Method for identifying the authenticity of stainless steel elbows

 1. Magnetic test: Magnetic test is a simple method to distinguish between annealed austenitic stainless steel and ferritic stainless steel. Austenitic stainless steel is a non-magnetic steel, but it will have mild magnetism after cold working under high pressure; And pure chromium steel and low alloy steel are both strong magnetic steels.

　　2. Nitric acid point test: One obvious feature of stainless steel elbows is their inherent resistance to corrosion of concentrated and dilute nitric acid. This performance makes it easy to distinguish from most other metals or alloys. However, high carbon 420 and 440 steels are slightly corroded during the nitric acid point test, and non-ferrous metals immediately corrode when they encounter concentrated nitric acid. Dilute nitric acid has strong corrosiveness to carbon steel.

　　3. Sulfuric acid test: The sulfuric acid immersion stainless steel elbow test can distinguish 302 and 304 from 316 and 317. The cut edges of the sample should be finely ground, and then cleaned and passivated for half an hour in nitric acid (with a specific gravity of 1.42) with a volume concentration of 20-30% and a temperature of 60-66 ℃. The volume concentration of the sulfuric acid test solution is 10%, and it is heated to 71 ℃. When 302 and 304 steel are immersed in this hot solution, they are corroded and generate a large number of bubbles, causing the sample to turn black within a few minutes; The samples of 316 and 317 steel are not corroded or react slowly (without bubbles), and the samples do not change color within 10-15 minutes. If samples with known composition are tested simultaneously for approximate comparison, it can make the test more accurate.

　　4. Copper sulfate spot test: The copper sulfate spot test is a convenient method to quickly distinguish between ordinary carbon steel and all types of stainless steel. The concentration of the copper sulfate solution used is 5-10%. Before conducting point tests, the test area should be coated with grease or various impurities, and a small area should be polished with a soft abrasive cloth. Then, a copper sulfate solution should be dripped into the cleaned area using a drip bottle. Ordinary carbon steel or iron will form a layer of surface metal copper within a few seconds, while the surface of stainless steel will not produce copper precipitation or display the color of copper.

Requirements for storage environment of seamless stainless steel pipes

 Seamless stainless steel pipes have certain requirements for their storage environment. If stored improperly, they may undergo oxidation and corrosion. After purchasing seamless stainless steel pipes, if not immediately used, customers will face storage issues. In order to ensure the quality of seamless stainless steel pipes for stainless steel welding, let me share with you below

　　When storing, use a stick to separate the seamless stainless steel pipe from the ground to avoid scratching the pipe body.

　　2. Seamless stainless steel pipes should pay attention to moisture, dust, oil, lubricating oil, etc. to avoid long-term storage in this environment, which can easily cause surface corrosion or other performance degradation.

　　3. Seamless stainless steel pipes should be stored in a clean and dry place to facilitate ventilation and easy disassembly under the original packaging conditions.

　　4. The film of seamless stainless steel pipes must avoid direct light. Replace immediately after storage (the film has a lifespan of 6 months).

　　5. If the packaging material is soaked during paper filling, please immediately remove the liner to avoid corrosion of the surface.

Classification of stainless steel elbows

 In the project, the stainless steel elbow is used to connect two pipes with the same or different nominal diameters to make the pipeline turn at an angle. Let's briefly introduce the classification of stainless steel elbows by the manufacturer of stainless steel elbows.

　　Classification of stainless steel elbows: According to angle, commonly used ones include 45 degrees and 90 degrees; And 180 degrees; Three types, in addition to 60 degrees according to engineering needs; Other abnormal angle elbows.

　　When we operate and use stainless steel elbows, the types of stainless steel elbows are mentioned above. We should all understand these types of stainless steel elbows, and the correct method of operating and using stainless steel elbows is what we all need.

　　Stainless steel elbows are formed by stamping a sheet metal of the same material as the pipe material into a half circular elbow using a stamping die, and the two half circular elbows are assembled and welded into shape.

What is the production process for stainless steel tees?

 　Stainless steel tees can be divided into equal diameter and reduced diameter, and the nozzle ends of equal diameter tees are of the same size; The main pipe connection size of the reducing tee is the same. So, do you know what the production process for stainless steel tees is?

　　1. Extruded stainless steel tees: The usual production processes include hydraulic bulging and hot pressing forming, both of which produce designed tees by subjecting the steel pipe section to plastic deformation according to the tee mold without damaging the metal structure.

　　2. Welded stainless steel tee: It is welded from multiple steel parts, and this type of stainless steel tee can be divided into three types: elbow type, right angle type, and flat welded joint. Their appearance and shape are different, but the welding process is basically the same, except that the shape of the welded steel parts is different.

　　There are two main types of stainless steel tees: welded stainless steel tees and extruded stainless steel tees. There are fundamental differences in the production processes of these two types of stainless steel tees.

How can seamless stainless steel pipes be applied in high-temperature and high-pressure environments?

 In fields such as petroleum, chemical, and power, pipeline installation in high-temperature and high-pressure environments is crucial. In this environment, stainless steel seamless pipes have become the best choice.

　　1. Application conditions under high temperature and pressure

　　In high-temperature and high-pressure environments, conventional steel pipes are often difficult to use due to the effects of temperature and pressure. Due to the molecular grain boundary fracture of conventional steel pipes, while stainless steel seamless pipes adopt a more dense and uniform crystal structure, they have superior performance in high-temperature and high-pressure environments.

　　2. Characteristics of stainless steel seamless pipes

　　The characteristic of stainless steel seamless pipe is its uniform and dense internal structure, which is seamless and not easily deformed, and the processing process is relatively convenient. Due to the strong corrosion resistance of stainless steel, it will not rust even after long-term exposure to an oxidizing atmosphere, ensuring the long-term use of the pipeline.

　　At the same time, stainless steel seamless pipes have strong corrosion resistance and can maintain long-term stability even in corrosive environments of strong acids, alkalis, and even seawater. Its material is more durable and can withstand vibration and impact in high-temperature and high-pressure environments, without causing damage, leakage, and other problems.

　　3. Application scope

　　In addition to being used in industries such as petroleum and chemical, stainless steel seamless pipes are also widely used in medical devices, precision instruments and devices, high-end building decoration, and other fields. With the implementation of Made in China 2025 Plan, more and more industries begin to use stainless steel seamless tubes to improve the quality and reliability of domestic products.

　　In summary, stainless steel seamless pipes have fully demonstrated their outstanding advantages in high-temperature and high-pressure environments. Precision manufacturing and excellent performance ensure its stable operation in even harsher environments, providing reliable and long-lasting solutions for various industries.

What are the pre welding preparations for stainless steel flanges

 1. Clean up the oil and other dirt on the stainless steel corrugated pipes and flange pipes that are about to be welded. If the leakage is caused by cracking at the welding joint, the original welding scar should be removed, and the straight pipe of the flange pipe should be polished with a metallic luster. The straight pipe of the corrugated pipe is too thin to be ground or polished. Use a hand sandcloth to polish it.

　　2. Welding assembly: The optimal assembly gap is 0, because there are processing and manufacturing errors with large time and space gaps, which can easily burn through during welding. The treatment method can be to overlay a layer (usually 3-5mm) on the straight pipe of the flange pipe, and machine it to a gap of 0-0.05mm or polish it with craftsmanship. If it cannot be fitted, the outer diameter of the flange pipe should be reduced or ground until it is suitable.

　　3. Welding machine selection: WS315 type, with DC positive connection.

　　4. Welding material selection: ER308, Ø 0.8mm

Is the 304 stainless steel pipe treated with wire drawing still rustproof?

 Stainless steel pipes are corrosion-resistant steel grades, mainly composed of elements such as iron, carbon, nickel, and chromium. Chromium will form a layer of high chromium protective film on the surface of stainless steel pipes to prevent further oxidation and corrosion of the pipes. After wire drawing treatment, the chromium rich protective film on the surface of 304 stainless steel pipe is damaged, resulting in a decrease in its corrosion resistance and susceptibility to rusting.

　　The common surface treatments for stainless steel pipes are divided into bright and matte surfaces. The brushed matte surface is more wear-resistant than ordinary bright stainless steel, and looks more upscale, which is deeply loved by the public. Although 304 stainless steel pipes have been brushed, their rust prevention effect is still good, but their performance is indeed reduced compared to ordinary bright pipes.

　　Although 304 stainless steel pipes have certain corrosion resistance and rust resistance after wire drawing treatment, they should not be used in outdoor exposed areas as much as possible. If used indoors, it is not only aesthetically pleasing, but also sufficient for rust prevention in indoor environments. If placed outdoors, attention should be paid to maintenance. Regularly apply rust preventive oil to stainless steel pipes and be careful not to damage the surface of the pipes.