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 hydrotest??
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 successfull complection 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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