Recent content by merrillwalt

Some company specifications call out minimum spacing of 1" or 4 X the wall thickness, whichever is greater. This is to separate the Heat Affect Zones of the two welds. However, as far as I know, this is not a code requirement.

Alejandro, the basic reason for using a weld-o-let is that it is self reinforcing! Very puzzled as to why you think you need to add a reinforcing pad.

My Taylor Forge 571 is dated 1957. It lists dimensions for 22" flange, but notes it is not covered by ASA (ANSI predecessor) B16.5!

Many companies use 4 X pipe wall thickness or 3" as the minimum spacing between welds. Some companies allow as little as 1" between welds. Basic reason is to prevent overlap of the heat affected zone of the welds. Thus spacing should generally be based on wall thickness, not on diameter of...

Sorry guys, it's not about the fins! There are shipping baffles that protect the fins during transit. Also, during the lifting process the sling would not contact the finned section of the tubes. I appreciate all the comments from everyone. Lots of good thoughts!

Each tube is actually a combination of 3" bare and 1-1/2" finned sections.

Mayda, many thanks!

Maybe I need to rephrase my question to ask if anyone has done calculations to show that a cradle is REQUIRED to lift the bundle from horizontal to vertical position. Bundle in question has 3" tubes that are welded into the tubesheets and is very stiff. It's hard for me to believe a cradle is...

To clarify, the cradle is only used for shipping and then for lifting the bundle from the horizontal to the vertical position. What is puzzling to me is that the cradle was constructed at a cost of probably $75,000, but there is no documentation clearly showing why it would be needed. As...

Still looking for some technical reason as to why a cradle would be needed that can be justified by calculations.

This is a replacement bundle. The shell is in place. The bundle has 6" thick tubesheets with the tubes welded to the tubesheets. There are 230 tubes in the bundle that are 1-1/2" finned tubes. My calculations indicate that there is no real need for a cradle. There is no documentation as to...

Anyone have experience in determining whether a cradle is needed for lifting the bundle for a large vertical exchanger from the horizontal position to the vertical position for installation in the shell? Cradle ostensibly is needed to prevent excessive deflection of the bundle in the horizontal...

As far as I know, it just has to be within the limits of reinforcement that are calculated per the code rules.

When did the ASME Section VIII Division 1 Code add the specific 3% limitation on the inlet pressure drop to relief valves in Appendix M?

The NBIC Interpretation is NBI 95-19 and it also states that "Repairs and alterations may be performed to the edition/addenda used for the original construction or a later edition/addenda most applicable to the work." I suspect your problem may be related to the flange rigidity calculation...