Tubular Steel Poles

Tubular steel poles are known as utility poles or steel tower, according to different applications, it also be named transmission pole, telegraph pole, telecommunication pole, power pole, hydro pole, which is used to support overhead power lines and various other public facilities, such as cables, optical fiber cables, as well as transformers and street lamps and other related equipment.

Also it is referred to as electric power pylon, overhead power cable pylon, traction current pylon, single tube cone steel tower in electric power system for transmission.

Along with the development of urban construction and the increase of electricity demand, as well as the continuous attention to the beautification of the city, the tubular steel pile is extensive used in transmission and distribution engineering. Especially in urban areas, central towns and special locations (such as narrow lines and corridors, beautiful environmental requirements, etc.), some of the original urban network lines also need to be renovated or altered. It is a right choice to erect power lines with steel poles. Steel pole has the irreplaceable advantage of other poles and towers and has become an indispensable force in power transmission and distribution project.

The Advantage of Steel Pole

Tubular steel poles not only have the advantages of prestressed concrete poles and steel towers, but also its incomparable advantages, mainly in the following aspects:

The steel piles occupy small space, land saving, this is the main advantage of steel poles. The traditional freestanding tower has the disadvantage of covering a large area, and its shape is not in harmony with the modern urban environment. Under the current market economic conditions, it is more and more difficult to occupy an area, and the investment is large. Some areas, such as the city centre, simply do not have the conditions for towers.

The tubular steel poles structures cover a small area, the embedded foundation of the tapered tubular steel poles is generally about 1/3 of the self-supporting steel tower, the head size of the steel pipe is smaller than the tower, so the required line corridor is also smaller and narrower. Therefore, the tapered transmission structure can meet the requirements of environmental protection on the whole and save floor space.

For the Embedded Foundation, usually we adopt the following kinds to meet the transmission poles construction methods and installation.

1. Drilled Shaft Foundation with Anchor Bolts

2. Direct-Embedded Foundation

3. Embedded Casing Foundation

There are also other methods such as spread, pile, rock anchor foundations, etc. Of cause,we need consider other factors when selecting foundation types. Such as Soil properties, Foundation loads, Design limitations, Equipment availability and accessibility, Environmental restrictions, Cost/budget...

Traditional transmission tower with high voltage cable cost is expensive; The longitudinal and circumferential cracks of reinforced concrete electric pole have not been solved well. The power steel pipe has the advantages of simple structure, clear force, easy processing and manufacturing, and less maintenance, so it is widely used in the power supply network of modern cities and play a significant role.

Electric Power Transmission Galvanized Steel Iron Monopole

can not only provide safe power supply, but also be convenient for transportation and installation, and also install lightning protection equipment on the top of the pole body, which can protect the buildings and tall trees near the city streets from lightning strikes. Lighting device can also be set in the middle of the electric steel pole. It not only solves the problem that the original city street lamps occupy the land, but also beautifies the overall environment of the city, which is worth promoting.

Utility steel pole is not adopted in recent years, as early ass the last century it has been used. The Design specification of Steel pole of transmission line in China is "Technical Regulations for the Design of Steel Poles for Aerial Transmission Lines" (DL/T5130-2001), which is a reference to the American specification "Design of Steel Transmission Pole Structures". The latest version of the American specification is 2011. Chinese steel pipe rod specifications have not been revised for 15 years.

Material and process of steel pipe:

The steel pipes shall be made of longitudinally welded pipe fittings of hot rolled construction

Carbon steel, in conformity with JIS-G-3444 (ST-51) or BS-4360 or in Comply with any international equivalent standard such as DIN 17100 (ST-52) considered

The design safety factor of the pipe (1.5) should be considered.

Our commonly used steel materials are Q235, Q345, Q355, Q420 and so on. It is equivalent to the international steel grade JIS G3101 SS400, EN10025 S235JR, EN10025 S235J0, JIS G3106 SM400A SM400B, EN10025 S235J2; ASTM A572Grade 50

GB/T 700: Q345-B, ISO: E355DD(σs355), DIN: Fe510D1(σs355), BS: Fe510D1(σs355), NF: Fe510D1(σs355), SA516Gr.70.

The following is a general introduction of the tubular steel poles in the shape of the structure, the shape of the pipe body, the connection mode of the pipe body section and the type of the connecting cross arm.

1. At present, the cross section type of steel pipe pole mainly includes round steel pipe pole and polygonal conical steel pipe poles (regular four, six, eight, twelve, sixteen deformation), and the common section uses regular twelve and hexadecimal taper pipe. The section type of steel pipe is mainly determined by the overall aesthetic degree of polygonal side length after pipe making.

2. The main connection modes of steel pipes include welding type, sleeve type and flange connection type. Welding type is not recommended because the quality of on-site operation and weld can not be controlled and unstable; According to the previous engineering operation experience, the socket deformation at the joint is not uniform, often produce large deflection; No similar phenomenon has occurred when the flange connection method is used, and the material used for the flange connection tower is less when only the net weight of the flange is calculated. Therefore, the flange connection is recommended for the main structure connection of the steel pipe pole.

3. The main structure forms of the cross arm are straight line and arc (some units called swallow wing type). Cross arm section type can also be divided into pipe pile type cross arm and main post connection using intersecting connection or flange connection. The non-tubular cross arm is connected with the main post by stiffening plate bolt connection; The former process is more complex, and has a great weakening of the post body, for the residual stress after welding can not be better control, the latter in the current stage has a more common application history in China.

4. At present, there are single pile structure and double post structure. Generally, the steel post adopts the single post form.

Some structural requirements in steel-pipe pole design:

1. The main pole section is generally divided into a section of 6-10 meters, and the intermediate value of 8 meters is usually added and subtracted.

2. The top of the pole should be welded to seal the cover plate.

3. Steel pipe pole should be installed with lifting points.

4. Climbing facilities should be set up for steel pipe body and cross arm.

Surface treatment after completion of structure:

acid pickling

galvanizing

Self-Weathering (Cor-ten)

Epoxy resin paint

Powder coating

Paint galvanizing

Below grade protective paint