Quality inspection and control of steel drum production process (1) (Xin Qiaojuan)

Quality inspection and control of steel drum production process (1)

Xin Qiaojuan

The most basic quality requirement for steel drums is that they cannot leak. If the steel drum leaks when it is filled with liquid, even if the appearance quality is good, the user will not want it; but if the inner quality is good, the appearance is wrinkled and pitted. The user is also not satisfied. With the rapid development of China's economy and the further enhancement of foreign trade, especially the increase in the export volume of petroleum, chemical, food, medicine and metals, steel drums as their external packaging are getting more and more used, in order to change the initial stage of China's reform and opening up. The first-class products, the second-class packaging, and the third-class price pattern, the export suppliers have higher and higher requirements for the quality of the external packaging. This is what many of our peers do not understand. It is always thought that users can't go with them and deliberately provoke. Someone called me and said that our bucket has been improved many times than it was ten years ago, but the user is always dissatisfied, always asking questions like this or the like. Looking at these issues from the perspective of a third party, it shows that our products still have problems in the production process, otherwise why are users not satisfied? At present, all of you here have basically passed the ISO9000 quality system certification. The first eight management principles of the ISO9000 quality management system are customer-focused. The customer's requirements are implemented and controlled through production methods under the leadership role. In the production process, we find problems, solve problems, and continuously improve the quality of our products. Who are you here to give to PetroChina and Sinopec, please raise your hand? I am not counting what I want to tell them about the inspection methods and the requirements for the steel drums. After several years of integration, China's lubricant industry has been stable. The Kunlun City of PetroChina, the Great Wall of Sinopec and the privately-owned three have formed a three-pronged trend. At present, CNPC and Sinopec enterprises have passed QHSE quality, occupational health and safety and environmental system certification. They require their suppliers to obtain QHSE certification when the next round of bidding is a hard indicator.

Q- quality Quality H-health Occupational Health S-Safety Safety (ISO18000) E-Environmental Environment (ISO14000)

The main focus of the quality management system is product realization process control; the main focus of the occupational health and safety management system is the personal health and safety and labor protection of employees in the production process; the focus of the environmental management system is to focus on the impact on society.

In the previous section, we briefly introduced the current quality management of steel drum enterprises should do those jobs, but how to do it, and do it in time, each enterprise is different according to its own situation. However, the user's requirements for the quality of steel drums are common to every steel drum company. Let us first talk about the general process and special process in quality management.

Quality Management Body 7.5.2 Confirmation of the production and service delivery process stipulates that when the process output of production and service provision cannot be verified by subsequent monitoring or measurement, so that the problem does not appear after the product is used or after the service is delivered, the organization shall respond Such process implementation confirmation. That is, the special process in the quality management system, the control of the special process is different from the control of the general process.

General process control:

Procured products that have not passed the inspection shall not be put into production. Inspectors and operators must first carry out post technical training, and they can be employed after passing the training. The working personnel must operate and inspect the production process according to the Equipment Safety Operation Regulations, Equipment Management System and Process Documents. This inspection is the first inspection and self-inspection. The inspection frequency is in line with the national standard GB/T2828- Under the premise of the 2003 standard, each enterprise shall stipulate itself, and in general, conduct a self-test every 200 times. The technical department prepares the technical documents required in the production process, determines the technical parameters and control points in the monitoring and measurement process, and is responsible for tracking and verifying the process technology. The production department provides the basic management of the working environment, facilities, and fixed management, tooling management, and document management required for the production process. Provide the required monitoring and measuring equipment for operators and inspectors, including: calipers, micrometers, pressure gauges, tape measures, etc. Each operator monitors the production process of the product as specified. When there is a non-compliance with the documentation requirements, stop the machine as soon as possible, report to the department leader, and then reproduce after the problem is solved.

Special process control:

In addition to the control of the general process, it is also required to perform the following requirements.

1. The technical department should clarify in the technical documents that the process is a special process and prepare the Operation Guide.

The contents of the work instructions shall include: operations, measurement methods and procedures; requirements for recording and confirmation and evaluation.

2. The production operation personnel shall monitor and measure the special process according to the requirements of the Operation Guide, and fill in the “process inspection record”.

3. Under the following circumstances, the production department or inspection department conducts the film-cutting test, and the inspector confirms the conclusion. If an abnormality is found, measures should be taken immediately, and the process and the products already produced should be reconfirmed; if it cannot be solved, the feedback report to the technical department to organize the relevant departments to solve.

When the groove shape changes;

When the equipment adjusts the crimping size still does not meet the process requirements;

The crimping continues to leak, and there is still leakage after adjusting the roller;

When leaking at the curling edge during type test.

4. The product inspector checks and records the main process parameters of the special process in each shift. The technical department shall conduct a process inspection and verification once a week. Immediately notify the production department, either verbally or in writing, if necessary, and develop corrective/preventive measures if necessary.

5. The operators of special procedures must be trained before they are employed. After passing the qualification examination, they can be confirmed by the confirmation department before they can be employed.

According to the above definition, the special process in the production process of steel drums should be sealing and spraying. Some units also incorporate seam welding into special processes. Although the seam welding process cannot be inspected and verified in this process, it is monitored and measured in later processes. It can be verified. Many enterprises have added pre-test leaks before the seal to improve the qualification rate of steel drum seals. This is the supervision and inspection of welds.

From the above analysis, we can see that the seal mainly controls the intrinsic quality of the steel drum, and the spray can control the appearance quality of the steel drum. Below we will talk about the quality inspection of steel drums from these two aspects.

Lecture 1: Internal Quality Control of Steel Barrels

To ensure that the steel drum does not leak after it is sealed, it is not necessary to do this process alone, but to strictly control the quality from the raw materials entering the factory. Under normal circumstances, our current 200-liter steel drums are made of cold-rolled steel sheets with a thickness of 0.5-1.5 mm. The quality of the materials directly affects the design of the steel drum process, the quality of the barrels and the use of the products. Life expectancy also directly affects the organization's balanced production and steel drum costs. The material cost of steel drums has already accounted for more than 80% of the cost of steel drums. At present, domestic steel drum manufacturers are increasing rapidly, and the profit margin of steel drums is getting smaller and smaller. Everyone is thinking about lowering production costs while playing price wars. . However, the cost of the production process can not be reduced to a certain extent, so the inferior steel plate of the small steel mill entered the steel drum production enterprise due to the price drop. Therefore, the current price difference of domestic steel drums is relatively large, and the weight of steel drums produced by steel plates of the same thickness is not the same. The steel plates rolled out by small steel mills are affected by the equipment and process conditions. The rolled steel plates are not thick and thick, and most of them are thick, so the steel drums are heavier. The formal big steel mills have been in recent years. The equipment transformation and process innovation were carried out. With new technology, new technology and new equipment, the thickness of the rolled steel plate was uniform, and the negative deviation was generally taken, so the steel drum produced was light. However, due to their advanced technology and technology, the material has good drawing and welding properties, so the material is thin. However, even if the small steel mill wants to thin, the equipment and process technology cannot be satisfied. In recent years, users' requirements for steel drums are getting thinner and thinner. The current thickness of oil barrels of PetroChina has become 0.8/1.0, and the thickness of many chemical barrels is also thinning, but the quality requirements for barrels cannot be reduced. . For example, although PetroChina lowered the material of the wrap-shaped steel drum by one step, the quality requirements for the steel drum were higher. PetroChina's new steel drum acceptance standard raised the drop height of the oil drum from the original 1.2 meters to 1.8 meters. The lubricating oil was Class II ordinary goods, but they required the standard inspection of Class I goods. This requires us to improve the structural processability of the steel drum on the one hand, in order to change the deformation conditions in the steel drum manufacturing process, to reduce the material requirements. On the other hand, the quality of the material is improved and stabilized to meet the deformation requirements of the material in the production process to produce high quality steel drums.

First, the quality requirements of steel drum production for raw materials

The material should have good plasticity (C-0.05%-0.15%, S, P, Si≤0.37%)

During the manufacture of steel drums, the internal stress of the material at the deformation site is mainly tensile stress, and the deformation is mainly elongation and thickness reduction. When the tensile stress of the main deformation site exceeds its plastic forming limit, it causes cracking. Therefore, the material is required to have good plasticity and plastic deformation stability. In this way, it is necessary to reduce the waste products and ensure the quality of the products.

The material should have the ability to resist pressure and wrinkle

When the stress inside the material of the deformation zone is a compressive stress, unstable wrinkles are easily generated. Therefore, the material is required to have not only a certain degree of plasticity, but also a high resistance to pressure and wrinkle.

Although we have many requirements for the physical and chemical properties of steel, it is impossible for us to establish a laboratory to test the physical and chemical properties of the steel plates as a steel sheet user. Therefore, it is generally required to obtain the certificate of conformity of the steel plates from the supplier. : Check whether the physical quantity of each batch of products conforms to the certificate of conformity, and whether the chemical composition analysis meets the national standard.

3, the surface quality requirements of the steel plate: should be smooth, flat, no rust.

1 cold plate (volume)
a. There must be no delamination, and the surface is not allowed to have cracks, crusting, folding, bubbles or inclusions.

b. The surface is allowed to have slight scratches and oxidized colors, yellowish and offset after pickling, and the depth or height is not greater than the local pitting, scratches and indentations of the half of the steel plate (steel strip) tolerance.
2 galvanized sheet

a, the surface is clean and shiny, and must not be stained;

b. Allow small spots of corrosion, uneven size of zinc flower dark spots, slight scratches, indentations, creases and slight pitting;

c. The zinc layer is tested without peeling and peeling when tested with a test rod.

The production of the test rod: the diameter of 6mm, the top is processed into a smooth semi-spherical shape, and the main working surface of the galvanized part with an area of ​​not more than 6cm2 is quickly and vigorously rubbed for 15 seconds.

Note: The applied pressure should be sufficient to polish the coating at each stroke, but not so large as to cut the zinc layer. The zinc layer with poor bonding strength will foam.

As the friction continues, the foaming continues to increase. If the quality of the zinc layer is poor, the bubble will rupture and the zinc layer will peel off the base metal.

If there are defects such as scratches, pitting, scratches, pores, shrinkage holes, etc., stress concentration will occur in the defect part during the production process, causing cracking; if the surface is warped, it will affect the cutting and punching positioning. Causes waste; surface rust is not conducive to the direction of the material during stamping. Due to the inconsistent flow rate of the material during stretching, the bottom top may be broken or partially thinned to produce microcracks. If the material is not cleaned during welding, welding defects such as breakdown may occur.

Material dimensional tolerance requirements (thickness is measured with a micrometer, width and length are measured with a tape measure)

4. Steel plates and steel strips should be accepted in batches. Each batch shall consist of steel or steel strips of the same heat number, the same thickness, the same heat or the same heat treatment specification.

Second, the quality requirements of steel drum production for auxiliary materials

1, paint and thinner requirements

a. Certificate of conformity: Check by batch, product certificate should be attached (if the certificate is attached to the outer packaging of the product, it may not be included in the inspection, but it should be indicated in the remarks column).

b. The state in the container (visual inspection): check one by one, take one barrel, open the container, stir the contents with a stir bar, and have no hard blocks, no mechanical impurities, and mix evenly.

c, viscosity: 40 ~ 80 seconds, once a week, with a coating -4 viscosity cup (25 ° C),

After the arrival of thinner materials, paints, etc., the purchaser and the warehouse manager will check and accept the quantity, specifications, packaging, appearance, and certification documents of the goods received. After the acceptance is passed, they will be directly put into the warehouse, and the warehouse manager will identify them; Contact the supplier for processing.

2. Incoming inspection of sealant

a. Certificate of conformity: Each batch of products is evenly accompanied by a certificate of conformity.

b. Solid content: 4 to 10g of sealant is weighed in one batch for each batch of feed, placed in a drying vessel with a diameter of 50-60mm, and the vessel is lightly distributed to make the sealant evenly distributed. The sealant was dried by placing the vessel in an oven at 70 ± 2 °C. When the sealant dries quickly, carefully flip the film and continue to dry at this temperature. The take-out vessel was placed in a desiccator for 30 minutes, and the dry film was accurately weighed. After the vessel was placed in the drying oven for 30 min, it was cooled and weighed according to the above operation method, and repeated until the film was kept constant. The difference in balance results is no more than 0.2%.

Total solids (%) = G2/G1-G0

G0: the mass of the vessel, in g

G1: quality of sealant and vessel before drying, unit g

G2: quality of dry film, unit g

Third, the control and inspection of steel drum production process

After the raw materials are inspected and qualified, they are put into production. In the production process, the procedures are strictly carried out according to the operating procedures and technical documents. The inspectors check the quality of each process according to the process requirements, find the problems, immediately rectify, and fail the produced ones. Rework and rework shall be carried out, and the following procedures shall be carried out after passing the verification and verification, until the non-leakage test is carried out after the sealing (the steel drums are currently inspected by more than 90% of the enterprises, and only a few individual seals in the country are sampled).

The performance test of steel drum is divided into two types: structural size inspection and type test. The structural dimension inspection is very clear to everyone. It is the inspection of the shape and dimensions of the steel drum. The type test is divided into: airtight test, hydraulic test, and drop. Test and stacking test.

Airtight test:

Also known as the non-leak test, it is generally completed in the process after the steel drum is sealed. Method GB/T 17344: Most enterprises use compressed air in the barrel (pressure value is 50-100Kpa), soapy water is applied to the outer weld and the seal of the barrel, and the weld and large circle are inspected after 6-10 seconds. There is no leakage method for testing. Of course, several large steel drum manufacturers and foreign-funded enterprises with strong domestic strength have already used the helium mass spectrometry leak detection method to conduct non-leakage inspection of steel drums. (see P342)

Hydraulic test:

1. The steel drum is not pretreated for temperature and humidity;

2. Fill the finished steel drum with water, connect the pressure pump to the injection port through the high-pressure pipe, start the pressurized water pump, and inject water into the barrel to pressurize until the specified test pressure is reached (Class I 250 Kpa, Class II) , Class III 100 Kpa), hold pressure for 5 minutes, check for leaks.

Drop test:

GB/T 4857.5 standard stipulates that the drop height is 1.8m; the steel drum is not pretreated for temperature and humidity;

1. Fill the small open steel drum with 98% water, and drop the weakest part of the edge of the steel bucket. [Select the edge 5, 6 points (the barrel weld and the top of the barrel and the bottom of the barrel) drop one, 56 lines ( The weld is down by one], and the hole is drilled at the highest part of the steel drum. When the pressure inside and outside the steel drum is balanced, observe whether the weld, the large circle and the falling deformation are leaking.

2. The medium-opening and full-opening steel drums contain 95% of a mixture of sand and wood chips with a density of 1.2g/cm3. The weakest part of the edge of the steel drum is dropped, and there is leakage and cracking after falling.

Stacking test:

According to the provisions of GB/T 4857.3, stacking height: 3m for land transportation and 8m for sea transportation. Steel drums are not subjected to temperature and humidity pretreatment;

1. Prepare a test plate. The standard specifies a steel plate with an edge larger than 100 mm of the test piece and a thickness of not less than 10 mm. Therefore, we generally use a steel plate with a diameter of 800 mm and a thickness of 10-15 mm as a test plate.

2. The size of the stacking load is calculated according to the following formula:


Where: the stacking load applied on the P-steel container, N; H-stack height, m; h-the scale of a single steel drum, m; M-the mass of the single-piece steel drum after the article is loaded, kg; K - The coefficient of deterioration is 1

3. Place a steel drum filled with contents on any water platform surface with a height difference of not more than 2 mm at any two points, and then place a steel plate of Φ800×10mm or 800×800×10mm in the center of the barrel, according to GB/T325-2000 The load specified in the container steel drum is uniformly loaded and placed for 24 hours. The steel drum shall not be tested for any deformation or severe damage that may reduce its strength or cause stack instability.

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