Or, if you have the pedigree which came with the tubes when originally purchased.

I'm thinking GMAW rather than an autogenous process for safe ending. I thought autogenous pipe welding was no long acceptable practice.

As an example, a Millerweld site (below) describes their 'Pipeworx' equipment for pipe fabrication applications. It contains links to procedures recommended for producing sound welds in joined pipe.

https://www.millerwelds.com/equipment/welders/multiprocess/pipeworx-welding-system-m00326

One removed flue and one tube (or more) would be cut into safe ends to salvage the other removed tubes and flues from the same batch. It seems if railroads like EBT forge welded safe ends successfully throughout their operating history, contemporary welding techniques would be superior, safe and should be considered when balancing the cost of material vs. services for 1472 day inspections.

Of course, you need to use water treatment and maintenance standards that preserve the tubes while they are in service so they can be recycled back into the boiler......

GMAW (MIG) pipe welding is relatively new to the welding industry. I've only heard of a few companies using the process, as it's not overly accepted, but is gaining popularity. Submerged arc welding (to the extent of my experience) wouldn't be used on anything as small diameter or thin as a super-heater flue, for a variety of reasons.

The boiler fabricator I work for does GTAW (TIG) for 99+% of our pipe roots, after which we will use SMAW, SAW (on larger diameter with thicker walls), or GTAW for fill and cap.

SMAW with 6010 is also a popular choice for pipe roots, but will require a lot more clean up (Naturally shoots a lot of slag and spatter around). From IRM's website they say 1630's flues were safe ended with a 6010 root and 7018 fill and cap.

I much prefer TIG roots on pipe, it's cleaner and easier to control the amount of push-through on the root; which is desired if you want a low-profile weld so as to not inhibit gas flow. TIG is also more suited for thinner walled pipes (like flues). If it were my decision, I would use this process for safe-ending.

-Sam A.

From photos, WMSRR 1309 tubes and flues looked to be in near new condition on removal. Anybody know if they are being salvaged?[/quote]

They were not reused. The previous management determined that $40,000 for seamless, new German manufactured tube with documentation was well worth the cost. The tubes, which were ordered through Steam Services of America, were on the property in late 2015.

Part of the reasons for this were failures of welds in 734's tubes in August of 2015.

Where were 734s tube weld leaks, at the end sheet seal ring welds, at safe end welds in a heat affected zone or per chance, if the tubes were not seamless was it a seam weld failure. Can you say how long 734s tubes were in service before discovering the leak?