PQR - WPS - PWHT P91 to CS

[Zakaria ghrab]

Dear experts,

  Need your support.

We performed one PQR P91 grade ( P number 15E) to Carbon steel (P number 1) welded GTAW/SMAW ER90S-B9 / E9015-B9, 11mm thickness, PWHT @ 740°C - 40 minutes.

PQR and related WPS already approved by our client. but the Owner consulting agency sent to us some comments :

1- No possible to weld P91 directly to CS shall add transition material P11 grade : We answer that it's design issue and i requested some explain / calculation from design.

2- Should use filler metal compatible with lower grade material : i answer that can make choice of  filler metal between to material grades (included) so we can weld with lower, heigher or iontermediate filler metal when mechanical properties is ok and don't have ebjection from project spec.

3- this is the main issue : PWHT @ 740 °c is heigher than lower critical temperature for CS so we must perform PWHT in intermediate Temperature : in this case if will do like this WPS will not supported by Prepared PQR;

PQR approved by Client and weld already done, i propose to perform hardness test, PMI and metallographic replic in production ( just one weld) to confirm.


Need your support .



Regards.





--

زكرياء غراب
GHRAB Zakaria

[pgoswami]

Hi Zakaria,

 

Dissimilar welds between Grade-91 to other lower alloyed steels e.g  grade 11 and grade 22 are quite common. However a straight change from Grade-91 to Carbon steel is a Bad Design, unless the margins provided by the OEM takes care of the service induced damages.

 

A straight service induced damages could be a few as mentioned:-

• Grade-91 steel operates at very high operating temperature regime (550-560 Deg C), which is is not safe for P1 material. P1 materials in the vicinity of the weld is  likely to get exposed to spheroidization (on exposure to this temperature range) and may result in failures by creep
• Thus welding of a intermediate or  transition  spool piece such as Grade-22 steel  would be a better design.

Grade-91 to Grade-22 could be welded in a few ways, see the following tables for welding materials selection and subsequent PWHT.

 

You may qualify a WPS /PQR , however that does not always mean that the good  engineering  design basis is maintained.

 

Also please see below the comments on your queries.

 

Thanks

 

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist

Ontario, Canada.

Email-p...@sympatico.ca,

pgos...@quickclic.net

Dissimilar Welding Filler Metal Selection-

 

Recommended PWHT Temperatures (

0F) for Dissimilar Welds

---

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Zakaria ghrab
Sent: Saturday, October 20, 2012 6:29 AM
To: material...@googlegroups.com
Subject: [MW:15720] PQR - WPS - PWHT P91 to CS

Dear experts,

 Need your support.

We performed one PQR P91 grade ( P number 15E) to Carbon steel (P number 1) welded GTAW/SMAW ER90S-B9 / E9015-B9, 11mm thickness, PWHT @ 740°C - 40 minutes.

PQR and related WPS already approved by our client. but the Owner consulting agency sent to us some comments :

1- No possible to weld P91 directly to CS shall add transition material P11 grade : We answer that it's design issue and i requested some explain / calculation from design. -- This  is a good and conservative design. If accepted one may have to weld the transition pieces, i.e involving welds between P91-P4 & P4-P1 base metal.The PWHT may be controlled to the better extent such that the P1 base metal would not get over tempered.

2- Should use filler metal compatible with lower grade material : i answer that can make choice of  filler metal between to material grades (included) so we can weld with lower, heigher or iontermediate filler metal when mechanical properties is ok and don't have ebjection from project spec. --If you're welding in the above sequence recommendation would be :

• P91-P4  -welds use -E/ER 8016/18 electrde/ filler metal
• P4--P1 -welds use -E/ER 8016/18 electrode/ filler metal

3- this is the main issue : PWHT @ 740 °c is heigher than lower critical temperature for CS so we must perform PWHT in intermediate Temperature : in this case if will do like this WPS will not supported by Prepared PQR; --740Deg Cis quite high a temeprature for P1 steel , which could cause over tempeating of this steel 

PQR approved by Client and weld already done, i propose to perform hardness test, PMI and metallographic replic in production ( just one weld) to confirm.


Need your support .



Regards.





--

زكرياء غراب
GHRAB Zakaria

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[kannayeram gnanapandithan]

Direct welding not accepted due to
1. PWHt of P91 will cross lower critical temp of CS (727)
2. Service temp
Pandithan

On 10/21/12, pgoswami <pgos...@quickclic.net> wrote:
> Hi Zakaria,
>
> Dissimilar welds between Grade-91 to other lower alloyed steels e.g grade
> 11 and grade 22 are quite common. However a straight change from Grade-91
> to
> Carbon steel is a Bad Design, unless the margins provided by the OEM takes
> care of the service induced damages.
>
> A straight service induced damages could be a few as mentioned:-
>

> *

>
> Grade-91 steel operates at very high operating temperature regime
> (550-560 Deg C), which is is not safe for P1 material. P1 materials in the
> vicinity of the weld is likely to get exposed to spheroidization (on
> exposure to this temperature range) and may result in failures by creep

> *

>
> Thus welding of a intermediate or transition spool piece such as
> Grade-22 steel would be a better design.
>
> Grade-91 to Grade-22 could be welded in a few ways, see the following
> tables
> for welding materials selection and subsequent PWHT.
>
> You may qualify a WPS /PQR , however that does not always mean that the
> good
> engineering design basis is maintained.
>
> Also please see below the comments on your queries.
>
> Thanks
>
>
>
> Pradip Goswami,P.Eng.IWE
>
> Welding & Metallurgical Specialist
>
> Ontario, Canada.
>

> Email-p...@sympatico.ca <blocked::mailto:Email-p...@sympatico.ca> ,
>
> pgos...@quickclic.net <blocked::mailto:pgos...@quickclic.net>

>
> Dissimilar Welding Filler Metal Selection-
>
>
>
>

> Recommended PWHT Temperatures (0F) for Dissimilar Welds
>
>
>
> _____

> *

>
> P91-P4 -welds use -E/ER 8016/18 electrde/ filler metal

> *

>
> P4--P1 -welds use -E/ER 8016/18 electrode/ filler metal
>
>
> 3- this is the main issue : PWHT @ 740 °c is heigher than lower critical
> temperature for CS so we must perform PWHT in intermediate Temperature : in
> this case if will do like this WPS will not supported by Prepared PQR;
> --740Deg Cis quite high a temeprature for P1 steel , which could cause over
> tempeating of this steel
>
> PQR approved by Client and weld already done, i propose to perform hardness
> test, PMI and metallographic replic in production ( just one weld) to
> confirm.
>
>
> Need your support .
>
>
>
> Regards.
>
>
>
>
>
> --
>
> زكرياء غراب
> GHRAB Zakaria
>
>
>
> --
> To post to this group, send email to material...@googlegroups.com
> To unsubscribe from this group, send email to
> materials-weld...@googlegroups.com
> For more options, visit this group's bolg at
> http://materials-welding.blogspot.com/
> http://www.linkedin.com/groups/MaterialsWelding-122787?home=

> <http://www.linkedin.com/groups/MaterialsWelding-122787?home=&gid=122787&trk
> =anet_ug_hm> &gid=122787&trk=anet_ug_hm

[Chandrakant Vaidya]

Greetings.

In my view the CS temp.attachments can be welded with Gr 91 mtrl.but not job mtrl.as rightly stated by Pradip & Zakeria.

Regards

C.L.Vaidya

[Kannayeram Gnanapandithan]

Lower critical temp for CS is 723 degree Celsius, how u can allow it to 740

THANKS & BEST REGARDS,

KG.PANDITHAN, IWE,  AWS-CWI, CSWIP 3.1,

CONSULTANT-WELDING & QUALITY

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[Mian gee]

Dear Mr.Pradip Goswami'

                                   Please shared the remaining avrbation of B1,B3,B9 IN TABLE.

[george....@gr.bureauveritas.com]

Don't think that a successful PQR leads always to successful production welds. Do not forget that sound engineering judgement us the first consideration. Therefore I would suggest to use an intermediate low alloy in order to avoid PWHT temperatures which do not are in conflict with lower transformation temperatures

Sent from my BlackBerry 10 smartphone.

From: Chandrakant Vaidya Sent: Πέμπτη, 31 Δεκεμβρίου 2015 - 09:37 To: Materials & Welding Reply To: material...@googlegroups.com Subject: [MW:24018] Re: PQR - WPS - PWHT P91 to CS

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[Vishwas Keskar Welding Manager Pune India]

CS  with Gr 91 - PQR can be successful. But CS will not withstand the high operating temperature (>535 Deg C  or greater).

On Saturday, October 20, 2012 at 3:59:03 PM UTC+5:30, Tunisian Quality Engineer wrote:

Dear eorxperts,

[c sridhar]

The temp of SR for CS could be 620 ± 20 0 for carbon content beyond 0.25 % 

and 600 ± 20 for lesser carbon .

 

The soaking time should be 60 minutes.

 

C Sridhar.

---

 

---

From: Vishwas Keskar Welding Manager Pune India <vvkes...@gmail.com>
To: Materials & Welding <material...@googlegroups.com>
Sent: Saturday, 2 January 2016 10:05 PM
Subject: [MW:24039] Re: PQR - WPS - PWHT P91 to CS

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[c sridhar]

When welding together two steels of different strength it is recommended to select a filler matching the strength 

of the weaker of the two. The lower strength filler metal would provide such benefits as better ductility, improved

weld ability, and lower cost.

Sometimes one can compensate for the reduced strength of the filler metal by increasing the section of the weld

performed, beyond the strict minimum. This practice is called over welding with under matching filler metal.

Preheat is needed in general for carbon content higher than 0.30% or for Hardness equal to or higher than 30 HRC. 

Post Weld Heat Treatment (PWHT) may be needed too in those cases.

For high strength steels one should specify low hydrogen filler metals to reduce susceptibility to cracking.

Requirements for filler metals exhibiting minimum Charpy V-notch (CVN) test value at given low temperatures are 

spelled out in certain Codes.

If stress relieving is required, it may reduce the weld strength. To maintain the strength required from the structure, 

one may need to use low alloy steel filler metals instead of low carbon steel.

Special requirement steels like weathering steels, low alloy steels and quenched and tempered steels may need special consideration  at times.

In conclusion the properties required from the structure to be welded (to perform adequately in service) will condition 

the choices available in the selection of appropriate filler metals.

 

sridhar

From: 'c sridhar' via Materials & Welding <material...@googlegroups.com>

To: "material...@googlegroups.com" <material...@googlegroups.com>
Sent: Sunday, 3 January 2016 5:36 PM
Subject: Re: [MW:24041] Re: PQR - WPS - PWHT P91 to CS

The temp of SR for CS could be 620 ± 20 for carbon content beyond 0.25 % 

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/245037819.5913487.1451822767613.JavaMail.yahoo%40mail.yahoo.com.

[Alan Denney]

This is a response on the general guidelines give in the email below, and not specifically on the subject of P91 to CS.

 

The ‘rule-of-thumb’ given below for situations when preheat is required is not conservative enough and cannot be used to argue that preheat is not required. Preheat of some level is normally necessary when welding carbon steels – of any carbon content. I suggest that one consults a code with more detailed requirements for determining preheat levels such as EN 10011 part 2. [One of many codes or guidance documents covering this subject].

 

Alan Denney

AKD Materials Consulting Ltd

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