RE: Inbore welding

From: <Steve>
Date: Wed Dec 10 2003 - 08:42:00 EST

Hi LAKSHMI NARAYANA V

I used to do this years ago on stainless steel heat exchangers of low pressure design. I assume by inbore welding you are referring to welding the tubes to the tubesheet bores to make the primary joint.

Advantages:

A far thinner and cheaper tubesheet can be used, pressures and design codes permitting. This is because the tube to tubesheet joint does not need to be sealed by rolling.
Greater protection against leakage.

Arguably slightly better tube entrance conditions as there is no tube protrusion.

Possibly some advantage in high temperature gas applications if there is a preference to avoid the use of ferrules.

Disdavantages:

Difficult to replace a failed tube.
Full retube not really practical with thin tubesheets; normally cheaper to replace the bundle.
Repairing a slight joint weep may require the exchanger to be fully cleaned out depending on service. With rolled joints a quick roll is sometimes all that is required.
Choice of tube/tubesheet combinations limited by weldability of the two materials.

In general I would expect a welded joint exchanger to be cheaper to buy but more expensive to maintain if the service is tough.

Cheers

Steve McKenzie

-----Original Message-----
From: Lakshmi V. Narayana [mailto:LNarayana@safco.net] Sent: Thursday, December 11, 2003 1:48 AM To: 'PipingDesign@yahoogroups.com'
Subject: [PipingDesign] Inbore welding

Hello friends,

Has any body faced the inbore welding of tubes in fixed type Heat Exchangers. What are the advantages/disadvantages in doing so? In which plant it has been used . Can any body give your experience on this?

Regards
LAKSHMI NARAYANA V



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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Received on Wed Dec 10 08:42:00 2003

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