Bellows seals are often used when the medium is poisonous, volatile, radioactive, or because it is extremely expensive and is not allowed to be brought out by reciprocating stem valves. Bellows seal valve is a valve used to control the size of the flow. The use of bellows seal design, completely eliminate the ordinary valve STEM filler seal aging fast and easy to leak shortcomings, not only improve the use of energy efficiency, increase production equipment safety, reduce maintenance costs and frequent maintenance, but also provide a clean and safe working environment. This special bonnet structure protects stem and valve fillers, avoids contact with process fluids, and uses standard or environmentally-friendly packing letter structures on bellows seals to avoid catastrophic consequences in the event of a bellows rupture failure.

Therefore, should pay attention to observe valve stem packing at ordinary times whether outside leakage, if filler seepage, bellows valve may have a problem.

I. CORRUGATED PIPE STRUCTURE form The bellows used for regulating valves usually have two kinds, one is machined forming, the other is welded sheet type bellows.

Welded sheet Bellows Overall height is relatively low, but because of its manufacturing methods and internal structural defects, the service life may be limited, mechanical processing formed bellows compared to the overall height, but higher reliability, longer life.

Second, the application should pay attention to the problem

Bellows seal pressure ratings with the increase in temperature, the bellows seal form should be carefully considered, after installation should pay special attention to the correct use and maintenance, in order to achieve the longest cycle operation life.

Iii. Typical Corrugated pipe products

The direct travel valve body structure is equipped with a bellows seal on the bonnet and the corresponding factors can be used to become bellows sealing valve.

(1) Bellows sealed small caliber single seat control valve

Valve body parts using HV3000 series of small-caliber single seat control valve, is a high-performance upper-oriented structural control valve, CV value range of 0.01~1.4, in addition to the overall height of a slight increase in weight, other body data are basically the same.

(2) Bellows sealed single seat control valve

Valve body parts using HV3000 series single seat control Valve, is a kind of upper-oriented structure control valve, dn:40~200, in addition to the overall height, the weight slightly increased, other body data are basically the same.

(3) Bellows sealed cage-type two-seater control valve

The valve body part adopts the HV3000 series cage two-seater control valve, is one kind of pressure balanced type control valve, dn:40~200, in addition to the overall height, the weight slightly enhances, other valve body data basically is consistent.

Iv. Alternative economic options For wet chlorine (to solve corrosion problems) and other requirements are not particularly high occasions, can be used "rotary valve + multistage filler" approach to solve. For example, the use of multi-level flexible graphite filler full-function ultra light control valve.