Punching head is a part of the container, depending on the geometry spherical, oval dish of spherical, conical shell peace covers, etc., can be divided into several, including spherical, oval dish, spherical cap type The head also collectively referred to as a convex head. Applied to a variety of container equipment, such as tanks, heat exchangers, towers, reaction vessels, boilers and separation equipment, etc.. The thickness of the GB150-1998 standard definition (1) calculate the thickness δ is the thickness of each chapter formula. When required, shall also be included in other load to the desired thickness. (2) design thickness δd the calculated thickness δ and corrosion allowance C1 and. (3) nominal thickness δn The design thickness δd plus the thickness of the steel negative deviation C1 rounded upward to the thickness of the steel standard specifications. That label in the pattern on the thickness. (4) the effective thickness δe nominal thickness δn minus corrosion allowance the C2 and steel thickness to the thickness of the negative deviation of C1 (5) As the relationship of various thickness (6) feeding thickness (ie blank thickness) according to GB150 --- 1998 the first 10 chapters of various thickness diagram: δs = δ + C1 + C2 + Δ1 (thickness of the first design rounded value) + C3 (amount of machining thinning) + (the thickness of the second manufacturing rounded value) 

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