Is PWHT required

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Nadakuditi kiran kumar

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Oct 2, 2019, 1:06:12 AM10/2/19
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Dear Gentleman,
We have received two vessels as per drawing. ASME U stamp done on both vessels, there is one bottom outlet nozzle of 6"NB in both vessels. Now client is asking us to remove the flange of the nozzle and hook up with piping. My doubt is 
1. Whether we have to take approval from authorized inspector before going to do any modification.
2. After hook up we have to do PWHT for that hook up joint
Please clarify, if possible please provide code reference.
Line SERVICE not call any PWHT
Construction code for vessel is ASME Sec VIII, Div 1, piping construction code is B 31.3.

Thanks in advance,


Hemant W Joshi

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Oct 3, 2019, 4:30:07 AM10/3/19
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Without knowing the piping matl or thickness, it would be imprudent to provide opinion about PWHT.

The flange it is assumed is a SO.  

Certainly it is required to communicate to the inspector for reinspection/restamping.   

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José Juan Jiménez Alejandro

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Oct 3, 2019, 4:30:08 AM10/3/19
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Greetings !, I see that it is a modification or alteration, usually this type of work is stamped "R" of the NB, I suggest you speak it with your Authorized Inspector that you have assigned to your company (this in case your company is certified with ASME and NB), as for the PWHT depends on the number P of the material and its thickness, consult it with your ASME Inspector.
Regards!.

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Rishikesh Kumar

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Oct 3, 2019, 6:07:07 AM10/3/19
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it is advice to do any modification or alteration with proper procedure.  this procedure shall be required approval from client / nominated TPI. PWHT depends on various parameters line P. No./ Group No. /thickness/ Pressure part/No Pressure parts etc  UCS -56 is refer for the same for decide PWHT required. 
for eg: for carbon steel grade material UCS-56-1 is applied. further there is provision provided to perform welding with preheating upto thickness 38mm ( general note a) and b)) without preheating. the similar provision is also incorporated in latest edition of B31.3 
Regards
Rishikesh kumar 

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Nadakuditi kiran kumar

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Oct 3, 2019, 7:42:39 AM10/3/19
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dear gents,
Please find below mentioned details.
MOC is A333 Gr 6, thickness of nozzle is 6" NB-14.27mm, pipe thickness is 6" NB -7.11 mm. Flange is WNRF - A350 LF2{(Which needed to be cut).


Hemant W Joshi

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Oct 4, 2019, 6:03:34 AM10/4/19
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Considering that A333 gr.6 is P-1 , there appears to be no PWHT requirement as per 31.3 table 331.1.1purely for the butt weld joint between the pipe portion of nozzle and the piping to be hooked up with it considering the pipe thickness .

 

It would be better if the specification writeup is shared to understand as to why PWHT has been put in place for the piping concerned as per your statement.  

Rishikesh Kumar

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Oct 4, 2019, 6:34:23 AM10/4/19
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Since both the material are  P No. 1.  it may proceed since  this alteration is required from your end. However,  proper procedure  from Initial stage ( removal) to final stage (NDT) should be  informed  and get approval if required and recorded for future reference.
further, please make sure,  welding shall be  performed with established WPS and qualified Welder.
Regards
Rishikesh kumar

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CLV

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Oct 6, 2019, 11:40:19 PM10/6/19
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As suggested by Jose the modification must be under R stamp,if u hv completed MDR & registered with NB.
Modification is possible as per customers requirements.Also PWHT after modifications may not be required if WPS/PQR is available.
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