Surface defect inspection of square and rectangular tubes

There are five main methods for detecting surface defects of square and rectangular tubes:

1. Eddy current inspection

Eddy current testing includes basic eddy current testing, far-field eddy current testing, multi-frequency eddy current testing, and single-pulse eddy current testing. Using the eddy current sensor to magnetically induce metal materials, the type and shape of the surface defects of the rectangular tube will cause different types of data signals. It has the advantages of high inspection accuracy, high inspection sensitivity, and faster inspection speed. It can inspect the surface and lower layers of the tested pipe, and is not harmed by residues such as oil stains on the surface of the tested square steel pipe. The disadvantage is that it is very easy to distinguish flawless structures as flaws, the false detection rate is high, and the inspection screen resolution is not easy to adjust.

2. Ultrasonic testing

When ultrasound enters an object and hits a flaw, a portion of the sound frequency creates a reflective surface. The multi-purpose function of receiving and sending can analyze the reflected surface wave, and can detect the faults accurately and accurately. Ultrasonic testing is commonly used in the inspection of steel castings. The inspection sensitivity is high, but the complicated pipeline is not easy to inspect. It is stipulated that the surface of the rectangular tube to be inspected has a certain degree of gloss, and the gap between the camera and the inspected surface is blocked with a silane coupling agent.

3. Magnetic particle inspection method

The basic principle of the magnetic particle inspection method is to complete the electromagnetic field in the raw material of the square steel pipe. According to the interaction between the defect leakage electromagnetic field and the magnetic particle inspection, when there is discontinuity or defect in the surface layer or near-surface layer, the magnetic field line will be partially deformed where there is no continuity or defect, resulting in a magnetic field. Its advantages are less investment in machinery and equipment projects, high stability and strong image. The defect is that the actual operation cost increases, the defect classification is inaccurate, and the inspection speed is relatively slow.

4. Infrared detection

According to the high-frequency magnetic induction electromagnetic coil, induced electromotive force is caused on the surface of the square tube. The induced electromotive force will cause the disadvantaged area to consume a lot of electromagnetic energy, causing the temperature of some parts to rise. Use infrared induction to check the temperature of some parts to identify the depth of the defect. Infrared sensors are generally used for the inspection of surface defects, and the discomfort is used for the inspection of irregular metal materials on the surface.

5. Magnetic flux leakage inspection

The magnetic flux leakage inspection method is very similar to the magnetic particle inspection method, and its application field, sensitivity and stability are stronger than the magnetic particle inspection method.

https://www.xysteelpipe.com/surface-defect-inspection-of-square-and-rectangular-tubes/

Degreasing and pickling passivation of carbon steel tubes

 For carbon steel pipe (CS pipe), it should be degreased first and then pickled, because grease is insoluble in acid solution. If pickling is performed first, neither the oil stains nor the rust covered by the oil stains can be removed.

Degreasing pickling method for carbon seamless steel pipe:

At present, the tank immersion method is often used in construction, and the liquid level exceeds the outer surface of the pipe by more than 50mm during immersion. Since the oxygen pipeline needs to be treated by degreasing, pickling and passivation, four tanks are generally made according to the actual diameter of the pipe used. That is, degreasing tank, pickling tank, neutralization tank, passivation tank. The oxygen pipeline degreasing and pickling process is: degreasing→water washing→pickling→water washing→neutralization→passivation→water washing→drying.

1. Degreasing

The formula of the degreasing solution is as follows: each liter of the solution contains 20g-30g of sodium hydroxide, 35g-50g of sodium nitrate, and 3g-5g of sodium silicate. The operating process requirements are: the liquid temperature is 70 ℃ ~ 80 ℃, the soaking time is determined by the test method according to the amount of oil on the surface of the pipe, generally about 10min ~ 40min. The heating method can be steam. Degreasing parts shall be inspected by any of the following methods. (1) Wipe the surface of the degreased part with clean and dry white filter paper, if there is no trace of grease on the paper, it is qualified. (2) Use 100% camphor below 1mm to check the condensate to flush the condensate, and it is qualified to keep rotating. (3) Check the surface of the degreasing part with ultraviolet rays with a wavelength of 3200-3800 angstroms, and the grease-free fluorescence is qualified. After degreasing treatment, the oil pollution on the pipe surface can be removed.

2. Water flush

Rinse with clean water with a pressure of 0.8MPa.

3. Pickling

Pickling is the use of acid solution to remove scale and rust on the surface of cs seamless pipes. The oxides of iron (Fe3O4, Fe2O3, FeO, etc.) such as scale and rust react with the acid solution to form salts that are dissolved in the acid solution and removed. The most commonly used pickling is sulfuric acid and hydrochloric acid. The formula of sulfuric acid solution is: the concentration of sulfuric acid solution is 5% to 10%. The operating process requirements are: temperature 60℃~80℃, soaking for 5min~20min. The formula of the hydrochloric acid solution is: the concentration of the hydrochloric acid solution is 5% to 20%. The operating process requirements are: temperature 20℃~50℃, soaking for 5min~20min. After the pipeline is pickled, check that the surface rust is removed, and the exposed metallic luster is qualified.

4. Water flush

Rinse with clean water with a pressure of 0.8MPa.

5. Neutralize

The formula of the neutralizing solution is: NH4OH diluted to a solution with a pH value of 10-11. The operating process requirements are: soaking at room temperature for 3 minutes.

6. Passivation

After pickling, water rinsing, and rinsing, the metal surface is very clean, very activated, and easily corroded. Therefore, passivation treatment must be performed immediately to form a protective film on the cleaned metal surface to slow down corrosion. The passivation solution formula is: NaNO2 concentration is 8% to 10%; NH4OH concentration is 2%. The operating process requirements are: immersion at room temperature for 10 minutes.

7. Water flush

Rinse with purified water with a pressure of 0.8MPa.

8. Dry

Drying must be done with clean, oil-free dry air or nitrogen.

9. Check

Wipe and check with white filter paper. If there is no trace of grease on the paper, it is qualified. After passing the inspection, seal the two ends of the pipe with plastic cloth and tape.

https://www.xysteelpipe.com/degreasing-and-pickling-passivation-of-carbon-steel-tubes/

Meeting With Middle Eastern Customers Again After Four Years

 It is always remember the special memory of my first customer. In 2014, we would follow the normal business process like quoting , sending samples, confirming the contract, checking the goods, and delivering to the customer.

Because of the first cooperation, the customer decided to inspection that the goods before loading. , A group of 3 peoples, They were very careful measurement and taking photos, Finally, customer recognized the service and quality of Xinyue and successfully sent the goods away.

Following four years, the customer did not come to China considering to our trust and recognition. Unluckily, When I cooperated for 2 years, there was a very regrettable thing to occur, Mr. Vinod, my dear friends, who went away suddenly. I wouldn’t accept this fact when I receive the email. In fact, a week ago we were still chatting the interesting things of their travels on the WhatAPP.

Another colleague, who we met in 2014, took over his job. They opened up their gas market. We provided product service support. And the annual small diameter seamless pipe orders for gas transfer grew steadily.

When we picked up customers , we looks like old friends, talking about the documents provided by the collection, the market needs to grow, their company continues to expand the market, in addition to diverge neighboring countries beside local market. ,It is expected to have a procurement plan in January 2018, And Hope to offer him the best Service and support as before.

We are serious about steel pipes business. We treat our friends with sincerity also. Build the world getting better and Serve for the global market. Warmly welcome to send Inquiry to Tianjin Xinyue Steel at any time.

http://www.tjxysteel.com/news/Meeting-WITH-Middle-Eastern-Customers-Again-688.html

Welcome Canadian client purchaser in China to visit Xinyue

 On 11 Dec, 2018, Xinyue group was very glad to welcome Mr.Peng from the procurement office of the Canadian client in China to audit our spiral pipe factory before procurement. Currently, the Canadian customer has a demand for more than 1100 tons of SSAW pipes for tunneling construction.

It’s the first time for Mr. Peng to visit Xinyue, he mainly visited our headquarters in Tianjin and factory, the two parties gave a comprehensive introduction and communication to each other in the meeting, which deepened the understanding of each other. Mr. Peng’s company has staff more than 70000 people, he is the leader of China area, the company headquarters in Germany, they need to purchase the welded pipe used in the project of Canada this time.

Mr.Peng is a very professional senior engineer who pays high attention to quality requirements. Our company has fully demonstrated our advantages in quality control through a series of quality control systems, including production equipment, production process, inspection and testing, packing, shipment etc., and ensured the production quality in strict accordance with the requirements of customer orders, such as API, European standard and other international standards, which has been recognized and affirmed by Mr.Peng with its actual strength. Xinyue always insists on the principle of "integrity-based, customer first, high quality, high efficiency", with the best service and quality of return customers, and pursuing 100% customer satisfaction.

Finally, Mr. Peng expressed his appreciation for the warm reception of Xinyue and he hope to start a pleasant cooperative relationship with Xinyue from this order.

http://www.tjxysteel.com/news/Welcome-Canadian-client-purchaser-visit-Xinyue-689.html

Israel steel plate project procurement pre-inspection

 Last week, Tianjin Xinyue Group ushered in a four-person inspection tour of an Israeli customer. Accompanied by our sales department and the factory technical department, the pre-purchase inspection of the Israeli construction steel plate project was carried out. The technical requirements of the project for steel plates are extremely high. This inspection also greatly promotes the development of good cooperation between Xinyue, steel mills and contractors.

During the entire inspection period, the customer first looked at the rolling mill line and had an understanding of the equipment and production process. Due to the customer's neatness and flatness of the steel plate, the requirements are very high. Then we took the customers to visit the shot blast line and the painting line. For the project, the technical parameters of the steel plate are confirmed by the customer and the technician and production manager of the factory. And witnessed the laboratory's experimental process and report. For the questions raised by the customers, the mill technology and Xinyue also carried out professional answers.

Finally, the customer gave a high evaluation of the strength of the steel mill, and said that after returning to Israel, They will decide to purchase the demand soon, hoping that we can give the best price. I believe that as long as we are committed to the best of our services, and always adhere to the "integrity-based, customer first, high quality and efficient" concept, customers will know in the communication and cooperation is a trustworthy partner.

http://www.tjxysteel.com/news/Israel-steel-plate-project-procurement-pre-inspection-794.html

Precautions for welding of tunnel steel support

 Weeds and shrubs are the main areas within the scope of tunnel site selection. During the field survey, the factors affecting the overall stability of the tunnel should not appear and occur. The selection of tunnel steel supports is also very particular, and there are also some principles that need to be paid attention to in welding construction operations.

There are several points to pay attention to when welding tunnel steel supports:

1. In the cold winter, if the steel plate is more than 9mm, it can be welded in several layers. This is to prevent the temperature from being too low, but in general, welding should be completed at one time and continuously. When welding, the defects left by the welding should be cleared first, and the welding can be continued after there is no problem.

2. In such a low temperature environment, the electrodes and wires used for welding steel supports should be low-hydrogen electrodes with low yield strength and good impact toughness under standard conditions.

3. The welding rods used for welding below zero degrees must be of formal standards, which need to be placed in a baking box of 80 to 100 degrees Celsius, and used when needed. If the electrode has been placed below zero for more than two hours, it needs to be re-baked, but the number of times should be less than three times.

4. In the open air environment, the welded steel support can build a shed just in case. Be careful not to get rain and snow on the weld.

https://www.xysteelpipe.com/precautions-for-welding-of-tunnel-steel-support/

Ultrasonic testing of seamless steel tube

 Principle of ultrasonic flaw detection of seamless steel pipe (smls):

Seamless steel pipe is a steel pipe that is perforated from a whole round steel and has no welds on the surface. Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemicals, boiler pipes, bearing pipes and high-precision structural steel pipes for automobiles, tractors and aviation.

The ultrasonic probe can realize the mutual conversion between electric energy and sound energy, and the physical characteristics of ultrasonic waves when they propagate in elastic media are the basis of the principle of ultrasonic flaw detection of seamless steel pipes. The directionally emitted ultrasonic beam encounters defects when propagating in the tube, causing both wave reflection and wave attenuation. After the signal processing of the flaw detector, if the reflection method is used for flaw detection, the defect echo signal can be obtained, and if the penetration method is used for flaw detection, the defect signal can be obtained by the attenuation of the transmitted wave. Both can give quantitative defect indications by the instrument. Different types of ultrasonic waves can be excited in the tube using the piezoelectric effect or the principle of electromagnetic induction. Therefore, both piezoelectric ultrasound and electromagnetic ultrasound can be used for ultrasonic inspection of pipes. But electromagnetic ultrasound is only suitable for ferromagnetic materials.

Ultrasonic flaw detection method of seamless steel pipe:

1. The shear wave (or plate wave) reflection method (or penetration method) is used for automatic inspection in the state of relative movement of the probe and the seamless steel pipe. Only special large-diameter seamless steel pipes can be manually inspected. Automatic or manual inspection shall ensure that the sound beam scans the entire surface of the pipe.

Note: During the automatic inspection, the two ends of the seamless steel pipe will not be effectively inspected, but this area should be controlled within 200mm.

2. When inspecting longitudinal defects, the sound beam propagates in the circumferential direction in the tube wall: when inspecting transverse defects, the sound beam propagates in the tube wall along the direction of the tube axis.

Inspections for and transverse flaws shall be carried out in two opposite directions of the pipe.

3. When the purchaser does not propose to inspect the transverse defects, the supplier only inspects the longitudinal defects. After negotiation and agreement between the supplier and the buyer, the inspection of vertical and horizontal defects shall be carried out.

Can only be done in one direction of the tube.

4. In automatic or manual inspection, the coupling medium with good coupling effect and no damage to the surface of the seamless steel pipe should be selected.

Suspicious seamless steel pipes can be handled by any of the following methods:

1. Carry out repeated flaw detection inspection according to the method specified in this standard. If there is no defect signal or the signal amplitude is lower than the preset alarm level, this inspection is considered to be qualified.

2. Carry out other non-destructive inspections on suspicious parts according to the methods and acceptance criteria agreed upon by both parties.

3. After the visible defects of the suspicious parts are removed, if the size of the seamless steel pipe is within the allowable tolerance range, the pipe shall be in accordance with the method specified in this standard.

method to re-detection inspection. If no defect signal is generated or the signal amplitude is lower than the preset alarm level, this inspection is considered to be qualified.

4. Excision of all suspicious sites.

5. Suspicious seamless steel pipes are rated as unqualified for this inspection.

https://www.xysteelpipe.com/ultrasonic-testing-of-seamless-steel-tube/