Seal-weld a plug onto the tube.

[harith07]

Hi,
Like to know the reason a plug has to be seal-welded to the tube of a heat exchanger.
It just so happens in the plant I am working, when a Turnaround take place, all heat exchangers with tube seal-welded to tubesheet has to have the plugs seal-welded to the tubes as well.
Thank you.

 

[eyec]

to prevent introduction of non-treated water into the treated water/steam system

 

[metengr]

I am not sure exactly what you are asking. If you seal weld a plug to the tubesheet to seal a tube to prevent leakage, you will be fusing the end of the tube as well unless you scarf the tube back.

 

[sjrfc2]

Depending on why the tube is being plugged you may need a seal weld at the tube and another seal weld at the tubesheet. We had tube failures that had to be plugged. The tube plug was welded to the tube end but there was subsequent leakage at the tube-to-tubeseat joint. This may have been driven by the heating of the tube when the plug was welded into it but the end game was the tube-to-tubesheet joint was seal welded too.

 

[garnet1]

There are varying reasons why clients want the plug seal welded tot he tube end. If the tube is leaking and the shell side is higher pressure than the t/s, it will prevent the plug from being blown out over time. If the t/s is higher pressure than the s/s, it will prevent leakage into the s/s stream. No real fixed answer. Depends on clients standards in most cases.