The relevant person in charge of an appraisal center in Shanghai told Cement.com that he had recently received a commission to appraise the cracking of a case barrel.

The thickness reduction of the steel plate at the crack of the cylinder involved is far greater than the normal requirements.

The above-mentioned appraisal center accepted the entrustment and immediately went to the site to conduct an investigation.

For kilns that burn solid waste or hazardous waste, we will communicate with our customers before sales, preferring to choose steel plates with better corrosion resistance in the selection of cylinder materials, and providing quality assurance services within 12-18 months from the ignition or shipment of the project.

In order to find out the cause of cylinder cracking, the relevant insurance company commissioned an appraisal center to conduct an appraisal on this matter.

Video: Replacing the kiln barrel During the cement manufacturing process, the cement rotary kiln is a key production equipment, mainly used for calcining cement clinker, and is also a core link in the production of the entire cement plant.

The fracture surface in other places is also about 35% thinner, and the material strength near the crack is significantly reduced.

Regarding the claim against the insurance company, the person in charge of the kiln equipment manufacturing enterprise mentioned above stated that cement enterprises often solve similar problems themselves.

After all, this area of the rotary kiln is the most stressed area.

For the issue of responsibility determination, a third-party institution recognized by both parties should be selected for relevant identification to determine the cause of cracking.

According to the information from the cement people website, there have been multiple kiln barrel cracking accidents in the cement industry in recent years.

The person in charge of equipment in a cement enterprise told Cement.com that it is difficult to define reasons such as improper maintenance.

It is mainly caused by the concentrated force of “corrosion+thick and thin butt joint+large torque”, which causes the cracking of the kiln shell.

The insurance for equipment is generally agreed upon to cover losses caused by force majeure factors, while the insurance for losses caused by human factors, process defects, and quality defects is generally not covered.

The cylinder of a cement rotary kiln in a cement company cracked after years of use, causing property losses.

The” burning of solid waste and hazardous waste “that has emerged in recent years has a significant impact on the kiln barrel.”.

Therefore, on the one hand, it depends on the agreement made by the enterprise in the insurance contract, on the other hand, it depends on the determination of liability.

Because most of the reasons are from the enterprise itself, such as some old lines, the requirements for burning solid waste and hazardous waste are not considered in the design of the kiln barrel.

A kiln maintenance engineer told the cement website, “On average, more than 20 cracks in the kiln barrel need to be repaired every year.

What if the kiln cracks? The appraisal center has said this…

“Or kiln bricks with relatively poor corrosion resistance are used, or improper construction of kiln bricks during laying may cause corrosive air in the kiln to come into direct contact with the cylinder, resulting in strong corrosion and injury to the kiln cylinder.”.

The fracture surface of the cylinder is flat without obvious plastic deformation, and the thinnest position of the fracture surface is nearly 50% thinner than the thickness of the original cylinder steel plate.

As one of the key equipment of the enterprise, the cylinder cracking problem of the rotary kiln will be classified and handled by the insurance company according to different situations during the claim settlement process.

The thickness of the kiln barrel around 2-3 meters from the tire will be thickened, usually 80-90 mm, while the thickness of the kiln barrel around 2-3 meters from the tire will gradually decrease, gradually reducing from 50-60 mm to within 20-40 mm.

Under normal circumstances, when the thickness of the cylinder is reduced by more than 30% of the original steel plate thickness, it needs to be reinforced or replaced.

In summary, the cause of the cracking is actually very simple.

Should the insurance company compensate for kiln cracking? Cylinder cracking is one of the common failures of cement rotary kilns, and is related to various factors, such as equipment manufacturing quality issues, wear and damage during use, and improper maintenance.

Unless there is conclusive evidence that it is caused by improper maintenance, even cracks caused by corrosion are within the scope of compensation.

How to identify the cause of the accident and effectively settle the claim has been the focus of controversy among all parties.

Therefore, cement enterprises attach particular importance to the operational safety of the kiln system.

Troubleshooting during the accident investigation stage: No major abnormality was found during the inspection of the center line of the rotary kiln involved, which ruled out that the cylinder was cracked due to long-term uneven stress on the third gear due to the uneven center line; The specifications of the rotary kiln cylinder meet the requirements of relevant standards, eliminating the possibility of eventual cracking of the cylinder due to incorrect selection of raw materials; The infrared real-time monitoring temperature on the outside of the cylinder is around 260~280 ℃, and there is no overtemperature phenomenon.

It is ruled out that the cylinder cracks due to overheating material embrittlement during operation; The crack location is not in the weld heat affected zone, and the sampling inspection results also indicate that it is not a weld heat affected zone structure, which precludes cylinder cracking due to welding factors such as welding stress and welding cracks.

The inspection results at the fracture surface indicate that there are oxidation and corrosion phenomena.

According to the information of Cement.com, cement enterprises usually invite bids for key equipment on an annual basis and agree on the specific coverage.

Most of the cracked kilns are located between the second and third gears, and some are small defects in design.

It would be better if the barrel was designed to be thicker.

There are certain amounts of P, S, Ca, and Al elements in the cement raw materials in the rotary kiln, which can promote the corrosion and thinning of the cylinder under the action of high temperature.
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Due to the difficulty in identifying responsibilities, the cost of finding a professional certification agency may be cheaper compared to the cost of buying a section of the kiln barrel.

Most enterprises contact the equipment supplier immediately after the kiln barrel cracks, seeking solutions on the one hand, and finding the cause of the cracks on the other hand.

“The partially cracked kiln measured on site has a partial cylinder thickness of only 40mm between the second and third gears, which is close to the second gear.” Regarding the thickness of the kiln barrel, the relevant responsible person of the kiln equipment manufacturing enterprise in the cement industry told the cement people website that the design concepts of large domestic equipment enterprises for cement kilns are basically the same.

At the same time, insurance claims require a certain amount of time for identification, which is even more valuable for cement companies.

For losses caused by quality and process design issues, once the responsibility is identified, the equipment manufacturer and relevant design agencies will bear greater responsibility.

Recently, a cement kiln in the northwest region cracked, causing considerable losses to the enterprise.

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