Bonding of metal plate in a surface submitted to high temperature 1

[roberto1brazil]

Hi everybody.
Please, I would like to have your support on the following issue if possible:
We have a turbine case (Inconel) that reaches a temperature of 350° C ( 662°F ) when in working. There is a identification plate (0,7 mm thick) welded by Resistance Spot in the wall (1,5 mm thick) of Turbine casing. The external turbine diameter is 400 mm approximately.
NOTE Dimension of plate (15mm x 100mm)
It was verified that the spot weld was not enough tough and so it broke up (see sketch attached as reference). My question is:
Is there in the market some kind of bonding able to support the heat from the turbine and keeping the plate in the turbine wall? We did a test with Loctite 5399 but it was unsuccessful.

Thanks and regards

Roberto

 

[btrueblood]

No.

Look at ways of either

a.) providing greater flexibility in the plate, to absorb differential thermal expansion, especially in the long axis - maybe something as simple as making it bow away from the wall when cold.
b.) using a mechanical fastener (rivets, screws, etc. - there is also somebody out there making inconel "velcro") with a degree of "slop" between fastener and plate, to take up those same thermal expansion differences
c.) try laser-engraving or similar directly on the casing surface

 

[btrueblood]

Sorry, stainless steel velcro:

http://www.levitthookandloop.com/index.php/hi-garde.html

 

[roberto1brazil]

Hello.
Thanks for the information. I never had heard about stainless steel velcro. I will research about. I appreciated so much your first option.
Regards.
Roberto

 

[tomwalz]

Brazing?

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[MikeHalloran]

I thought the gold standard for this sort of thing was a Parker-Kalon drive rivet through a hole at each end of the tag, pressed into a drilled blind hole in the casing.

If you could arrange for a tangentially drilled or cored hole in an axial rib, you could use Panduit or other stainless steel cable ties, the ones with a wide area for labels, embossed or photoetched thereon.

If the surface of the pockets between the typical axial and circumferential ribs is sufficiently rough, you could make a stainless label with four upturned flanges, to be jammed into one of said pockets, flanges 'up' and pointing out a bit. Could you peen or locally upset the pocket edges to doubly retain such a label, without distorting something else?

Could you cast or machine (or laser-etch per btb) the label data in a pocket, eliminating the label entirely?


Mike Halloran
Pembroke Pines, FL, USA

 

[roberto1brazil]

Hi Mike and Thomas and Btrueblood.

I have appreciated so much your suggestions and comments about. In fact I work in a site in Brazil of an Aeronautical Industry and I cannot apply the suggestions described without consulting our main site. Of course I will contact them in order to show the possibles options to be applied in this case. Really I thank all of you so much for the suggested ideas.
Regards
Roberto

 

[tbuelna]

Your sketch shows the ID plate resistance welded eight places (4 places at each end). Did all eight welds fail, or just one or two of them?

I'm assuming the ID plate is made of an alloy that readily resistance welds to the Inconel used for the casing. As others suggested it would help to use a thinner plate material that is less stiff, or to use a pattern of welds that is less constraining under thermal expansion conditions.

Of course, you could also make a custom Inconel sheet metal ID plate that has a joggle formed somewhere between the weld locations to serve as a strain relief/expansion joint.

I can't imagine any type of mechanical fastener being acceptable for this particular application. And I don't know of any adhesive that would work at the conditions described.

 

[dvd]

Is the identification plate made of inconel also? if not, there could be a mis-match between the thermal expansion of the materials, There may also be some galvanic corrosion due to material mis-match.

 

[tbuelna]

roberto1brazil-

Here's a quick sketch of how you can modify your existing ID plate with two brake formed joggles to provide some strain relief between the welds at each end.

 

[roberto1brazil]

Hello dvd and tbuelna. Just for information, the plate is made of stainles steel series 300. I believe that your suggestion is something easy to do. Ok, we will test this configuration of plate on the turbine casing.
Thanks and best regards

Roberto