Views: 2 Author: Site Editor Publish Time: 2025-08-08 Origin: Site
In modern industrial pipeline systems, steel pipes serve as key carriers for fluid transportation and structural support, and their quality and performance directly affect the safety and stability of the project. Hot rolled seamless pipes have become an indispensable basic construction material in fields such as petroleum, chemical, and mechanical manufacturing, thanks to their unique advantages of high strength and toughness. This article will comprehensively analyze the industrial value of hot-rolled seamless pipes from definition, process flow, material characteristics, core advantages to application scenarios.
Hot rolled seamless pipe refers to steel pipes without welded joints produced through hot rolling process. The billet is solid round steel (pipe blank), which is processed into hollow tubular steel through perforation, rolling and other processes after heating. Compared with welded steel pipes, seamless structure is its most prominent feature - the pipeline is formed as a whole without welding seams, fundamentally avoiding stress concentration and weak corrosion points in the welding area, and ensuring safe production in extreme environments such as high pressure, high temperature, and strong corrosion.
According to different materials, it can be divided into categories such as carbon structural steel, alloy structural steel, stainless steel, etc., and suitable materials can be selected according to engineering needs; According to their usage, they can be divided into conveying, structural, boiler, high-pressure, etc., covering diverse scenarios in the industrial field.
The production of hot-rolled seamless pipes is a precise "high-temperature shaping" system, and each step directly affects the performance of the final product. The core process flow is as follows:
Preparation of raw materials
heating
perforated
Rolling sizing and straightening
Cooling and testing
Cutting and packaging
The hot rolling process refines and evenly distributes the internal grains of steel, endowing the pipe with high strength and toughness characteristics. Taking 20 # carbon structural steel hot-rolled seamless pipe as an example, its tensile strength can reach 410-550MPa, yield strength ≥ 245MPa, elongation ≥ 24%, and can withstand radial pressure and axial load during high-pressure fluid transportation. It can also resist external impact and vibration in structural support.
Through the precise control and sizing process of the rolling mill, the outer diameter tolerance of hot-rolled seamless pipes can be controlled within ± 0.5%, the wall thickness tolerance is ≤ 10%, and the straightness deviation is ≤ 1mm/m. This high-precision feature ensures the sealing of pipeline connections, reduces the risk of leakage during fluid transportation, and meets the strict requirements for component dimensions in mechanical processing.
The structure without welds avoids the problem of material degradation in the welding heat affected zone, and the chemical composition and microstructure distribution of the pipe are uniform throughout. Whether it is corrosion resistance, wear resistance, or thermal conductivity, it can maintain consistent stability. For special materials such as stainless steel and alloy steel pipes, the hot rolling process can better highlight the advantage of uniform distribution of alloy elements.
Seamless pipes can be produced in specifications ranging from 1/2 inch to 24 inches in outer diameter, with wall thickness grades including SCH 10, SCH 20, SCH 40, STD, XS, SCH 100, SCH 120, SCH 160, XXS. They can meet diverse needs from low-pressure water transportation to high-pressure oil and gas transportation, from light mechanical components to heavy-duty structural support. Meanwhile, by adjusting materials such as A106B, ASTM A335 P12, SS304 stainless steel, etc., it can be adapted to different media and environmental conditions.
| Nominal Size | OD | Thickness | |||||||||||||||||
| DN | inch | mm | 5S | 10S | 10 | 20 | 30 | STD | 40S | 40 | 60 | XS | 80S | 80 | 100 | 120 | 140 | 160 | XXS |
| 6 | 1/8 | 10.3 | 1.24 | 1.73 | 1.73 | 1.73 | 2.41 | 2.41 | 2.41 | ||||||||||
| 0.28 | 0.37 | 0.36 | 0.37 | 0.47 | 0.48 | 0.47 | |||||||||||||
| 8 | 1/4 | 13.7 | 1.65 | 2.24 | 2.24 | 2.24 | 3.02 | 3.02 | 3.02 | ||||||||||
| 0.51 | 0.63 | 0.64 | 0.63 | 0.80 | 0.82 | 0.80 | |||||||||||||
| 10 | 3/8 | 17.1 | 1.65 | 2.31 | 2.31 | 2.31 | 3.20 | 3.20 | 3.20 | ||||||||||
| 0.64 | 0.84 | 0.86 | 0.84 | 1.10 | 1.12 | 1.10 | |||||||||||||
| 15 | 1/2 | 21.3 | 1.65 | 2.11 | 2.77 | 2.77 | 2.77 | 3.73 | 3.73 | 3.73 | 4.78 | 7.47 | |||||||
| 0.82 | 1.01 | 1.27 | 1.30 | 1.27 | 1.62 | 1.65 | 1.62 | 1.95 | 2.55 | ||||||||||
| 20 | 3/4 | 26.7 | 1.65 | 2.11 | 2.87 | 2.87 | 2.87 | 3.91 | 3.91 | 3.91 | 5.56 | 7.82 | |||||||
| 1.04 | 1.31 | 1.69 | 1.71 | 1.69 | 2.20 | 2.24 | 2.20 | 2.90 | 3.64 | ||||||||||
| 25 | 1 | 33.4 | 1.65 | 2.77 | 3.38 | 3.38 | 3.38 | 4.55 | 4.55 | 4.55 | 6.35 | 9.09 | |||||||
| 1.33 | 2.13 | 2.50 | 2.55 | 2.50 | 3.24 | 3.29 | 3.24 | 4.24 | 5.45 | ||||||||||
| 32 | 1¼ | 42.2 | 1.65 | 2.77 | 3.56 | 3.56 | 3.56 | 4.85 | 4.85 | 4.85 | 6.35 | 9.70 | |||||||
| 1.68 | 2.76 | 3.39 | 3.46 | 3.39 | 4.47 | 4.56 | 4.47 | 5.61 | 7.77 | ||||||||||
| 40 | 1½ | 48.3 | 1.65 | 2.77 | 3.68 | 3.68 | 3.68 | 5.08 | 5.08 | 5.08 | 7.14 | 10.15 | |||||||
| 1.95 | 3.1 | 4.05 | 4.13 | 4.05 | 5.41 | 5.51 | 5.41 | 7.25 | 9.56 | ||||||||||
| 50 | 2 | 60.3 | 1.65 | 2.77 | 3.91 | 3.91 | 3.91 | 5.54 | 5.54 | 5.54 | 8.74 | 11.07 | |||||||
| 2.44 | 4.01 | 5.44 | 5.54 | 5.44 | 7.48 | 7.63 | 7.48 | 11.11 | 13.44 | ||||||||||
| 65 | 2½ | 73.0 | 2.11 | 3.05 | 5.16 | 5.16 | 5.16 | 7.01 | 7.01 | 7.01 | 9.53 | 14.02 | |||||||
| 3.77 | 5.36 | 8.63 | 8.81 | 8.63 | 11.41 | 11.64 | 11.41 | 14.92 | 20.39 | ||||||||||
| 80 | 3 | 88.9 | 2.11 | 3.05 | 5.49 | 5.49 | 5.49 | 7.62 | 7.62 | 7.62 | 11.13 | 15.24 | |||||||
| 4.60 | 6.59 | 11.29 | 11.52 | 11.29 | 15.27 | 15.59 | 15.27 | 21.35 | 27.68 | ||||||||||
| 90 | 3½ | 101.6 | 2.11 | 3.05 | 5.74 | 5.74 | 5.74 | 8.08 | 8.08 | 8.08 | |||||||||
| 5.29 | 7.55 | 13.57 | 13.84 | 13.57 | 18.63 | 19.01 | 18.63 | ||||||||||||
| 100 | 4 | 114.3 | 2.11 | 3.05 | 6.02 | 6.02 | 6.02 | 8.56 | 8.56 | 8.56 | 11.13 | 13.49 | 17.12 | ||||||
| 5.96 | 8.52 | 16.07 | 16.40 | 16.07 | 22.32 | 22.77 | 22.32 | 28.32 | 33.54 | 41.03 | |||||||||
| 125 | 5 | 141.3 | 2.77 | 3.40 | 6.55 | 6.55 | 6.55 | 9.53 | 9.53 | 9.53 | 12.70 | 15.88 | 19.05 | ||||||
| 9.67 | 11.82 | 21.77 | 22.20 | 21.77 | 30.97 | 31.59 | 30.97 | 40.28 | 49.11 | 57.43 | |||||||||
| 150 | 6 | 168.3 | 2.77 | 3.40 | 7.11 | 7.11 | 7.11 | 10.97 | 10.97 | 10.97 | 14.27 | 18.26 | 21.95 | ||||||
| 11.55 | 14.13 | 28.26 | 28.83 | 28.26 | 42.56 | 43.42 | 42.56 | 54.20 | 67.56 | 79.22 | |||||||||
| 200 | 8 | 219.1 | 2.77 | 3.76 | 6.35 | 7.04 | 8.18 | 8.18 | 8.18 | 10.31 | 12.70 | 12.70 | 12.70 | 15.09 | 18.26 | 20.62 | 23.01 | 22.23 | |
| 15.09 | 20.37 | 33.31 | 36.81 | 42.55 | 43.39 | 42.55 | 53.08 | 64.64 | 65.95 | 64.64 | 75.92 | 90.44 | 100.92 | 111.27 | 107.92 | ||||
| 250 | 10 | 273.1 | 3.40 | 4.19 | 6.35 | 7.80 | 9.27 | 9.27 | 9.27 | 12.70 | 12.70 | 12.70 | 15.09 | 18.26 | 21.44 | 25.40 | 28.58 | 25.40 | |
| 23.08 | 28.34 | 41.77 | 51.03 | 60.31 | 61.52 | 60.31 | 81.55 | 81.55 | 83.19 | 96.01 | 114.75 | 133.06 | 155.15 | 172.33 | 155.15 | ||||
| 300 | 12 | 323.9 | 3.96 | 4.57 | 6.35 | 8.38 | 9.53 | 9.52 | 10.31 | 14.27 | 12.70 | 12.70 | 17.48 | 21.44 | 25.40 | 28.58 | 33.32 | 25.40 | |
| 31.89 | 36.73 | 49.73 | 65.20 | 73.88 | 75.32 | 79.73 | 108.96 | 97.46 | 99.43 | 132.08 | 159.91 | 186.75 | 208.14 | 238.76 | 186.97 | ||||
| 350 | 14 | 355.6 | 3.96 | 4.78 | 6.35 | 7.92 | 9.53 | 9.53 | 11.13 | 15.09 | 12.70 | 19.05 | 23.83 | 27.79 | 31.75 | 35.71 | |||
| 35.06 | 42.14 | 54.69 | 67.90 | 81.33 | 81.33 | 94.55 | 126.71 | 107.39 | 158.10 | 194.96 | 224.65 | 253.56 | 281.70 | ||||||
| 400 | 16 | 406.4 | 4.19 | 4.78 | 6.35 | 7.92 | 9.53 | 9.53 | 12.70 | 16.66 | 12.70 | 21.44 | 26.19 | 30.96 | 36.53 | 40.49 | |||
| 42.41 | 48.26 | 62.64 | 77.83 | 93.27 | 93.27 | 123.30 | 160.12 | 123.30 | 203.53 | 245.56 | 286.64 | 333.19 | 365.35 | ||||||
| 450 | 18 | 457.2 | 4.19 | 4.78 | 6.35 | 7.92 | 11.13 | 9.53 | 14.27 | 19.05 | 12.70 | 23.88 | 29.36 | 34.93 | 39.67 | 45.24 | |||
| 47.77 | 54.36 | 70.57 | 87.71 | 122.38 | 105.16 | 155.80 | 205.74 | 139.15 | 254.55 | 309.62 | 363.56 | 408.26 | 459.37 | ||||||
| 500 | 20 | 508.0 | 4.78 | 5.54 | 6.35 | 9.53 | 12.70 | 9.53 | 15.09 | 20.62 | 12.70 | 26.19 | 32.54 | 38.10 | 44.45 | 50.01 | |||
| 60.46 | 70.00 | 78.55 | 117.15 | 155.12 | 117.15 | 183.42 | 247.83 | 155.12 | 311.17 | 381.53 | 441.49 | 508.11 | 564.81 | ||||||
| 550 | 22 | 558.8 | 4.78 | 5.54 | 6.35 | 9.53 | 12.70 | 9.53 | 22.23 | 12.70 | 28.58 | 34.93 | 41.28 | 47.63 | 53.98 | ||||
| 66.57 | 77.06 | 86.54 | 129.13 | 171.09 | 129.13 | 294.25 | 171.09 | 373.83 | 451.42 | 527.02 | 600.63 | 672.26 | |||||||
| 600 | 24 | 609.6 | 5.54 | 6.35 | 6.35 | 9.53 | 14.27 | 9.53 | 17.48 | 24.61 | 12.70 | 30.96 | 38.89 | 46.02 | 52.37 | 59.54 | |||
| 84.16 | 96.37 | 94.53 | 141.12 | 209.64 | 141.12 | 255.41 | 355.26 | 187.06 | 442.08 | 547.71 | 640.03 | 720.15 | 808.22 | ||||||
The material of hot-rolled seamless pipes is usually selected according to different usage scenarios and requirements. Commonly used materials include carbon steel, alloy steel, stainless steel, etc.
1. Carbon Steel
Carbon steel is a commonly used hot-rolled seamless steel pipe material, which has the advantages of good strength, plasticity, toughness, and ease of processing and manufacturing. The heat treatment process of carbon steel is simple, the price is relatively low, and it is suitable for occasions with low strength requirements. Common carbon steels include ASTM A106B, P235GH, etc.
Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo | V | Cu | Nb | Al | Ti | Cr+Cu+Mo+Ni |
| ASTM A106B | MIN | 0.29 | 0.10 | ||||||||||||
| MAX | 0.30 | 1.06 | 0.035 | 0.04 | 0.400 | 0.40 | 0.15 | 0.080 | 0.40 | ||||||
| P235GH | MIN | 0.02 | |||||||||||||
| MAX | 0.16 | 1.20 | 0.025 | 0.020 | 0.35 | 0.30 | 0.30 | 0.08 | 0.02 | 0.3 | 0.01 | 0.04 | 0.7 |
Mechanical Properties
| MATERIAL | T.S (MPA) | Y.S (MPA) | EL % |
| ASTM A106 GR B | 415 min | 240 min | 22 min |
| P235GH | 360-500 | 235min | 25min |
2. Alloy Steel
Alloy steel is made by adding an appropriate amount of alloying elements to carbon steel to improve its mechanical properties and service life. Alloy steel has good strength, corrosion resistance, heat resistance, and other properties, making it suitable for applications that require high performance of steel pipes. Common alloy steels include ASTM A335 P12, 13CrMo4-5, etc.
Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo | Al | Cu |
| ASTM A335 P12 | MIN | 0.05 | 0.30 | 0.80 | 0.44 | ||||||
| MAX | 0.15 | 0.61 | 0.025 | 0.025 | 0.50 | 1.25 | 0.65 | ||||
| 13CrMo4-5 | MIN | 0.10 | 0.40 | 0.70 | 0.40 | ||||||
| MAX | 0.17 | 0.70 | 0.03 | 0.02 | 0.35 | 0.30 | 1.15 | 0.60 | 0.04 | 0.30 |
Mechanical Properties
| MATERIAL | T.S (MPA) | Y.S (MPA) | EL % |
| ASTM A335 P12 | 415 min | 205 min | 30 min |
| 13CrMo4-5 | 440-590 | 290 min | 22 min |
3. Stainless Steel
Stainless steel is a hot-rolled seamless steel pipe material with high corrosion resistance and heat resistance, commonly used in fields such as chemical engineering and marine engineering. There are many types of stainless steel, commonly including 304, 316, etc. The heat treatment process of stainless steel is complex and expensive, but it has excellent corrosion resistance and heat resistance, which can meet the needs of various special occasions.
Chemical Composition
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo |
| ASTM A312 TP304 | MIN | 8.00 | 18.00 | ||||||
| MAX | 0.08 | 2.00 | 0.05 | 0.03 | 1.00 | 11.00 | 20.00 | ||
| ASTM A312 TP304L | MIN | 8.00 | 18.00 | ||||||
| MAX | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 13.00 | 20.00 | ||
| ASTM A312 TP316 | MIN | 11.00 | 16.00 | 2.00 | |||||
| MAX | 0.080 | 2.00 | 0.045 | 0.030 | 1.00 | 14.00 | 18.00 | 3.00 | |
| ASTM A312 TP316L | MIN | 10.00 | 16.00 | 2.00 | |||||
| MAX | 0.035 | 2.00 | 0.045 | 0.030 | 1.00 | 14.00 | 18.00 | 3.00 |
Mechanical Properties
| MATERIAL | T.S (MPA) | Y.S (MPA) | EL % |
| ASTM A312 TP304 | 515min | 205 min | 35 min |
| ASTM A312 TP304L | 485 min | 170 min | 35 min |
| ASTM A312 TP316 | 515min | 205min | 35 min |
| ASTM A312 TP316L | 485 min | 170 min | 35 min |
The structural reliability far exceeds that of welded pipes
Flexible processing performance
Adapt to extreme working conditions.
Significant long-term economic viability
Oil&Gas: Oil well casing, oil pipelines, drilling equipment.
Chemical industry: high temperature and high pressure reactors, heat exchangers, and transportation of corrosive media.
Electric energy: boiler tubes, superheater tubes, nuclear power pipelines.
Mechanical manufacturing: hydraulic cylinders, bearing sleeves, heavy machinery structural components.
Automotive&Aviation: Drive shafts, high-pressure oil pipes, aircraft landing gear components.
From underground oil and gas pipelines to high-altitude steel structures, from high-temperature boilers to deep-sea drilling platforms, hot-rolled seamless pipes have become an indispensable core material in the industrial field due to their "seamless reliability" and "adaptability to all working conditions". Whether in harsh industrial environments or high-precision mechanical manufacturing, seamless pipes can provide excellent performance guarantees. Its high strength, corrosion resistance, and absence of welds make it an irreplaceable pipeline material in many industries.
