Painting before hydrotest
Painting before hydrotest
(OP)
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?
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?





RE: Painting before hydrotest
I know of no users/engineers that would allow it.
RE: Painting before hydrotest
However it does point out that paint could mask leaks which would otherwise be visible.
No client I have ever worked with has accepted external or internal painting or coating prior to hydrotest.
You need to discuss this with your client.
RE: Painting before hydrotest
The hydrotest is for checking the joints strength;- if it is feasible to you to mask the welds before painting, the rest can be painted without restriction. Also, if you had lots and lots of tests done on those welds, the hydrotest is only a formality. If the skin of the paint is holding your column together, you should look for another job perhaps.
Cheers,
gr2vessels
RE: Painting before hydrotest
You have got this the wrong way around. What is stopping you painting? Is there any part of spec or standard that says do not paint prior hydrotest. If there is then you need to put in a concession. If there is not then you are free to paint before hydrtotest.
RE: Painting before hydrotest
RE: Painting before hydrotest
Thanks.
RE: Painting before hydrotest
I'll echo roca, davefitz, and vesselfab - I have not worked for or with an Owner company that would allow paiting before a hydrotest.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: Painting before hydrotest
He said we could paint the shell prior, but we saw no point in painting part, only to come back and paint the rest later.
Ultimately, it would be up to your customer, but I would check with your AI to make sure he is happy with the arrangement as well.
RE: Painting before hydrotest
RE: Painting before hydrotest
If you are focussed on the final leak tightness of the system, you will not. There is an article by Jon Batey that shows how you could burst vessels with holes drilled in them, that were subsequently painted but before leak testing, that would burst under internal pressure before leaking through the drilled holes that were painted over.
RE: Painting before hydrotest
RE: Painting before hydrotest
RE: Painting before hydrotest
RE: Painting before hydrotest
RE: Painting before hydrotest
Agree 100%, blasting before hydrotest is pointless - as stated, it'll have to get done again.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: Painting before hydrotest
Did your AI supply a Code reference supporting the no painting rule, or is asking you to tailor your process to his/her personal likes or preferences. AIs are charged with following, enforcing, and verifying the Code rules, not deciding what is sound engineering. If it is not prohibited, it is allowed.
RE: Painting before hydrotest
While I agree with your basic statement about AI duties, they do sometimes impose upon manuafcturers their own quirky opinions. It's not supposed to be that way, but it does happen. That said, if I were the AI I would not allow painting before hydro either as it could mask a leak. It's not specifically addressed by the Code, but it's a Code-related issue and worthy of action by the AI.
I would also agree that the Code does not cover all instances, but I'm not so sure that I could go as far as agreeing that "If it is not prohibited, it is allowed".
Joe Tank
RE: Painting before hydrotest
RE: Painting before hydrotest
This topic was well debated, but without a consensus is unfinished. It seems that the coating issue on the vessel, before hydrotest, is raising a leak detection obstruction issue. It is a reflex engineering to have the welds totally open for inspection, particularly during the final, last chance to detect a possible failure. That is in despite of blind fate in the PQR which in many cases is a substitute for good 100% inspection and tests. Better still, we have 100% confidence in the certificates for materials, welding procedure, PWHT, 100% tests and inspections. But no skin of paint on my weld, please, it could cover a tiny leak which went undetected, even after radiography tests, UT's, etc...
Indeed, the blast cleaning would remove that little pore covering, to allow the spring of the leak...However, you have to paint in about 2 hours after the blast cleaning, so you better hurry with the hydrotest, then quickly transport it to the paint shop...unless you paint it before hydrotest..
Gents, there is the Australian Pressure Vessel Code, the AS1210, which specifically prohibites the painting before the hydrotest, to prevent the masking of a potential leak (Clause 5.10.2.5). But again, that was issued in 1997, written probably in '95, '96.
This is a weird word, one is contradicting the other, we should have a common, unified code, valid in China, Australia and Italy also..
Until then, I'll try to be an engineer and use my skils rather than emotions.
cheers,
gr2vessels
RE: Painting before hydrotest
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?
RE: Painting before hydrotest
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
RE: Painting before hydrotest
RE: Painting before hydrotest
I would suggest that the tradition holds - hydrotest before paint.
Nigel Armstrong
Karachaganak Petroleum
Kazakhstan
RE: Painting before hydrotest
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!