How to control cracks when weld P91 and P91

[Roy LIU刘艺]

Dear All,
I just meet a problem from one of my customers.
It is a Boiler Manufactory in China.
 
Details as follow:
base material: P91
process: SMAW (root) + SAW (filler metals)
Heat Input: high  
I=380A
U=35V
V=250mm/min
Preheat, Interpass Temperature: 锟斤拷250锟斤拷
 
How to control cracks?
How to increase impact properties afer PWHT?

 

Best regards

 

Roy LIU

[Prakash Hegde]

A) Cracks in theweld and HAZ depends upon varios factors like

i) Not meeting Uniform through thickness preheating heating and post heating

ii) Weld configuration and temporary supports /stiffeners( excessive stiffener) causing restraint joint including excesive root gap

iii)Weld  and Base metal chemistry having higher Mn,P,S

iv)Improper root run (Effect of oxidation on otherside of root)

 

For improving Impact value

The weld bead configuration and thick ness plays imporatant role in addition to heat input

 

Regards

Hegde P.B.

 

---

From: Roy LIU刘艺 <stand...@hotmail.com>
To: material...@googlegroups.com
Sent: Sun, 14 November, 2010 5:59:37 PM
Subject: [MW:8258] How to control cracks when weld P91 and P91

Dear All,
I just meet a problem from one of my customers.
It is a Boiler Manufactory in China.
 
Details as follow:
base material: P91
process: SMAW (root) + SAW (filler metals)
Heat Input: high  
I=380A
U=35V
V=250mm/min

Preheat, Interpass Temperature: ≤250℃

 
How to control cracks?
How to increase impact properties afer PWHT?

 

Best regards

 

Roy LIU

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[Nandha]

Dear  Roy,

 

Pl, conform  tp P91 by PMI.Because, I have  also china  customer

& their  composition  is  different  from ASTM/BIS.

Review   PQR  once again.

Thanks,

 With Warm Regards,

Keep in touch,

 K.NANDAGOPAL;

09977729258

09360049258-

 

 

 

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Roy LIU??
Sent: Sunday, November 14, 2010 6:00 PM
To: material...@googlegroups.com
Subject: [MW:8258] How to control cracks when weld P91 and P91

 

Dear All,

I just meet a problem from one of my customers.
It is a Boiler Manufactory in China.
 
Details as follow:
base material: P91
process: SMAW (root) + SAW (filler metals)
Heat Input: high  
I=380A
U=35V
V=250mm/min

Preheat, Interpass Temperature: ≤250℃

 
How to control cracks?
How to increase impact properties afer PWHT?

 

Best regards

 

Roy LIU

--

[pgoswami]

Hello Liu,

 

I've attached some information on recommended welding consumables and welding parameters for P-91 steel. Being the products of Metrode certainly these products are very well known in the welding world.

 

The typical formula for heat input as per Sec-IX is = 

  =380X35X60 / 25=3192 J/mm =3.2 KJ/mm

 

The heat input looks to be  at least 25-50% higher than the optimum level 2-2-5. KJ/mm. This may be controlled by increasing the travel speed. SAW welds produces wider HAZ, as compared to SMAW or GTAW. Impact properties for SAW welds are relatively less than GTAW -P-91 weld metal One of the possible causes for reduced impact strength could be higher "Si" in the weld metal and relatively higher input in SAW

 

As regarding PWHT-- all welds in utility (power plant) services would require PWHT at 760°C ± 14°C (1400°F ± 25°F) minimum, regardless of wall thickness or diameter.

 

Te preheat and interpass temperature looks fine.The recommendations  would be :-

 

Controlling Cracks:-For controlling cold cracks, maintain the preheat, interpass control,immediate cooling to 100deg C for complete martensitic transformation as below. Hot cracks could be controlled through a strict control of:C" and 'Si" in the weld.

 

As regarding PWHT:- Ensure the PWHT temperature does not exceed the base metal tempering temperature and stays in the above mentioned temperature range. In fact it would be advisable to work out the best welding parameters after verifying the base metal CMTR(especially impact)

 

Thanks.

 

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Specialist & Consultant

Email-pgoswami@sympatico.ca,

pgos...@quickclic.net

 

---

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Roy LIU??

Sent: Sunday, November 14, 2010 7:30 AM

To: material...@googlegroups.com
Subject: [MW:8258] How to control cracks when weld P91 and P91

Dear All,
I just meet a problem from one of my customers.
It is a Boiler Manufactory in China.
 

Details as follow:
base material: P91
process: SMAW (root) + SAW (filler metals)
Heat Input: high  
I=380A
U=35V
V=250mm/min

Preheat, Interpass Temperature: ≤250℃
 
How to control cracks?

How to increase impact properties afer PWHT?

 

Best regards

 

Roy LIU

--

[pras ari]

Dear Sir,

What can I do, if PWHT can't continue after weld joint complete because it will conduct RT on lower temperature ( < 50 degree), after RT pass PWHT will be proceed (may be 1 or 2 day after).
Please give me reference and heat treatment chart.

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

Your answer is in the paragraph 131.6.2 of ASME B31.1.
I would suggest to add to the Code requirements a hydrogen bake-out treatment (at 200 degC for 2 hours)

best regards

Dr. Georgios Dilintas

Authorized Nuclear Inspector
Authorized Inspector Supervisor


I&F REGIONAL TECHNICAL MANAGER
BUREAU VERITAS HELLAS

Tel: +30 210 40 63 113/4
Fax: +30 210 40 63 118
Cell: +30 69 44 64 62 04
(See attached file: Dilintas_George.vcf)

pras ari ---13/10/2014 16:01:45---Dear Sir, What can I do, if PWHT can't continue after weld joint complete because it

From: pras ari <alhani...@gmail.com>
To: material...@googlegroups.com
Cc: pgos...@quickclic.net
Date: 13/10/2014 16:01
Subject: [MW:22094] Re: MW: 8258- How to control cracks when weld P91 and P91
Sent by: material...@googlegroups.com

---

Dear Sir,

What can I do, if PWHT can't continue after weld joint complete because it will conduct RT on lower temperature ( < 50 degree), after RT pass PWHT will be proceed (may be 1 or 2 day after).
Please give me reference and heat treatment chart.


On Tuesday, November 16, 2010 11:20:16 AM UTC+7, pgoswami wrote:
Hello Liu,
 
I've attached some information on recommended welding consumables and welding parameters for P-91 steel. Being the products of Metrode certainly these products are very well known in the welding world.
 
The typical formula for heat input as per Sec-IX is =

  =380X35X60 / 25=3192 J/mm =3.2 KJ/mm
 
The heat input looks to be  at least 25-50% higher than the optimum level 2-2-5. KJ/mm. This may be controlled by increasing the travel speed. SAW welds produces wider HAZ, as compared to SMAW or GTAW. Impact properties for SAW welds are relatively less than GTAW -P-91 weld metal One of the possible causes for reduced impact strength could be higher "Si" in the weld metal and relatively higher input in SAW
 
As regarding PWHT-- all welds in utility (power plant) services would require PWHT at 760°C ± 14°C (1400°F ± 25°F) minimum, regardless of wall thickness or diameter.
 
Te preheat and interpass temperature looks fine.The recommendations  would be :-
 
Controlling Cracks:-For controlling cold cracks, maintain the preheat, interpass control,immediate cooling to 100deg C for complete martensitic transformation as below. Hot cracks could be controlled through a strict control of:C" and 'Si" in the weld.
 
As regarding PWHT:- Ensure the PWHT temperature does not exceed the base metal tempering temperature and stays in the above mentioned temperature range. In fact it would be advisable to work out the best welding parameters after verifying the base metal CMTR(especially impact)
 

 

Best regards

 

Roy LIU

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

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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[mazlan abd aziz]

Dear friends,

In my current job we maintain the interpass temperature between 200 to 300deg C for P91 material and let it cooling down after weld completed for RT ,so far no crack observed and the hardness test after PWHT showing good result

Best Regards

Mazlan Abd Aziz
Freelance Inspector
Email: mazlan...@gmail.com
    
Mobile:+6019-4772079

On Mon, Oct 13, 2014 at 7:30 PM, pras ari <alhani...@gmail.com> wrote:

This message is eligible for Automatic Cleanup! (alhani...@gmail.com) Add cleanup rule | More info

Dear Sir,

What can I do, if PWHT can't continue after weld joint complete because it will conduct RT on lower temperature ( < 50 degree), after RT pass PWHT will be proceed (may be 1 or 2 day after).
Please give me reference and heat treatment chart.


On Tuesday, November 16, 2010 11:20:16 AM UTC+7, pgoswami wrote:

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

 
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.

[Sayee Raghunathan]

P91 has been shown to be susceptible to SCC in as-welded condition when exposed to even atmospheric condensation and that is why PWHT is carried out typically immediately after completion of welding.

Regards

[Ghafor Mohamad]

Sir

Proceed with postheating for two hours (>315degC) each time finish the weld.

Best Regard
Ghafor Mohamad
SQE
Alstom

[Kannayeram Gnanapandithan]

SMAW for root is  not ok. 

Use GTAW root and Hot pass and then SMAW + SAW

Use induction heating till completion of welding

THANKS & BEST REGARDS

KG.PANDITHAN, AWS-CWI, CSWIP 3.1

CONSULTANT-WELDING & QUALITY