Materials & Welding: December 2011

Saturday, December 31, 2011

Re: [MW:13376] Hydro test for different pressure

Mr. kanagarajan
please insure the following points
1. The piping class i.e. pipe thickness and rating
2. second check the piping matergaly if the one cs and other high
alloy such as ss etc then in ss some specicaly requiremetn such as DM
water etc

regards,
satyendra

On 12/28/11, Kanagarajan G <g.kanagarajan@gmail.com> wrote:
>>
>> Hi,
>>
>> Shall we carryout two different hydro pressure packs together in one hydro
>> test for the maximum one.
>>
>> For example, One test pack 30 PSI and another test pack 200 PSI.(Material
>> same)
>>
>> Regards,
>>
>> Kanagarajan.G
>>
>
> --
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>

Re: [MW:13374] Failure Of Root bend test of Welding (CS to SS)

Dear HAREESH,

What was the welding position? If It was not 1G or 2G which on of the root samples failed (acc. to he test sketch in ASME Sec. IX)?

Regards

On Sat, Dec 31, 2011 at 8:35 AM, HAREESH K V <hareesh13h@gmail.com> wrote:

Dear Sir,

Advance happy new year to all.

I have done a PQR(As per ASME Sec ix) of 6", Sa106 GrB to Sa 312 TP 316L. One of the root bend of the same failed.

Consumable used: ErNiCr-3.

Tesile strength T1=507 and T2=514MPa(Min Rqd 415MPa);

Hardness:

Sa106 Gr B side p.metal: 160,151,147

Sa106 Gr B side HAZ:160,156,156

Weld: 193,170,165

Sa312 TP316L P.metal: 175, 175,181

Sa312 TP316L HAZ: 165,151,151

Face bends are satisfactory.

One root bend satisfactory.

Please give me the possible reasons and the precautions on further doing the PQR.

Regards,

Hareesh K V

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M. Shokri Arfaei

International Welding Engineer (IWE)

ASNT NDT Level III

ERI Metallurgy Lab. Manager

Tel: +98-21-66282127

Fax: +98-21-66282779

Please don't print this e-mail unless you really need to. BeGreen!

RE: [MW:13372] Room Temp/High temp Properties & allowable stresses in P92 pipes

Dr Dilintas and Mr. Arora,

I am referring to Sec-II, Pt-D, 2010 edition( effective date 01 July). This material is included in Sec-II Pt-A, e.g SA 213, but till 01 July, P-92 material was not included in the stress tables , in Sec-II, Pt-D.

SAME code case 2179-7 (approval date Jan, 2009) provides details on the stress value of this steel, including compositions and heat treatment.

I'm not sure about the updates, as I don't have them handy, I absence of code updates one could follow the above code case.

Thanks.

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of george.dilintas@gr.bureauveritas.com
Sent: Friday, December 30, 2011 5:41 AM
To: materials-welding
Subject: Re: [MW:13366] Room Temp/High temp Properties & allowable stresses in P92 pipes

Check in ASME section II-A and II-D
Best regards
Dr Georgios Dilintas
Authorized Nuclear Inspector
Authorized Inspector Supervisor
HBS Regional Technical Manager

From: Ved Bhushan Arora [vbarora48@gmail.com]
Sent: 30/12/2011 09:52 ZE5B
To: materials-welding@googlegroups.com
Subject: [MW:13365] Room Temp/High temp Properties & allowable stresses in P92 pipes

Dear All

I need the P92 pipe material properties , physical , mechanical, high temp & allowable stresses etc.

Thanks

Ved Bhushan Arora

[MW:13373] Failure Of Root bend test of Welding (CS to SS)

Dear Sir,

Advance happy new year to all.

I have done a PQR(As per ASME Sec ix) of 6", Sa106 GrB to Sa 312 TP 316L. One of the root bend of the same failed.

Consumable used: ErNiCr-3.

Tesile strength T1=507 and T2=514MPa(Min Rqd 415MPa);

Hardness:

Sa106 Gr B side p.metal: 160,151,147

Sa106 Gr B side HAZ:160,156,156

Weld: 193,170,165

Sa312 TP316L P.metal: 175, 175,181

Sa312 TP316L HAZ: 165,151,151

Face bends are satisfactory.

One root bend satisfactory.

Please give me the possible reasons and the precautions on further doing the PQR.

Regards,

Hareesh K V

Re: [MW:13371] Regarding Deletion of welding Process.

Please read the ASME BPVC SEC-IX , QW- 200.4 Combination of Welding Procedures

On Fri, Dec 30, 2011 at 11:27 PM, Madhusudan Rout <madhusudan.rout@gmail.com> wrote:

Dear Experts,

I need the coorect clause fro deletion of process which
will be use for structural fillet wed, Is it mention on any
International Standard, ASME or Shell DEP,
here Our client disagree with this piont , if Wps with GTAW+ SMAW.

Only SMAW can not use.

I need some refrence form you.

Thanks & regards

Madhusudan Rout.

On 12/30/11, george.dilintas@gr.bureauveritas.com
<george.dilintas@gr.bureauveritas.com> wrote:
> Yes you do can
> Best regards
> Dr Georgios Dilintas
> Authorized Nuclear Inspector
> Authorized Inspector Supervisor
> HBS Regional Technical Manager
>
>
> ----- Original Message -----
> From: Madhu [madhusudan.rout@gmail.com]
> Sent: 29/12/2011 06:07 PST
> To: "Materials & Welding" <materials-welding@googlegroups.com>
> Subject: [MW:13363] Regarding Deletion of welding Process.
>
>
>
> Dear ALLExperts,
>
> I badly need your help for Deletion welding
> Process for Using fillet welding Structural.
>
> I have Qualified W.P.S (GTAW-root/hot+SMAW -fill/
> cap)for Piping welding as per SEC-IX
> & its qualified for fillet in all dia/size/
> thickness & diameter as per SEC-IX.
> Can I use only SMAW process for Fillet welding
> In structural or Only GTAW process can be used.
>
> Or I have to Use both GTAW+SMAW process.
>
> Kindly Enlighten me regarding this matter or any
> code clause I have to follow ( ASME-B31.3 & Shell DEP Standard.)
>
>
>
>
> Thanks & Regards
>
> Madhusudan Rout.
>
> &
>
> Wishing All of you & Your Families A Healthy & Prosperous New Year.
>
> --
> To post to this group, send email to materials-welding@googlegroups.com
> To unsubscribe from this group, send email to
> materials-welding+unsubscribe@googlegroups.com
> For more options, visit this group's bolg at
> http://materials-welding.blogspot.com/
> The views expressed/exchnaged in this group are members personel views and
> meant for educational purposes only, Users must take their own decisions
> w.r.t. applicable code/standard/contract documents.
>
> --
> To post to this group, send email to materials-welding@googlegroups.com
> To unsubscribe from this group, send email to
> materials-welding+unsubscribe@googlegroups.com
> For more options, visit this group's bolg at
> http://materials-welding.blogspot.com/
> The views expressed/exchnaged in this group are members personel views and
> meant for educational purposes only, Users must take their own decisions
> w.r.t. applicable code/standard/contract documents.
>

--
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

Friday, December 30, 2011

Re: [MW:13370] Regarding Deletion of welding Process.

Dear Experts,

I need the coorect clause fro deletion of process which
will be use for structural fillet wed, Is it mention on any
International Standard, ASME or Shell DEP,
here Our client disagree with this piont , if Wps with GTAW+ SMAW.

Only SMAW can not use.

I need some refrence form you.

Thanks & regards

Madhusudan Rout.

On 12/30/11, george.dilintas@gr.bureauveritas.com
<george.dilintas@gr.bureauveritas.com> wrote:
> Yes you do can
> Best regards
> Dr Georgios Dilintas
> Authorized Nuclear Inspector
> Authorized Inspector Supervisor
> HBS Regional Technical Manager
>
>
> ----- Original Message -----
> From: Madhu [madhusudan.rout@gmail.com]
> Sent: 29/12/2011 06:07 PST
> To: "Materials & Welding" <materials-welding@googlegroups.com>
> Subject: [MW:13363] Regarding Deletion of welding Process.
>
>
>
> Dear ALLExperts,
>
> I badly need your help for Deletion welding
> Process for Using fillet welding Structural.
>
> I have Qualified W.P.S (GTAW-root/hot+SMAW -fill/
> cap)for Piping welding as per SEC-IX
> & its qualified for fillet in all dia/size/
> thickness & diameter as per SEC-IX.
> Can I use only SMAW process for Fillet welding
> In structural or Only GTAW process can be used.
>
> Or I have to Use both GTAW+SMAW process.
>
> Kindly Enlighten me regarding this matter or any
> code clause I have to follow ( ASME-B31.3 & Shell DEP Standard.)
>
>
>
>
> Thanks & Regards
>
> Madhusudan Rout.
>
> &
>
> Wishing All of you & Your Families A Healthy & Prosperous New Year.
>
> --
> To post to this group, send email to materials-welding@googlegroups.com
> To unsubscribe from this group, send email to
> materials-welding+unsubscribe@googlegroups.com
> For more options, visit this group's bolg at
> http://materials-welding.blogspot.com/
> The views expressed/exchnaged in this group are members personel views and
> meant for educational purposes only, Users must take their own decisions
> w.r.t. applicable code/standard/contract documents.
>
> --
> To post to this group, send email to materials-welding@googlegroups.com
> To unsubscribe from this group, send email to
> materials-welding+unsubscribe@googlegroups.com
> For more options, visit this group's bolg at
> http://materials-welding.blogspot.com/
> The views expressed/exchnaged in this group are members personel views and
> meant for educational purposes only, Users must take their own decisions
> w.r.t. applicable code/standard/contract documents.
>

Re: [MW:13369] Oxygen level in purging gas during welding of duplex stainless steel

Dear Martin:

Attached file will be helpful...

Regards

Ramin Kondori

QC/Welding Engineer

IWE AT 0070

On Thu, Dec 29, 2011 at 5:44 PM, sudhakar kuppuswamy <mechsudhakar@gmail.com> wrote:

Dear Mr Martin,

I am glad to write about DSS on this group,It is always good to understand the metallurgy of DSS before welding.

   As we all know DSS are two phase alloys i.e 50% ferrite (BCC structure)& 50 % Austenite (FCC structure). The weld joint (weld metal +HAZ) shall also contain the same proportions after welding, but achieving these proportions is a nightmare..!!!

Usage of DSS materials is particularly meant where Chloride stress corrosion cracking (CI SCC)& pitting corrosion cracking resistance are required.

If 50:50 phase balance is not achieved during welding the loss of properties can be acute.

If ferrite content goes high on the weld joint, it may loss the toughness properties and if austenite content goes high weld joint will loss CI SCC resistance.

During welding ,the DSS weld metal solidify essentially as 100 % ferrite ,at high temperatures around 1300°C the Austenite nucleates and grows with the help of Austenite –stabilizing elements(Carbon,Nickel,Nitrogen,&Copper).The ferrite –stabilizing elements are Cr, Mo, W. (It is advised to have a clear idea about De-Long Diagram&WRC diagram)

By selecting proper filler wires, welding parameters and shielding gases, the near 50:50 phase equilibrium can be achieved.
                  i.      Filler wire.  It is always advised to weld with over alloyed filler wires (usually Ni & Cr content shall be high than base material).
                ii.      Welding Parameters.
  Heat Input should not be too low or too high.
    If heat Input is too low rapid cooling occurs and ends up with more ferrite content.
    If heat input is too high chance for intermetallic compound formation are high.
               iii.      Shielding gases.
   In order to get good pitting corrosion resistance Ar+2% N max mixer combination can be used for SDSS..
   Since nitrogen is good Austenite stabilizer it helps to form a thin layer of Austenite at root surface, which will the increase corrosion resistance..
Oxygen content shall be closely monitored during root welding,(max 0.2% is highly recommended ).
Convey the following Tips to Welders..

Advice welder to avoid too many start &stops during welding,as it leads to rapid cooling..
  Avoid autogenous welding. (I.e. without addition of filler )..usually welders use to do autogenous welding while tack weld fro fitup purpose& while arc termination on capping pass welding.

If possible,kindly mail me the design and material details like UNS number ,design temperature etc..if time permits I will write more on this topic..

--
regards,

K.Sudhakar

IWE, Welding Engineer,

Larsen and Toubro Electromech,

Muscat, Sultanate of Oman.

--
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

Re: [MW:13368] Re-expansion of tubes for Air Fin Cooler.........

Yes ..I agreed with Mr. Izad ....

Suresh

On Thu, Dec 29, 2011 at 1:57 PM, hizad idris <hizad.idris@gmail.com> wrote:

Dear Vinod,

If still leaking after re-expand, my suggestion to plug off the tube, if the performance still within the required coolers performance. Normally , cooler have over design up to 20%. Need to calculate the cooler performance with the remaining tube, after plug off.

-izad-

On Wed, Dec 28, 2011 at 9:40 AM, Vinod Jotwani <poojvin@yahoo.com> wrote:

Dear Experts,

We have one of our fin fan cooler leaking from tube to tubesheet joint. The tube material is Duplex stainless steel.

We would like to carry out re-expansion of the tubes, your advise is needed for %age expansion allowed when these tubes are to be re-expanded. The tubes are in operation since last one year in Sour Water Recovery Unit ( H2S service).

Also if some body can share their experience in case of leakage even after re-expansion how to repair the tube to tube-sheet joint. For information the header is welded constuction.( Ref attached file )

Thanking you,

Vinod

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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

--
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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

--
Thanks & Best Regards,

Suresh

Mobile No: 91-92 92 905 905

Re: [MW:13367] Regarding Deletion of welding Process.

Yes you do can
Best regards
Dr Georgios Dilintas
Authorized Nuclear Inspector
Authorized Inspector Supervisor
HBS Regional Technical Manager

----- Original Message -----
From: Madhu [madhusudan.rout@gmail.com]
Sent: 29/12/2011 06:07 PST
To: "Materials & Welding" <materials-welding@googlegroups.com>
Subject: [MW:13363] Regarding Deletion of welding Process.

Dear ALLExperts,

I badly need your help for Deletion welding
Process for Using fillet welding Structural.

I have Qualified W.P.S (GTAW-root/hot+SMAW -fill/
cap)for Piping welding as per SEC-IX
& its qualified for fillet in all dia/size/
thickness & diameter as per SEC-IX.
Can I use only SMAW process for Fillet welding
In structural or Only GTAW process can be used.

Or I have to Use both GTAW+SMAW process.

Kindly Enlighten me regarding this matter or any
code clause I have to follow ( ASME-B31.3 & Shell DEP Standard.)

Thanks & Regards

Madhusudan Rout.

Wishing All of you & Your Families A Healthy & Prosperous New Year.

Re: [MW:13366] Room Temp/High temp Properties & allowable stresses in P92 pipes

Check in ASME section II-A and II-D
Best regards
Dr Georgios Dilintas
Authorized Nuclear Inspector
Authorized Inspector Supervisor
HBS Regional Technical Manager

Dear All

I need the P92 pipe material properties , physical , mechanical, high temp & allowable stresses etc.

Thanks

Ved Bhushan Arora

[MW:13365] Room Temp/High temp Properties & allowable stresses in P92 pipes

Dear All

I need the P92 pipe material properties , physical , mechanical, high temp & allowable stresses etc.

Thanks

Ved Bhushan Arora

Thursday, December 29, 2011

[MW:13361] RE: 13356] welding P355NL2

Dear Sir,

P355NL2 is low carbon steel for pressure vessels at low temperature applications, material delivered according to EN 10028-3 (Flat products made of steels for pressure purposes - Part 3:

Weldable fine grain steels, normalized). As the title of the material specification already mentions it has good welding properties like all low carbon steels because of low carbon content (<0,18%).

All welding processes are possible, you only have to take care about layer thickness and heat input during welding in case you need high impact values at low temperature. We normally weld this material with a standard SG3 type solid welding wire (GTAW / GMAW / SAW).

Met vriendelijke groeten / Best Regards

Herman Pieper

Pieper Quality Support & Inspection

Phone: +31 (0)521 380083

Fax: +31 (0)84 7539225

Cell: +31 (0)6 51691215

www.pieper-qsi.nl

Van: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] Namens Himan Nikdin
Verzonden: woensdag 28 december 2011 18:08
Aan: materials-welding@googlegroups.com
Onderwerp: [MW:13356] welding P355NL2

Dear Experts

would you please share some information about welding P355NL2?

Regards

Himan Nikdin

[MW:13364] Oxygen level in purging gas during welding of duplex stainless steel

Dear Mr Martin,

I am glad to write about DSS on this group,It is always good to understand the metallurgy of DSS before welding.

As we all know DSS are two phase alloys i.e 50% ferrite (BCC structure)& 50 % Austenite (FCC structure). The weld joint (weld metal +HAZ) shall also contain the same proportions after welding, but achieving these proportions is a nightmare..!!!

Usage of DSS materials is particularly meant where Chloride stress corrosion cracking (CI SCC)& pitting corrosion cracking resistance are required.

If 50:50 phase balance is not achieved during welding the loss of properties can be acute.

If ferrite content goes high on the weld joint, it may loss the toughness properties and if austenite content goes high weld joint will loss CI SCC resistance.

During welding ,the DSS weld metal solidify essentially as 100 % ferrite ,at high temperatures around 1300°C the Austenite nucleates and grows with the help of Austenite –stabilizing elements(Carbon,Nickel,Nitrogen,&Copper).The ferrite –stabilizing elements are Cr, Mo, W. (It is advised to have a clear idea about De-Long Diagram&WRC diagram)

By selecting proper filler wires, welding parameters and shielding gases, the near 50:50 phase equilibrium can be achieved.

                  i.      Filler wire.  It is always advised to weld with over alloyed filler wires (usually Ni & Cr content shall be high than base material).
                ii.      Welding Parameters.
  Heat Input should not be too low or too high.
    If heat Input is too low rapid cooling occurs and ends up with more ferrite content.
    If heat input is too high chance for intermetallic compound formation are high.
               iii.      Shielding gases.
   In order to get good pitting corrosion resistance Ar+2% N max mixer combination can be used for SDSS..
   Since nitrogen is good Austenite stabilizer it helps to form a thin layer of Austenite at root surface, which will the increase corrosion resistance..
Oxygen content shall be closely monitored during root welding,(max 0.2% is highly recommended ).
Convey the following Tips to Welders..

Advice welder to avoid too many start &stops during welding,as it leads to rapid cooling..
  Avoid autogenous welding. (I.e. without addition of filler )..usually welders use to do autogenous welding while tack weld fro fitup purpose& while arc termination on capping pass welding.

If possible,kindly mail me the design and material details like UNS number ,design temperature etc..if time permits I will write more on this topic..

regards,

K.Sudhakar

IWE, Welding Engineer,

Larsen and Toubro Electromech,

Muscat, Sultanate of Oman.

[MW:13363] Regarding Deletion of welding Process.

Dear ALLExperts,

I badly need your help for Deletion welding
Process for Using fillet welding Structural.

Or I have to Use both GTAW+SMAW process.

Kindly Enlighten me regarding this matter or any
code clause I have to follow ( ASME-B31.3 & Shell DEP Standard.)

Thanks & Regards

Madhusudan Rout.

Wishing All of you & Your Families A Healthy & Prosperous New Year.

Re: [MW:13362] Hydro test for different pressure

Check the Pipe system rating(pipe class).If both are same technically you can go ahead with hydrotesting together.But still you need to get the designers approval.

On Wed, Dec 28, 2011 at 11:08 AM, Kanagarajan G <g.kanagarajan@gmail.com> wrote:

Hi,

Shall we carryout two different hydro pressure packs together in one hydro test for the maximum one.

For example, One test pack 30 PSI and another test pack 200 PSI.(Material same)

Regards,

Kanagarajan.G

--
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For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

RE: [MW:13360] RE: 13349] Oxygen level in purging gas during welding of duplex stainless steel

Martin,

The only way if control the O2 level. Less than 0.05%

The back purge for stainless steel and nickel alloys shall reduce the oxygen level below 0.05%. An oxygen analyzer should be used to determine the oxygen content inside the pipe during purging.

Sure G48 will pass.

With Kind Regards,

S.Elumalai.

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Martin Prad
Sent: Thursday, December 29, 2011 9:58 AM
To: materials-welding@googlegroups.com
Subject: RE: [MW:13358] RE: 13349] Oxygen level in purging gas during welding of duplex stainless steel

Dear Goswami,

Thanks for your detail email as always. A pitting corrosion test to G48 shall be carried out. I am afraid a test reslut can not pass in the root part. Just looking a best practical solution what % of gas mixes is best to use as purging. There is an Oxy Monitor from Weld-Tech (Finland Company) to monitor the O2 level in purge gas. I will try to summirize your below reccommendation to use on this occasion.

Very kind regards,
Martin.

From: pgoswami@quickclic.net
To: materials-welding@googlegroups.com
Subject: [MW:13352] RE: 13349] Oxygen level in purging gas during welding of duplex stainless steel
Date: Wed, 28 Dec 2011 17:44:09 -0500

Martin,

Nice to hear from you after quite a while..I have come across this question in the past while qualifying procedures for duplex S.S, on the strict requirements of oxygen, in purge gas. Please see below the extracts/recommendations of consumable manufacturers, and the general design practices from API and as well as the technical specification of an oil major. The API recommended practice and duplex/super duplex S.S product manufacturers recommendations is between 2500-5000 ppm of oxygen in the purge gas. Note the general guidelines do not always address the most stringent requirements.

For the clients in the oil and gas production industries the requirement is typically 50 ppm or below for the (typically offshore applications)..My feel is that, it's difficult to pass the pitting corrosion test (G-48) without such strict control on the level of oxygen. However literatures suggests that a proper purging gas can be effective at higher level of oxygen in the root pass. Depending on the residual level of oxygen one can get various levels of discolorations in the weld root (see the attached document, welding.pdf). However for offshore applications I would feel the requirements are very cut throat due to the reasons mentioned above.

I've attached an extract from Avesta Welding Manual , it also calls for 50 ppm max of O2.

If both the specification applies for the same project, then you need to discuss with the client about discrepancies. Could you please specify:-

From O2 level of 5000 ppm, what're the additional testing requirements over and above ASME Sec-IX
For 25ppm allowable oxygen h=what're the weld testing requirements in the coupon?

If you could post some updates later it would be appreciated.

Thanks.

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

Examples:-

1. API 938C-C.2.4 All single-sided welds shall be made with a GTAW root pass and back purged until at least 1/4 in. (6 mm) of weld metal thickness has been deposited. Backing gas shall be welding grade 90 % nitrogen/10 % hydrogen mixture, pure nitrogen or argon/nitrogen mixture with not less than 5 % nitrogen. The oxygen content of the back purged volume shall be less than 0.25 % (2500 ppm). The seller shall submit details of the method and equipment to be used for monitoring oxygen content as part of the WPS. Shielding gasses can be argon or argon with 2 % maximum nitrogen.

2.WEIR MATERIALS, Guidelines for Welding, ZERON 100

Back Purging:- When welding Zeron 100, it is recommended that commercial purity argon is used to displace the air behind the joint. The oxygen content of the resulting argon/air mixture must be monitored and controlled to ensure that sufficient nitrogen is retained in the backing gas “mixture’ in order to inhibit loss of nitrogen from the weld pool. In practice the oxygen level of this mixture should be controlled at approx 0.5% (5000ppm) oxygen monitored at the start of the welding sequence. In this way, a positive partial pressure of nitrogen is maintained behind the joint thus preventing nitrogen loss from the root bead, whilst the oxidation produced remains acceptable. Passes subsequent to the root pass can be made with minimum oxygen contents.

The backing gas composition should be monitored at the joint line using a portable oxygen monitor immediately prior to starting or re-starting welding in order that consistency can be maintained. Adhesive tape low in sulphur and chloride is used around the open joint seam, and the tape should be removed progressively during the welding sequence.

3. Metrode:-Duplex & superduplex ferritic-austenitic stainless steels

Purging

A gas purge must be used for root runs deposited using the TIG process and will normally be maintained for the first three layers or approximately 10mm of deposit. Commercially pure argon is generally used as the purge gas. Purge flow rates are determined by the pipe size but it is important that following the removal of tacks, grinding etc that the purge is allowed to stabilize again before welding. The efficiency of the purge should be monitored with an oxygen monitor to ensure the oxygen content is maintained below 0.5% (5000 pap) oxygen.

4.0 Worldwide:- Oil and Gas Major

During welding, DSS shall be protected from oxidation by providing a shielding purge on the inside with the same composition as the shielding gas for welding. The purge gas shall replace all air. No welding shall start until the oxygen content has dropped to below 50 ml/m3(i.e 50 ppm). During welding the root run, there may be a surge when welding is started and welding shall be stopped if this surge goes higher than 500 ml/m3. This shall be measured with an oxygen analyzer, capable of measuring oxygen contents between 0 and 1000 ml/m3.

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Martin Prad
Sent: Wednesday, December 28, 2011 2:56 AM
To: materials-welding@googlegroups.com
Subject: [MW:13349] Oxygen level in purging gas during welding of duplex stainless steel

Hi friends,

I have 2 different specification which the requirements are different for the oxygen level in purging gas during the welding of super duplex pipe.

One of them calls for 25 ppm (0.0025%) another one calls for 5000 ppm (0.5%). Could you please shed some light on this as which one is up to the standard with references?

Thanks,
Martin.

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[MW:13353] UTS/YS values for SEW 089 & SEW 680 materials

We have very old shell and tube exchanger (30 years old) which has the following material. We need recheck with design calculation, however we are unable find the specification for these materials. Can anybody provide where can I get the allowable stresses and mechanical properties of this material, particularly we are looking for yield stress value of following material at 50 °C.

I tried to contact German Iron and Steel Institute (VDEh) @ Heinz-Friedrich.Hach@vdeh.de, but no response (http://www.stahl-online.de/english/Stahlinstitut_VDEh/Standards.php?highmain=5&highsub=0&highsubsub=0)

Plate material – TT st E36 SEW 089 (Google search ~ nearest equivalent SA 537 cl 1)

Pipe material – TT st 35N SEW 680 (Google search ~ nearest equivalent SA 333 Gr 1/6)

Re: [MW:13359] Re-expansion of tubes for Air Fin Cooler.........

Dear Vinod,

If still leaking after re-expand, my suggestion to plug off the tube, if the performance still within the required coolers performance. Normally , cooler have over design up to 20%. Need to calculate the cooler performance with the remaining tube, after plug off.

-izad-

On Wed, Dec 28, 2011 at 9:40 AM, Vinod Jotwani <poojvin@yahoo.com> wrote:

Dear Experts,

We have one of our fin fan cooler leaking from tube to tubesheet joint. The tube material is Duplex stainless steel.

We would like to carry out re-expansion of the tubes, your advise is needed for %age expansion allowed when these tubes are to be re-expanded. The tubes are in operation since last one year in Sour Water Recovery Unit ( H2S service).

Also if some body can share their experience in case of leakage even after re-expansion how to repair the tube to tube-sheet joint. For information the header is welded constuction.( Ref attached file )

Thanking you,

Vinod

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RE: [MW:13358] RE: 13349] Oxygen level in purging gas during welding of duplex stainless steel

Martin,

For the clients in the oil and gas production industries the requirement is typically 50 ppm or below for the (typically offshore applications)..My feel is that, it's difficult to pass the pitting corrosion test (G-48) without such strict control on the level of oxygen. However literatures suggests that a proper purging gas can be effective at higher level of oxygen in the root pass. Depending on the residual level of oxygen one can get various levels of discolorations in the weld root (see the attached document, welding.pdf). However for offshore applications I would feel the requirements are very cut throat due to the reasons mentioned above.

I've attached an extract from Avesta Welding Manual , it also calls for 50 ppm max of O2.

If both the specification applies for the same project, then you need to discuss with the client about discrepancies. Could you please specify:-

From O2 level of 5000 ppm, what're the additional testing requirements over and above ASME Sec-IX
For 25ppm allowable oxygen h=what're the weld testing requirements in the coupon?

If you could post some updates later it would be appreciated.

Thanks.

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

Examples:-

2.WEIR MATERIALS, Guidelines for Welding, ZERON 100

Back Purging:- When welding Zeron 100, it is recommended that commercial purity argon is used to displace the air behind the joint. The oxygen content of the resulting argon/air mixture must be monitored and controlled to ensure that sufficient nitrogen is retained in the backing gas "mixture' in order to inhibit loss of nitrogen from the weld pool. In practice the oxygen level of this mixture should be controlled at approx 0.5% (5000ppm) oxygen monitored at the start of the welding sequence. In this way, a positive partial pressure of nitrogen is maintained behind the joint thus preventing nitrogen loss from the root bead, whilst the oxidation produced remains acceptable. Passes subsequent to the root pass can be made with minimum oxygen contents.

3. Metrode:-Duplex & superduplex ferritic-austenitic stainless steels

Purging

4.0 Worldwide:- Oil and Gas Major

Materials & Welding

Saturday, December 31, 2011

Re: [MW:13376] Hydro test for different pressure

Re: [MW:13374] Failure Of Root bend test of Welding (CS to SS)

RE: [MW:13372] Room Temp/High temp Properties & allowable stresses in P92 pipes

[MW:13373] Failure Of Root bend test of Welding (CS to SS)

Re: [MW:13371] Regarding Deletion of welding Process.

Friday, December 30, 2011

Re: [MW:13370] Regarding Deletion of welding Process.

Re: [MW:13369] Oxygen level in purging gas during welding of duplex stainless steel

Re: [MW:13368] Re-expansion of tubes for Air Fin Cooler.........

Re: [MW:13367] Regarding Deletion of welding Process.

Re: [MW:13366] Room Temp/High temp Properties & allowable stresses in P92 pipes

[MW:13365] Room Temp/High temp Properties & allowable stresses in P92 pipes

Thursday, December 29, 2011

[MW:13361] RE: 13356] welding P355NL2

[MW:13364] Oxygen level in purging gas during welding of duplex stainless steel

[MW:13363] Regarding Deletion of welding Process.

Re: [MW:13362] Hydro test for different pressure

RE: [MW:13360] RE: 13349] Oxygen level in purging gas during welding of duplex stainless steel

[MW:13353] UTS/YS values for SEW 089 & SEW 680 materials

Re: [MW:13359] Re-expansion of tubes for Air Fin Cooler.........

RE: [MW:13358] RE: 13349] Oxygen level in purging gas during welding of duplex stainless steel

[MW:35346] Cast-iron welding

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