PWHT OF P91 BY INDUCTION HEATING

[sandeep monody]

Dear experts,

 

In my site we conducted a demonstration of PWHT on SA335 P91 material (OD-450mm X 70mm Thk) as our clients requirement and details as given below.

 

Heating/cooilng rate;-60 deg C,Holding temparature:-760deg C and holding time:-180minutes,Heating band width:-210mm and insulation band width 630mm,Heating method :-Induction heating

 

During pwht we observed a temparature difference on outside and inside of pipe more than 80 deg C.

 

Now problem is that client is not accepting this method and asking for uniform temparature in outside and inside of pipe.

 

How can i control temparature at both sides?

Is it possible a uniform temp on both side with induction heating?

 

Please give ur valueble advice in this matter.

 

 

Sandeep.

QC Engr

[Harish Kannepalli]

Dear sandeep,

                 Please try putting coil inside the pipe also. As per code more than 60°C difference is not allowed.

2012/3/24 sandeep monody <smv.m...@gmail.com>

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regards,

Harish.

[MEERAN]

Try to put metal plug dummy on both side of the joint to avoid heat losses for maintaining the temperature

Nagoor Meeran

L&T-KAPP

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[E.S.Mani]

Dear Harish,

Can you please tell me which code is accepting the 60°C difference & where.

Regards,

E.Subramanian.

On Mon, Mar 26, 2012 at 4:13 PM, E.S.Mani <mani...@gmail.com> wrote:

Dear sandeep,

 

Ya this is not acceptable. Because the temperature difference range is 732 Deg, C to 774 Deg C for P15E material as per B31.3 (2010 Edition).

 

I have understood from your mail, there is access to put the thermocouple means you can put more thermo wool to with stand the heat & start to monitor the temperature recorder, still it is coming down try to put more wool & dummy on both sides.

Regards,

E.Subramanian/Balaji.R

--

Regards,

E.Subramanian

--

Regards,

E.Subramanian

[E.S.Mani]

Dear sandeep,

 

Ya this is not acceptable. Because the temperature difference range is 732 Deg, C to 774 Deg C for P15E material as per B31.3 (2010 Edition).

 

I have understood from your mail, there is access to put the thermocouple means you can put more thermo wool to with stand the heat & start to monitor the temperature recorder, still it is coming down try to put more wool & dummy on both sides.

Regards,

E.Subramanian/Balaji.R

On Sun, Mar 25, 2012 at 12:04 AM, Harish Kannepalli <harishka...@gmail.com> wrote:

--

Regards,

E.Subramanian

[sandeep monody]

Dear Mani/Balaji,

 

This was a demonstration of PHWT which we are going to follow on jobs,so client is not allowing to put wool inside.They want PHWT demo in the same manner ,which we are going to do on jobs. We had put metal dummy on both sides but no wool or coil.This is thermal power plant project and the acceptance codes are ASME sec I & ASME B31.1

 

Thanks &Regards

 

Sandeep.M.V

QC Engineer

[sandeep monody]

Dear Mani/Balaji,



This was a demonstration of PHWT which we are going to follow on
jobs,so client is not allowing to put wool inside.They want PHWT demo
in the same manner ,which we are going to do on jobs. We had put metal
dummy on both sides but no wool or coil.This is thermal power plant
project and the acceptance codes are ASME sec I & ASME B31.1



Thanks &Regards



Sandeep.M.V

QC Engineer

On Mar 26, 1:13 pm, "E.S.Mani" <manie...@gmail.com> wrote:
> Dear sandeep,
>
> Ya this is not acceptable. Because the temperature difference range is 732
> Deg, C to 774 Deg C for P15E material as per B31.3 (2010 Edition).
>
> I have understood from your mail, there is access to put the thermocouple
> means you can put more thermo wool to with stand the heat & start to
> monitor the temperature recorder, still it is coming down try to put more
> wool & dummy on both sides.
>
> Regards,
>
> E.Subramanian/Balaji.R
>
> On Sun, Mar 25, 2012 at 12:04 AM, Harish Kannepalli <
>
>
>
>
>
> harishkannepa...@gmail.com> wrote:
> > Dear sandeep,
> >                  Please try putting coil inside the pipe also. As per code
> > more than 60°C difference is not allowed.
>

> > 2012/3/24 sandeep monody <smv.mon...@gmail.com>

> *
> Regards,
>
> E.Subramanian*
>
>

[Harish Kannepalli]

Dear sandeep,

                     Please refer ASME Section VIII Div.1 UCS-56.

2012/3/26 E.S.Mani <mani...@gmail.com>

--

regards,

Harish.

[pgoswami]

Hi Sandeep,

 

Service application of Grade 91 steel is  for very demanding applications, which involve extremely high design pressure and temperature.Anything wrong  associated with fabrication could cause serious harm both to plant and equipments as well as to human beings.

 

From the description provided below the intended design or application would be the main steam line for a super critical power plant, which would be designed for extremely high pressure and temperature. In as welded  condition P-91 alloys would invariably have a hardness of 350BHN or more. Upon PWHT hardness  could be reduced to any value between 240-280 HB.Many utilities restrict this hardness values to 275 HB Max .

 

From the PWHT scenario by  induction coils if the temperature difference between OD and ID is more than 80 deg C, then the I.D (wetted surface) would not be properly post weld heat treated and evenly tempered at all. The resultant hardness could be anyone's guess ?? Such a heat treatment condition would definitely not be acceptable to any client

 

AWS-D-10.10, the universally accepted standard for local PWHT in piping accepts induction heating as one of the methods for local PWHT. As per this code the  frequencies coils to be used are typically 60,480 and 9600 HZ. Higher the frequency quicker would be  the heating, but the heat would stay more on the skin (OD) and would  cause hot spots.Thus a moderate frequency for coils and a slower heating and cooling rate  from 600 deg C upwards would be desirable, along with the insulations inside the pipe to minimize heat losses.The heat treating contractor has to demonstrate that soaking temperature of 740- 760 Deg (usually recommended for P-91steel in electric utilities) is achieved both in the O.D and I.D.

 

As a due diligence , if  the  PWHT mockup could  be sectioned in the lab and  hardness gets recorded it would provide far more confidence on the PWHT method with induction heating.

 

You may find the attached article and the link below as a good resource. In the hyperlink below look at page 50, which shows the significant cross sectional variance of hardness in grade -91 alloys.Also author of the paper(Jonathan.Parker) is a well known authority on P-91 fabrication and life management and is  known to us.

 

I hope the attached information would be of good use to you.

 

Thanks.

 

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario, Canada.

Email-p...@sympatico.ca,

pgos...@quickclic.net

 

 

1. www.vgb.org/en/event_mqa_pres.html?dfid=23397

 

---

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Harish Kannepalli
Sent: Saturday, March 24, 2012 12:04 PM
To: material...@googlegroups.com
Subject: [Norton AntiSpam]Re: [MW:13986] PWHT OF P91 BY INDUCTION HEATING

[MM]

Dear Sandeep,

 

If you are doing PWHT for Sec VIII Div 1 requirements then refer UCS 56 (d) (3)

 

(3) The vessel or vessel part shall be held at or above

the temperature specified in Table UCS-56 or Table UCS-

56.1 for the period of time specified in the Tables. During

the holding period, there shall not be a greater difference

than 150°F (83°C) between the highest and lowest temperature

throughout the portion of the vessel being heated,

except where the range is further limited in Table UCS-56.

 

Cheers

MM

[sandeep monody]

Dear Pradip Sir,

Thank you very much for your valuable information. Still some doubts
are there as given below.

As per AWS D10.10( Clause2.3.1)temperature variation up to 83deg is
acceptable and AWS D10.10 itself says that there is no way to
eliminate temperature variation though out the wall thickness(Clause
2.3).

Actually in our site we have materials with various thicknesses and
some up to 139mm and now question is.. what will be the temperature
variation for 139mm thickness(On jobs its not possible to measure
inside temperature).

Have any equation or formula to find out the temperature variation
throughout the thickness?

Have any role of Thermal conductivity of P91 in this case?

Is it possible a uniform temperature at OD and ID regardless of
thickness?

Awaits for your reply

Thanks and regards

Sandeep
QC Engineer

[bijoy joseph]

Temperature differeancr is lesssthan 20-30 degree is acceptable.  how you can measure inside and out side temperature.you put 3 thermocouple 120 degree aprat out dide of the pipe and the temerature differeane max is 30 dedegree

--

[pgoswami]

Sandeep,

 

AWS D-10.10 is written to facilitate local PWHT for all types of C-Mn and low alloy steels. Grade-91 requires special considerations. Attached is the specification for P-91 and P-92 steels written by one of the well reputed EPC organization in North America. This specification,though a bit generic is downloadable form the link below.

 

I ve highlighted the clauses very relevant to local PWHT on P-91 . You may read and use these recommendations at your discretion.

 

To answer to your point, P-91 requires a complete soak at the suggested PWHT cycle. For guidance in the  attached spec  if the O.D is @ 760 Deg then the ID should be 730 Deg.If induction heating of up to 139 mm thickness could attain this temperature range, then this technique would be acceptable otherwise do not use it subject to your client and your management's discretion.

 

As I mentioned before P-91 is a dangerous steel, IT IS NOT JUST ANOTHER Cr-Mo steel. Hence one has to ensure that a through PWHT is performed on weld of this grade.

 

I have cross referred the clauses of D-10.10, you had mentioned in your earlier email.But AWS interpretation(see attached) looks different.

 

Also see below the purple colored text on what AWS recommends on uniformity of temperature for a PWHT operation.

 

I would say discuss this issue with the PWHT contractor such that the temperature could be maintained within the range as specified above.

 

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist & Consultant
Ontario, Canada.
Email-p...@sympatico.ca,
pgos...@quickclic.net

http://www.scribd.com/doc/47805169/Q110-Welding-of-9Cr-1Mo-V-Grade-91-and-9Cr-2W-Grade-92

 

D -10.10

11.1 Temperature Uniformity. Requirements regarding temperature uniformity are generally specified separately for the heating/cooling and hold portions of the PWHT cycle. ASME Section III limits temperature variation during heating and cooling to not more than 250°F (138.9°C) within any 15 ft (4.6 m) interval of weld length. This limit generally acts as a circumferential temperature gradient due to the fact that it is most often applied to  heating of circumferential butt welds. The requirement in B31.3 which states "The heating method shall provide the required metal temperature, metal temperature uniformity,... " does not provide useful guidance. Generally, the required uniformity during the hold period amounts to staying within the bounds of the maximum and minimum temperature requirements specified by the codes.

Concerns about temperature uniformity during PWHT are related to the resulting stresses and possible distortion or cracking which could occur as discussed in 11.2 and 11.4. Use the lesser of the maximum temperature differences shown below or that provided in the governing document for PWHT.

Maximum Recommended Temperature Differences for PWHT:- During heating and cooling, the maximum temperature difference within the heated band should be 250°F (139°C) or as limited by the maximum axial temperature gradient.During hold, the maximum temperature difference within the soak band should be 100°F (55°C) or the allowed temperature range, whichever is less. During hold, the maximum temperature difference around any circumferential plane within that portion of the heated band outside of the soak band should be 100°F (55°C)

] On Behalf Of sandeep monody

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[pgoswami]

Sandeep,

 

AWS D-10.10 is written to facilitate local PWHT for all types of C-Mn and low alloy steels. Grade-91 requires special considerations. Attached is the specification for P-91 and P-92 steels written by one of the well reputed EPC organization in North America. This specification,though a bit generic is downloadable form the link below.

 

I ve highlighted the clauses very relevant to local PWHT on P-91 . You may read and use these recommendations at your discretion.

 

To answer to your point, P-91 requires a complete soak at the suggested PWHT cycle. For guidance in the  attached spec  if the O.D is @ 760 Deg then the ID should be 730 Deg.If induction heating of up to 139 mm thickness could attain this temperature range, then this technique would be acceptable otherwise do not use it subject to your client and your management's discretion.

 

As I mentioned before P-91 is a dangerous steel, IT IS NOT JUST ANOTHER Cr-Mo steel. Hence one has to ensure that a through PWHT is performed on weld of this grade.

 

I have cross referred the clauses of D-10.10, you had mentioned in your earlier email.But AWS interpretation(see attached) looks different.

 

Also see below the purple colored text on what AWS recommends on uniformity of temperature for a PWHT operation.

 

I would say discuss this issue with the PWHT contractor such that the temperature could be maintained within the range as specified above.

 

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist & Consultant
Ontario, Canada.
Email-p...@sympatico.ca,
pgos...@quickclic.net

http://www.scribd.com/doc/47805169/Q110-Welding-of-9Cr-1Mo-V-Grade-91-and-9Cr-2W-Grade-92

 

D -10.10

11.1 Temperature Uniformity. Requirements regarding temperature uniformity are generally specified separately for the heating/cooling and hold portions of the PWHT cycle. ASME Section III limits temperature variation during heating and cooling to not more than 250°F (138.9°C) within any 15 ft (4.6 m) interval of weld length. This limit generally acts as a circumferential temperature gradient due to the fact that it is most often applied to  heating of circumferential butt welds. The requirement in B31.3 which states "The heating method shall provide the required metal temperature, metal temperature uniformity,... " does not provide useful guidance. Generally, the required uniformity during the hold period amounts to staying within the bounds of the maximum and minimum temperature requirements specified by the codes.

Concerns about temperature uniformity during PWHT are related to the resulting stresses and possible distortion or cracking which could occur as discussed in 11.2 and 11.4. Use the lesser of the maximum temperature differences shown below or that provided in the governing document for PWHT.

Maximum Recommended Temperature Differences for PWHT:- During heating and cooling, the maximum temperature difference within the heated band should be 250°F (139°C) or as limited by the maximum axial temperature gradient.During hold, the maximum temperature difference within the soak band should be 100°F (55°C) or the allowed temperature range, whichever is less. During hold, the maximum temperature difference around any circumferential plane within that portion of the heated band outside of the soak band should be 100°F (55°C)

-----Original Message-----
From: material...@googlegroups.com [mailto:material...@googlegroups.com

] On Behalf Of sandeep monody

Sent: Wednesday, March 28, 2012 2:58 AM
To: Materials & Welding

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[sandeep monody]

Dear Pradip Sir,

Thank you very much for valueble informations. We are going to conduct
another PWHT mock test,considering all these facts and skilled
technicians have been called for the same.

Regards,


Sandeep
Qc Engineer

[kannayeram gnanapandithan]

For Local PWHT of P91, Induction Heating is best method compare to
Resistance pad heating as temp diff is more in Resistance heating and
also ensure that it does not cross over 775 degree celsius
we have done lot on P/T91 from thick 6mm to 60 mm
Pandithan
Welding Consultant

On 2/13/13, Chinnapureddy Kotireddy <chinnapured...@gmail.com> wrote:
> Dear Sandeep,
> I have also got similar problem
> By using induction heating for PWHT of p91,There is a huge difference
> between the temp of ID and OD.
> Kindly share your experience and suggestions so that it may benefit us to
> proceed furthur in PWHT of p91
>
> koti
> cell:9486575298

>
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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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[HAREESH K V]

Dear Sir,

May you please specify what is the size of the pipe/vessel.

Regards,

Hareesh K V 

On Wed, Feb 13, 2013 at 9:41 PM, Chinnapureddy Kotireddy <chinnapured...@gmail.com> wrote:

Dear Sandeep,
I have also got similar problem
By using induction heating for PWHT of p91,There is a huge difference between the temp of ID and OD.
Kindly share your experience and suggestions so that it may benefit us to proceed furthur in PWHT of p91

koti
cell:9486575298

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Hareesh K V
+91-9447625012

[Bala Nechur]

Hello Reddy,

 

What was the difference in temperature?

 

Bala

7802040239

 

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Chinnapureddy Kotireddy
Sent: February 13, 2013 9:12 AM
To: material...@googlegroups.com
Subject: [MW:16758] Re: PWHT OF P91 BY INDUCTION HEATING

 

Dear Sandeep,
I have also got similar problem
By using induction heating for PWHT of p91,There is a huge difference between the temp of ID and OD.
Kindly share your experience and suggestions so that it may benefit us to proceed furthur in PWHT of p91

koti
cell:9486575298

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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.

[bijoy joseph]

Dear sir,
 You have to provide  insulation to pipe inner surface to  protect the heat loss by convection. Marginal changes you  can observe.Additionally both end of the pipe you have to close to protect the free air movement. Zero temperature difference is not possible 10 to 15 degree may happen.You have to go ahead with induction method.

bijoy joseph

On Thu, Feb 14, 2013 at 2:42 PM, vineet kumar <vinee...@gmail.com> wrote:

Dear ,

Attached procedure might help you.

Regards,

Vineet

--