steam turbine distorted diaphragms

[GoodOleRebel]

Has anyone out there any experience with repair of distorted (dished) diaphragms? I am trying to evaluate bids from the OEM (GE) and from TurboCare and MD&A. Based on the big difference I see in pricing from the low bidder I am concerned that they are not offering the same repair method. This is a 1968 vintage GE Lynn turbine (155 MW) reheat, double flow exhaust. One of the largest made in Lynn, MA. Any help is appreciated and I can provide more detail on the work scope if I get a response. Thanks.

 

[MikeHalloran]

If you accept the low bid, you are the legitimate prey of the low bidder.



Mike Halloran
Pembroke Pines, FL, USA

 

[byrdj]

I would think you would want to get an itemized discription of what each is bidding.

for example,
is there any partition repair included...major weld build up requiring stress relief or just dressing trailing edges

then the method for dish correction, whether jig forced while in stress oven or rosebud and hammer.

 

[rmw]

I'd be very careful here and make each of them justify their bid and demonstrate their ability to repair a Lynn machine. It isn't like there are a lot of them being built anymore with a lot of expertise lurking around.

Ask for a reference list of similar Lynn machines that they have done - not Schenectady machines, Lynn machines. I was trained on both types many years ago, and they did the same thing different ways sometimes.

While the latter two bidders have lots of experience in that type of work - probably much more on Schenectady machines than Lynn models, GE at least does somewhere have the original Lynn drawings. I suspect that they are the high price and that is because they have the brand name to protect.

And, yes, that is big for a Lynn machine.

rmw

 

[GoodOleRebel]

Thanks for the responses. As suspected, the low bidder was not the same repair method. (I always review low bids very carefully and look for differences in workscope). They were proposing a cold straightening while the diaph. was held to a strong back and then stress relieving it in an oven. This is a method we had unsuccessfully tried about 10 years ago and it does not work for the amount of dishing we have. They alway tend to "spring back" and still have some amount of distortion. We were looking for a best repair which means cutting out the web and installing a new one or removing the weld on the inner and outer rings, straightening the diaph. then rewelding and stress relieving. We have reviewed the workscope with all 3 vendors and their revised response along with their pricing is much more in line.

 

[byrdj]

Thanks for the reply back

 

[rmw]

The more things change the more they stay the same.

rmw