Pre heat requirement for split welding procedures from combined PQR.

[Muhammed Ibrahim]

Hi friends,

 

I would like to clarify one important thing about preheat. My PQR is qualified with SMAW+FCAW. When I start the welding I preheated to 24 degree C. After root and hot pass compleated with SMAW before starting FCAW the plate temperature is 87 degreeC. If I split this PQR to make a WPS only for FCAW, Is it required to preheat the plate to 87 degree C or can I give 24 degree celcius as preheated in the starting of PQR test coupon?. Your response will be highly appreciated.

 

The AI insisting to put preheat of 87 degree shall be considered when we split the PQR for FCAW because when FCAW process starts the temperature of the plate to be considered as the preheat temperature (87 degreeC).

Thanks & Regards
Muhammed Ibrahim PK

[Tulasi Ramu Saka]

Hi,

 

If metal temp is above Preheat temp & below Max. Interpass temp. No problem if u split or combined two processes. below the preheat temp one should not start welding.

so i think you are correct.

further to this we should also consider where this WPS going to use. ie for LTCS ( ITCS) or with PWHT.

 

As per Sec IX QW406.2, preheat is non essential variable.

[ARI]

Dear Ibrahim,

 

You should specify the thickness of the Original PQR and the current thickness of the job, which you intended to utilize FCAW. Based on which only, the experts can respond!

 

regards,

 

[Raj]

The min pre heat shall be 32 Deg C in this case. (87-55)

Rgds

raj

<br

[jhen...@deltak.com]

Your AI is correct. You may not use the 24C preheat recorded for the
SMAW process as a basis for FCAW. Each process is qualified
independently as far as essential variables is concerned. QW-200.2(b)
states, in part: "The completed PQR shall document all essential
variables of QW-250 through QW-280 for each welding process used
during the welding of the test coupon". QW-406.1 is an essential
variable for the FCAW process and therefore the minimum temperature
used during the welding of the FCAW pass(es) becomes the "preheat"
value used for the WPS. Of course, the WPS may have a preheat 100F or
55C less than the lowest recorded temperature for the process per
QW-406.1.

Thickness of base metals, thickness of the deposited weld metal have
no bearing on this - you have two welding processes and the essential
variables shall be recorded for each seperate process and the WPS
shall be based on those values.

In your case, the WPS for the FCAW process (PQR minimum preheat
recorded 87C) may have a minimum preheat of 32C.

If you think about it this makes sense. Assume you were to use GTAW
for the root pass and FCAW for the fill and the material was carbon
steel with a carbon equivalent of, say, 0.55. This material would
have some sensitivity to hydrogen induced cracking. GTAW has very low
hydrogen potential, <H4, and would probably require no preheat above
ambient in order to prevent HIC. However, standard FCAW with a
hydrogen content of >H8 may require preheat to prevent HIC. Would you
want to assign no preheat to a WPS of FCAW only?

We will see what the other pundits have to say. Cheers.

J

[piepe...@kpnmail.nl]

Dear J,

Your explanation is correct regarding the problem with hydrogen cracks
but you call them HIC cracks and in my opinion you only get typical
HIC cracks (better known as stepwise cracking) when a sensitive
material is exposed to a H2S containing gas. Cracks will start
anywhere in the microstructure on dislocations and/or MnS inclusions
because of hydrogen collecting at such location and building op
internal pressure by which the crack will find his way through the
microstructure by following the path with the lowest resistance.

The typical cracks due to Hydrogen during welding mostly called cold
cracking.

Hope this information is useful.

Best Regards,

Herman Pieper

> > Muhammed Ibrahim PK- Tekst uit oorspronkelijk bericht niet weergeven -
>
> - Tekst uit oorspronkelijk bericht weergeven -

[Chaitanya Purohit]

Dear All,

 

I am facing problem during NDT (RT) of Duplex St.Steel) . The RT film shows 4-5” long white indication in the weld area. We tried changing the screen but still the same things appear on the film.

 

The welds are welded with SAW process. Generally the porosities are expected if we use SAW welding for Duplex but this indications are strange for me. Does anybody have experienced the same ?

 

Regards.

 

C. K. Purohit

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[nd...@acuren.com]

How thick is the duplex, what film are they using and what source

Sent from my Verizon Wireless BlackBerry

---

From: "Chaitanya Purohit"
Date: Fri, 27 Mar 2009 11:03:30 +0800
To: <material...@googlegroups.com>
Subject: [MW:1813] RT of Duplex Stainless Steel

[Mohamed Mubarak Syed]

Dear Raj,

 

Could you please explain how become 32 C

 

[Sukamal Naskar]

As on the PQR mentioned for FCAW process the preheating was 79 deg C, and according to QW-406.1, Decrease > 55 deg C is essential variable, hence for this case if in the WPS mentioned Preheating is ( 79 - 55 =32 deg C minimum), then requalification is not required. If the temperature is less than 32 deg C , then requalification is required.

hence it is 32 deg C.

 

Regards

 

[Raj]

QW 200.2(b) : PQR to be documented for each process.

QW 255 : Decrease > 100°F (55°C)  essential variable

 

In this case the recorded pre heat temp of FCAW is 87°C. Therefore the minimum pre heat will be 87-55=32°C

raj

<br

[Sayee Raghunathan]

On a code basis, the explanation given by others limiting the decrease of preheat on WPS to 55Deg C below that of the PQR is correct, and I agree that the preheat shall be the minimum interpass temperature recorded for the FCAW process-55Deg C, purely from a perspective of application/interpretation of ASME Section IX code requirements.

For a more comprehensive answer, the preheat is determined by the combined thickness, the carbon equivalent of the material(s), the level of diffusible hydrogen in the weld metal and the heat input or arc energy of the process. These factors either affect the cooling rate(s) or the hardenability of the material and the susceptibility to hydrogen induced cracking. Higher the hardness in the HAZ and higher the diffusible hydrogen content in the wm, greater is the susceptibility to cracking. The method of calculating the preheat temperatures is explained very clearly in EN 1011-2, which can be downloaded from the BSI website.

Therefore in my personal opinion, I would be looking at which has the lower susceptibility to cracking, the FCAW process with potentially high weld metal hydrogen, 24Deg preheat or with 32Deg preheat and compare with the TIG process with diffusible hydrogen levels <5ml/100gm weld metal, 24Deg preheat and lower arc energy(?). In my personal opinion the change in preheat temperature will hardly be critical for welding C-Mn steels with less than 0.43CEQ (IIW) and thicknesses lower than typically 25mm. I mention this thickness and CEQ limit because from the level of preheat specified by you, I would assume this is the case.

Regards

Sayee

TWI Ltd
Registered Number: 3859442 England
Registered Office: Granta Park, Great Abington, Cambridge, CB21 6AL, UK

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[Chaitanya Purohit]

Dear (ndion),

 

Thickness : 20mm

 

Method : X- ray

 

Film      : Class 2

 

Screen used : 0.125mm Pb

 

Regards.

 

C. K. Purohit

General Manager - QC

KNM Process Systems Sdn Bhd - Malaysia

 

HP No. : 6016-3376448

---

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of nd...@Acuren.com

Sent: Friday, March 27, 2009 11:13 AM
To: material...@googlegroups.com

[nd...@acuren.com]

There are only three things that will cause white indications, tungsten in the weld, contaminated flux or excessive filler material.

Sent from my Verizon Wireless BlackBerry

---

From: "Chaitanya Purohit"
Date: Fri, 27 Mar 2009 15:11:21 +0800
To: <material...@googlegroups.com>
Subject: [MW:1820] RE: 1814] Re: RT of Duplex Stainless Steel

[dharmesh arvadia]

Dear        C.K.P        If this black & white indicatios are cont...You may minimise this white patched by using higher energy x rays.     Best Regards.     D J Arvadia... --- On Fri, 27/3/09, nd...@Acuren.com <nd...@Acuren.com> wrote:

Method : X- ray   Film      : Class 2   Screen used : 0.125mm Pb   Regards.   C. K. Purohit General Manager - QC

Dear All,

Regards.   C. K. Purohit ***DISCLAIMER NOTICE *** "This email and any files transmitted with it is confidential and is intended only for the use of the recepient(s) named above.. If you are not the intended recipient, any review, retransmission, dissemination, distribution, printing, copying or use the information contained in this message or any part thereof in other manner is strictly prohibited. If you receive this email in error, please notify the sender immediately by return email and delete the email and any of its attachments. Any personal views or opinions expressed by the sender shall be understood as neither given nor endorsed by KNM or any of the companies within the Group."

***DISCLAIMER NOTICE *** "This email and any files transmitted with it is confidential and is intended only for the use of the recepient(s) named above. If you are not the intended recipient, any review, retransmission, dissemination, distribution, printing, copying or use the information contained in this message or any part thereof in other manner is strictly prohibited. If you receive this email in error, please notify the sender immediately by return email and delete the email and any of its attachments. Any personal views or opinions expressed by the sender shall be understood as neither given nor endorsed by KNM or any of the companies within the Group."

Add more friends to your messenger and enjoy! Invite them now.

[jhen...@deltak.com]

Sayee,

My reply was based solely on the ASME Section IX code requirements. I
agree with you on the fact that many factors need to be included if
(1) you are going to deviate from Code requirements, (2) have
experienced a cold cracking problem, or (3) are dealing with a
material with which you are unfamiliar. You failed to include in your
list the degree of restraint - more highly restrained joints require
greater preheat.

From my experience, the one common material (ASME Spec.) used in
building routine carbon steel presure vessels, SA-105, which has a
maximum specified carbon content of 0.35%, can easily exceed a carbon
equivalent of 0.43. Thankfully, cold cracking has become a very rare
occurrence, at least in our shops, because most of the filler metals/
processes have reasonably low diffusible hydrogen contents (SMAW,
FCAW, SAW).

Not to say that we don't have our share of welding problems, but cold
cracking is not one of them.

J

On Mar 27, 2:01 am, "Sayee Raghunathan" <Sayee.Raghunat...@twi.co.uk>
wrote:

> _______________________________________________________________________- Hide quoted text -
>
> - Show quoted text -

[nd...@acuren.com]

You should do UT to confirm the indication

Sent from my Verizon Wireless BlackBerry

---

From: nd...@Acuren.com
Date: Fri, 27 Mar 2009 10:57:22 +0000
To: <material...@googlegroups.com>
Subject: [MW:1822] Re: 1814] Re: RT of Duplex Stainless Steel

[ARI]

Hi,

 

By using Type-I films, which has slow speed, very high contrast, & very fine grain, using films Kodak M, TMX, T, Agfa D2, D4, Fuji 50, you may try!!!

 

Regards,

Ari

[nilesh parsekar]

Dear All,

 

          We also encountered the same problem in Duplex but we concluded that it is due high ferrite content in the weld during weld.We send the sample in the lab for analysis and we found that there is a variation in the ferrite content in the two area and due to which we could find the line only in that area.

 

regds

 

Nilesh

--
Nilesh Parsekar
Sr QC Co-ordinator
Exterran Belleli Energy
Fujairah - Sidem
Mobile - 0506561785

[pjo...@technip.com]

Dear all,

Thanks for the good discussion we had in below mails from J and Sayee. I
would just like to add the following from my experience.

When we discuss the Code, we have to judiciously follow the
provisions/limitiations therein. The explanation by J is the most
appropriate so far as the ASME is concerned. In case, the lower preheat
temperature are required to be used, the new qualification may be executed.
That is the only way. This doesnot mean that if we do not follow, there
would be really some problem of the sort we discussed in below mail.

It is something like this. When you are going on a highway, you have to
follow the maximum speed limit specified for the same even though by
exceeding the limit. This may be due to a no. of reasons, as we all know.
Similarly, when we need to follow certain standard, specification, code,
etc. we may have to make the best use of the provisions for our situation
before qualification of procedures and use the worst situation in
qualification so that during actual production welding, there would be
minimum problems.

Best regards,

Prasad



"Sayee
Raghunathan"
<Sayee.Raghunatha To
n...@twi.co.uk> <material...@googlegroups.com
Sent by: >
materials-welding cc
@googlegroups.com
Subject
[MW:1819] RE: 1812] Re: Pre heat
27/03/09 11:01 AM requirement for split welding
procedures from combined PQR.

Please respond to
materials-welding
@googlegroups.com

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[Devang Patel]

can we use fabricated stiffeners in external pressure design of shell of
pressure vessel?

If, yes than please tell, can we use staggered intermittent weld to
fabricate T or Angle?

Please reply.

Regards,

Devang Patel
Manager Engineering

INOX INDIA Ltd.
Ph :+91-265-3056392-3056100
Fax :+91-265-2333398-2341449
email : dev...@inoxindia.com
www.inoxindia.com

[Somesh Kumar Pandey]

Dear Devang,

Fabricated stiffeners can be used in external pressure design of shell
of
pressure vessel as per ASME Sec. VIII Div.1. You can refer UG -29 , Fig.
UG 29.1 , UG-30 & Fig. UG-30 of ASME Sec. VIII Div.1 for more details on
the acceptable method of attaching stiffener rings

Regards

Somesh Kumar Pandey
KBR Energy & Chemicals
79 Anson Road #20-01
Singapore 079906
Office: +65 6210 7459
Fax: +65 6210 7250
Email: Somesh...@kbr.com

-----Original Message-----
From: material...@googlegroups.com
[mailto:material...@googlegroups.com] On Behalf Of Devang Patel
Sent: March 30, 2009 12:24 PM
To: material...@googlegroups.com

This e-mail, including any attached files, may contain confidential and privileged information for the sole use of the intended recipient. Any review, use, distribution, or disclosure by others is strictly prohibited. If you are not the intended recipient (or authorized to receive information for the intended recipient), please contact the sender by reply e-mail and delete all copies of this message.

[Devang Patel]

Thanks, Somesh,

Yes, you are write but my question is can we do staggered intermittent weld
to fabricate the stiffeners?

ASME Sec. VIII Div-1 told about the stiffeners to shell welding only.

Regards,


Devang Patel
Manager Engineering

INOX INDIA Ltd.
Ph :+91-265-3056392-3056100
Fax :+91-265-2333398-2341449
email : dev...@inoxindia.com
www.inoxindia.com

[Somesh Kumar Pandey]

Devang,

As per ASME it is no where specified for external pressure design to use
the staggered intermittent weld to fabricate the stiffeners. Hence, in
my opinion it should not be used. You have to meet the required moment
of inertia for the provided section. It is advisable to fabricate the
stiffener with continuous welding only.

[Johnson Madukayil]

Hi Devang,

I don't think you can.

In the fig UG-29.1 of ASME VIII-1, the term 'butt-welding' is used for stiffener to stiffener welding.

Also, UG-29 (e) states that

Any internal stays or supports used as stiffeners
of the shell shall bear against the shell of the vessel
through the medium of a substantially continuous ring.

The word 'substantially continuous ring' is important here.

Thanks

Johnson Madukayil
Mechanical Engineer
CCI Thermal Technologies Inc.
2721, Plymouth Drive
Oakville, ON L6H 5R5
Canada

[shah B.K]

You can use fabricated stiffener with if it is considered fabricated stiffener in Design Calculation. You can do the staggered intermittent welding on bottom side of the Stiffener.

Regards

B.K.Shah

[Yagnesh Desai]

Its so because the design is guided by buckling and not induced stress.


"Somesh Kumar Pandey" <Somesh...@kbr.com>

"Somesh Kumar Pandey" <Somesh...@kbr.com> Sent by: material...@googlegroups.com 03/30/2009 11:58 AM Please respond to material...@googlegroups.com

To <material...@googlegroups.com> cc Subject [MW:1843] RE: 1841] Re: 1838] Fabricated Stiffeners

[Devang Patel]

If that is the case than why ASME permit a staggered weld between shell to stiffeners weld? As per my opinion we can do staggered weld for stiffeners fabrication b'cas same redial pressure load + Redial shear load (please refer UG-30(e))acting on stiffener weld.

[jmadu...@gmail.com]

Hello Devang,

The Code is not explicit about the use of 'non continuously welded'
stiffener though it talks about permitting intermittently staggered
welding at the stiffener to shell interface for which it gives the
following rule among others:

[UG-30 c): The total length of weld on each side of the stiffening
ring shall be:
(1) not less than one-half the outside circumference of the vessel for
rings on the outside; and
(2) not less than one-third the circumference of the vessel for rings
on the inside.]

Even Section III has the same wording for nuclear pressure vessel
stiffeners.

But, remember UG-29 e) says the following:
[Any internal stays or supports used as stiffeners of the shell shall

bear against the shell of the vessel through the medium of a
substantially continuous ring.]

The use of the phrase 'substantially continuous ring' is very
important here. A substantially continuous ring definitely cannot be a
ring that is fabricated by staggered welding.

So far as the Code goes, it is only concerned about the design of
pressure retaining components and gives minimum guidelines for the
same. Everything else is left to the engineering judgement of an
engineer who is supposedly sound in his or her engineering
fundamentals.

Per the Code [The Code is not a handbook and cannot replace education,
experience, and the use of engineering judgment. The phrase
engineering judgment refers to technical judgments made by
knowledgeable designers experienced in the application of the Code.
Engineering judgments must be consistent with Code philosophy and such
judgments must never be used to overrule mandatory requirements or
specific prohibitions of the Code.]

If I were your customer and if you were to use staggered welded
stiffener ring, I would certainly ask you to provide structural
calculations proving that this construction does not compromise the
design (the same way I would expect calculations for the saddle
support or lugs or legs, where seismic or wind loads apply over and
above the static and weight loads).


Regards

Johnson Madukayil, P.Eng.
Canada

On Mar 31, 12:57 am, "Devang Patel" <deva...@inoxindia.com> wrote:
> If that is the case than why ASME permit a staggered weld between shell to stiffeners weld? As per my opinion we can do staggered weld for stiffeners fabrication b'cas same redial pressure load + Redial shear load (please refer UG-30(e))acting on stiffener weld.
>
> Regards,
>
> Devang Patel
> Manager Engineering
>
> INOX INDIA Ltd.
> Ph :+91-265-3056392-3056100
> Fax :+91-265-2333398-2341449

> email : deva...@inoxindia.comwww.inoxindia.com

>
>   ----- Original Message -----
>   From: Yagnesh Desai
>   To: material...@googlegroups.com
>   Sent: Tuesday, March 31, 2009 9:42 AM
>   Subject: [MW:1850] Re: 1841] Re: 1838] Fabricated Stiffeners
>
>   Its so because the design is guided by buckling and not induced stress.
>

>   "Somesh Kumar Pandey" <Somesh.Ku...@kbr.com>
>
>                 "Somesh Kumar Pandey" <Somesh.Ku...@kbr.com>

>                 Sent by: material...@googlegroups.com
>                 03/30/2009 11:58 AM Please respond to
>                       material...@googlegroups.com
>

>               To
>               <material...@googlegroups.com>
>
>               cc
>
>               Subject

>               [MW:1843] RE: 1841] Re: 1838] Fabricated Stiffeners
>

>   Devang,
>
>   As per ASME it is no where specified for external pressure design to use
>   the staggered intermittent weld to fabricate the stiffeners. Hence, in
>   my opinion it should not be used. You have to meet the required moment
>   of inertia for the provided section. It is advisable to fabricate the
>   stiffener with continuous welding only.
>
>   Regards
>
>   Somesh Kumar Pandey
>   KBR Energy & Chemicals
>   79 Anson Road #20-01
>   Singapore 079906
>   Office: +65 6210 7459
>   Fax: +65 6210 7250

>   Email: Somesh.Ku...@kbr.com

>
>   -----Original Message-----
>   From: material...@googlegroups.com
>   [mailto:material...@googlegroups.com] On Behalf Of Devang Patel
>   Sent: March 30, 2009 1:48 PM
>   To: material...@googlegroups.com
>   Subject: [MW:1841] Re: 1838] Fabricated Stiffeners
>
>   Thanks, Somesh,
>
>   Yes, you are write but my question is can we do staggered intermittent
>   weld
>   to fabricate the stiffeners?
>
>   ASME Sec. VIII Div-1 told about the stiffeners to shell welding only.
>
>   Regards,
>
>   Devang Patel
>   Manager Engineering
>
>   INOX INDIA Ltd.
>   Ph :+91-265-3056392-3056100
>   Fax :+91-265-2333398-2341449

>   email : deva...@inoxindia.com

>  www.inoxindia.com
>
>   ----- Original Message -----
>   From: "Somesh Kumar Pandey" <Somesh.Ku...@kbr.com>
>   To: <material...@googlegroups.com>
>   Sent: Monday, March 30, 2009 10:45 AM
>   Subject: [MW:1840] RE: 1838] Fabricated Stiffeners
>
>   Dear Devang,
>
>   Fabricated stiffeners can be used in external pressure design of shell
>   of
>   pressure vessel as per ASME Sec. VIII Div.1. You can refer UG -29 , Fig.
>   UG 29.1 , UG-30 & Fig. UG-30 of ASME Sec. VIII Div.1 for more details on
>   the acceptable method of attaching stiffener rings
>
>   Regards
>
>   Somesh Kumar Pandey
>   KBR Energy & Chemicals
>   79 Anson Road #20-01
>   Singapore 079906
>   Office: +65 6210 7459
>   Fax: +65 6210 7250

>   Email: Somesh.Ku...@kbr.com

>
>   -----Original Message-----
>   From: material...@googlegroups.com
>   [mailto:material...@googlegroups.com] On Behalf Of Devang Patel
>   Sent: March 30, 2009 12:24 PM
>   To: material...@googlegroups.com
>   Subject: [MW:1838] Fabricated Stiffeners
>
>   can we use fabricated stiffeners in external pressure design of shell of
>
>   pressure vessel?
>
>   If, yes than please tell, can we use staggered intermittent weld to
>   fabricate T or Angle?
>
>   Please reply.
>
>   Regards,
>
>   Devang Patel
>   Manager Engineering
>
>   INOX INDIA Ltd.
>   Ph :+91-265-3056392-3056100
>   Fax :+91-265-2333398-2341449

>   email : deva...@inoxindia.com

>  www.inoxindia.com
>
>   This e-mail, including any attached files, may contain confidential and
>   privileged information for the sole use of the intended recipient.  Any
>   review, use, distribution, or disclosure by others is strictly
>   prohibited.
>   If you are not the intended recipient (or authorized to receive
>   information
>   for the intended recipient), please contact the sender by reply e-mail
>   and
>   delete all copies of this message.
>
>
>

>  graycol.gif
> < 1KViewDownload
>
>  ecblank.gif
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[Tirumala B N Tagore]

Provided stiffener 's Section modulus shall be valid through out its length. Therefore fabricated angle or T shall be with continuous welds only. Staggering , intermediate welds are applicable  for shell  to stiffener weld only.

Tagore