The advantages and disadvantages of flanged telescopic butterfly valve:
 
The flange telescopic butterfly valve (the structure length can be retracted within a certain range) not only facilitates the disassembly and assembly of the valve, but also relieves the pipeline stress and protects the valve. At the same time, it also concentrates the installation mode of butterfly valve with telescopic device, making the space more compact.Under normal circumstances, such valves do not need special maintenance, and only need to regularly observe whether the expansion part has leakage, pull off and other phenomenons.The initial cost of the flange telescopic butterfly valve is lower than that of the flange butterfly valve with the telescopic device, but considering the maintenance cost in the future,the loss outweighs the gain.
 
If the sealing part of the butterfly valve is damaged and the sealing ring cannot be replaced, and the butterfly valve needs to be scrapped, the expansion part shall be scrapped together, so that the loss is large.If the sealing part of the butterfly valve needs maintenance, the valve can not be repaired online maintenance without disassembly only by compressing the expansion part,the installation method of butterfly valve with telescopic device has great advantages，it is only necessary to remove the telescopic device, so there is manual maintenance space to realize the valve's maintenance without disassembly（The butterfly valve is heavy, the telescopic device is light, and the labor intensity for disassembling the extender is low）.
 
Notes for installation of flanged telescopic butterfly valve：
 
1.It is strictly prohibited to disassemble the flanged telescopic butterfly valve at the pipeline construction site；It is strictly forbidden to stretch or shorten the telescopic butterfly valve repeatedly on site.
 
2.It is required that the pipelines at both ends of the expansion valve must be concentric, and the two flange surfaces on the pipeline must be parallel.
 
3.The flange fixing bolts should be tightened symmetrically. Do not force the flange fixing bolts to be tightened unilaterally.
 
4.The expansion tube is installed behind the valve.
 
5.The expansion part of the expansion valve shall not be installed at the corner or end of the pipe.
 
6.The expansion flange butterfly valve must be laid flat before installation, and shall not be bumped at wil.
 
7.The structural length of the expansion flange butterfly valve is the minimum length when it leaves the factory. When it is installed, it shall be pulled to the installation length (that is,the design length).
 
8.When the length between pipes exceeds the installation length of the telescopic butterfly valve, please adjust the pipe spacing. Do not pull the telescopic valve forcibly to avoid damaging the expansion valve.
 
9.Expansion flange butterfly valve can be installed at any position,for temperature compensation, support shall be added at both ends along the axis of the pipe after the installation of the pipe to prevent the expansion pipe of the expansion valve from pulling out,it is strictly prohibited to remove the support during operation.
 
10.When the expansion flange butterfly valve is not used for temperature compensation but only for installation, replacement and maintenance of the valve, it can be limited by bolts，symmetrically clamp the expansion flange butterfly valve to prevent the expansion pipe from pulling out and damaging the expansion butterfly valve, pipeline devices or buildings.The bolt diameter can be in accordance with the flange bolt diameter, and it is strictly prohibited to remove the bolts during operation (bolts are additionally equipped).