Grouting holes plugs

[21121956]

Hello everybody:

For steel liner of pressure shaft, power tunnels, bottom outlets, etc. in hydroelectric power plants, it is usually indicated to use steel plates conforming to ASTM A-572, Grade 50.

After completion of skin, contact and consolidation grouting, the grouting nozzle holes are plugged with steel plugs of the same material that are welded in an appropriate manner.

But, for some other hydropower plants, the Technical Specifications clearly say that the plugs should be made of stainless steel ASTM A276 type 304L, and welded with electrode E309.

For practical purposes, what difference does it make to adopt stainless steel plugs instead of the same carbon steel base material?

Thanks in advance for your comments.


El que no puede andar, se sienta.

 

[Duwe6]

Just the reverse - stainless is a poor idea due to In-Service testing difficulties. TVA used 600 or higher inconel [non-ferromagnetic] to weld in "gamma port" plugs on Main Steam piping. Made the testing for cracking difficult; had to use PT [dye penetrant] and clean off the heat scale and polish the plug area to get a valid test. Each plug took hours to test. When the plug welds were changed to the same filler used on the pipe, these ports could now be inspected in about 20 seconds using MT - magnetic particle testing. Only hand-brushing of the plug area was needed for a valid MT test, prep took 5-minutes or less.