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1.End cover usage
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¡ñEnd cover is an essential component used in pressure vessels of petroleum chemical, atomic energy, food, pharmacy, etc industry.
¡ñ End cover is used on pressure vessels. It is the main pressure-bearing component.
¡ñ 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.
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P r essure vessels are used in chemical plants
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P r essure vessels are used in LPG station
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| 2. Importance of end cover quality |
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| 3. Importance of end cover shape
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National standard GB150 the relationship between end cover shape and requisite plate thickness
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Section Shape of End Cover
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Curvature in center of end cover
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Designed requisite plate thickness of end cover
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Designed end cover plate thickness at 20mm drum plate thickness
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Semi-sphere(HH) |
R=D¡Á0.5 |
thickness of drum plate ¡Á1/2 |
10mm |
2:1 oval(EH) |
R=D¡Á0.9(approximate) |
the same thickness as that of drum plate |
20mm |
10 £¥ sourcerization end cover(DHB) |
R=D |
thickness of drum plate¡Á1.54 |
31mm |
Flat cover(flat plate) |
R= unlimited |
thickness of drum plate¡Á8 |
160mm |
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| 4.
Requirements of end cover shape |
JB/T4746 end cover standard specifies:
¡ñ End cover shall be checked by full size sample plate.
¡ñ Shape tolerance: O utside convex ¡Ü 1.25%Di; Inside concave ¡Ü 0.625%Di.
¡ñ Inside radius in transient section shall not be less than the drawing specification.
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¡ñ Spherical surface: curvature affects end cover thickness.
¡ñ Transient section: decrease the peak bonding stress between spherical surface and drum.
¡ñ Straight edge: avoid composition of transient section peak stress and drum assembly welding stress. |
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| 5.Fabricating methods of end cover
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Type
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Fabricating Method
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Fabricating Range of Beihai End Cover
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Cold fabricating |
Cold stamping |
Thickness:2 ¡« 24mm; Diameter:¦µ 108 ¡« ¦µ 3200mm |
Cold spinning |
Thickness: ¡« 24mm; Diameter:¦µ 750 ¡« ¦µ 8800mm |
Separation method |
Thickness: ¡« 32mm £» |
Expansion method |
Beihai End Cover plan is in process. |
Hot fabricating |
Hot stamping |
Thickness: ¡« 250mm; Diameter: ¡« ¦µ 3200mm |
Hot spinning |
Thickness: ¡« 80mm; Diameter:¦µ 1700 ¡« ¦µ 4200mm |
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| 6. Cold Fabricating vs. Hot Fabrication
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Cold Fabricating Characteristic
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Hot Fabricating Characteristic
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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.
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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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