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Why a $14 M aero engine rust after all detailed analysis study and design done ?

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rQuestionEngineering

rQuestionEngineering

Mechanical
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Why a $14 M engine rust after all detailed analysis study and design done ?

There are heaps of API and NACE standards apply on it . Correct ?

image_2022-06-18_082845817_mfqgrp.png
 
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Improper layup. Preservation of machinery is laborious and expensive. If this was a test engine it's not certified and not worth preserving.

Your 3rd picture shows serious damage to the engine. Why preserve broken machines?
 
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The photos show high temperature deterioration; from service temperatures. Gas turbines are primarily alloys which will not oxidize at ambient temperatures. The lowest alloy is likely 13 % chrome blades in the compressor . 13 % chrome can rust but is resistant ; for example most modern auto exhaust pipe are 13 chrome and perform well.
 
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The point is a $14M highly engineered product should not rust.

An automotive exhaust is a cheap product, and it is expected to rust and be replaced easily.
 
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You said this was a test engine. It appears to have been operated outside of it's design parameters based on the melting of the blades in the 3rd picture. If operated within design this engine wouldn't be so rusty.
 
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I have seen brand new turbines destroyed by improper exposure and storage.
13% Cr is barely stainless when it is unoxidized and clean.
So do you know that this turbine was cleaned, laid up and stored according to recommendations?
These are precision machines and need to be treated as such.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
 
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rQuestionEngineering said:
The point is a $14M highly engineered product should not rust.
Click to expand...

No alloy is corrosion-resistant in all environments.

EdStainless said:
13% Cr is barely stainless when it is unoxidized and clean.
Click to expand...

Just store a 13 chrome or 13-4 hydro turbine in the parking lot for a year and see what happens. (Hint: the color changes.)

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."
 
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Still looks like service deterioration; possibly a failure of blade coating ; also some service deposits. 13 Cr is the main material of steam turbines that I have seen . Only problem is GE uses high hardness and occasionally can hydrogen stress crack /corrosion fatigue. Lower hardness-no problem- no rust. 13 Cr is not 825 or 625 but is a substantial improvement to carbon steel with good applications. We added it to API 5 CT for well casing and tubing about 40 years ago; primary application is sour gas; gas + H2S, CO2, water ,and salt. Also some high sulfur refinery streams for furnace tubes; you don't need HP modified for all furnace tubes.!3 % Cr auto exhaust systems are great improvement . Anyone who does not appreciate that has never changed out his own exhaust, twenty times. 13 Cr can be screwed up: long ago we got a order of 13 Cr production tube ( 4.5 "),it looked so good the vendor wrapped the palate in plastic for sea voyage. A month wet with sea water is bad for 13 Cr.
 
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The point is a $14M highly engineered product should not rust.
Click to expand...

No it shouldn't but then we have no idea,
How old it is
What usage it has had
What the coating is that seems to be present and coming off
what the materials are
How it was used
How it was inspected
How it was maintained
How it was stored
Whether it has had a load of grit and dirt go through it
Was it used by the seaside / morine environment but was never designed for that
When did the $14M apply - when it was bought new or now?
What is your role in all of this?

Etc etc.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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It's obvious from the photos that this turbine is damaged by overheat from pic #3. Most of the rest of the corrosion is normal for stationary turbines. What do you want us to tell you?
 
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Well it looks like a piece of junk ATM, so get some inspections done and offer a LOT less than $14M

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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Tug is correct... this is over-temp operational damage with what looks like molten splatter... not corrosion, necessarily... all-over.

HOW MANY engines are You finding in this condition?

IF this is 'the only one' then determine what parameters were exceeded.

IF this is a trend, with several engines, then this is a critical issue that the engine OEM and the FAA/certifying agency need to resolve.

What country is this operating in.
Is the Jet fuel controlled from source-to-jet and monitored for contaminates... especially metal ions?
Did this[these?] engine encounter weather or environmental sources of contamination/abrasion... like massive dust or volcanic ash... etc?

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]
 
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Show it to a turbine specialist from a manufacturer. They could tell you on the spot what it is ant what caused it; the rest of us are guessing.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"
 
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Whereas you have stated that you represent the buyer for this used turbine, tell him it's a piece of used junk turbine scrap. I would assume there was a reason for the previous owner/operator to decommission this turbine and offer it for sale.
 
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When I have looked at used gas turbines for purchase, they looked good. Darkened with oxide, but no erosion, no deposits , no odd surface patterns ,( they were all J-47 if I remember right). I think a lot of explanation and verification is necessary to consider that machine. Also, we were using retired engines for stationary power, not aircraft.
 
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