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The quality standard and usage method of the size head

Release Time:

2020-12-01

The corresponding standards of flanges and tube plates for the large and small electric power department standard GD0506~0507 pressure vessel: JB/T4700~4707-2000 implement the national standard (GB/T9112-2000), the Ministry of Machinery standard (JB/T81-1959, JB /T74-1994), Ministry of Petrochemical Standards (SH3406-1996), Ministry of Chemical Industry Standards (HG/T5010-1958, HG/T20592-2009) and so on. The material of the exported forged steel flange conforms to the American ASTM A105 standard.

The corresponding standards of flanges and tube plates for the large and small electric power department standard GD0506~0507 pressure vessel: JB/T4700~4707-2000 implement the national standard (GB/T9112-2000), the Ministry of Machinery standard (JB/T81-1959, JB /T74-1994), Ministry of Petrochemical Standards (SH3406-1996), Ministry of Chemical Industry Standards (HG/T5010-1958, HG/T20592-2009) and so on. The material of the exported forged steel flange conforms to the American ASTM A105 standard.
The quality of the eccentric reducer shall meet the current national standards, and the allowable deviation of the size of the head and head shall meet the requirements of Table 4.2.2-3. The roundness of the small and small heads should not be greater than 1% of the outer diameter of the corresponding end. The eccentric reducer should not have cracks or heavy skins. The wall thickness should be greater than the wall thickness of the large-diameter end pipe section, and the allowable deviation is ±3mm; concentric different The center lines at both ends of the diameter pipe should coincide, and the allowable deviation of the eccentricity value is ±5mm.
Use of size head:
When the pipe diameter itself is not large and the difference between the front and rear pipe diameters is not large, the concentric reducer may be used, and the air resistance may not be so obvious. The air pressure of the self-priming type does not change so much during the water absorption process, so the harm is not reflected.
When water is absorbed, the water pressure of the suction pipe section decreases, and the gas originally dissolved in the water will separate out. If a concentric reducer is used, these gases cannot be discharged in time, and they will accumulate and block the protrusions and form air resistance. The water pump will also be noisy and the water delivery capacity will be greatly reduced. If an eccentric reducer is used, the separated gas will be discharged in time and no air resistance will be formed.

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