Blast surface profile

[Kumar]

Dear Experts,

Greetings for the day.

I have a query regarding surface profile of CS for blast surfaces of
pressure vessels, piping & structural.

Client spec. calls for- the surface profile for CS shall be 30-70
microns as measured with a replica technique (typically testex tape
used in accordance with NACE RP 0287).

But the paint manufacturer allows for 30-85 microns grade fine to
medium G; Ry 5 (ISO-8503-2). with SA 2.5 surface roughness.

Here, it is obvious that on practical grounds, it would be somewhat
difficult to achieve a maxm. 70 microns finish as it may go beyond
also ( which is foreseen by the paint manufacturer). but client is
strict for 70. how could we convince them in this regard.

Thanking all in advance,

Kumar.

[Perumal Govindan]

Hi Kumar

Surface Profile as per Client/project specification is 30 - 70 microns. Profile range was specified by the paint manufacturer will not be considered, always Client requirement shall only be followed.

After blasting the surface profile shall be within the above mentioned range, its not mandatory that the surface profile should be 70 microns minimum.

Alternativly the profile will be also checked by profile gauge (elco meter).

Explain to Client representative for acceptance.

With kind regards
Govindan Perumal