Question on Steam powered turbine piping

[littlechappy]

The company I work for was allowing the supervisors to start their turbines with out the proper license. When it was brought to their attention, the decreased the size of the inlet pipe going to the trubine too decrease the amount of horsepower so that anyone could start them. Here are my questions:

1) Is this legal? How can you take a 5" pipe or better and just before the turbine, make it to 1 3/8? This change has made the turbine scream out of control.
2) Is this safe?

I wish I could be more clear about this, but I am only a high school grad. I have to work near by these turbines, and the screaming seems to go right through my hearing protection. I do not wish to cause this company trouble, but I do wish to have a safe place to work. The company has said it to be nothing more than a nucense.
If you need more imformation before you can help me, please tell me what you need. I have the help of a firman who works in the boiler room. With your questions, maybe I can find the imformation you need...
Again, I am not out to harm the company.. I only wish to have a safe place to work.

Thank you for any help

LittleChappy

 

[davefitz]

Changing the pipe size from 5" to 1 3/8" reduced the inlet area by a factor of 13, so if the initial velocity was 130 fps. the modified velocity is 1700 fps, or equal to a mach number of 1 for low temperature steam.

Extreme noise can occur anytime the velocity exceeds about 45% of soundspeed, so I guess the noise is from the choked flow thru the 1 3/8" pipe. The lower turbine output an lower plant cycle efficiency is probably costing a lot of money as well.

A better solution is to have the operator obtain a license, and restore the pipe to 5" .

If you cannot get the license, then replace the 5 by 1 3/8" reducer with a series of orifices which has the effect of frictionally choking the flow while not casuing the max velocity from exceeding 45% soundspeed. This implies the smallest hole in the orifices would be at least 2.25" .

 

[OILnGAS]

noise could damage your health for sure.
But for the turbine is still safe no matter it the flow is choked or not. If the flow is choked the pressure on the upstream is higher, and also the horsepower is becoming less.