Abrasive blast of surface after PWHT

[yasernoman]

I was wondering if anyone has an idea whether abrasive blasting may not be suitable before PWHT. I know almost everyone blasts surfaces for painting after PWHT and after hydrotest to avoid corrosion problems. However, would blasting negatively influence material properties (i.e. would be equivalent to hammering or peening the surface and welds) which may lead to hardening of the surface? I am specially worried about blasting of internal surface in preparation for internal coating. I have a vessel that needs PWHT and internal coating at the same time. Your help is most appreciated in this matter.

Cheers,

Yaser

 

[rmw]

I think you are overthinking this. Look at it this way. If abrasive blasting would suffice for peening, the peening companies would go out of business tomorrow. I don't think that they are worried about abrasive blasting one bit and you shouldn't be either.

rmw

 

[metengr]

However, would blasting negatively influence material properties (i.e. would be equivalent to hammering or peening the surface and welds) which may lead to hardening of the surface?

No.

 

[metengr]

Why? The media used for grit blasting is intended to remove surface scale and oxide with no significant work hardening of the substrate.


Shot peening is not intended for cleaning. This methos uses an entirely different media to cold work the surface with some penetration into the substrate.

 

[GenB]

I WOULD PREFFER BLAST AFTER PWHT. why? because PWHT will produce scale...
then you will need blast again.