The design pressure of the ventilation pipe wall bushing is greater than 1.6MPa for the casing with gas medium, 2.5MPa for the casing with liquid medium, and the casing with flammable, explosive or toxic medium above medium hazard. The ventilation pipe wall bushing shall perform dye penetrant inspection or radiographic inspection on the inner surface of the outer surface of the weld that can be used for flaw detection. The wall bushing of ventilation pipe shall be used for the casing of gas medium with design pressure greater than 0.1MPa but less than or equal to 1.6MPa, and the wall bushing of ventilation pipe with design pressure greater than 0.1MPa but less than or equal to 2.5MPa and used for liquid medium.
For each batch of longitudinal welds with the same material and thickness, at least 10% of the samples shall be subject to dye penetrant inspection or radiographic inspection, and at least one weld shall be sampled. The stain damage is only applicable to the single weld with the thickness of tube blank not more than 2mm. The acceptance criteria are: no linear indications such as cracks, four or more rows of dense circular indications with edge distance less than 1.5mm, five or more random scattered circular indications with diameter greater than 1/2 of the tube blank thickness within any 150mm weld length. There are usually two types of wall bushing used for ventilation duct, one is machined and the other is wall bushing for ventilation duct.
The overall height of the wall bushing of the ventilation pipe is relatively low, but its service life may be limited due to its manufacturing method and inherent structural defects; Compared with the overall height, the machined wall bushing of the ventilation pipe has higher reliability and longer service life. The large corrugated casing used for the connection of pipe network system is required to have a pressure of 4MPa, a temperature resistance of 400 ℃, and a certain corrosion resistance stability. The temperature adaptability of the wall bushing of the ventilation pipe depends on the temperature resistance of the elastic material used.
Therefore, according to the use temperature range of the wall bushing of the ventilation pipe, select the elastic materials with appropriate temperature performance parameters to process and manufacture qualified components of the wall bushing of the ventilation pipe. Due to different working conditions, the mode of component damage or failure is different. The elastic element of the instrument works within the elastic range, and is basically in a static state. It has a long service life, usually tens of thousands to hundreds of thousands of times.