There are two kinds of galvanizing: hot-dip galvanizing (hot-dip galvanizing) and cold galvanizing (electro galvanizing). The hot-dip galvanizing layer is thick and has the advantages of uniform coating, strong adhesion and long service life. The cost of electro galvanizing is low, the surface is not very smooth, and its corrosion resistance is much different from that of hot-dip galvanized pipe. How to check the quality of galvanized pipe?
According to the standard requirements, the galvanized pipe factory points out that the geometric dimension inspection of galvanized square pipe mainly includes the wall thickness, outer diameter, length, curvature, Ovality and end face shape of galvanized square pipe.
1. Wall thickness inspection
The main tool used for wall thickness inspection is micrometer. During inspection, measure the wall thickness of galvanized square pipe one by one with a micrometer. Before inspection, first verify whether the certificate of the micrometer is within the validity period, check whether the micrometer is aligned with the zero position, whether the rotation is flexible, and the measuring surface shall be free of scratches and rust spots. It can be used only after it is qualified. During the inspection, hold the micrometer support with the left hand and rotate the exciter with the right hand. The screw rod shall coincide with the diameter of the measuring point. The end face measurement shall not be less than 6 points. If the wall thickness is found to be unqualified, it shall be marked.
2. Outer diameter and ovality inspection
Calipers and vernier calipers are mainly used to check the outer diameter and ovality. During inspection, measure the outer diameter of galvanized square pipe one by one with qualified caliper. Before inspection, first verify whether the quality certificate of caliper is within the validity period, and calibrate the caliper used with vernier caliper to check whether there are scratches and rust spots on the measuring surface. It can be used only after it is qualified. During inspection, the caliper shall be perpendicular to the axis of the galvanized square pipe, and the galvanized square pipe shall rotate slowly. Measure the maximum and minimum points of the section. If it is found that the outer diameter is too large or too small, it shall be marked.
The tool used to check the length of galvanized square pipe is mainly steel tape. When measuring the length, align the "O" point of the tape with one end of the galvanized square pipe, and then tighten the tape to make one side of the scale close to the surface of the galvanized square pipe. The length of the tape at the other end of the galvanized square pipe is the length of the galvanized square pipe.
4. Bending inspection of galvanized square pipe
The curvature inspection of galvanized square pipe is mainly to inspect the total length curvature and curvature per meter of galvanized square pipe, and the tools used are mainly level gauge, feeler gauge and fishing line. When measuring the total curvature of the galvanized square pipe, align the fishing line with one end of the galvanized square pipe, then tighten the fishing line so that one side of the fishing line is close to the surface of the galvanized square pipe, and then use a feeler gauge to measure the spacing at the maximum gap between the surface of the galvanized square pipe and the fishing line. The measured maximum spacing is the total length curvature of the galvanized square pipe.
What is the universality of the application of [cold rolled sheet]
Cold rolled sheet is cold rolled with hot rolled coil as raw material at room temperature. It is not heated during production and processing, so its great advantage is that there are no pitting and scale defects in the hot rolling process. Its great advantage lies in its good surface quality and high finish, so it is widely welcomed by the market and praised by customers.
Cold rolled sheet has been widely used in automobile, iron barrel printing, construction, cutting, bicycle and other industries because of its good performance. In addition, because of its good durability, its service life is longer than that of galvanized steel plate, so it has many varieties and uses. However, its good thermal reflectivity, silvery white gorgeous surface, processing properties and spraying properties similar to galvanized steel plate also make cold rolled steel plate a good choice for the production of organic coated steel.
[galvanized sheet roll] who is better than stainless steel
As the name suggests, the galvanized sheet roll is an iron plate coated with 80-120 grams of zinc, with snowflake patterns on it. Stainless steel sheet is whiter than galvanized sheet and softer than galvanized sheet. Galvanizing is mainly for beauty and non rusting. The primary property of stainless steel is rust.
Galvanized sheet roll is to brush a layer of metal zinc on the iron sheet for corrosion prevention, including cold plating and hot plating. In short, the zinc on the surface will fall off and the iron will be corroded for a long time. Stainless steel does not require corrosion protection. Of course, the price is very expensive. For some special materials, stainless steel will be tempered at 200-300 ℃, but the temperature is too low. Generally, the zinc on the surface of galvanized sheet coil will be slowly baked off at high temperature (200-300 ℃). There are many kinds of stainless steel. Galvanized steel coil shall be galvanized only once on the surface of steel plate or iron plate. The galvanized steel coil itself is an ordinary steel plate, which only goes through surface treatment. Stainless steel plate is acid resistant alloy plate. According to your purpose, 200-300 degrees is not a high temperature. The price of relatively cheap stainless steel 430 plate should be twice that of galvanized plate of the same specification.
Stainless steel can change the steel composition by adding trace elements and achieve the anti-corrosion function. Galvanized sheet is rolled on the surface of ordinary steel plate for galvanizing, so as to achieve the purpose of anti-corrosion by sacrificing zinc. 200 degrees and 300 degrees are not a problem for metals. Depending on the environment, there will be some very small effects, but it will take a long time to change.
