Steam Turbine Driven Pump Piping

[Doiscond]

Hello All,

I am looking at some steam turbine-driven pumps in a paper mill/recovery boiler feedwater application and have a few questions about the inlet and outlet piping.

The original system from the 60s/70s had spring cans on both sides and a whole host of supports that had been modified/replaced/removed over the years. They have frequent bearing failures and want to redo the system. Stress analysis is being performed, and one option that has been suggested is to put expansion joints on both the inlet and outlet sides of the turbines. I have seen in past posts, (

https://www.eng-tips.com/viewthread.cfm?qid=168615),

where this has been discussed, but wanted to check in again and see if anything has changed since 2006 with turbine piping layouts. I have seen some vendors offering expansion joints that are rated well over that pressure, but it'd be a new application to me personally.

I anticipated having spring cans on the inlet side and an expansion joint/spring cans on the low-pressure outlet side, but didn't expect to see joints on both as a solution. The steam turbine OEM nozzle allowables are also difficult to meet, but that's something to be solved through stress analysis.

Has anyone here seen 475 psig or higher steam turbine inlet side expansion joints?
Are there any additional resources/guidance for this type of design that others would be willing to share?

Thanks!

 

[EngrPaper]

Turbine allowables are notoriously difficult to meet due to the combination of rotating equipment and hot piping. If it's at all possible to avoid using an expansion joint, it is better to if only because expansion joints are a maintenance item and require much more careful installation. If the stress engineers can find a routing with springs that would work without a joint, more power to them, but sometimes it's just necessary to use an expansion joint.

More specific to you, 475 psig is not that high and you'll be able to find reputable joint manufacturers who make those all the time. Just make sure that design conditions, displacements, required cycles, etc. are clearly communicated and the vendors are usually able to put together a datasheet for purchase in a couple of days.

 

[LittleInch]

abot,

Too much is detail design of your system to be able to supply anything more than general guidance.

Expansion joints are feasible, but need to be located right and that depends hugely on your layout, the flexibility of the system and whare the piping stops, guides and rests are as well as what temp you're running at and allowable nozzle loads.

You need a good piping designer / stress analyst to come up with options and then choose the one right for you. There are also many different types of expansion joints - many need to be constrained to work properly or to work within certain limits or angular only etc.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Doiscond]

Thanks for the feedback, it's good to know that it's an option. Hopefully, we can make the layout work without them and save some money/maintenance on the system.

 

[1503-44]

Can you post an iso of that line?

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."