Stacking and drop performance evaluation of 200L blow molding barrel

Stacking and drop performance evaluation of 200L blow molding barrel

Text / Guo Changhua

Foreword

As a substitute for steel drums of the same specification, 200L polyethylene blow molding drums are used more and more widely, especially in the packaging of dangerous chemicals. However, due to the defects of the plastic materials themselves, on the one hand, many enterprises' products cannot pass the commodity inspection requirements during high-temperature stacking and low-temperature drop during commodity inspection. On the other hand, the products are deformed and cracked during transportation and use. Many people have proposed to amend the standard while reducing the standard requirements. As a practitioner, where do we go from here? This article gives a performance evaluation of the main performance of the 200L blow barrel used in the packaging of hazardous chemicals, stacking and dropping.

First, product introduction

200L polyethylene blow molding barrel, double barrel design, using ultra high molecular weight polyethylene resin, one-time blow molding. In addition to special requirements, it is generally dark blue, and the content is black when the risk factor is high. It is divided into single ring and double ring from the structure. The upper and lower bottom surfaces of the double "L" ring barrel and the barrel body are integrally formed with a "L" ring-shaped protrusion ring on the upper and lower sides, and the structure is symmetrical and convenient to carry, so that the use is wider.

2. Classification and packaging requirements for hazardous chemicals

The packaging requirements for hazardous chemicals depend primarily on their hazard and the relative density of the product.

The packaging materials are classified into categories I, II, and III according to the risk of chemicals. Class I has the highest risk. The commodity inspections are represented by the X, Y, and Z three-level symbols. The highest level of X, can be used for the packaging of Class I, II and III hazardous chemicals; Class Y can be used for the packaging of Class II and III hazardous chemicals; Class Z packaging can only be used for Class III hazardous chemicals and common chemicals. package.

The relative density determines the weight of each package unit and determines the performance requirements of the package, especially the stacking and drop performance. The danger and density of the product can be easily identified on the “UN” mark of the packaging container.

Such as:

U 1H1 /yd /PPP /XX
N CN /AAAABB

UN: UN dangerous goods packaging symbol

1H1: closed plastic bucket

y: indicates the package category, class I is X, class II is Y, class III is Z

d: indicates the relative density of the contents, such as 1.8 when the density is 1.8 g/cm3.

PPP: hydraulic test pressure (Kpa)

XX: indicates the last two digits of the production year, such as 09 in 2009.

CN: Manufacturing country code, abbreviation of CHINA (China)

AAAA: Entry-Exit Inspection and Quarantine Bureau code

BB: Container manufacturer code

Third, stacking and drop performance requirements

1, stacking test

According to the requirements of GB/T4857.3, the stacking load should be calculated according to formula (1). The test time is 28 days at 40 °C, requiring no obvious deformation and damage.

The stacking load is calculated as follows:

P={(H/h)-1}・M·9. 807

In the formula:

P——the stacking load applied on the plastic container in Newtons (N);

M——the quality of a single piece of packaging (the product of density and actual capacity, plus barrel weight), in kilograms (kg);

H - stacking height, 3m;

H——the height of a single container in meters (m);

H/h - take an integer number (round off after the decimal point);

9.807 - Conversion factor.

2, stacking test:

Test according to the requirements of GB/T4857.5, and put the sample drum into the test medium, and pre-treat it in an environment of 18 °C for 24 hours, then drop the surface, edge and angle separately according to the height specified in the table, and ask for the test sample. The gravity line passes through the dropped faces, points, and lines, and each sample falls once to check for leaks. The liquid containing the anti-coagulant is not less than 98% of the capacity of the barrel. After the drop test, drill a small hole in the appropriate part of the barrel, or otherwise balance the internal and external pressure to check for leaks.

The drop height requirements are shown in the table below:

When the density of the contents does not exceed 1.2g/cm3:

Packing category

I

II

III

Drop height

1.8m

1.2m

0.8m

When the packing density exceeds 1.2g/cm3:

Packing category

I

II

III

Drop height

d×1.5m

d×1.0m

d×0.67m

Fourth, the actual transportation, storage, loading and unloading conditions of the current 200L packaging

Storage: If the content has no special requirements for light, heat and temperature, the product is generally stored indoors or outdoors in a natural state. It may exceed 30 ° C in winter and 40 ° C in summer, and may exceed 60 ° C when exposed to the sun. Storage periods vary, days or months, or even more than a year.

Transportation: motor or sea. The export shipping cycle is long, from one month to three months, or even longer. The temperature inside the container during shipping is higher, up to 60-70 °C.

Loading and unloading: 200L packaging should be loaded and unloaded with a special tool to catch the "L" ring, but the country is generally "barbaric" loading and unloading, laying some tires and other buffers on the ground, pushing the bucket down from the car.

V. The actual quality level of China's current 200L blow molding barrel

Due to the obsolete manufacturing equipment, weak technical strength, irregular use of raw materials, low sales prices, and rising freight rates, the quality of China's 200L blow molding barrels is relatively low. In particular, some small enterprises are arbitrarily reducing the weight of the barrels in order to pursue low prices. The 200L blow molding drum used for dangerous goods packaging has a weight of 10.5KG. When the content density is large or it is a Class II dangerous goods, it even reaches 11KG. When the 200L barrel is a single ring structure or a double layer structure, it can be appropriately reduced. The weight of the barrel is about 500 grams. However, some enterprises now have a Class I 200L crisis package that actually achieves 8KG.

The general level is: stacking code can not meet the high temperature requirements, the drop can not meet the low temperature requirements, and can only meet the vertical drop can not meet the level or tilt drop requirements, there are serious quality hazards. The main quality hazards are as follows:

1. Deformation during stacking or transportation: The molecular weight of the raw material is low (200L blow barrel should use ultra-high molecular weight HDPE), the proportion of recycled raw materials exceeds 50%, the minimum wall thickness of the product is lower than 3MM or the wall thickness ratio of symmetric part exceeds 1: At 1.3 o'clock (uneven wall thickness), product storage or transportation environment temperature is too high, the product will be deformed or even collapsed.

2, "L" ring or barrel crack: "L" ring position is not easy to form, is the weakest position of the 200L barrel, when the lifting is not standardized, impacted, prone to cracking. When the wall thickness of the barrel is uneven or there is a longitudinal scratch, it is easy to crack from the weak point, especially when the barrel is left in a low temperature environment for a long time.

Sixth, stacking and drop performance analysis

The performance is to meet the requirements of use, the experimental method is derived from the use conditions, for the higher value of 200L hazardous chemicals packaging, high temperature transportation environment (above 40 ° C, more than 28 days), low temperature storage environment (less than - 18 ° C, more than 24 hours), irregular loading and unloading operations will lead to products with higher than standard practice, such a result will inevitably lead to barrel rupture, leakage and other phenomena, causing losses to customers.

To produce a high-performance 200L blow molding barrel for safe use, the following points are required:

1. Equipment must ensure continuous and stable production;

2, the use of ultra-high molecular weight raw materials, reasonable adjustment of the formula (according to customer conditions, content characteristics, seasons and regions, etc.), such as: cold zone or winter, should consider the drop performance, appropriate increase the proportion of flexible materials; In the hot season or region, the stacking performance should be considered more, and the proportion of rigid materials should be appropriately increased);

3, the wall thickness must be uniform to ensure a minimum wall thickness of 3MM;

4, self-test can not be sloppy;

5, understand the customer's use, transportation conditions, understand the characteristics of the content, tell the customer the correct way to use.

Conclusions and recommendations

At present, most of China's product standards are lower than the international standard requirements of similar products. Manufacturers pursue profit reduction standards, users pursue profits and lower prices, causing the industry to be in a vicious circle.

Due to low thresholds, low investment, large demand, and inadequate supervision, the market for 200L blow molding barrels is quite chaotic, winning by low-price competition, while low prices are mainly achieved by lowering raw material costs, such as using imported recycled materials and filling non-additives. Ultra high molecular weight resin, lower product weight, etc. This will directly lead to reduced product performance and increased risk of use.

Through the above analysis, I believe that the current standard is reasonable and should absolutely guarantee that the product meets the standard requirements. When the product is exported or sold to special areas of the environment, it is necessary to raise the testing standards (such as increasing the stacking temperature or number of days and prolonging the freezing time). However, if it is a close-range transportation and customer service specification, the two parties may agree on the agreement standard and appropriately reduce the requirements.

Commodity inspection, quality inspection, and technical supervision departments should standardize and play the role of a supervisor, let the industry go on the track of normal operation, reduce costs and improve products by improving automation, improving the technical level of equipment and processes, and saving energy and reducing consumption. Performance, rather than falling back in the opposite direction, lowers the standard.

references:

1. GB18191-2000 Plastic drum for packaging dangerous goods packaging

2, GBT13508-92 polyethylene blow molding barrel

3, GBT4587.3-92 packaging transport package static load stacking test method

4, GB/T 4857.5 packaging transport package drop test method

5. General technical conditions for dangerous goods transportation and packaging

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