Introduction to the different classifications of spiral steel pipes and the advantages and disadvantages of each type

Spiral steel pipe is the most widely used steel pipe category in the steel pipe industry. At the same time, spiral steel pipe is also a steel pipe material with many types, wide uses, and detailed classification. So according to different classification methods, how many types of spiral steel pipe are there? This article will give you a detailed analysis of the types of spiral steel pipes, as well as the standards, advantages and disadvantages of various types.

1.Classification of steel pipes

Classification by production method

(1) Seamless steel pipes-hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, jacked pipes

(2) Welded pipe

 (a) By process - arc welded pipe, resistance welded pipe (high frequency, low frequency), gas welded pipe, furnace welded pipe

 (b) According to welding seam - straight seam welded pipe, spiral welded pipe

2. Classification according to cross-sectional shape

(1) Simple cross-section steel pipes – round steel pipes, square steel pipes, oval steel pipes, triangular steel pipes, hexagonal steel pipes, rhombus steel pipes, octagonal steel pipes, semi-circular steel pipes, others

(2) Complex cross-section steel pipes – unequal hexagonal steel pipes, five-petal plum blossom-shaped steel pipes, double-convex steel pipes, double-concave steel pipes, melon-shaped steel pipes, conical steel pipes, corrugated steel pipes, watch case steel pipes, and others

3. Classification by wall thickness

Thin-walled steel pipe, thick-walled steel pipe

4. Classification by use

Steel pipes for pipelines, steel pipes for thermal equipment, steel pipes for mechanical industry, steel pipes for petroleum and geological drilling, container steel pipes, steel pipes for chemical industry, special purpose steel pipes,

2.Welded steel pipe standards

Welded steel pipe, also called welded pipe, is a steel pipe made of steel plates or steel strips that are welded after being curled and formed. The production process of welded steel pipes is simple, the production efficiency is high, there are many varieties and specifications, and the equipment investment is small, but the general strength is lower than that of seamless steel pipes.

Since the 1930s, with the rapid development of continuous rolling production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has continued to improve, and the varieties and specifications of welded steel pipes have increased day by day, and have replaced non-woven steel pipes in more and more fields. Sewing steel pipe. Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of the weld.

The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. The strength of spiral welded pipes is generally higher than that of straight seam welded pipes. Welded pipes with larger diameters can be produced from narrower billets, and welded pipes with different diameters can also be produced from billets of the same width. However, compared with straight seam pipes of the same length, the weld length is increased by 30~100%, and the production speed is lower.

Therefore, smaller diameter welded pipes mostly use straight seam welding, while large diameter welded pipes mostly use spiral welding.

1. Welded steel pipe (ASTM A135) for low-pressure fluid transportation is also called general welded pipe, commonly known as black pipe. It is a welded steel pipe used to transport water, gas, air, oil, heating steam and other general lower pressure fluids and other purposes. The wall thickness of steel pipe connections is divided into ordinary steel pipes and thickened steel pipes; the connection end forms are divided into unthreaded steel pipes (plain pipes) and threaded steel pipes. The specifications of steel pipes are expressed in nominal diameter (mm), which is an approximate value of the inner diameter. It is customary to express it in inches, such as 11/2, etc. In addition to being directly used to transport fluids, welded steel pipes for low-pressure fluid transportation are also widely used as the original pipes for galvanized welded steel pipes for low-pressure fluid transportation.
2. Galvanized welded steel pipe (ASTM A53) for low-pressure fluid transportation is also called galvanized electric welded steel pipe, commonly known as white pipe. It is a hot-dip galvanized welded (furnace welded or electric welded) steel pipe used to transport water, gas, air oil, heating steam, warm water and other general lower pressure fluids or other purposes. The wall thickness of steel pipe connection is divided into ordinary galvanized steel pipe and thickened galvanized steel pipe; the connection end form is divided into non-threaded galvanized steel pipe and threaded galvanized steel pipe. The specifications of steel pipes are expressed in nominal diameter (mm), which is an approximate value of the inner diameter. It is customary to express it in inches, such as 11/2, etc.
3. Ordinary carbon steel wire casing (ASTM A513) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil buildings and installation of machinery and equipment.
4. Straight seam electric welded steel pipe (ASTM A135) is a steel pipe in which the weld seam is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipes, electric welded thin-walled pipes, transformer cooling oil pipes, etc.
5. Generally, spiral seam submerged arc welded steel pipes (API 5L) for low-pressure fluid transportation are made of hot-rolled steel strip coils as pipe blanks, which are spirally formed at regular temperatures, and are made by double-sided automatic submerged arc welding or single-sided welding for water use. Submerged arc welded steel pipes are used for transporting general low-pressure fluids such as gas, air and steam.
6. Spiral welded steel pipe for piles (ASTM A252) is made of hot-rolled steel strip coils as pipe blanks, often heated and spirally formed, and made by double-sided submerged arc welding or high-frequency welding. It is used in civil construction structures, docks, bridges, etc. Steel pipes for foundation piles.

3.Advantages and Disadvantages of Spiral Steel Pipe

Spiral steel pipe is a spiral steel pipe made by bending strip steel or coiled plate in a spiral shape and welding the inner and outer seams with double-sided submerged arc automatic welding. It can be widely used in water, electricity, and chemical industries for the following reasons. In production in other industries.

1) As long as the forming angle is changed, steel pipes of various diameters can be produced from strip steel of the same width, which is easy to adjust.

2) Because it is continuously bent and formed, the fixed length of the spiral tube is not limited and the length can be determined at will.

3) The spiral shape of the weld is evenly distributed on the entire circumference of the spiral tube, so the spiral tube has high dimensional accuracy and strong strength.

4) Easy to change size, suitable for the production of small batches and multiple varieties of spiral pipes.

The weld seams of spiral steel pipes are longer than those of straight seam pipes of the same specification. Under the same wall thickness, spiral steel pipes bear the greatest pressure.

The weld defects of spiral steel pipes are “oblique defects”. During use, the main stress direction of the steel pipe, that is, the equivalent defect length in the axis direction of the steel pipe, is smaller than that of the straight seam pipe. Secondly, since the pipeline steels are all rolled steel plates, the impact toughness has a large anisotropy, and the rolling The CVN value in the rolling direction can be 3 times higher than the CVN value perpendicular to the rolling direction.