Talk about 200 liter steel-plastic composite barrel
Jiangsu Baoying Metal Products Factory Qiao Ping
Since its inception, the 200-liter steel drum has been widely used and has been increasing year by year due to its superior mechanical strength, resistance to harsh environments and impact, and convenient storage and transportation. However, because it cannot withstand the corrosion of various chemicals such as acid and alkali, the scope of use of steel drums is limited. In order to solve this problem, the steel barrel industry has successively developed steel-plastic composite barrels and inner-coated steel barrels. As far as the current situation is concerned, the steel-plastic composite barrel has extremely superior performance, far exceeding the inner spray steel drum.
200 liter steel-plastic composite barrel, referred to as 200 liter steel-plastic barrel. This is a composite steel drum with a complete plastic container inside the steel drum. Appendix 1 of the International Maritime Dangerous Goods Code defines the composite packaging as follows: Composite packaging refers to an overall packaging formed by an outer packaging and an inner packaging container. Once assembled, it is always used as a single unit during filling, storage, transportation and emptying. The outer packaging is made of a metal material to protect the inner container from damage during transportation and handling, but it does not have the function of holding goods. The 200-liter steel-plastic bucket is an organic combination of plastic drums and steel drums to form a unitary packaging container. Due to the form of such a composite package, the function of the original package is greatly improved, however, the inner spray steel drum does not have such superiority.
First, the internal injection of steel drum equipment is relatively large. The interior spray coatings currently used in China are mainly polyvinyl fluoride coatings, polyethylene powder coatings, epoxy resin coatings, etc., which are almost all thermosetting coatings. If the steel drums use these coatings, they must have drying tunnels or baking equipment, and the capital investment is large, which is difficult for small and medium-sized enterprises.
Second, the process is more complicated. Since the surface of the steel drum has almost grease, rust and oxide film, the steel drum must be pre-coated before painting. Generally, a series of processes such as degreasing, pickling, and phosphating are required to ensure the quality of the coating.
Third, the coating structure is not tight, and it is not easy to guarantee the contents. quality. Since the spraying in the steel drum is carried out before assembly into a steel drum, it is inevitable that the coating will be damaged by collision during the processing, especially in the assembly process, when the curling is curled, the coating at the circumferential seam is easily peeled off or cracked, so that the contents and the steel are made. The surface of the barrel is in contact, causing the coating to lose its antiseptic function. In addition, the threaded portion of the closure and the inner coating of the edge of the barrel are also easily peeled off, which affects the use.
In the past two years, the order quantity of steel-plastic composite barrels of our factory has exceeded the number of inner spraying barrels, and there is still a tendency to continue to rise. This is because in addition to the above advantages, there are two points in the steel-plastic composite barrel:
1. Aluminum prices have risen. Many of the products originally packaged in aluminum drums were replaced with steel-plastic drums to reduce packaging costs.
2. The prices of paints for internal spraying, personnel wages, and electric power continue to rise, making the gap between the price of inner spray barrels and steel-plastic barrels smaller and smaller. For a chemical product that is expensive, a barrel difference of 20 to 30 yuan, and its proportion of finished packaging, can be said to be negligible.
The inner container of the steel-plastic barrel is a polyethylene plastic liner (referred to as a liner), which can hold almost any solvent, so the steel-plastic barrel is widely used. In addition to meeting the general requirements for steel drums, 200-liter steel-plastic drums also have certain special requirements.
Special requirements for the liner:
(l) The liner must be made of corrosion-resistant, high- and low-temperature resistant high-pressure or low-pressure polyethylene and EVA copolymer, and meet the requirements of SG959 standard: the wall thickness of the liner should be greater than 1mm; the air in the liner wall is free of bubbles and obvious impurities. (Each 100mm2 surface, no more than 5 black spot impurities, black spot impurity maximum length is not more than 3mm), no penetrating impurities are allowed; no oil and foreign matter in the gallbladder; waste edge trimming is smooth; parts are not obvious Notched or deformed.
(2) The closure is assembled, easy to use, and the insert and the inner tank are welded well. When used to hold food, food additives or medicines, it must also comply with the relevant provisions of the Food Sanitation Law.
2. Special requirements for assembly
When assembling, the inner tank and the steel drum must follow the principle of properness, so that the outer surface of the inner liner and the inner surface of the steel barrel are as close as possible to reduce the space. No burrs are allowed in the straight seam joints of steel drums to avoid scratching the liner during assembly and causing leakage. The closure should also avoid the formation of incisions, otherwise the force will be concentrated after loading the goods, causing leakage at the insert.
3. Special requirements for inspection
(1) Stacking test: Place the test sample in the specified place. Place a flat plate on the steel drum and place the corresponding weight on the plate. 8å€ã€‚ The weight is at least 1.8 times the sum of the total weight of the steel drums. After 24 hours, the contents were free of leakage, and no permanent deformation that threatened transportation safety was observed. When testing on the stacking test machine, after the test pressure reaches the specified requirements, the contents are free of leakage, and no permanent deformation that threatens transportation safety is obtained.
(2) Leakage test: Compress air with a pressure of not less than 20kpa in the steel-plastic barrel, at least for 10 minutes, to see if it has leakage. If it does not leak, it is qualified.
(3) Hydraulic test: Fill the steel and plastic barrel with clean water, put a certain pressure into it, and keep pressure for 10 minutes to see if there is leakage and any permanent deformation that endangers transportation safety. If it does not appear, it is qualified.
11.75 is multiplied by the vapor pressure of the material being loaded at 50 ° C, minus 100 kPa, but the minimum test pressure is 100 kPa.
21. 5 Multiply the vapor pressure of the material being transported at 55 ° C, minus 100 kPa, but the minimum test pressure is 100 kPa.
(4) Drop test: The steel plastic drum is filled with a liquid not less than 98% of its capacity, and the temperature of the test sample and its contents is lowered to below -18 °C. The liquid to be tested should be kept in a liquid state, and an antifreeze may be added if necessary. The test sample is then free to fall onto a hard, inelastic, smooth, flat and level plane. The way to fall: Determine the most vulnerable part of the bottom of the steel drum is the impact point. The drop height depends on the relative density of the loaded goods. If the density is less than 1.2, the Class I package is 1.8m; the Class I package is 1.2m; and the Class I package is 0.8m. If the density is greater than 1.2, the drop height is calculated as follows, rounded to one decimal place. Class I packaging is 1.5Xdm; packaging is l1. 2Xdm; Class I packaging is 0.67 Xdm (d is the density of the intended cargo). If there is no loss after falling, the contents are qualified. A small amount of material seeps out of the seal after impact, and should not be considered unqualified as long as there is no further leakage.
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