Spiral submerged arc welded pipe seam was spiral distribution, weld length, especially in the dynamic conditions of welding, the weld was too late to leave the molding point, easy to produce hot welding cracks. The direction of the crack and the weld parallel, and the steel pipe axis into a certain angle, usually between 30-70 °. This angle is just consistent with the shear failure angle, so its bending, tensile, compression and torsional performance is far less than straight seam submerged arc welded pipe. At the same time due to welding position restrictions, the resulting saddle-shaped and fish-shaped welds affect the appearance. In addition, during the construction process, the spiral welded pipe at the node of the intersecting line welds split the spiral joints, resulting in a larger welding stress, thus greatly weakening the safety performance of components. Therefore, it is necessary to strengthen the weld seam weld seam nondestructive testing efforts to ensure the quality of welding, or in the case of important steel structure should not use spiral submerged arc welded pipe.
Welded steel pipe is a continuous online production, the thicker the wall, the greater the unit and the investment in welding equipment, it is more economical and practical. The thinner the wall thickness, its input-output ratio will be a corresponding decline. The process of the product to determine its advantages and disadvantages, the general welding steel pipe with high precision, uniform wall thickness, tube inside and outside the table high brightness (steel plate surface grade steel pipe surface brightness), can be any length. Therefore, it is in the high-precision, low-pressure fluid applications reflects its economy and aesthetics.
Welding steel pipe production process is simple, high production efficiency, low cost, rapid development. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe, and the pipe with larger diameter can be produced with the narrow billet. The pipe with different diameter can also be produced with the same width. However, compared with the same length of the straight pipe, the weld length increased by 30 to 100%, and the production rate is low. Therefore, the smaller diameter of the pipe are mostly used straight seam welding, large diameter welded pipe are mostly used spiral welding.
Eddy current testing principle
The signal generating circuit generates an alternating current to supply the detecting coil; the alternating magnetic field of the coil induces the eddy current in the workpiece, and the eddy current is affected by the material or defect of the test piece; in turn, the impedance of the coil changes; the amplifying circuit first detects the weak detection coil Signal to amplify; then through the signal processing circuit to eliminate interference in the interference factors to identify the “defect” effect; finally show the test results.
Detection system overview
Eddy current testing equipment mainly include: eddy current probe, eddy current testing equipment, auxiliary devices and marking alarm device.
The role of eddy current probe: eddy current induced in the specimen and measure the quality of the specimen with the eddy current signal;
The role of eddy current testing instrument: for the detection coil to provide AC and from the measured to the signal with a large number of information to identify the existence of “defects”;
The role of auxiliary devices: the completion of the workpiece saturation magnetization and other functions;
Precision purification AC power supply: a regulator of high precision, high overload capacity, good reliability, anti-interference ability, high efficiency, fast response, etc., but also can effectively suppress the grid voltage spikes and a variety of noise interference, Anti-electromagnetic interference ability;
Installation Location: Recommended installation in the back of the sink, both sides of a compact round to ensure smooth steel pipe.
Now in our daily life, different kinds of steel pipe are used in construction fields frequently and the range is also widely in the field of all walks of life. According to the relationship of steel pipe terms and applications, we can divide steel pipes into many types and specifications. Besides, the effect is also different in different industries. Maybe we will consider what the main type of steel pipe is in construction. Welded steel pipe is a kind of representative product which is very popular among customers. Now we can discuss the main knowledge of this kind of steel pipe.
What is the welded steel pipe? That is mainly refers to the steel pipe with seam which is formed by bending plate and then it can be turned into round or square shape. The final step is welding if you want to shape the pipe. The main method of welding is arc welding , high frequency or low frequency electrical resistance welded and so on. It will has different performances or properties because of the different types of welding methods. For example, the property of cold rolled steel pipe vary from that of hot rolled steel pipe.
According to the different technology methods of square steel pipe, products can be divided into different catalogues. For example, according to the different welding methods, they can be called electric arc welding tube, gas welding tube and furnace welded pipe and so on. If your classification method is the different shapes of welding，it can be divided into straight seam welded pipe and spiral welded pipe. However, it will be classified into ordinary welded pipe, galvanized welded pipe as well as oxygen welded pipe etc. That being said, it can play a better effect in different areas because of the diversity classifications.
The round steel tube sizes is various and corrosion resistance of this pipe is very competitive. In the actual production, we can exercise its benefits by professional technical testing and technology refining so that they can be used for a long time. However, in our daily life, we should pay more attention to various factors if you want to make the pipes yield well. For example, you must understand the basic property of the steel tube and you should know the proper usage method. Theoretical knowledge is associate with our daily life. Steel pipe experts need to update their knowledge by actual demand so life is the best teacher. We will acquire more information and knowledge about welded steel pipe in our daily life when we meet complex problems.
(This article comes from DongPengBoDa editor released)
Welded vs. seamless. It’s a debate that’s been around for a long time, and it’s still going strong today.
So when your next project arrives, what side of the debate will you fall on? Will you choose a welded steel pipe, a welded carbon pipe? Or will you go with one of their seamless counterparts?
Here are some of the advantages of both types of pipes to help you make your decision.
Advantages Of Welded
- Welded pipes are typically more cost effective than their seamless equivalents.
- Welded pipes are usually more readily available than seamless. The longer lead time required for seamless pipes can not only make timing problematic, but it also allows more time for the price of the materials to fluctuate.
- The wall thickness of welded pipes is generally more consistent than that of seamless pipes.
- The internal surface of welded tubes can be checked before manufacturing, which isn’t possible with seamless.
Advantages Of Seamless
- The main perceived advantage of seamless pipes is that they don’t have a weld seam. Traditionally, the seam of welded pipes has been viewed as a weak spot, vulnerable to failure and corrosion. For many years, this fear was probably justified. However, in recent years improvements in the manufacturing process for welded steel pipes and other welded pipes have boosted the strength and performance of the weld seam to levels indistinguishable from that of the rest of the pipe.
- Seamless pipes provide peace of mind. Although there should be no issues with the seams of welded pipes supplied by reputable manufacturers, seamless pipes prevent any possibility of a weak seam.
- Seamless pipes have better ovality, or roundness, than welded pipes.
(This article comes from St. Louis Pipe & Supply editor released)