Difference between Control thickness & nominal material thickness ( Para. 331.1.3(c)

[anhtrangnghieng]

Dear Experts, 

Could you please advise me for following question: 

Which thickness , Control thickness or Nominal material thicness as defined in Para. 331.1.3(c), shall be used to determine whether PWHT required or not in case preheat of 95 Deg C is NOT applied ? ( P-No. 1)

For case below, in accordance with ASME B31.3 2016 Ed , PWHT is required or not when preheat of 95 Deg C is NOT applied ? 

Thanks in advance.

[Kannayeram Gnanapandithan]

Both are used in different occasions

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[anhtrangnghieng]

Dear Experts, 

Re-send with the attached files: 

Could you please advise me for following question: 

Which thickness , Control thickness or Nominal material thickness as defined in Para. 331.1.3(c), shall be used to determine whether PWHT required or not in case preheat of 95 Deg C is NOT applied? ( P-No. 1)

For case below ( see Picture 1) , in accordance with ASME B31.3 2016 Ed , PWHT is required or not when preheat of 95 Deg C is applied? 

Thanks in advance.

Vào Th 7, 3 thg 8, 2019 vào lúc 11:59 anhtrangnghieng <anhtran...@gmail.com> đã viết:

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[Bien_ND / weldinginspections.net]

See Note 2 and Para. 331.1.3 Definitions of thickness.

Regards

Bien ND

[anhtrangnghieng]

Dear Gents, 

Pls help me to clarify: 

Which thickness , Control thickness or Nominal material thicness as defined in Para. 331.1.3(c), shall be used to determine whether PWHT required or not in case preheat of 95 Deg C is NOT applied ? ( P-No. 1)

Thank you.

Vào 14:19, CN, 11 Th8, 2019 Bien_ND / weldinginspections.net <bck...@gmail.com> đã viết:

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[pkra...@gmail.com]

Control thickness is the thickness of weld and Nominal material thickness is the thickness of material

PWHT Requirement is based on control thickness (Table 331.1.3)

Preheat requirement is based on nominal material thickness

Hope you understand

Raneesh pk

QC Engineer

UAE 

[Kannayeram Gnanapandithan]

Not only control thickness. 

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[atul khatri]

Hello all,

Here in the particular case the controlled thickness at weld shall be 6 mm.

Now as per table 331.1.3, for P.No-1 , for all control thickness , PWHT is exempted only if preheat of 95 deg c is applied on nominal material thickness > 25 mm. Here nominal material thickness is defined as thicker of the materials being joined.

So in this case, preheat shall require before welding.

thanks & regards

Atul Khatri

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[Kannayeram Gnanapandithan]

Nominal material Thickness as  Example--- Pressure pipe is supported by another pipe( non pressure part) is being welded, Pressure part pipe thickness is 20mm whereas non pressure part thickness is 10mm,  In this case Nominal material thickness is 20mm. This is my understanding

 

THANKS & BEST REGARDS,

KG.PANDITHAN, BE, IWE,  CSWIP 3.1,

ISO 9712 Level 2 in VT,

ASNT-Level II in PT,MT,RT & UT,

LA ISO 9001-2015,

International Welding Engineer. 

CONSULTANT-WELDING & QUALITY

Mobile no: +919940739349

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[anhtrangnghieng]

Dear Gents, 

i understand that if control thickness less than 25.4 mm , preheat & PWHT is not required as per Code ? 

thank you. 

Vào Th 6, 23 thg 8, 2019 vào lúc 15:25 Kannayeram Gnanapandithan <kgpan...@gmail.com> đã viết:

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[atul khatri]

No, Exemption on PWHT is based on Nominal thickness not control thickness.

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[Raghuram Bathula]

The control thickness (nothing but a governing thickness for PWHT)  is defined in para. 331.1.3 (a) shall be used.

[atul khatri]

Hi  anhtrangnghieng,

It seems that your question and the subsequent answers have created some confusion.

Your last question:
"i understand that if control thickness less than 25.4 mm , preheat & PWHT is not required as per Code ?   "- Yes , PWHT can be exempted for all control thickness  (even if greater than 25.4 mm ) but  if your nominal thickness is > 25mm than preheat is required for PWHT exemption. In your case if i remember correctly, your nominal thickness was 30 mm so preheat is required.

Hope it clears.

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