Hi,
First of all I’m not good writing in English but I do it because I need help. I’m doing an impossible stress analysis. I have a turbine (27 MW) with two inlets (diameter 10 in), the operation conditions are 65 Bar and 505 °C. I’ve tried whit many pipes distribution, different supports… but nothing, the forces and moments are exceeded conform NEMA SM23.
I need to know your knowledge about pipes distribution in that kind of turbines whit two inlets in that conditions.

Thanks,
Katherine
Katherine_ospina@yahoo.com

I can't say that I've ever worked on a turbine that hot, big and high pressure. In general, getting a turbine to pass NEMA SM-23 is always a challenge, especially at high temperature. SM-23 doesn't care what the steam conditions are, only what the nozzle sizes are. As you are well aware, high pressure and high temperature means much more expansion combined with heavier wall pipe that is much stiffer.

You are going to expect a lot of spring supports and big loops. You will probably also need to make judicious use of struts connected to large blocks of reinforced concrete to give you effective restraints. Caesar defaults to a 1e12 stiffness for anchors and restraints, which you're really not going to get with a typical steel beam. Often, if we're just looking for an anchor for a loop in a pipe rack, the stiffness isn't so critical. In your case, with very stiff heavy wall pipe, you are going to need anchor points that are built very stout to give minimal deflection under load.

Finally, because your turbine is a pretty extreme design, you will want to work closely with your rotating equipment engineer and the turbine vendor to see if they can give you a multiplier on your allowables. Rotating equipment allowables are typically driven by the need to minimize deflection of the rotating shaft. Because the turbine is going to need a heavy shell to handle the pressure, it may be able to take more external load than SM-23 indicates without having deflection problems for the shaft. It's certainly worth checking into with the vendor.

katherine,

For equipment nozzle allowables we only use the equipment codes (i.e. NEMA, API, ANSI, etc.) as reference when we don't have the vendor data.

Specifically for critical piping attaching to critical equipments we need to obtain this values from the equipment vendors. For your case, you have a high temperature (941F) and pressure (945psi) values which could have high nozzle allowables from vendor because the higher the pressure a probable stronger equipment design could have been made. NEMA, API, etc. are the minimum requirements for such equipments thus giving the vendor the right to design equipments with higher nozzle allowables compared to the code standards.

Goodluck!

If your 505 deg C is a design temperature you may well be able to use normal operating temperature to get the loads to pass.

be prepared as the others have said...

If your a rookie it may prove to be beyond your skill level!

For equipment loads (but NOT stresses), you can use the hot Young's modulus value in your calculation. That ought to get the nozzle loads down quite significantly at 505 deg C.

If you need to meet NEMA turbine nozzle loads then don't forget you also need to check the outlet nozzle loads and the combined inlet and outlet nozzle loads as well.