Double seal design of welded bellows if the bellows fails, the stem packing will also avoid leakage, It also conforms to the international sealing standards; there is no fluid loss, reduces energy loss, and improves the safety of plant equipment; it has long service life, reduces maintenance times, and reduces operating costs; the solid and durable bellows seal design ensures zero leakage of the valve rod and provides maintenance free conditions; the welded bellows gas medium valve seat adopts PTFE soft sealing material to improve the sealing performance of the valve; it has high resistance The valve seat with temperature ≤ 425 ℃ is hard sealed with conical surface.
Welded bellow is a kind of metal tube which is made of many thin hollow diaphragms formed by stamping and made by precise welding. Its composition is that two formed hollow diaphragms are welded to form a pair of diaphragms by concentric circles, and then multiple diaphragms are welded together to form a corrugated section by outer edges, and then both ends and end plates are welded together Forming a bellows group, so that it can reciprocate with other moving parts according to external needs.
With the development of science and technology, the application field of welded bellows is expanding day by day. The main purpose of welded bellows is: as the detection element of control mechanism, transmitter or regulator, it can also be used as the measurement element of temperature, pressure and liquid level, as well as various sealing and energy transmission elements.
In addition to being used as measuring elements, welded bellows can also be used as sealing, connecting, compensating and isolating elements, which are widely used in many fields.
1. Instrument industry
Welded bellows are mainly used as pressure measuring elements in measuring and control instruments, which can be used instead of capsule strings. Welded bellows can also be used as volume compensation element in gyroscope, seal isolation element in regulating valve, flexible coupling, pressure switch, etc.
Welded bellows are also used in aerospace. In addition to some instruments used in aircraft, welded bellows are also used in parachute automatic release pressure regulator. In addition, the utility model can also be used as a shaft seal door on a rocket engine.
3. Electronics and other industries
Welded bellows are also used in electronic devices. For example, micro welded bellows with outer diameter of 10 mm, inner diameter of 5 mm and wall thickness of 0.05 mm are used in the klystron of satellite communication ground station. It is also used as a vacuum seal, axial connector, expansion joint, oil reservoir, accumulator and other aspects of attention by various departments.
At present, saw tooth wave expander widely used in electric power industry is also a typical application example of welded bellows. The welded bellows actually play the role of volume compensation here. The working coils of voltage transformer and current transformer are all immersed in the insulated oil tank. With the change of the ambient temperature and working current, the temperature of the insulating oil changes greatly. Therefore, in a totally closed system, the volume change caused by the expansion and contraction of insulating oil must be compensated.
Welded bellows is a new type of component rising at home and abroad in recent years. Welded bellows can be used as sensitive component, sealing component, isolation medium, pipeline connection and temperature compensator. In addition to the advantages of pressure resistance, temperature resistance, corrosion resistance and good sealing, the welded bellows has two outstanding advantages over the traditional formed bellows: large deformation and long service life.
The selection of welding bellows material is very strict, in addition to the requirements of high temperature and corrosion resistance, the bellows are also required to have sufficient rigidity. The welding technologies used or under development include tungsten inert gas welding, micro plasma welding, power beam welding and laser welding, among which micro plasma welding and laser welding are commonly used.