erw steel pipe leakage defects introduced by galvanized steel

　　Galvanized steel sheet refers to a layer of zinc plated steel . Zinc is a frequently used method for economical and effective antiseptic , about half of the world production of zinc are used for such processes.

　　In general, to reduce costs and increase the strength of steel , often add to the high silicon steel base in . Excessive addition of silicon increases surface tension , reduce wetting liquid steel capacity of zinc , plated to increase the likelihood of leakage . Furthermore, it is readily oxidized to form SiO2, are not easily removed in the acid , thus easy to form defects in the SiO2 breakout gathering region .

　　To solve this problem , the use of non- continuous pickling hot-rolled steel hot dip galvanizing process . Pickling hot-rolled steel without directly into the reduction furnace and steel in the reduction furnace temperature was raised to 650-750 ℃, holding time increased to 120-400s. Protection of H2 gas volume fraction increased to more than 20%. At this time , since the volume of the hot-rolled strip of expanded scale cracks and voids , H2 can enter through these cracks and voids , so that it becomes a porous oxide layer is composed of the pure Fe and FeO . When hot-dip galvanizing , the surface forming Fe-Al-Zn alloy layer to improve the adhesion of the coating to eliminate the leakage defects in the steel .

　　. Generally , the thicker the galvanized erw steel pipes allow larger errors , rather than a fixed 0.02-0.04 mm , also depending on the thickness deviation yield , tensile coefficient , etc. have different requirements , usually in the deviation width 5mm, the plate the thickness is generally between 0.4-3.2 .

　　Hebei shengtian pipe-fitting group Co., ltd is specialized in manufacturing and exporting forged flanges and buttwelded pipe fittings. In additation to the standard products mentioned above, we are also able to make non-standard, special-designed items according to customers’ requirement. Should any of the items be of your interests, please do not hesitate to contact us for latest information.