ASME BPV Sec VIII div1 , UCS-68(b) - PWHT requirements

[Raghuram Bathula]

Can you please provide your interpretation for the following requirements of UCS-68(b)
Vessel MDMT - 48 °C , PWHT - not required

In accordance with para UCS-68(b) PWHT is required except for Category A and B joints with 100% RT, lightly loaded attachments and seal welds only.
and it is silent on category C , D welds and other attachments.

Question: does this mean PWHT is required for Category C and D, even though it is exempted for Category A and B welds? then vessel will undergo local PWHT
In my opinion we should not interpret this way and look for only what is code specifies (i.e. if Category A and B or other welds as specified is exempted entire vessel is exempted)  

[MW]

If a weld joint has a coincident ratio higher then 0,35 then the same need to be PWHT with the following exemptions from PWHT (even if coincident ratio is higher than 0.35):   

Category A and B joints which respect the condition indicated in UCS-68(b)(1) - e.g. 100%RT.

Lightly loaded attachments (<25% stress value) which respect the condition indicated in UCS-68(b)(2)(-a) 

Seal welds (tube to tube sheet)

 It does not exempt from PWHT the category “C” and “D” joints , and fillet welds (except as defined as “lightly loaded attachments” 

[govindan krishnamoorthy]

Since the Code is specifically indicated exemption only  for Category A and B joints. ( I checked for ASME INTREPRATION sheet not found any specific on this query).

Hence , this does not give provisions to take exemption credit for other categories which doesn't indicated in the code specifically. 

Plz provide if u have any latest interpretation if any for further discussion. 

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From: material...@googlegroups.com <material...@googlegroups.com> on behalf of MW <raghura...@gmail.com>
Sent: Wednesday, 23 September 2020, 11:06
To: Materials & Welding
Subject: [MW:31500] Re: ASME BPV Sec VIII div1 , UCS-68(b) - PWHT requirements

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[George Dilintas]

Yes C and D welds are not exempted. most probably because a geometrical discontinuity is always associated with a C and D weld.

There is also an interpretation relevant to UCS-68(b):

Standard Designation:	BPV Section VIII Div 1
	Edition/Addenda:
	Para./Fig./Table No:
	Subject Description:	Section VIII, Division 1 (1998 Edition, 1999 Addenda); UCS-68(b)
	Date Issued:	01/14/2000
	Record Number:	BC99-597
	Interpretation Number :	VIII-1-98-99
	Question(s) and Reply(ies):	Question: Do the requirements of UCS-68(b) in Section VIII, Division 1 apply to tube-to-tubesheet welds? Reply: Yes.

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Dr. Georgios Dilintas,

Dipl. Ing. In Aeronautic and Space Engineering

Ph.D in Mechanics of Solids - Computational Mechanics

A.I.S, A.N.I, IRCA Lead Auditor

Welding, Stress Analysis, Corrosion, QA/QC, Failure Analysis, Risk Analysis