Problem in welding tube to tube sheet welding

[chandan sharma]

Dear Experts,

 

We are facing problem of leakage during service condition in heat exchanger. Leakage are coming in the  tube to tube sheet welding in service condition. Attached are the reference photos

Details are defined below,

Construction code – ASME SEC-VIII Div-1 and Div-2

Material – Tube Sheet - SA 240 UNS 31803

Tube   - SA789 UNS 31803

Filler – ER2209

  Allowable Temperature – Shell –    +180 / -30 C, Pressure- 1 bar /FV

   Allowable Temperature-   Tube- +200 /+10 C, Pressure 10 bar

                               MDMT -0 C

Service Media –            Shell – Methanol + LIBR

Tube – Thermal oil

 

Let us know why such failure occurs and preventive actions

 

[George V Aliyattukudy]

Dear Chandan Sharma,

The leaks in your tube bundle appears to be from the cracks in the Tube/Tube sheet welds. Please look at your fabrication details for the tube bundle. The cracking could be caused by the expansion of the tubes while in service.  

A thorough investigation into the Manufacturing process will be needed before attempting a repair procedure.

Regards

George V Aliyattukudy

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[Mukkaish K]

Dear Chandan,

Can you provide the type of heat exchanger & the weld joint confirgation of the tube to tubesheet.

Regards

[Mehdi Vafakhah]

Dear Chandan,

The problem is after any service shutdown? cause (in 820 picture) it seems you have a Lon.Crack and it cant be a fabrication defect if you have used any NDT method.

Did you run any mockup test for your WPS?

A periodic welder performance test using mockup examination could be very useful.

Best Regards.

[Nitin Shetty]

Dear Chandan,

Consumable used is right for the material specified by you. Off late we have been constructing vessels with superduplex consumables. This comes from our client requirements when the MDMT is lower as it is in your case. Just a question looking at the tube to tube sheet photograph, doesn't you/ client demand for a projection of tubes beyond the tubesheet face. I got this question since I could not see a projection. If you look, it appears that it is on the edge where the tube is supposed to end. Also if the expansion is been done after welding that could be a reason. Cracks might have already been there becoz of expansion but it increased when put in service.

Regards,

Nitin

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