Features and Uses of Small Caliber Spiral Welded Pipe

Although small caliber spiral welded pipe is small, its function is a lot. So what the features and uses of small diameter spiral welded pipe are?

Features of small-diameter spiral welded pipe:

The production process of spiral welded pipe is simple, but it has high production efficiency. It can use material to form a larger pipe diameter pipe, it can also use the same width of preform body to product pipes with different diameter. However, compared with the same LSAW steel pipe, the length of weld seam is increased by 30% to 100%, and its production rate is low. Therefore, the smaller diameter of the steel pipe mostly use straight welding, large diameter welded pipes mostly use spiral welded pipe.

Uses of small-diameter spiral welded pipe:

Spiral welded pipe is mainly used in tap water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, and it is one of the 20 key products for the development of China. It is used for liquid delivery: water supply, drainage. It is used for gas transmission: gas, steam, liquefied petroleum gas. It is used for the structure: piling pipe, bridge girder, the pipe for wharf, road, building structure and so on.

Two Ways of High-frequency Welding

Steel pipe has a variety of production processes. High-frequency welding technology is one of them, it usually used by pipe manufacturers to produce ERW steel pipe. Actually, high-frequency welding can be divided into two ways, resistance welding and IWinduction welding.

What is resistance welding?

The resistance welding is carried out by using a pair of copper electrodes to contact on both sides of the welded steel pipe, induction current penetration is good, the two effects of high frequency current are maximized using since the copper electrode directly contact with the steel plate. The welding efficiency of the resistance welding is high and the power consumption is low, so it is widely used in the production of high speed and low precision pipe. And in the production of special thick steel pipe, it is also necessary to use resistance welding.

But there are two shortcomings in resistance welding: first, copper electrode is in touch with steel plate, so it will wear quickly; second, due to the influence of the flatness of the surface of the steel plate and the straightness of the edge, the current stability of resistance welding is poor, the burr inside and outside the weld is higher. So pipe manufacturers generally do not used this way when welding high-precision and thin-walled tube.

What is IWinduction welding?

IWinduction welding is way that using a turn or more turns of the induction coil harness the outside of welded steel pipe. The effect of multi-turn is better than that of single turn, but the fabrication and installation of multi-turn induction coil is more difficult. When the spacing between induction coil and the steel pipe surface is small, the efficiency is higher, but it is easy to cause electro-discharge between the induction coil and the pipe. Generally, it is appropriate that keep the induction coil from the surface of the steel pipe having 5 ~ 8 mm gap. When using IWinduction welding, as the induction ring is not in contact with the steel plate, there is no wear, which ensures the stability of the welding. The quality of welding steel pipe surface is good, and the weld is flat, so in the production of high-precision pipe,such as API and others, it basically uses the form of induction welding.

Characteristics of Spiral Welded Pipe Production

Several days ago, we shared the introduction of spiral welded pipe (also called SSAW steel pipe), now, let us continue to understand characteristics of spiral welded pipe production.

Characteristics of spiral welded pipe production includes:

(1)Manufacturers can use the same width of the strip steel to produce a variety of diameter steel pipe;

(2)The flatness of pipe is good, the size of it is more accurate, the spiral weld inside and outside increases the rigidity of pipe body, so the production process of SSAW steel pipe doesn't need sizing and straightening process after welding;

(3)Easy to achieve mechanization, automation and continuous production;

(4)Compared to other equipments those have similar size, it has a small size, small footprint and investment, and fast construction;

(5)Compared with the same size of the straight seam welded pipe, the weld seam per unit length of tube stock is comparatively long, which makes spiral welded pipe production has lower productivity.

Two Ways of High-frequency Welding

Steel pipe has a variety of production processes. High-frequency welding technology is one of them, it usually used by pipe manufacturers to produce ERW steel pipe. Actually, high-frequency welding can be divided into two ways, resistance welding and IWinduction welding.

What is resistance welding?

The resistance welding is carried out by using a pair of copper electrodes to contact on both sides of the welded steel pipe, induction current penetration is good, the two effects of high frequency current are maximized using since the copper electrode directly contact with the steel plate. The welding efficiency of the resistance welding is high and the power consumption is low, so it is widely used in the production of high speed and low precision pipe. And in the production of special thick steel pipe, it is also necessary to use resistance welding.

But there are two shortcomings in resistance welding: first, copper electrode is in touch with steel plate, so it will wear quickly; second, due to the influence of the flatness of the surface of the steel plate and the straightness of the edge, the current stability of resistance welding is poor, the burr inside and outside the weld is higher. So pipe manufacturers generally do not used this way when welding high-precision and thin-walled tube.

What is IWinduction welding?

IWinduction welding is way that using a turn or more turns of the induction coil harness the outside of welded steel pipe. The effect of multi-turn is better than that of single turn, but the fabrication and installation of multi-turn induction coil is more difficult. When the spacing between induction coil and the steel pipe surface is small, the efficiency is higher, but it is easy to cause electro-discharge between the induction coil and the pipe. Generally, it is appropriate that keep the induction coil from the surface of the steel pipe having 5 ~ 8 mm gap. When using IWinduction welding, as the induction ring is not in contact with the steel plate, there is no wear, which ensures the stability of the welding. The quality of welding steel pipe surface is good, and the weld is flat, so in the production of high-precision pipe,such as API and others, it basically uses the form of induction welding.