Talking about Several Tests in Steel Barrel Production
Jiangsu Baoying County Metal Products Factory Qiao Ping
The quality inspection of steel drums is a complex and important task. It involves not only the individual processes but also the production. Therefore, the inspectors must be very familiar with and familiar with the content, requirements, and means and methods of inspection, in order to ensure the accuracy of the inspection to avoid misdetection, missed inspection and repeated inspection.
The inspection runs through the entire process of production and operation of steel drum enterprises. In the following, some of the inspection work will be analyzed and discussed in order to make the inspection more reasonable and more perfect.
First, the inspection of steel plates
Steel plates are the main raw material for the production of steel drums. The inspection must be carried out one by one according to the requirements of the raw materials entering the factory inspection rules. Generally speaking, all raw materials entering the factory must have complete packaging and moisture-proof measures, and must have a quality certificate and a trademark certificate. After the information is basically complete, the steel plate can be inspected.
The usual inspection items for steel sheets are visual inspection, geometric dimensional inspection and mechanical performance inspection. For the first time supply of the manufacturer's sheet, under the premise of providing the quality certificate, the whole project inspection, that is, the appearance, geometric size and mechanical performance inspection. For the plates of the regular supply units, only the appearance and geometric dimensions of the inspections can be made after the quality certificate is provided. In case of disputes, mechanical performance tests are also required.
Due to the large amount of steel plate inspection, in the case where the supplier provides a quality certificate, the quality of the steel plate can be considered to be basically stable, so the sampling test method can be preferred. In fact, most barrel companies also choose the method of sampling inspection.
When inspecting steel plates, the required plates should be randomly selected as samples for inspection. The appearance quality should be such that the surface has no cracks, no knots, no folding, bubbles, impurities, no delamination, smooth surface, no scratches, no rust and other defects. The geometric dimensions shall comply with the provisions of GB708. Mechanical properties should meet the requirements of GB700. Generally used for cold bending test and tensile test. A visual appearance is usually used. The geometry is measured with a universal gauge. Mechanical properties are measured using special equipment.
The data of these tests must also be completely recorded during the inspection process. Through the statistics of these data, the inspectors must also compare with the standards and make a judgment on whether they are qualified or not. If the inspection is unqualified, in general, the tightening scheme is used to re-test once. If it is still unqualified, it will be returned or notified to the supplier for processing. Regardless of the test results, the inspection department must carefully fill out the inspection report form and notify the relevant departments.
Second, the inspection of the bottom cover of the barrel
The geometry and precision of the bottom cover of the bucket are guaranteed by the mold fixture, and the frequency of inspection is relatively small. However, the first test here is especially important. Through the first piece inspection, defects such as severe wear of the mold or incorrect positioning of the installation can be found, so that improvement measures can be taken to prevent the occurrence of batch defective products.
There are many items for the inspection of the bottom cover of the bucket, but it can be summarized as the inspection of the geometric dimensions and the inspection of the thread and the airtightness.
The geometrical dimensions are generally measured by universal gages, and the threads are inspected with special gauges, ie plug gauges and ring gauges. The method is basically simple, while the airtightness test is relatively more complicated.
The air tightness test is for the lid of the bucket, more precisely for the closure. After debugging the closure lock mold, first use the waste to test the lock, and then carry out the inspection. After the inspection is passed, the bucket cover is used for locking and inspection. The inspection method is as follows: the barrel plug is respectively tightened with a torque wrench with a torque of 35 Nm and 20 Nm, and placed on a special test equipment <Note>, and a compressed air having a pressure of 200 kPa is introduced, and the compressor is closed. Add soap to the pressure and keep the pressure for 5 minutes to check for leaks. Those who do not leak are qualified.
Third, the factory inspection
The purpose of the factory inspection is to prevent the non-conforming product from flowing to the user, causing losses to the user, and also to protect the reputation of the barrel manufacturer.
The GB325-91 standard specifies the contents of the factory inspection. It includes basic requirements, performance requirements, and quality requirements for steel drums.
In fact, each barrel manufacturer can guarantee the basic requirements of steel drums. The sealer has been rigorously inspected before the steel drum is assembled. Therefore, the main contents of the factory inspection are air tightness inspection and protective layer and appearance inspection.
According to the standard, the factory inspection lot is one inspection lot for each class. The appearance can be visually observed. If the protective layer is galvanized, the thickness of the galvanized layer can be measured with a magnetic thickness gauge. If coating with a coating, a sample is required. If there is no sample, use the paint film plane of the steel drum to make a sample and measure it directly.
Fourth, type inspection
Type inspection is a more comprehensive inspection of finished products than factory inspection. Steel drums must be type tested after stereotypes, overhaul trials, or changes in structure, materials, and processes. Type inspection includes all technical requirements for steel drums, including four performance tests. The performance test of steel drums is somewhat time-consuming, costly, and destructive, so sampling methods are used. Due to the safety of the steel drums used in the test, it must also be carried out in accordance with the inspection methods and inspection rules stipulated by the national standards.
Taking the stacking test as an example, the stacking test is used to evaluate the stability of the steel drum stacking code. The GB325-91 packaging container steel drum standard stipulates that the stacking height of the stacking test is 8m. The duration is 24h, and the stacking load is calculated according to the following formula:
F=K[(Hh)/h]W
In the formula:
F - stacking load (N);
H - stacking height (m);
H-single piece steel drum height (m);
W--the weight of the single-piece steel drum after the item is loaded (N);
K - the coefficient of deterioration.
Steel drums are not pretreated for temperature and humidity.
In the routine test, GB325-91 requires its test method to be tested according to the provisions of GB4857・3. First, test equipment should be prepared, such as test horizontal plane, loading plate, weight or weight, and measuring equipment and safety equipment. Once these devices are ready, you need to calculate the stacking load. According to this formula, the density of the intended product must be known to calculate the weight of the single-piece steel drum. And because W = dV, you can indirectly get the weight of a single-piece steel drum. The GB325-91 standard adopts the IMO International Maritime Dangerous Goods Code (hereinafter referred to as the “Dangerous Regulationsâ€) for the performance test of the steel drum. The ninth chapter amendment “Basic Requirements and Performance Test of Packagingâ€, the test value is equivalently adopted. The value of the Code of Ethics. Take the 200L steel drum as an example, the formula is (Formula 1):
F=K[(Hh)/h]W=K×[(8-0.9)/0.9]×W=7.9KW
The professional standard issued by the State Administration of Commodity Inspection, ZBA870001, "Code for Inspection of Packaging for Maritime Export Dangerous Goods" is also recommended according to the IMO "Hardware Regulations" Appendix I packaging recommendations, and with reference to ISO standards. In this standard, the following calculation formula is specified for the stacking load:
M. =(X/h-1)M1
In the middle
M. - the total weight N to be applied on the package; X - the lowest stacking height m; h - the height of a single package m; M1 - the gross weight of a single package N;
We still take 200L steel drum as an example, this formula can be calculated as (Formula 2):
M. =(X/h-1)M1=(8/0.9-1)M1=7.9M1
It is not difficult to see that both Equation 1 and Equation 2 are derived from the IMO standard. The difference is that the difference is K, except that the code used is inconsistent (but essentially the same). The former has, the latter has no. If the coefficient K = 1, then Equation 1 is equal to Equation 2. If the coefficient is greater than 1, the stacking load is large, and vice versa. In my opinion, since the materials used in the steel drums are consistent in structure, the stability of the stacking is nothing more than the density of the contents and the stacking height. In order to increase the choice, and add a coefficient in front of these two influencing factors, it may not be effective. In fact, in order to ensure safety, the GB325-91 standard has increased the stacking height by nearly two times ("Hardware Regulations" 3m, "GB325-91" 8m). It can be seen that if the original formula is not changed, the inferior coefficient K=1 is sufficient to meet the requirement.
Steel drums are generally used to store or transport petroleum and chemical products. The density of chemical products is generally lower than that of water, and the density exceeds that of water, and the density reaches about 1.3. For safety reasons, it is reasonable to choose 1.2 as the calculation base for the density of the contents. Taking a 200L steel drum as an example, its stacking load is:
F=7.9×K×W=7.9×1×[1.2×200+22]=2070kg=20284N
Japanese Industrial Standard JIS 21601 "Steel Barrels (for Liquids)", the stacking test is defined as: applying a load equal to the total weight of the same type of transported articles placed on the container in the transport. When a substitute is used as a sample, the test load is calculated by the density of the object to be transported when the density of the substance is different from the density of the transported liquid. The test method is to calculate the total weight when the filler having a density of 1.5 is stacked to a height of 3 m, and perform the stacking test with the equivalent mass as the load. The load calculated by the standard is:
F=K[(Hh)/h]W=1×[(3-0.84)/0.84]×(1.5×200+22)=828kg=8114N
It can be seen that the stacking test requirements of the GB325-91 standard have greatly exceeded the requirements of the "Dangerous Regulations" and "JIS21601". In actual work, under normal circumstances, the coefficient of variation KI is taken, and the density of the contents of the package is 1.2 as the calculation value of the stacking test load, which basically satisfies the requirements. If the relative density of the intended item is greater than 1.2, the load shall be calculated as the latter.
According to the test principle of GB4857-3, the test can be completed by applying a load on the test sample by placing it on a horizontal surface. Therefore, the essence of the stacking test is the load test.
Generally speaking, the test method of the stacking test is to place the mixture in the test steel drum with a density of 1.2 on the stacking ground, and then place the load plate in the center of the top surface of the steel drum, and then do not cause impact. in the case of. Place the weight on the load plate and make it evenly contact with the load plate. The error between the total weight of the weight and the load plate and the specified value is controlled within ±2%. The stacking code is checked after 24 hours. If the test steel drum has neither the possibility of reducing its strength nor any deformation or leakage causing stacking instability, it is acceptable. Due to the long test time, it is possible to test several test samples at the same time, which can greatly shorten the test time.
The inspection of steel drum products is far more than these. It is a systematic project to carry out the inspection of steel drum products, which requires the joint efforts of the whole enterprise.
Note: Special test equipment is generally designed with reference to the airtightness test device of the GB325 standard appendix. I won't go into details here.
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