mklotz
Well-Known Member
The design/construction book for the steam roller I'm building calls for a welded steel vertical boiler...
4.5" OD DOM tubing, 0.25" wall thickness boiler shell
8 copper firetubes (L grade, 5/8" OD, 0.037" wall)
2 steel tube sheets (0.25" thick)
1 CRS 5/16" boiler stay
Working pressure = 100 psi
Hydro test pressure = 300 psi
Construction calls for (TIG or MIG) welding the tube sheets to the stay, inserting the structure into the shell and welding the tube sheets to the shell. (Since I don't weld, I would have that work done by a professional welding shop.) The firetubes are then inserted into the tube sheets and expanded in place. Beyond this expansion, no sealing of the firetubes is specified. The author claims that this will provide a satisfactory seal. I have my reservations but I'll give it a try.
I'm interested in building the boiler as designed (hear that, Zee?). Steel is cheaper than copper and the 1/4" wall thickness means that bushes are not required. Welding is strong and the massiveness of the boiler should make it very safe at the relatively low working pressure.
I have some concerns though and I'm hoping that this post will elicit responses from the boiler experts on those points.
My first concern is, of course, corrosion. On my copper boilers, after use, I drain the boiler and open the steam pipe to the atmosphere and continue firing at low level until no steam exits. I would plan to do the same thing with this boiler. Is that sufficient to minimize corrosion on the steel boiler or are there other procedures I should follow?
If I ever get this thing built (a very big if), it would probably be run only very occasionally - perhaps once a month. Given that, how often should the boiler be hydro-tested?
Barring a laparoscope, how do you assess the internal corrosion?
Having never worked with steel boilers, what important questions have I NOT asked? Please offer whatever wisdom you think I should consider. I (and perhaps others) will welcome any steel boiler information you have.
Finally, may I request that we limit this thread to a discussion of STEEL boilers. I'm well aware of the advantages of copper and, frankly, would feel more comfortable if this boiler were copper. Nevertheless, I'd like to understand the pros and cons of steel before I commit to building this thing. If your comments scare me enough, I may yet elect to build a copper boiler.
4.5" OD DOM tubing, 0.25" wall thickness boiler shell
8 copper firetubes (L grade, 5/8" OD, 0.037" wall)
2 steel tube sheets (0.25" thick)
1 CRS 5/16" boiler stay
Working pressure = 100 psi
Hydro test pressure = 300 psi
Construction calls for (TIG or MIG) welding the tube sheets to the stay, inserting the structure into the shell and welding the tube sheets to the shell. (Since I don't weld, I would have that work done by a professional welding shop.) The firetubes are then inserted into the tube sheets and expanded in place. Beyond this expansion, no sealing of the firetubes is specified. The author claims that this will provide a satisfactory seal. I have my reservations but I'll give it a try.
I'm interested in building the boiler as designed (hear that, Zee?). Steel is cheaper than copper and the 1/4" wall thickness means that bushes are not required. Welding is strong and the massiveness of the boiler should make it very safe at the relatively low working pressure.
I have some concerns though and I'm hoping that this post will elicit responses from the boiler experts on those points.
My first concern is, of course, corrosion. On my copper boilers, after use, I drain the boiler and open the steam pipe to the atmosphere and continue firing at low level until no steam exits. I would plan to do the same thing with this boiler. Is that sufficient to minimize corrosion on the steel boiler or are there other procedures I should follow?
If I ever get this thing built (a very big if), it would probably be run only very occasionally - perhaps once a month. Given that, how often should the boiler be hydro-tested?
Barring a laparoscope, how do you assess the internal corrosion?
Having never worked with steel boilers, what important questions have I NOT asked? Please offer whatever wisdom you think I should consider. I (and perhaps others) will welcome any steel boiler information you have.
Finally, may I request that we limit this thread to a discussion of STEEL boilers. I'm well aware of the advantages of copper and, frankly, would feel more comfortable if this boiler were copper. Nevertheless, I'd like to understand the pros and cons of steel before I commit to building this thing. If your comments scare me enough, I may yet elect to build a copper boiler.