Painting before hydrotest 1

[starrproe]

We have a column, 2m ID x 10.6 m T/T length.
Design pressure is 35.6 kg/cm^2.

We are planning to paint the column prior to final hydrotest in order to save a few days in schedule and deliver it in time.
Is it technically acceptable?

 

[roca]

gr2vessels
The amount of testing done on the welds is not the same for each and every vessel.
If the client is happy to paint first before hydro then its his decision – he’s paying remember.
If the codes are so outdated then why do all the major oil / chemical companies still insist on hydro first then paint?
Have you ever convinced a client to paint first using your engineering skills?

 

[gr2vessels]

I am one of the "Clients"..
I do mind if any fabricator in Australia would contradict the AS1210, Clause 5.10.2.5 and sure it will mind the witnessing inspector also. A specific interdiction in the AS1210 is not the Client's option, paying or not. I don't mind to discuss options with the ASME, PD fabricators and involve the AI in discussions... Some fabricators would voluntarily increase their NDE's at no extra cost to the Client, if the painting before hydro would benefit them. However, one has to weigh-up the benefit of extra NDE, to eliminate the surprise of undetected weld pore (highly unlikely anyway with the WPS/PQR and NDE's)
It's quite a frequent occurence these days to allow the fabricator to paint before hydrotest, if this will shorten the delivery by 3 weeks, for eg. Any damage to the paint is obviously at his cost. Yes, I'm using my engineering skils, together with the fabricator's skils, to maximise the hydrotest purpose and minimise the damages risk.
cheers,
gr2vessels

 

[roca]

By client do you mean the end user or the engineering contractor acting on behalf of the client?

 

[ndeguy]

No matter how well-proven the WPS may be defects will occur. There is a high probability of a difference in quality between a procedural weld test and a production weld in shop or field - nothing will persuade me otherwise. Small pinholes are notoriously easy to miss by RT/UT and/or MT/PT, if they were not then corrosion monitiring would be much simplified.

I would suggest that the tradition holds - hydrotest before paint.

Nigel Armstrong
Karachaganak Petroleum
Kazakhstan

 

[moltenmetal]

So: no concern about the effects of painting prep, including blasting, on the wall thickness of the materials involved? Never seen a blaster remove a bit too much material then?! Or damage an improperly masked flange face?

It's the owner's call.

BTW, in the case of an internally lined vessel I'd want the hydrotest done FIRST, along with any other NDE required to ensure that I was able to deposit a holiday-free coating- and then a coating inspection done afterward. The last thing you'd want to do is to put an expensive internal coating on something which is scrap!