Table 331.1.3 is granting an exemption for PNo1 BASED ON NOMINAL THICKNESS. Note 6 says that the nominal thickness is defined in 331.1.(c). Looking in this para the nominal thickness is the thickness of the thicker parts.
So if it is below 25 mm you dont need preheat to get exemption
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, 14 Ī£ĪµĻ 2020 ĻĻĪ¹Ļ 11:02 Ļ.Ī¼., Īæ/Ī· Nazeer <naz.mhd@gmail.com> ĪĪ³ĻĪ±ĻĪµ:
Dear All,Request Clarification on which thickness (Control thickness / Nominal thickness) to be applied in the B31.3 2014 -Table 331.1.3 for PWHT & Preheat exemption. Details furnished below.Weld Joint Details:Joint : Header Pipe to WeldoletWeld Type: Integrally Reinforced Branch Connection (B31.3, Fig 3285.4)Material: P.No 1Header Pipe Size: NPS 16 , 12.7mm thickWeldolet Size: NPS 16 x NPS 3 , sch 40joint groove Thickness (At crotch of Header pipe & weldolet): 22mmNominal Thickness (Tm) As per B31.3, Fig 3285.4 : 22mmCalculated Control Thickness (Tm+Tc): 28mm (22 + 6mm)Based on above scenario, we had applied weldolet nominal material thickness Tm of 22mm (thicker member of the joint) on B31.3 Table 331.1.3 and not performed PWHT & preheat of 95 Deg C.Whereas for PWHT exemption, Client is applying the control thickness of 28mm on B31.3 Table 331.1.3 and insisting us to perform PWHT on the joint due to 95 Deg C preheat not applied.In my opinion, nominal Thickness to be applied for PWHT exemption and control thickness to applied for calculating Minimum PWHT holding time.Please advice and enlighten further, whether PWHT is mandatory for the above specified weld joint.Thanks & RegardsNazeer
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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
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https://www.linkedin.com/groups/122787
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