Re: [MW:32545] RE: Pl help/advice please - HEX tube leakage case is stated hw

Hi Vishwas, 

Seems tubes are expanded more than Tubesheet thickness. And it damaged from weldseam. 

Normally we left 3 mm with no expansion zone on shell side end of Tubesheet. 

Have you performed Mock up with expansion? 

Solution

Plug the tubes . Normally process keep some extra area. You can check with process. 

BR

Deval

On Sat, 2 Oct, 2021, 17:35 , <pgoswami@rogers.com> wrote:

H Vishwas,



To me, the issue looks to be with the ERW welds. It's possible that full
expansion is opening up defects in the ERW seam. ERW welds  on a thin tube
involves very little contact areas. Mechanical expansion could cause the
thin weld seam to open up during expansion. This would not be the case while
testing the tubes in the mill, as tubes would not be expanded.



ERW tubes are cheap options for any heat exchanger for long term service
life. It's a bad design. I've always dealt with and  advised on using
seamless tube products for exchangers The cost difference does not matter,
integrity of equipment comes first.



Talk to the designer, about changing the tubes to seamless.



Thanks.



Pradip Goswami.P.Eng, IWE.

Independent Welding & Metallurgical Engineering Specialist

Saudi Aramco Approved Designated Project Welding Engineer (DPWR)

Qatar Petroleum Approved, SME-Materials & Corrosion Engineering.

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From: Vishwas Keskar <vvkeskar123@gmail.com <mailto:vvkeskar123@gmail.com>
>
Sent: September 30, 2021 5:46 AM
To: pgoswami@rogers.com <mailto:pgoswami@rogers.com>
Subject: Pl help/advice please - HEX tube leakage case is stated hw



Good evening Sir,

A heat exchanger is under construction with following details



TUBE SHEET - SA 182 F11 - 250 MM THK  with overlay -  TYP308 L

TUBE - SA 268 TYP 439 - ERW

Welding Groove - 1mm Chamfer -

Welding - Strength Welded

Welding Process - GTAW  - Manual

Filler WIRE - ER309( SA 268 TYP 439 TO Overlay TYP308L)

Tubes are expanded  in full thickness tube sheet.(Expansion - 5-6 %)

After full welding , shell side Air leak test shown 4 tubes leakages. These
were plugged and re test done . 10 leaks were found.

Boroscopy shows water jet  in some tubes or droplets in some tubes.

These location found to be near ERW seam.

After that it was decided to go for Hydro test. 15 leakages in tubes are
observed.

The tubes are ;located all over tube sheet zone. No specific location trend
.

All are in expanded length area of tube sheet thickness( within 250 mm
zone)



Inspection details - It is observed that all leakages are in expanded zone
area.

Before insertion, all these raw tubes were  100 %  Hydro tested at Mill End
Pl. help for what could be reason for so many leakages .



We have fabricate further 2nos of HEX with same configuration of materials.
Pl. suggest Corrective action and preventive action to avoid re occurrence.



Vishwas





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