[MW:6374] Re: 6359] Re: Quarry on an Inspection requirement

Dear Mr. Das,

I would say if you really have to execute a corrosion test according
ASTM A923 the sample should be max. 2 thickness taken from the root
side in order to ensure no carbon steel is present in the specimen.
Even than you have to take car of mix up during welding because you
weld a single side V-groove. To prevent to much dilution of carbon
steel you perhaps should choose a special V-groove preparation in
which the cladding is not in line with the rest of the V-groove, in
other words remove some carbon steel and keep the clad. The total weld
size will become wider but if you weld like this there will be no mix-
up during welding the clad.

Best Regards

Herman Pieper

On 7 aug, 12:19, "subrata das" <s...@pkgroup.org> wrote:
> Dear Sir
> Clad thickness is 3mm and base metal is 10mm thk.
>
> Regards
> Subrata Das
>
>
>
> -----Original Message-----
> From: materials-welding@googlegroups.com
>
> [mailto:materials-welding@googlegroups.com] On Behalf Of hpi001
> Sent: Saturday, August 07, 2010 3:41 PM
> To: Materials & Welding
> Subject: [MW:6359] Re: Quarry on an Inspection requirement
>
> Dear Mr. Das,
>
> I'm not familiar with API 938-C but worked at a laboratory for 12
> years where we executed such corrosion tests and I must say that we
> often faced problems with testing duplex clad steel welds.
>
> What is the thickness of your duplex clad? This because when you need
> to execute a corrosion test according to ASTM A 923 practice C you
> need to be sure that no carbon steel is included in the specimen
> because this will increase your corrosion rate above the max. allowed
> during the test . Also dilution from the carbon steel weld metal in
> the duplex clad weld need to be minimized and/or excluded from the
> test specimen.
> See below for the aim of this corrosion test and test parameters.
>
> Part of ASTM  A923 - Method C:
> 14.1 This test method describes the procedure for conducting
> the ferric chloride corrosion test for detecting the presence
> of detrimental intermetallic phases in duplex stainless steels.
> The presence or absence of corrosion attack in this test is not
> necessarily a measure of the performance of the material in
> other corrosive environments; in particular, it does not provide
> a basis for predicting resistance to forms of corrosion not
> associated with the precipitation of intermetallic phases.
>
> 19.4 Unless otherwise specified, the test temperature for
> S32750 products shall be 40°C (104°F), maintained within an
> accuracy of 61°C (2°F) during the test.
>
> Regarding ferrite measurements the following: I assume that API
> prescribes the method for determining the ferrite content, this can be
> done by way of ferrite counting on the cross-section micro structure
> or measuring the content by way of Magne Gauge or Ferritscope.
> Normally for duplex stainless steels you need to determine the content
> at the weld metal as well as the heat affected zone at both side of
> the v-groove.
> When a specification mentioned "All weld location shall be checked for
> % ferrite measurement" in my opinion they meant that all production
> welds need to be tested afterwards by methods like Ferritescope.
>
> Hope this will help you a little bit further.
>
> Best Regards,
>
> Herman pieper
>
> On 7 aug, 11:08, "subrata das" <s...@pkgroup.org> wrote:
> > Dear Sir
>
> > Can you guide about
>
> > 1.       Ferric chloride corrosion test as per ASTM A 923 Method C.
>
> > 2.       What are the additional tests applicable as per API 938-C for
> > qualifying PQR.
>
> > 3.       Reference document for Cross section macro examination and
> ferrite
> > measurement.
>
> > 4.       What is the meaning of "All weld location shall be checked for %
> > ferrite measurement"
>
> > My Job description : Single 'V' Groove weld joint to be done between
> Cladded
> > plates. Cladded plates are Duplex SS UNS S32750 to SA516 Gr.70 ).  
>
> > Regards
>
> > Subrata Das
>
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