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Head of common sense

1.End cover usage

Pressure vessels are used in chemical plants
Pressure vessels are used in LPG station
   ●End cover is an essential component used in pressure vessels of petroleum chemical, atomic energy, food, pharmacy, etc industry. ●End cover is used on pressure vessels. It is the main pressure-bearing component. ● End cover quality is essential to long, safe and reliable operation of pressure vessels. Pressure vessels are used in LPG station. Pressure vessels are used in chemical plants.
2. Importance of end cover quality
3. Importance of end cover shape
National standard GB150 the relationship between end cover shape and requisite plate thickness
Section Shape of End Cover
Curvature in center of end cover
Designed requisite plate thickness of end cover
Designed end cover plate thickness at 20mm drum plate thickness
Semi-sphere(HH)
R=D×0.5
thickness of drum plate ×1/2
10mm
2:1 oval(EH)
R=D×0.9（近似値）
the same thickness as that of drum plate
20mm
10 ％ sourcerization end cover(DHB)
R=D
thickness of drum plate×1.54
31mm
Flat cover(flat plate)
R= 无限大
thickness of drum plate×8
160mm
4. Requirements of end cover shape
●Spherical surface: curvature affects end cover thickness. ●Transient section: decrease the peak bonding stress between spherical surface and drum. ●Straight edge: avoid composition of transient section peak stress and drum assembly welding stress. JB/T4746 end cover standard specifies: ●End cover shall be checked by full size sample plate. ●Shape tolerance: Outside convex ≤ 1.25%Di; Inside concave ≤ 0.625%Di. ●Inside radius in transient section shall not be less than the drawing specification.
5.Fabricating methods of end cover
Type
Fabricating Method
Fabricating Range of Beihai End Cover
Cold fabricating
Cold stamping
Thickness:2 ～ 24mm; Diameter 108 ～ Φ 3200mm
Cold spinning
Thickness: ～ 24mm; Diameter 750 ～ Φ 8800mm
Separation method
Thickness: ～ 32mm ；
Expansion method
Beihai End Cover plan is in process.
Hot fabricating
Hot stamping
Thickness: ～ 250mm; Diameter: ～ Φ 3200mm
Hot spinning
Thickness: ～ 80mm; Diameter 1700 ～ Φ 4200mm
6. Cold Fabricating vs. Hot Fabrication
Cold Fabricating Characteristic
Hot Fabricating Characteristic
1 Because of no heating, materials do not deteriorate. It is suitable for fabricating stainless steel end cover.
 Because of heating, materials deteriorate. Corrosion resistance of stainless steel end cover becomes poor. It is not suitable for fabricating of stainless steel end cover.
2 Without heating, there is no contraction due to no cooling. The dimensions will not change. The shape keeps well. The precision and consistence of the dimension are good.
 Because of heating forming, the heated die expands. End cover becomes cold and contracts. Their dimensions are hard to control. The consistence is poor.
3 Without heating, end cover surface keeps smooth and looks nice.
 With heating, lots of oxide scale forms on end cover surface. It is hard to remove.
4 Fuel is not needed. Limited energy consumption.
 Fuel is needed. Large energy consumption.
5 Without heating, there is no harmful gas and smog. Environmental pollution and the earth warming can be avoided. It conforms to China 's policy.
 With heating, lots of harmful gas generates, pollutes the environment and results in public nuisance. It violates China 's policy.
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