i just want your opinion about this one. vendor gave me this allowables:

Fx = 800N
Fy = 800N
Fz = 1000N
Mx = 800N-m
My = 800N-m
Mz = 1000N-m

line size is 6" and temp is 360 deg C.

This allowable loads are incredibly low!! What are your experiences about this? please share... thanks a lot!

I guess your moments are in Nm.

I checked your values without knowing shaft direction against 1x NEMA SM-23 and they come up about 75% of the allowable for an individual nozzle.

I do not agree that these are incredibly low, but certainly worth a discussion with the machine manufacturer. You might propose a factor of 1.5 for instance. It can be helpful to ask them to justify their limits, since they may be ancient history or arbitrary.

Depending on pressures, it's common to ask for 3x, 5x, or even 10x NEMA SM23 when purchasing the equipment.

I just finished a 2-stage CO2 compressor with a 20 NPS suction, 1500# discharge, and it was nearly impossible to get the loads down to 3x NEMA as specified by the equipment engineer. This one certainly should have been specified to 10X NEMA, as the resulting piping was not very practical and may have process issues with pressure drop and possible vibration due to the number of springs.

The higher the pressure, the thicker the pipe, and the higher you should go for nozzle loads.

ooops! sorry. moments are in N-m

anyway, according to the equipment engineer, i can only use 1X of the given allowable loads. and also the given nozzle displacements are:

x = 9.9 mm
y = -10 mm
z = 0.67 mm

(shaft direction is on the x-axis)

Paul,

I have also negotiated large NEMA factors with COMPRESSOR manufaturers, but not with STEAM TURBINE builders. There is really no comparison. I assumed from the question that this referenced a steam turbine.

Cheers.

actually, its a turbine driven compressor.

Good point MoverZ, I've only done one steam turbine (it was a turbo expander). We needed pressure balanced bellows to get that one to work with 1x NEMA.