How to Identify Inferior Stainless Steel Welded Pipes?

What is the stainless steel welded pipe？

Stainless steel welded pipe, referred to as welded pipe, is a steel pipe made by welding common steel or steel strip after it is curled and formed by a unit and a die. Its production process is relatively simple, with high production efficiency, and it can produce a wide variety of specifications, with less equipment investment, but its general strength is lower than that of seamless steel pipe.

Due to its advantages of good corrosion resistance, high strength and good sealing performance, it is widely used in many fields such as oil and gas transportation, chemical industry, medicine, food, construction, machinery manufacturing, environmental protection and water treatment. For example, in the oil and gas industry, it can withstand extreme pressure and temperature to ensure safe transportation; in the construction industry, it is often used to make decorative components such as railings and handrails.

The harm of inferior stainless steel welded pipe

In the construction field, if inferior stainless steel welded pipes are used as structural support components, over time, due to their lack of corrosion resistance and strength, the building structure may deform or even collapse. For example, in some small construction projects, inferior welded pipes were used to make stair handrails for cheap reasons. After several strong winds and rainstorms, the handrails were severely rusted and deformed, and some railings loosened and fell off, posing a great safety hazard to residents.

In the chemical industry, if the stainless steel welded pipes used to transport corrosive media are inferior products, they are easily corroded and perforated in a short period of time, causing the media to leak. This will not only pollute the environment, but may also cause dangerous accidents such as fire and explosion, posing a serious threat to personnel safety and corporate property.

How to identify inferior stainless steel welded pipes?

1. Stainless steel welded pipes folding

Fake and inferior welded stainless steel pipes are prone to folding. Folding is a variety of fold lines formed on the surface of stainless steel pipes. This defect often runs through the entire longitudinal direction of the product. The reason for the folding is that fake and inferior manufacturers excessively pursue high efficiency and the amount of pressing is too large, resulting in ears in the pipe. Folding is formed during the next rolling process. The folded product will crack after bending, and the strength of the stainless steel pipe will be significantly reduced. The surface of fake and inferior welded stainless steel pipes will have a pockmarked surface. The pockmarked surface is the irregular uneven defect on the surface of the stainless steel material caused by severe wear of the rolling groove.

2. Stainless steel welded pipes scarring

The surface of fake stainless steel welded pipes is prone to scarring. There are two main reasons for this. One is that the material of the inferior stainless steel welded pipes is uneven and has many impurities. The other is that the sanitation equipment of the fake stainless steel welded pipe manufacturers is simple and easy to stick to the steel. These impurities bite into the rollers and easily form scarring.

3. Stainless steel welded pipes cracks

The surface of fake and inferior stainless steel welded pipes is also prone to cracks, because the blank is adobe, which has many pores. During the cooling process, the adobe is subjected to thermal stress, forming cracks, and there will be cracks after rolling.

4. Surface of stainless steel welded pipes

The surface of inferior stainless steel welded pipe has no metallic luster, and will show a light red or pig iron-like color. There are two reasons for this. One is that the blank is adobe. The other is that the rolling temperature of the fake and inferior pipe is not standard. The steel temperature is visually measured, so it cannot be rolled in the specified austenite area, and the performance of the stainless steel pipe naturally cannot meet the standard.

Inferior stainless steel welded pipes are also easily scratched because the production equipment of inferior stainless steel welded pipe manufacturers is simple, which can easily form burrs and scratch the surface of the steel. Deep scratches will also weaken the strength of the stainless steel pipe.

The transverse ribs of inferior stainless steel welded pipes are thin and low, and often fail to fill up. This is because the manufacturer, in order to achieve a larger negative tolerance, makes the first few passes of the finished product too large, the iron mold is too small, and the hole type is not fully filled.

The cross-section of inferior welded stainless steel pipes is oval. This is because the manufacturer increases the amount of pressure in the first two passes of the finished product roller in order to save materials.

5. Specifications and dimensions of stainless steel welded pipes

The negative tolerance of poor quality stainless steel welded pipes usually exceeds the specification. Poor quality stainless steel pipes contain a lot of impurities, the stainless steel pipe material density is low, and the size is too poor. Therefore, if there is no vernier caliper, it can be weighed and checked.

Read more: How to Choose High Quality Stainless Steel Welded Pipes?

Article source: https://article-realm.com/article/Business/71791-How-to-Identify-Inferior-Stainless-Steel-Welded-Pipes.html