Seamless Steel Pipe – Everything You Wanted to Know About It

The seamless steel pipe is known as stronger alternatives to welded pipe versions for its ability to fuse pipes without any seams. This is ideal for eliminating the problem of pipes that are weaker at the seams.

Advantages of Seamless Steel Pipes

There are many advantages of seamless pipes as compared to those of other pipe varieties. As has been mentioned before, they are much stronger and hence are more reliable especially in harsh working conditions. They are great for performing heavy duty activities in important industry sectors. This steel pipe variety is far more refined than other metal or even steel pipes. Also, they are highly resistant to corrosion and can resist high heat and pressure.

The Making of Seamless Steel Pipe

The first step involved in the making of this pipe is heating solid ingot. A piercing rod is then inserted in this so that you can get a hollow tube, to be used as pipe. Due to this method of production, they are also known as ‘Hot Finish Seamless Pipe’. There are many important techniques involved in completing the finishing process of these kinds of steel pipes. 

Sizes and Shapes of Seamless Steel Pipes

The seamless steel pipe has many different sizes and dimensions .  You can get them in thin to large diameter pipe as per your area of application. You can also get them in solid and hollow variants. While the solid forms are known as rods or bars and are used extensively in construction facilities, the hollow ones known as tubes or pipes are used mostly in the transporting oil and gas etc. Seamless steel pipes & tubes can be purchased in rectangular, square, triangular and round shape as well.

Uses of Seamless Steel Pipe

This pipe finds wide application in various important industry sectors. Though they are expensive compared to their welded counterparts, yet they are preferred for their extremely high performance quotient. Some of the areas where these are used are the aviation sector, aircraft, missiles, anti-friction bearing, ordinance etc. The wall thickness of most of seamless steel pipe range from 1/8 to 26inch outside diameter.

To get the best quality and price of Seamless Steel Pipe , Hunan Prime Steel Pipe Co., Ltd is your best choice . 

Technical Requirement for Welded Steel Pipe

According to the API/ASTM stadnards, there are many technical requirements for producing welded steel pipe. 

The nominal pipe diammeter ranges from 6-150mm, nominal wall thickness ranges from 2.0-

6.0mm and the length of the pipe is usually from 4 to 10. The pipe surface shoule be smooth, no collapse, no cracks, no delamination, and no lap welding defects exist. The wall thickness is not allowed to over the deviation, no scratches, no weld dislocation, no burns and scarring and other minor defects. 

Welded steel pipe should perform mechanical test, flattening test and flaring test to achieve the standard requirements. 2.5 Mpa internal pressure test is allowed to keep over 1 minue without leakage. It allows use eddy current testing method instead of the hydrostatic test. After the eddy current testing, welded steel pipe will be cut to a predetermined length by flying saw and then flip-off from the assembly line. Then both ends of the pipe should be flat head chamfering, painting, marking and hexagonal packing before delivery.

Clients visiting for negotiating with a new project

Today, we warmly welcomed clients from Qatar for an ERW steel pipe project. PRIME STEEL PIPE, as the subsidiary under SHINESTAR HOLDINGS GROUP, is the intergrated

procurement service provider exclusively for ERW steel pipe. We have invested five production lines for ERW steel pipe, and the production size ranges from 21.3mm to 660mm with the wall thickness between 1mm and 25mm. In Hunan, and Jiangxi, we owns two sets of small diameter ERW steel pipe production line (21.3~88.9mm). In Tianjin & Hebei, we have invested one production line covers the outside diameter between 88.9mm and 219mm, and one covers the outside diameter ranges from 219mm to 457mm, and another production line for the pipe outside diameter from 457mm to 660mm.

The advanced processing units including high frequency welding machine WELDACG2600KW, on line ultrasonic detecting units AS-200 UT imported from Isreal, and roller units from German. Based on the technical support from our proudction team, high frequency welding theory is based on the "skin effect" of the electromagnetic induction principle, the exchange of charges in the conductors, the proximity effect and eddy current heating effect. Those effects make the local steel weld edge heated to a molten state, and the roller squeeze can make the butt welds achieve indirect crystal together, so as to achieve the purpose of the welding. High frequency welding is widely applied in steel pipe production due to the production advantages such as no weld filler required, no welding spatter, narrow HAZ, good weld forming appreance and good mechanical properties etc. 

High Frequency Resistance Welded Steel Pipe Units

High frequecy resistance welded pipe mill usually consists of flow forming, high frequency welding, extrusion, cooling, sizing, flying saw cutting units, the front end unit with accumulator looper, the rear end of unit with a steel fram plipping, electrical prat of the main high frequency generator, DC generator exictation and instrument control devices and other components. Taking our OD 165mm frequency welded pipe units as an example, the main technical parameters are as follows:

3.1 Finished Pipe:

Tube outer diameter: φ111 ~ 165mm

Square tube: 50 × 50 ~ 125 × 125mm

Rectangular tube: 90 × 50 ~ 160 × 60 ~ 180 × 80mm

Finished wall thickness: 2 ~ 6mm

3.2 Forming speed: 20 to 70 m / min

3.3 High Frequency Sensor:

Thermal power: 600KW

Output frequency: 200 ~ 250KHz

Power supply: Three-phase 380V 50Hz

Cooling: Water-cooled

Welding Technology for producing ERW steel pipe

Welding technology controls the production and quality of ERW steel pipe. Below are the technical control methods we applied to ensure the high quality and efficiency of ERW steel pipe production.

1. Weld Gap Control
2. Welding Temperature Control
3. Pressing Force Control
4. Frequency Induction Loop Position Control
5. Impedance Check and Replacement
6. Burr Remove

Now, we apply our OD 32mm & WT 2mm welding process as an example, the parameters are as below:

Strip Size: 2 × 98mm in diameter to expand the bandwidth by adding a small amount of profiling allowance
Steel Material: Q235A
Input field voltage: 150V excitation current: 1.5A Frequency: 50Hz
DC output voltage: 11.5kV DC Current: 4A Frequency: 120000Hz
Welding speed: 50 m / min
Parameter adjustment: the timely adjustment of output voltage and welding speed according to the welding line energy change. After the fixed parameters generally do not adjust.