PD5500 - Pressure testing and Paint

[EuroWeld]

Hello All,

I have e question about the sequence and order of execution of pressure testing with paint according to PD5500.

In our company we have a design of a headerbox of an air cooled cooler that can only be hydrotested after applying paint. Otherwise we have to change the design and make a lot of extra effort and increase of costs to produce otherwise.

Can somebody inform me if this is allowed by PD5500? Or depending on selected category?
I have searched the specification without finding the answer.

I have searched codes as API661, ASME VIII div 1 (non lethal) where it is allowed to do so. Other codes like Rtod, EN 13445 and AD2000 will not allow, or in special circumstances. Overall knowing that it's manufacturer own responsibility.

Before asking our NoBo i'm hoping to get the right answer here.
Can anyone provide me with the correct answer?

Thanks in advance,

EuroWeld

 

[gr2vessels]

The hydrotest is impervious of your paint, only the leak test (low pressure test) might be altered by paint. The hydrotest is checking the integrity of material and welds (apart of the gasketted joints) after fabrication, in addition to the numerous non destructive tests applied during the fabrication.
You won't find a direct reference of prohibition of hydrotest after painting, unless your AI (or notified body) has other particular reason to prevent the painting of welds, perhaps when controlling the deformations during the hydrotest or similar. This principle applies particularly in the fabrication of air coolers, when the painting of the tubesheet after tube expansion and/or welding is almost impossible. That's another reason the box has to be PWHT before tubing. Soon after PWHT, the surface preparation and painting has to be completed.
Cheers,
gr2vessels

 

[r6155]

As concept, please see ASME VIII Div.1 UG-99
"...the user is cautioned that such painting /
coating /lining may mask leaks that would otherwise have
been detected during the pressure test."

Regards.

r6155

 

[pennpiper]

EuroWeld'

You wrote:
"a headerbox of an air cooled cooler that can only be hydrotested after applying paint."

Did you really mean "after"?

This does not sound right.

 

[bernoullies123]

PD 5500 as does most codes, does not provide sequence of construction.

I think the answer lies in section 5.8.2.2 (2009) where the hydro procedure to be followed shall be agreed beforehand with all parties. If a procedure hasn't been agreed, or if it has, but the issue wasn't specifically addressed then it will basically be up to the Inspection Authority.

 

[EuroWeld]

Thanks for all the response.

@Penpipper I do mean hydrotesting after applying paint. Why does this not sound right?

Normally the rearside/tubeside of the headerbox is painted before inserting the tubes becuase this area can not be reached afterwards.

Forgot to mention that there is not mutch welding involved in this design and welding only consists out of end plates and nozzles. Also I am aware of the content of UG-99-k. This is always the full responsibility of the fabricator, but is it ain't always?
All codes say little about this subject but could not find this in the PD5500. When it is allowed by the applied code and there is not mutch welding involved this issue will always be discussed with our client in advance. After assembling the complete cooler bundle hydrotest will be performed. This decision is also depending on service, risks and used materials and design.

I believe that bernoullies123 has answered my question, thanks.