Detecting Slivers - Steel beams

[Rich2001]

Any idea for detecting slivers on steel beams (W24's thru W42's), prior to abrasive blasting. Currently we fab. the steel beams, then run them through the Shot blasting machine. Any slivers are then detected and repaired by grinding etc. This grind changes the surface profile, that could result in improper coating adhesion. I am looking for a simple method of detecting these prior to abrasive blasting.

 

[bruv]

Have you considered liquid penetrant examination?

 

[moseley]

Rich,
I beleive that Bruv is right, that seems to be the easiest and most productive way to find these. Other NDE would probably be too costly and time consuming to get the findings which you require.

 

[quadswift]

As you have found, shot blasting is one of the best methods to reveal the slivers.
You could ensure that the grinding / wire brushing leaves an abraded surface of e.g. Swedish 2 1/2 such that the first coating would achieve a bond. This is an acceptable method during localised repairs to paintwork.

Check your paint spec and see what are the minimum requirements for repairs, that may give you a clue.

Dye pen would be messy and time-consuming in that you would need to de-grease and if you are coating afterwards you need to clean off all the residue (though the blasting may do this for you)& not conducive to a production-line process.

A form of magnetic particle exam, by passing the sections through an eddy current rig may be better. This should detect surface and slightly sub-surface discontinuities and be more amenable to a production line process.You can use U/V additives in the fliud and U/V light.

As in all things, finding out the the root cause of the problem and rectifying it is the real answer, as not all beams / steel sections have slivers to a degree that causes ongoing problems.

 

[quadswift]

As you have found, shot blasting is one of the best methods to reveal the slivers.
Perhaps you could ensure that the grinding / wire brushing leaves an abraded surface of e.g. Swedish 2 1/2 such that the first coating would achieve a bond. This is an acceptable method during localised repairs to paintwork.

Check your paint spec and see what are the minimum requirements for repairs, that may give you a clue / answer.

Dye pen would be messy and time-consuming in that you would need to de-grease and if you are coating afterwards you need to clean off all the residue (though the blasting may do this for you)& is not conducive to a production-line process.(requires dipping and tanks etc)
A form of magnetic particle exam, by passing the sections through an eddy current rig may be better. This should detect surface and slightly sub-surface discontinuities and be more amenable to a production line process.There are various aids to detection in a production line environment e.g U/V.
As in all things, finding out the the root cause of the problem and rectifying it is the real answer, as not all beams / steel sections have slivers to a degree that causes ongoing problems.
Regards, Quadswift