Seamless pipe

A steel pipe without seams on the surface. Seamless steel pipes are made by piercing a whole round steel bar, resulting in a steel pipe without weld seams, known as a seamless steel pipe. Depending on the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, extruded seamless steel pipes, and jacking pipes. According to the cross-sectional shape, seamless steel pipes are divided into circular and special-shaped types, with special-shaped pipes including square, elliptical, triangular, hexagonal, almond-shaped, star-shaped, and various complex shapes such as finned pipes. The maximum diameter can reach 900mm, and the minimum diameter is 4mm. Depending on their use, there are thick-walled and thin-walled seamless steel pipes. Seamless steel pipes are mainly used as oil and geological drilling pipes, cracking pipes for petrochemical use, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.

Function

Fluid Conveyance

Features

No seams on the surface

Common Material Resources

10#, 20#, 35#, 45#, 16Mn

Classification

Circular and non-circular

Academic Discipline

Rolling Steel Technology
Also Known As
Small-diameter Seamless Steel Tubes, Large-diameter Seamless Steel Tubes, Thick-walled Steel Tubes

Table of Contents

.1 Classification
.2 Applications
.3 Manufacturing Processes
.4 Mechanical Performance Indicators
.5 Quality Requirements Classification
Steel pipes with no seams along their cross-sectional periphery. They are classified into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, and jacking pipes based on different production methods, each with their own process regulations.
Materials include common and high-quality carbon structural steels (Q215-A to Q275-A and 10 to 50 steels), low-alloy steels (09MnV, 16Mn, etc.), alloy steels, stainless acid-resistant steels, etc.
They are divided into general-purpose (used for water and gas pipelines, structural components, and mechanical parts) and special-purpose (used for boilers, geological exploration, bearings, acid resistance, etc.) based on their applications.

Seamless steel pipes are widely used.

1. General purpose seamless steel pipes are made from common carbon structural steel, low alloy structural steel, or alloy structural steel, with the highest production volume. They are mainly used as pipelines for fluid transportation or structural components.
2. Supplies are divided into three categories based on different uses:
? ?a. Supplied according to chemical composition and mechanical properties;
? ?b. Supplied according to mechanical properties;
? ?c. Supplied according to hydrostatic testing. Seamless pipes supplied under categories a and b, if used for withstanding liquid pressure, must also undergo hydrostatic testing.
3. Special purpose seamless pipes include those for boilers, chemical and power use, geological use, and oil use, among others.

Current Seamless Steel Pipe Standards in China:

1. Current seamless steel pipe standards: There are a total of 47 standards, including: GB/T25 standards, HB3 standards, 19 special purpose standards; 2 basic standards and 45 product standards.
2. Common standards:
① GB/T2102-2018 Acceptance, packaging, marking, and quality certificate of steel pipes.
② GB/T17395-2008 Dimensions, shape, weight, and permissible deviations of seamless steel pipes.
③ GB/T5310-2018 Seamless steel pipes for high-pressure boilers.
④ GB/T9948-2018 Seamless steel pipes for petroleum cracking.
⑤ GB/T6479-2018 Seamless steel pipes for high-pressure chemical fertilizer equipment.
⑥ GB/T18248-2018 Seamless steel pipes for gas cylinders.