Double Normalizing

[Jayesh Parekh]

Recently we faced one issue. Shell side heat exchanger is by mistake subjected to Normalizing in place of PWHT. Material is SA387 Gr.11 Cl2 with 3 mm SS304L Cladding.THickness22mm+3mm cladding.  So due to this hardness is reduced and it is in range of 140 BHN and overall length is increased. For this issue what will be best solution.

Equipment will subject to tempering at 720 deg C for 1 Hr. and then PWHT at 690 deg C for 1 Hour. Due to this heat treatment is there any problem come into materila? Is material property is above minimum required value? What will be effect on SS304L cladding after this much heat treatment? In this condition ,Will equipment suitable for application ? or any other option ? 

Please need expert advice on this issue.

[George Dilintas]

which hardness was reduced? That of SA387 or that of the cladding?

What was the normalization temp? 900 deg?

Was the cooling after the normalization done at still air or it was done under the insulation? if you heated at 900degC and then cooled slowly under insulation, then you have recrystallized and increased the grain size, so metallurgical properties have been deteriorated 

The cladding risk sensitization if the ss is not stabilized with Ti. You have to check the cladding to check if chromium carbides have precipitate to the grain boundaries

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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

[Ramin Kondori]

Equipment will subject to tempering at 720 deg C for 1 Hr. and then PWHT at 690 deg C for 1 Hour 

I love to meet the engineer who has specified such a sequence of heat treatments...

Or maybe I am ancient and this is the newest method...

Ramin  Kondori

Sr. QA/QC & Welding Engineer

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PG-Dip. in Welding Engineering (IWE  AT  0070)

BSc. in Civil Engineering (IUT)

BGAS Painting Inspector

ASNT Level I&II

                        

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[Kannayeram Gnanapandithan]

Generally after Normalising , Hardness will get increased but u have mentioned it reduced . If u do Tempering, again Hardness will come down, and SR also reduce Hardness in turn mechanical properties will get detoriating. 

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