the outer diameter.
Fixed or multiple lengths can be supplied upon agreement, with allowable deviations specified.
Bending:
Pipes with an outer diameter ≤16 mm may have allowable bending that does not affect usability.
For pipes >16 mm, bending must comply with specified limits.
Ovality:
The difference between the maximum and minimum outer diameters at any cross-section must meet specified requirements.
2.4 Technical Requirements
Chemical Composition:
Allowable deviations for elements such as carbon (C ≤ 0.25%), manganese (Mn: 0.30%-1.65%), and silicon (Si ≤ 0.55%) are specified.
Mechanical Properties:
Yield strength must be ≥235 MPa.
Tensile strength must range between 375 MPa and 500 MPa.
Welding Quality:
Weld seam quality is ensured through requirements for transverse tensile testing and non-destructive testing (e.g., ultrasonic testing).
Galvanizing Requirements:
For galvanized pipes, the weight and thickness of the zinc coating must meet specified standards, with coefficients for unit weight and thickness conversion provided.
2.5 Test Methods
Chemical Analysis:
Methods for analyzing chemical components are referenced from other standards (e.g., GB/T 222, GB/T 223 series).
Mechanical Testing:
Tensile tests, bending tests, and flattening tests are conducted according to specified procedures.
Non-Destructive Testing:
Ultrasonic testing is used to detect longitudinal and/or transverse defects in the weld seam.
2.6 Inspection Rules
Sampling:
Sampling schemes and inspection items are defined to ensure product quality consistency.
Judgment Criteria:
Criteria for accepting or rejecting batches based on test results are specified.
2.7 Marking, Packaging, and Quality Certificates
Marking:
Pipes must be marked with information such as the standard number, manufacturer's name or logo, steel grade, and batch number.
Packaging:
Packaging methods must protect the pipes during transportation and storage, with specific requirements for bundling, wooden cases, etc.
Quality Certificate:
Each batch must be accompanied by a quality certificate containing details such as the manufacturer's information, standard compliance, test results, and inspection stamps.
3. Applications
These steel pipes are widely used in:
Mechanical and Structural Applications:
Construction frameworks, scaffolding, and support structures.
Fluid Transportation:
Water supply and drainage systems, gas pipelines, and agricultural irrigation.
Other Industries:
Fence posts, greenhouse structures, and general engineering purposes.
