CIRCULAR HOLLOW SECTION
What is Circular Hollow Section (CHS)?
Circular Hollow Sections (CHS) are round steel pipes with a hollow central section. These pipes are often used in structural applications such as construction, machine fabrication, and other general engineering purposes. The term ‘hollow section’ refers to the fact that these pipes have a hollow central section. The round shape of these pipes makes them strong and durable, and they can resist large loads without deforming. CHS pipes are manufactured from hot-rolled steel coils, and they are available in a variety of sizes and thicknesses. The standard length of these pipes is 6 meters, but they can also be cut to order to meet the requirements of specific projects. Circular Hollow Sections are an essential part of many constructions and engineering projects, and they are widely used due to their strength and versatility.
Table of Contents
Dimension and Sizes of Circular Hollow Section (CHS)
| DN | O. D. | W. T. | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Inch | mm | SCH5S | SCH10S | SCH10 | SCH20 | SCH30 | SCH40 | SCH60 | SCH80 | SCH100 | SCH120 | SCH140 | SCH160 | Sth | XS | XXS | |
| 50 | 2″ | 60.3 | 1.65 | 2.77 | – | – | – | 3.91 | – | 5.54 | – | – | – | 8.74 | 3.91 | 5.54 | 11.07 |
| 65 | 2 1/2″ | 73 | 2.11 | 3.05 | – | – | – | 5.16 | – | 7.01 | – | – | – | 9.53 | 5.16 | 7.01 | 14.02 |
| 80 | 3″ | 88.9 | 2.11 | 3.05 | – | – | – | 5.49 | – | 7.62 | – | – | – | 11.13 | 5.49 | 7.52 | 15.24 |
| 90 | 3 1/2″ | 101.6 | 2.11 | 3.05 | – | – | – | 5.74 | – | 8.08 | – | – | – | – | 5.74 | 8.08 | – |
| 100 | 4″ | 114.3 | 2.11 | 3.05 | – | – | – | 6.02 | – | 8.58 | – | 11.13 | – | 13.49 | 6.02 | 8.56 | 17.12 |
| 125 | 5″ | 141.3 | 2.77 | 3.4 | – | – | – | 6.55 | – | 9.53 | – | 12.7 | – | 15.88 | 6.55 | 9.53 | 18.05 |
| 150 | 6″ | 168.3 | 2.77 | 3.4 | – | – | – | 7.11 | – | 10.97 | – | 14.27 | – | 18.26 | 7.11 | 10.97 | 21.95 |
| 200 | 8″ | 219.1 | 2.77 | 3.76 | – | 6.35 | 7.04 | 8.18 | 10.31 | 12.7 | 15.09 | 18.26 | 20.62 | 23.01 | 8.18 | 12.7 | 22.23 |
| 250 | 10″ | 273.1 | 3.4 | 4.19 | – | 6.35 | 7.8 | 9.27 | 12.7 | 15.09 | 18.26 | 21.44 | 25.4 | 28.58 | 9.27 | 12.7 | 25.4 |
| 300 | 12″ | 323.9 | 3.96 | 4.57 | – | 6.35 | 8.38 | 10.31 | 14.27 | 17.48 | 21.44 | 25.4 | 28.58 | 33.32 | 9.53 | 12.7 | 25.4 |
| 350 | 14″ | 355.5 | 3.96 | 4.78 | 6.35 | 7.92 | 9.53 | 11.13 | 15.09 | 19.05 | 23.83 | 27.79 | 31.75 | 35.71 | 9.53 | 12.7 | – |
| 400 | 16″ | 406.4 | 4.19 | 4.78 | 6.35 | 7.92 | 9.53 | 12.7 | 16.66 | 21.44 | 26.19 | 30.96 | 36.53 | 40.49 | 9.53 | 12.7 | – |
| 450 | 18″ | 457.2 | 4.19 | 4.78 | 6.35 | 7.92 | 11.13 | 14.27 | 19.05 | 23.83 | 39.36 | 34.93 | 39.67 | 45.24 | – | – | – |
| 500 | 20″ | 508 | 4.78 | 5.54 | 6.35 | 9.53 | 12.7 | 15.09 | 20.62 | 26.19 | 32.54 | 38.1 | 44.45 | 50.01 | – | – | – |
| 550 | 22″ | 558.8 | 4.78 | 5.54 | 6.35 | 9.53 | 12.7 | – | 22.23 | 28.58 | 34.93 | 41.28 | 47.63 | 53.98 | – | – | – |
| 600 | 24″ | 609.6 | 5.54 | 6.35 | 6.35 | 9.53 | 14.27 | 17.48 | 24.61 | 30.96 | 38.89 | 46.02 | 52.37 | 59.54 | – | – | – |
Material Component Properties of Circular Hollow Section (CHS)
| Chemical Requirements | ||||
|---|---|---|---|---|
| Â Element | Composition, % | |||
| Grades A, B, and D | Grade C | |||
| Heat Analysis | Product Analysis | Heat Analysis | Product Analysis | |
| Carbon, max A | 0.26 | 0.30 | 0.23 | 0.27 |
| Manganese, max A | 1.35 | 1.40 | 1.35 | 1.40 |
| Phosphorus, max | 0.035 | 0.045 | 0.035 | 0.045 |
| Sulfur, max | 0.035 | 0.045 | 0.035 | 0.045 |
| Copper, min B | 0.20 | 0.18 | 0.20 | 0.18 |
Mechanical Properties of Circular Hollow Section (CHS)
| Item | Grade A | Grade B | Grade C | Grade D |
|---|---|---|---|---|
| Tensile strength, mn, ps (MPa) | 45 000 (310) | 58 000 (400) | 62 00 (427) | 58 000 (400) |
| Yield strength, mn, psi (MPa) | 33 000 (228) | 42 000 (290) | 46 000 (317) | 36 000 (250) |
| Elongation in 2 in. (50.8 mm), min, %A | 25B | 23C | 21D | 23C |
Production Standards of Using Circular Hollow Section (CHS)
The following standards describe the geometric features of the cross-section for typical Circular Hollow Sections (CHS):
- EN 10210-2: Hot finished structural hollow sections of non-alloy and fine grain steels
- EN 10219-2: Cold-formed welded structural hollow sections of non-alloy and fine grain steels
- ASTM A500: Standard Specification for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes
- AS/NZS 1163: Cold-formed structural steel hollow sections
- JIS G3444: Carbon Steel Tubes for General Structure
Appearance of Circular Hollow Section
The outside and inner surfaces of the Circular Hollow Section must be free of fissures, cracks, material overlay, and non-metallic contaminants. Small scratches, dents, a thin layer of welding cinder, or traces left after cleaning manufacturing faults are permissible so long as the wall thickness does not fall below the minimum permissible limits. The weld must be compact and continuous, with no fractures or other imperfections that reduce the resistance of the weld below that of the base metal.
The external ledge of the welding seam is erased. Within the range of permitted diameter constraints, seam thickening is allowable. The interior burr of the welding seam is not eradicated. Inadmissible is unevenness on the metal strip’s edges along the weld seam. The ends of the Circular Hollow Section must be trimmed perpendicular to its axis. It is OK for the pipe ends to have a burr as a result of the cutting operation. The distortion of pipe ends is prohibited.
The Advantage of Using Circular Hollow Section (CHS)
There are many advantages to using circular hollow sections. They are typically made from steel, which is a strong and durable material, making them ideal for use in applications where strength and durability are required. In addition, steel is less likely to corrode than other materials, making it an ideal choice for use in outdoor applications. Circular hollow sections are also readily available from most hardware stores and can be easily cut to size with a saw. This makes them ideal for use in a variety of projects, from building temporary structures to repairing or replacing existing piping.
In offshore structures, circular hollow section (CHS) pipes are preferred over other types of pipes due to their superior wave force capacity and structural efficiency. The structural efficiency of CHS pipes is due to the uniform distribution of material around the pipe’s polar axis, which leads to a better strength-to-weight ratio in buildings. CHS pipes are also known for their aesthetic appeal, which makes them a preferred choice for architects. Additionally, the hollow interior of CHS pipes provides an advantage for building services such as fire protection, ventilation, and heating. In terms of corrosion resistance, CHS pipes perform better than other open sections due to their round edges and smaller surface area. Ultimately, the many benefits of CHS pipes make them the preferred choice for offshore structures.
