Steel drum sealing packing and application
【Abstract】The role of sealing packing in the quality assurance of barrel production is proposed for the sealing problem of steel drum. The characteristics and sealing mechanism of the sealing packing are described. In combination with practice, how to choose the sealing packing according to the medium contained in the steel drum, and the problem that the sealing process of the sealing packing should be paid attention to.
[Keywords] sealing filler steel barrel coating process
1 Introduction
In the GB325 standard for packaging container steel drums, steel drums are used as packaging products to contain various products, and strict leakage prevention, damage, loading and unloading transportation and sea export are all required to be strict, that is, the container structure is required to be firm and intact, and the seal is not leaking. Performance requirements such as air tightness, water pressure, drop and stacking must be guaranteed. In order to meet the above requirements, in the production of steel drums, the sealing seam of the steel drum, the sealing of the seam, the sealing quality of the seal are the three key processes to ensure the quality of the finished product of the steel drum. The quality of the edging, the quality of the spot welding lap and the quality of the seam welding are guaranteed.
The quality of the seam of the steel drum is different from that of the vertical seam. The vertical seam welding uses resistance heating to melt the metal, and the steel plate is welded into a whole after being pressurized. The sealing property mainly depends on the quality of the welding itself, and the steel barrel crimping belongs to Cold working, even if the processing is perfect, the rolled shape meets the requirements, and the sealing requirements cannot be met. Because the steel plates are tightly bonded together, there are still voids. Therefore, it is necessary to add a certain elastic material to the kneading place to fill all the steel plate joint voids to seal the seal. Similarly, the sealing requirements of the sealer It is also similar to the crimping requirements. It is necessary to add elastic packing to the top of the coil and the top of the bucket. After locking, the sealing of the sealer can be ensured.
2 The role and characteristics of sealing packing
Since the sealing filler itself has a certain elasticity, strength and elongation at break, when the steel drum is deformed by collision, the sealing filler can expand under the action of various internal media, which can still bear the sealing effect, which is that it can withstand All kinds of harsh conditions, especially in the case of steel drum damage, have better ability to follow the deformation and deformation, can effectively prevent the liquid contained in the steel drum from leaking outward, and play a good role in preventing leakage.
As a practical sealing material, it must have the following characteristics:
(1) Fillability. Can fill all the depressions and gaps, and have good wetting properties on the metal surface;
(2) Densification. In the joint gap, the sealing filler itself is dense and flexible, and it is not easy to generate elastic fatigue phenomenon;
(3) Anastomosis. The sealing filler has good adhesion to the metal joint surface, and can adhere firmly to the metal surface even under impact and vibration;
(4) Continuity. The film sprayed on the metal joint surface must be continuous and uninterrupted;
(5) Stability. The sealing filler does not corrode the metal surface and does not undergo any chemical reaction on the sealed medium;
(6) Adaptability. Does not lose or reduce its sealing performance due to changes in external environmental conditions such as temperature, humidity, etc.;
(7) Processability. Can adapt to various construction conditions.
3 Sealing mechanism of sealing packing
Sealing fillers vary in formulation, type and basic polymer compound properties, and they have different forms. According to their sealing operation process, there are solid gaskets, solid rubber strips, and half of the viscous state. Dry viscoelastic sealant and non-dry adhesive sealant, various sealing fillers, the sealing mechanism is also different.
The solid gasket is mainly formed by a tight locking between the two joint faces to form a sealing ring. The hardness of the solid gasket is required to be much less than the hardness of the two joint faces, and the thickness of the gasket is also moderate, so that it acts under a certain pressure. Next, the uneven surface of the joint surface is pressed into the surface of the gasket to form a densely connected sealing surface.
Solid rubber strip, which is mainly embedded in the center of the radius of the circumferential skirt of the barrel and the top of the barrel and the bottom of the barrel. Due to the elasticity of the solid strip, it can better fill the barrel and the bottom of the barrel and the top of the barrel. The void which occurs during the winding is deformed by the internal pressure on the winding surface, and during the deformation process, it continuously absorbs the energy of the internal pressure, so that the energy generated by the internal pressure is consumed insufficiently to cause leakage.
For the semi-dry elastic and non-dry adhesive sealing packing in a viscous state, it is sprayed, and at the center of the barrel body and the top of the barrel and the bottom of the barrel, the solid state is formed by the viscous state by self-drying, that is, the formation is solid. A thin sealing film has a sealing mechanism similar to that of a solid rubber strip. Due to its fluidity, it can fill the gap between the steel sheets as the curling shape changes. Therefore, as long as it is crimped, It is very difficult to spray the sealing packing on the rolling surface evenly and roll it up correctly, and it is very difficult to make the internal pressure of the steel barrel to deform the sealing packing in the winding layer to cause leakage. This means that this thin layer of sealing packing is completely sufficient for sealing.
4 problems in the application of sealing packing for steel drums
At present, there are many kinds of sealing fillers produced in various parts of China. Our factory has developed several kinds of sealing packings. How to choose the sealing packing according to the medium filled in the steel drums? Generally, the following problems should be paid attention to when selecting the sealing packing:
(l) Corrosion resistance of the sealing packing and the internal medium. That is to ensure that the sealing packing is incompatible with the internal medium, does not corrode the steel drum and the internal medium, and maintains the chemical properties of the internal medium. Therefore, before using the sealing packing for the internal medium, the sealing packing selected should be used first. Resistance to medium performance test, test its corrosion resistance, soaking time is generally more than 30 days, Table 1 is the immersion test of several sealed packings in various internal media.
(2) Preparation of sealing packing. The sealing packing is generally composed of a base material, a filler, an auxiliary agent and a solvent. When preparing the sealing packing, firstly, according to the required sealing medium, the suitable base material should be selected, and then the filling material is added according to a certain ratio. The agent and solvent are used to prepare the sealing filler. For example, the purchased sealing packing should also check whether the quality meets the requirements of the coating process. For solid foaming fillers, the strips should be cut according to the requirements of sealing and sticking, and the sticking agent should be prepared. For liquid glue, if it needs to be sprayed, the required viscosity should be adjusted and measured to ensure the spraying quality.
(3) The coating process of the sealing packing. Before painting, if there is oil, rust, water or ash layer on the metal surface, it should be removed so that the sealing filler can be wetted or adhered to the surface, fully fill the surface of the depression, and firmly bond with the joint surface. Otherwise, it will affect the sealing effect. In the painting, there are different ways of painting according to the state of the sealing packing. For the solid foaming filler, after being cut at a suitable width, it is pasted on the joint between the barrel body and the top of the bucket and the bottom of the bucket. For the liquid sealing packing and the method of coating the glue, it can be selected according to the situation, and can be manually brushed by a brush. Glue can also be sprayed automatically with a spray gun. The thickness of the glue is matched with the bead. Generally, it is best to fill the gap with the sealing material after the crimping. It is too thin and too thick, too thin to achieve the sealing effect. It is too thick, not only for a long drying time, but also when the coated part is squeezed out, it is not only wasted, but also pollutes the equipment, shortens the life of the roller, and even affects the quality of the curling.
After the sealing packing is applied, it must have a certain drying time. Otherwise, when the unsealed sealing packing is curled, the sealing material will be pulled out of the barrel due to the weak adhesion, and the sealing ability will be lost. Therefore, In the gluing process, the drying time is very critical. Generally, the solid rubber strip is coated with a solvent when pasted, so that after the solvent is volatilized for half an hour after the sticking, the strip is firmly adhered to the sealed metal surface. At this point you can curl. If the liquid type sealing packing is used, it is generally required to be dry to non-stick after the glue is applied, and the crimping machine does not peel off the sealing packing, and then is crimped, the drying time and the type of the sealing packing used, the solvent and the thickness of the coating, The ambient temperature is related to humidity and the like. Generally, the liquid sealing filler has a longer drying time than the solid sealing filler, and the non-volatile solvent filler has a longer drying time than the volatile solvent filler.
Sealing packing has a certain storage period. If it is improperly stored or stored for too long, it will deteriorate and lose its effectiveness. Therefore, before use, the date and time of sealing packing, storage period and instruction manual must be checked.
