The GB steel pipes are made from a ingot or a solid billet through piercing, and then by hot rolling, cold rolling or cold dial.
The GB seamless steel pipe is made of steel ingot or solid tube blank through perforation, and then made by hot rolling, cold rolling or cold drawing. GB steel pipe has an important position in China's steel pipe industry. Tubing shall be made seamless, plain or upset and coupling with high-seal connections. Coupling-free connections are possible. GB standards cover different types of seamless steel pipes, including GB/T18984, GB5310, GB3087, GB/T5312, GB/T3639, GB/T8163, and GB/T9948. These standards specify the technical requirements, dimensions, materials, and testing methods for seamless steel pipes.
GB seamless steel pipes are available from various manufacturers and suppliers in China. They come in different sizes, grades, and surface finishes to meet specific project requirements.
According to incomplete statistics, there are more than 240 national standard steel pipe production enterprises and more than 250 seamless steel pipe units.
| Steel Grade | Chemistry Constitute | |||||||||
| C | Si | Mn | Cr | Ni | Mo | P | S | Ti | Cu | |
| Q195 | 0.06-0.12 | ≤0.30 | 0.25-0.50 | ≤0.3 | ≤0.3 | - | ≤0.045 | ≤0.050 | - | ≤0.30 |
| Q235 | 0.14-0.22 | ≤0.30 | 0.30-0.65 | ≤0.3 | ≤0.3 | - | ≤0.045 | ≤0.050 | - | ≤0.30 |
| Q345B | ≤0.20 | ≤0.55 | 1.00-1.60 | - | - | - | ≤0.040 | ≤0.040 | - | - |
| 10# | 0.07-0.13 | 0.07-0.37 | 0.35-0.65 | ≤0.15 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.25 |
| 20# | 0.17-0.23 | 0.07-0.37 | 0.35-0.65 | ≤0.25 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.25 |
| 35# | 0.32-0.39 | 0.07-0.37 | 0.50-0.80 | ≤0.25 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.25 |
| 45# | 0.42-0.50 | 0.07-0.37 | 0.50-0.80 | ≤0.25 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.25 |
| 20Cr | 0.18-0.24 | 0.07-0.37 | 0.50-0.80 | 0.70-1.00 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 40Cr | 0.37-0.44 | 0.07-0.37 | 0.50-0.80 | 0.80-1.10 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 20CrMo | 0.17-0.24 | 0.07-0.37 | 0.40-0.70 | 0.80-1.10 | ≤0.3 | 0.15-0.25 | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 30CrMo | 0.26-0.34 | 0.07-0.37 | 0.40-0.70 | 0.80-1.10 | ≤0.3 | 0.15-0.25 | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 35CrMo | 0.32-0.40 | 0.07-0.37 | 0.40-0.70 | 0.80-1.10 | ≤0.3 | 0.15-0.25 | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 42CrMo | 0.38-0.45 | 0.07-0.37 | 0.50-0.80 | 0.90-1.20 | 1.00-1.40 | 0.15-0.25 | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 20CrMoTi | 0.17-0.23 | 0.07-0.37 | 0.40-0.70 | 0.45-0.75 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 35Mn2 | 0.32-0.39 | 0.07-0.37 | 1.40-1.80 | ≤0.3 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 40Mn2 | 0.37-0.44 | 0.07-0.37 | 1.40-1.80 | ≤0.3 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 35SiMn | 0.32-0.40 | 1.10-1.40 | 1.10-1.40 | ≤0.3 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.30 |
| 15Mn | 0.12-0.16 | 0.07-0.37 | 0.70-1.00 | ≤0.25 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.25 |
| 20Mn | 0.17-0.23 | 0.07-0.37 | 0.70-1.00 | ≤0.25 | ≤0.3 | - | ≤0.035 | ≤0.035 | - | ≤0.25 |
| Deviation level | Standardized outer diameter tolerance |
| D1 | ±1.5%，min ±0.75 mm |
| D2 | ±1.0%。min ±0.50 mm |
| D3 | ±0.75%．min±0.30 mm |
| D4 | ±0.50%。min ±0.10 mm |
With years of expertise, we provide a diverse array of steel tube processing options. From sawing and machining tube blanks to intricate bending and upsetting operations, we actively assist you throughout your projects.
Our capabilities extend to eccentricity reduction and concentricity enhancement through turning and grinding. We excel in creating complex geometries using processes like rotary swaging and axial forming. Additionally, we offer property modifications via partial heat treatment, ensuring tailored solutions for your specific needs.
Seamless steel pipe is regularly used in the transportation of fluids such as water, natural gas, waste and air. It is also regularly required in many high-pressure, high-corrosive environments such as in the oil & gas, power generation and pharmaceutical industries. Some common uses of seamless pipes include:
Chemical composition inspection, mechanical properties test(tensile strength,yield strength, elongation, flaring, flattening, bending, hardness, impact test), surface and dimension test,no-destructive test, hydrostatic test.
identification of the chemical composition of the metal used to manufacture the fitting. Uses PMI sensors, including X-ray fluorescence or optical emission spectrometry.
Steel pipe delivery status(condition): cold / hard (BK), cold / soft (BKW), after cold stress relief annealing (BKS), annealing (GBK), normalized (NBK).
| Term | Symbol | Explanation |
| Cold-finished/hard (cold-finished as-drawn) | BK | No heat treatment after the last cold-forming process. The tubes therefore have only low deformability. |
| Cold-finished/soft (lightly cold-worked) | BKW | After the last heat treatment there is a light finishing pass (cold drawing) With proper subsequent processing, the tube can be cold-formed (e.g. bent, expanded) within certain limits. |
| Annealed | GBK | After the final cold-forming process the tubes are annealed in a controlled atmosphere or under vacuum. |
| Normalized | NBK | The tubes are annealed above the upper transformation point in a controlled atmosphere or under vacuum. |
The general cold strip mills, volume should go through continuous annealing (CAPL unit) to eliminate cold hardening and rolling stress, or batch annealing reach the mechanical properties of the corresponding standard specifies. Cold rolled steel surface quality, appearance, dimensional accuracy better than hot-rolled plate, and right-rolled thin product thickness is about 0.18mm, so the majority of users favor.
Cold rolled steel coil substrate products deep processing of high value-added products. Such as electro-galvanized, hot dip galvanized, electro-galvanized fingerprint resistant, painted steel roll damping composite steel, PVC laminating steel plates, etc., so that the excellent quality of these products has a beautiful, high resistance to corrosion, has been widely used.
Cold rolled steel coil finishing after annealing, cut the head, tail, trimming, flattening, smooth, heavy volume, or longitudinal clipboard. Cold-rolled products are widely used in automobile manufacturing, household electrical appliances, instruments, switches, buildings, office furniture and other industries. Steel plate strapping package weight of 3 to 5 tons. Flat sub-volume typically 3 to 10 tons / volume. Coil diameter 6m.
Bare packing/bundle packing/crate packing/wooden protection at the both sides of tubes and suitably protected for sea-worthly delivery or as requested.
There are probably hundreds of different methods for packing a pipe, and most of them have merit, but there are two principles that are vital for any method to work prevent rusting and Sea transportation security.
Our packing can meet any needs of the customers.
Commonly used alloying elements and their effects are listed in the table given below.
| Alloying Elements | Effect on the Properties |
|---|---|
| Chromium | Increases Resistance to corrosion and oxidation. Increases hardenability and wear resistance. Increases high temperature strength. |
| Nickel | Increases hardenability. Improves toughness. Increases impact strength at low temperatures. |
| Molybdenum | Increases hardenability, high temperature hardness, and wear resistance. Enhances the effects of other alloying elements. Eliminate temper brittleness in steels. Increases high temperature strength. |
| Manganese | Increases hardenability. Combines with sulfur to reduce its adverse effects. |
| Vanadium | Increases hardenability, high temperature hardness, and wear resistance. Improves fatigue resistance. |
| Titanium | Strongest carbide former. Added to stainless steel to prevent precipitation of chromium carbide. |
| Silicon | Removes oxygen in steel making. Improves toughness. Increases hardness ability |
| Boron | Increases hardenability. Produces fine grain size. |
| Aluminum | Forms nitride in nitriding steels. Produces fine grain size in casting. Removes oxygen in steel melting. |
| Cobalt | Increases heat and wear resistance. |
| Tungsten | Increases hardness at elevated temperatures. Refines grain size. |
Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.
Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.
Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.
The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.
Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.
The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.
