Flexible Metal Hose - Reciprocating Compressor

[FrancoBr]

Hello guys!
Recently I specified a flexible metal hose for N2 service that is conected a reciprocating compresor nozzle.

Operation condition:
Pressure: 440 psig
Temperature: 40°C

When I bought it a more experience engineer, said that we have a standard that said that is not recomended use flexible hose in nozzle compressor. For theses cases we have specify a expansion joint.

When I ask him, why I shouldn't connect the FMH in the nozzle. he explained about fadigue caused for the movement of piston in the compressor.
I can't see any problem about that.

My friends, could you explain me, if have any problem install the flexible metal hose in the reciprocating compressor nozzle, or any standard talking about it?

Below follow the link of the FMH

http://www.sptf.com.br/produto/cond...aco-inoxidavel-inoflex-passo-fechado-isf.html

Many Thanks

 

[BigInch]

Gas discharge pulsation and vibration and a pressurization cycle of the hose during each revolution.

Independent events are seldomly independent.

 

[MikeHalloran]

The problem is not that the piston reciprocates, but that it has mass _and_ it reciprocates.
The reaction forces necessary to propel that reciprocating mass cause the compressor itself to move around, even it it's "rididly" mounted, which is not usually the case.

So the flexible metal hose is connected to a compressor nozzle that's vibrating whenever the compressor runs, and the building piping system, which we hope doesn't move around much. In addition to that vibration, as BigInch points out, the pressure inside the FMH changes with every stroke of the piston.

FMHs are not known for having particularly good fatigue resistance, and it's easy to make things worse at installation.





Mike Halloran
Pembroke Pines, FL, USA