Anyone recently gone through this procedure? What type of welding did you do and did you hydro the flues after safe ending?

Been a while since I did supeheater flues but we butted up and arc welded burning in good for maximum penetration of the joint. We did make up a sort of expandable plug type rig and hydroed them before swaging and installation. The welding rig was made with casters and allowed the flue to be rolled while maintaining alignment for the welders convenience. Of course stock 2" aren't worth the cost of safe ending so I assume you are talking about the big stuff here.

Dave

lathro19@idt.net

Dave, Haven't made up my mind yet as to safe ending or putting in new flues. I will have to look at cost V both methods. These are 3.5" for type E superheater units. The length is almost 21 foot.

Would suggest you clean and inspect the flues you removed - if they are eroded or oxygen pitted, replace them. If not, safe ending could be the best bet if you can find a good welder who works at reasonable price. I have seen 4 or 5 safe ends welded on a flue before.

Dave

lathro19@idt.net

I have seen most every welding method used to safe end tubes and all were successful. On larger tubes we generally use stick although while at Steamtown in Vermont we used MIG in a semi automatic welding lathe. Years ago when I was at the Hobart Welding School I saw them using an automatic TIG machine on tubes that I believe were used in the initial retubing of 765. On smaller tubes we use a store bought backup ring with little pins on it to insure proper end gap. In China most all the shops safe end using gas welding.
I believe that the practice of hydro testing each tube is prudent and universally accepted practice. We have a test rig made out of angle iron with a screw clamp on one end to secure the tube. The other end has a pair of tapped holes (water in and out) with valves and a line hooked up to a small hydro pump.
If you have little money and lots of volenteer labor, it is a good way to go. Good luck.

jdconrad@snet.net

When Pere Marquette 1225's first set of tubes were safe-ended, we used some handy rail instead of angle irons, and instead of a screw clamp used a Porta-power cylinder behind one of the rubber-gasketed end caps. This might save some time over a screw arrangement.

Aarne H. Frobom
Project 1225
The Steam Railroading Institute
P. O. Box 665
Owosso, MI 48867-0665

froboma@mdot.state.mi.us

The old railroad method was to remove the flues, clean them in a flue "rattler", which was kind of like a big cement mixer that turned and let the flues bang into each other, which knocked off the scale.

After that, they inspected them visually. Pits, cracks, blisters, bulges, obvious thin spots, mud burns, etc. were cause for scrapping, unless confined to a small area of the flue. If so, that area would be cut off and the remainder used to make safe ends. Also, flues could not legally be safe-ended more than twice...and still can't; so any flue that already had two safe ends on it when removed was scrapped without being cleaned or inspected. Granted, probably nobody has a rattler these days, but the other things noted above should still be followed.

Anyway, the flues to be kept then had the torch-cut ends sawed off, and the end to be welded was machined square with a bevel on the end. The safe end was also beveled, and when butted together for welding, this allowed virtually a full-penetration weld. The weld is then ground down flush with the surface of the flue, or as close as possible.

The result can be tested by hydro, by eddy current, or by x-ray.

The cost of all the above in terms of labor, time, tools, gas, machine time, grinding wheels, material for making safe ends, etc. can quickly add up, especially if you have to use paid labor. It can easily exceed the cost of simply buying new flues, so it should be costed out carefully before you make the decision. Sounds like you are already doing that.

The cost of installation is the same either way.