Sandblasting for NDE - minimising extent of damage to surface

[WPM3022]

Hello,

I am getting the welds in a tube examined by NDE (ultrasonics). I need to prepare the welds on the inside of the tube (which is a confined space).

The thickness of the tube is extremely important. The NDT technician has requested sand blasting, I do not want to remove any material from the tube.

I am aware of different types of sandblasting media - walnut, CO2, different sized garnet.

I am very reluctant to use C02 given the confined space and the associated atmospheric changes. Does any one have any information on the surface removal depth of ordinary garnet or walnut shell?

Thanks.

 

[racookpe1978]

What is the ID of the tubes,
the length of the tube,
the type of coating/damage/sludge/corrosion involved that the NDE wants removed?
How far down the tubes do you need NDE checks on the surface?

Seems to me that you'd need to find a sandblast/dustblast company able to get the blast agent into and down the tubes, then to get the tubes and opposite end (other head ?) accessible and cleaned out of the grit afterwords.

We've used waterblasting for oil cooler tubing and heads, sometimes after soaking in cleaner for a few days

 

[WPM3022]

Thaks Racookpe

Average ID is 800mm (tapers slightly)
length is 10m
Not sure how the above is relevant, however gives an idea of the confined space size.

Still interested in what material would be removed from the shell using different blast media?