From: GOSWAMI Pradip -THERMAL <pradip.goswami@opg.com>
Date: Fri, Oct 1, 2010 at 9:13 PM
Subject: [MW:7313] Can we do painting prior to hydrotest?
To: materials-welding@googlegroups.com
Satish,
ASTM has a standard, E-1003, for hydrotest, which clearly specifies that "New systems should be tested prior to painting, where practical".
The responses posted by Mr Arunachalam cites several discussions and replies on the same issue. I've also attached the gist of the article by J.E.Batey, which was published in, ASNT journal materials evaluation.
If you look at ASME Sec-VIII,DIV-1,UG-99,(see below):-
(k) Vessels, except for those in lethal service, may be painted or otherwise coated either internally or externally, and may be lined internally, prior to the pressure test. However, the user is cautioned that such painting /coating /lining may mask leaks that would otherwise have been detected during the pressure test. The above sentence implies "do it at your risk and be ready for the consequences". ASME as a code have to be fabricator friendly, but for Lethal Services failures due to suggested wrong practices would mean liability. However at the same time fabricator have to exercise judgement and good engineering practice.
Depending on the type of paints used, paints will have tendency to mask defects or hinder meaningful inspection. If the vessel or piping is subject to PWHT, any defect noted during hydrotest, would call for repair and re-stress relieve, the time and money spent on rework may out-weigh your initial gain.
Generally in North American utilities (Nuclear) painting before hydro test is not an accepted practice. The same guidelines are followed by large oil Companies also. An extract from such a specification :-
· Hydrostatic pressure testing shall be performed prior to the application of paint or other protective coatings to the welds and heat affected zones, unless otherwise approved by the Principal.
I would say, given a choice painting shall always be done after hydro test. If the project is a rush and time is a constraint, painting of piping or vessel may be done, leaving welds and at least 2 " on each side as unpainted during hydrotest, which would be painted following hydrotest.
Thanks.
Pradip Goswami,P.Eng.
Welding & Metallurgical Engineer/Specialist
Email-pgoswami@sympatico.ca,
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Satish Hingalkar
Sent: Friday, October 01, 2010 2:10 AM
Dear all members,
Thanks for reply on my query.
As suggested by you guys, i can say to contractor to go ahead for painting before hydrotest by holding more time up to all visual check of joints. I have one more concern as: As per company specification, we are doing 10%MT & 10%RT that is OK or we have increase the % of MT & RT.
Please respond.
Regards,
Satish
On Thu, Sep 30, 2010 at 2:05 PM, <francis.lobo@indiatimes.com> wrote:
Dear All,
In the modern fast track projects these deviations are common , You can accept the deviation provided you extend the hold time for min 4 hrs for joints not seen or painted with chart recorder and accounting any pressure variation with tempt,
This is practiced in most of the offshore projects. However for onshore /subsea pipeline hold period is 24hrs and pressure variations vs. tempt accounted.
Francis Lobo
----- Original Message -----
From: Bathula Raghuram (Mumbai - PIPING)
To: 'materials-welding@googlegroups.com'
Sent: Thu, 30 Sep 2010 15:03:40 +0530 (IST)
Subject: RE: [MW:7285] Can we do painting prior to hydrotest?
Interesting, and you have a valid point but nothing is proven, until then just go with the flow (tried and tested methods). No Inspector would be happy but bound to accept as per code. remember your company specification prohibits it and you are intended to accept, hence code reference is given, Masking of any discontinuity by thin layer of paint, may be yes perhaps may be not. If you refer the paragraphs of these codes which will give a cautionary statement at the end "painting/coating may mask the leak". Normally weld joints are left open and rest of the area is painted before hydro. In my opinion 105 bar is too high for a layer of paint to with stand, or you may allow only blasting and priming before hydro and final coating after hydro. If I remember correctly only Australian code AS1210 prohibits it.
From: Satish Hingalkar [mailto:shingalkar@gmail.com]
Sent: Thursday, September 30, 2010 12:49 PM
To: Bathula Raghuram (Mumbai - PIPING)
Subject: Re: [MW:7283] Can we do painting prior to hydrotest?
Hi,
Thanks for prompt reply
Piping system of having pipe rack near about 4 KM,service-Nitrogen,Code ASME B31.3
As u said,ASME B 31.3 allows, but my query is that whether painting will affect the joint leak detection normally found in hydro test??
As per my knowledge, Painting has ability to penetrate and plug/ seal off small pin holes which are normally detected in hydro test. After curing, paint can withstand pressure in small pin holes that can obstruct the leaks. But during operation, paint can be decomposed and start leaking, please comment.
Regards,
Satish
On Thu, Sep 30, 2010 at 7:27 AM, Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com> wrote:
You have not specified the type of component, fluid and design code. ASME code for both vessels and piping have this provision. Sec VIII div 1 allows except for lethal service (UG 99) and B31.3 allows except for sensitive leak testing (345.3.1)
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Satish Hingalkar
Sent: Wednesday, September 29, 2010 11:55 PM
To: Materials & Welding
Subject: [MW:7276] Can we do painting prior to hydrotest?
Dear Members,
Our contractor has raised a design change request for painting prior to hydrotest.As per COMPANY specification, painting to be carried out after successful completion of hydrotest,but contractor wants to do painting before hydrotest,can we accept this deviation? if we want to accept the deviation, what criteria to be follow??
Our design conditions are 105 barg hydrotest pressure and design temp.85 deg.c,NDT is 10% MT & 10% RT.
Waiting for reply. Pl.respond ASAP.
Regards,
Satish
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