Firebox Repairs on a Case 65

Forming die

Forming die and clamping assembly used to flange corners.

Content Tools

525 West Van Buren Avenue Naperville, Illinois 60540

The 1993 annual show of the Northern Illinois Steam Power Club of Sycamore, Illinois, opened with one engine conspicuously absent. Longtime participant Charlie Fruit of Kirkland, Illinois, and his 65 HP Case engine, Number 35072 were not found in their usual spot under the oak tree. We learned from Charlie later that day that his engine had failed its recent biannual state boiler inspection and would require very extensive repairs to its firebox before it would be allowed to be fired in public again. This article will tell how these repairs were made.

In Illinois our hobby boilers are subject to a very rigorous inspection process that includes hydrostatic, ultrasonic and visual testing. It was during the hydrostatic test phase that the problem with Charlie's boiler was discovered. Water began to leak in one rear corner of the mudring in the lower ogee curve area. Closer investigation revealed severe wasting to the entire mudring area and the state boiler inspector made the decision to fail the boiler. He did not however rule out the possibility of repairing it at this time, and Charlie was left with some hope that his engine would be operable again at some future date. It was at this time which we became involved. Paul Andermann, Larry Marek and I have been involved in the repair of several traction engine boilers in the past, and we became interested in the possibility of repairing Charlie's boiler. Over the next several weeks following the show various plans were discussed with our state inspector, and the decision was made to move the engine to Wheatland Machine Shop in Naperville, Illinois. This business is operated by Paul Andermann, a steam engine man himself, and is the meeting place of many of us with like interest.

Before a more complete analysis of the condition of the firebox was possible, it was necessary to remove all of the accumulated soot and scale which coated the inside of the firebox. This was done with a needle sealer and it was during this process that it became apparent just how badly wasted the lower mudring area was, as we actually broke through the boiler plate in several areas. These areas were later removed with a torch and a more complete inspection revealed that the entire lower mudring area was wasted below allowable limits and would have to be replaced. Our inspector wanted us to remove all the metal from the second row of staybolts down. This required removing all 78 rivets and 64 staybolts from the lower firebox area. The rivets were removed by burning both heads off and blowing a hole through the center of the rivet almost to the edge; the rivet was then punched out with a drift. The staybolts were cut around the edges in the firebox sheets and then burned back so that the sheets would clear when they were dropped down. After the lower firebox sheets were removed, the remainder of the staybolts were cut flush with the inside of the wrapper sheet. The heads of the staybolts were then burned off on the outside, a hole was then blown through the center and most of the material was burned out just to the threads. The remainder was removed with a sharp chisel.

With the lower firebox sheets removed it was possible to take a closer look at the inside of the wrapper sheet, throat sheet and back head. This inspection showed some wasting around the hand hole openings, at the point where the ogee curve met the outer sheets and also at the point where the staybolts met the outer sheets. We were pleased, however, that the outer sheets did not appear to be as bad as the firebox sheets. At this time our boiler inspector took another look at the boiler and approved the repair of these areas with pad welding. Each of these steps were followed by another inspection and the approval to go to the next phase. I should add that one of these inspections also found a section of the crown sheet adjacent to the fusible plug to be thin, so this too would need to be repaired. After much discussion with the state inspector regarding the different possibilities for fabricating the necessary replacement parts, we learned that no modification to the original design would be allowed. We would have to flange and rivet the replacement mudring sheets exactly like the original. We had done several jobs in the past involving flanging replacement boiler sheets, but this was to be by far the most extensive yet. We were still fairly innocent at this time and not scared off by hard work, so we pressed forward.

The first step in this process was to design and fabricate special dies over which to flange the boiler plate. We found that the amount of offset in the front and rear ogee curve was different, so it was determined that two dies (made out of cast iron) would be required. The patterns for these dies were made out of wood and with allowance for shrinkage were shaped to provide the proper radius and offset to bend all four corners of the lower firebox sheets. Special steel is used in the construction of boilers and boiler replacement sheets and is tightly regulated by A.S.M.E. Code. Several sheets of this plate was purchased from Joliet Boiler & Welding with all necessary documentation in 5/16', 3/8' and ' thicknesses. All these plates were stamped with a number that could be traced should there be any question regarding their acceptability for this purpose. The dies were mounted on a heavy steel fixture table with a sturdy hydraulic clamping device to hold the plates during the actual flanging process. It must be remembered that the dies were only to be used for flanging the corners of the ogee curve area; the other areas of this curve could be formed on a heavy press brake. After this was done, it was time to start on the corners. Before it is possible to work this heavy plate by hand, however, it is necessary to heat it to a bright orange color. This was done in a large coal forge owned by Larry Marek. As the plate to be flanged was being heated, we preheated the die with a rosebud tip. We did not want this four hundred pound piece of cast iron drawing all the heat out of the sheet. After the sheet was brought up to the proper heat, it was quickly moved to the die and clamped into place. The actual flanging then was accomplished by bending the plate over the die with sledgehammer blows with several people at once swinging before the heat left the piece. This process was repeated about seven times before the sheet conformed to the required shape. This flanging required very heavy labor and many Saturdays before it was complete.

One concern raised during the flanging process was of the possibility of thinning out or fracturing the sheets in the most heavily worked areas. This fear, however, proved to be false, as subsequent inspection showed that thinning was marginal. We were careful to work the plates in such a way that pushed the excess material to the edges. Care was also taken not to work the plates after the heat had left them or to scar the plates with the hammers, always striking the plate with the face of the tool and not the edge. Some areas were driven into place with specially built fullers and flatters struck by a sledgehammer. With careful smith work under the direction of Larry Marek a very professional job was done. This part of the project proved to be by far the most difficult and time consuming, many weeks, many hundreds of pounds of coal and much energy expended in the process. In retrospect however, it is this phase of the job of which we are most proud; brute force applied with skill produced the shapes that we would need to bring this engine back to life.

Riveting mudring; note coal forge in background. Larry Marek placing heated rivet into hole, Paul Andermann (not shown) in firebox forming heads, and Charlie Fruit shown about to use rivet hammer for bucking.

After the flanging phase was complete it was time to trim and fit the plates to replace the sheets removed from the firebox. As seen in the photo, six separate sheets were fabricated to accomplish this goal. The actual fit-up and installation of these sheets also presented quite a challenge. Lifting this heavy plate in and out to check fit was tiring work. Much adjustment and fitting were necessary before we felt the seams could be drawn close enough to make them steam tight. Where the sheets overlapped scarfing was needed to taper the edges down to eliminate the gap left by the plate thickness. This was done by heating the corner in the forge and drawing the edge out on the anvil. Finally, after all the sheets began to look like they may fill up the gaping hole in the bottom of Charlie's boiler, we began to transfer the rivet and staybolt holes. First, the rivet holes in the vertical seams were drilled, bolts were then used to hold the entire assembly together for final fit-up as the mudring rivet holes were transferred. I might add that these holes were all drilled undersize so final reaming could be done prior to driving rivets, so perfect hole alignment would be assured. Lastly, the staybolt holes were transferred by using a staybolt tap with a hole through the center to guide a transfer punch. These too were drilled undersize so that a staybolt tap could be used after final assembly to tap both holes in perfect alignment. Paul made all of the staybolts on his lathe by chasing the threads with a sharp 'V' tool bit, quite a job when you remember that there were 64 stay-bolts to be replaced! I should add that documentation also had to be provided to the state inspector on the material used to manufacture these staybolts. After the last of the holes were drilled and the final fit-up had been checked, we sent the replacement sheets out to be annealed to relieve all stress that had been put into the sheets due to the heating and bending. The vertical seams were riveted prior to installing the entire assembly into the firebox for welding into place. Final approval was given by our inspector on line-up and we were given the okay to weld the entire replacement assembly into place. With the entire replacement assembly in place for the last time, the project then turned over to Joliet Boiler & Welding. The welding process was left to the professionals as per the requirements of the A.S.M.E. Code. With our inspector there to witness the root pass, the okay was given to weld the entire assembly to the remaining firebox sheets. This was the day we had been working towards for a long time! The actual welding process was fairly straightforward, but the guys from Joliet Boiler took the better part of two afternoons to complete the job. A horizontal weld around the entire firebox joined the new and old sheets together. Two vertical welds were needed to join the two halves of the replacement sheets at front and back. And last, the patch in the crown sheet was welded into place. It can be seen from the photographs that all of the staybolts adjacent to weld seam areas were welded. This was done for two reasons: first, to eliminate leakage due to the heat of welding. Second, to build up the wasted area adjacent to the staybolt head, a condition often found around staybolts' heads subject to the heat of the firebox.

With the replacement sheets all firmly welded in place, it was time to replace all the mudring rivets and staybolts. A crew of four of us spent the better part of a Saturday driving the new rivets into place. Larry was the forge man, heating the rivets to a bright orange heat and with a pair of tongs inserting them into the open holes. Paul was in the firebox with an air hammer to form the heads. Charlie was on the outside with an air hammer to buck the rivets, and I removed the bolts and reamed the holes with a bridge reamer to insure perfect alignment. Working as a team we worked our way around the entire mudring, putting in a rivet every several minutes. We had done quite a bit of rivet work before this job, so this phase of the project went very well. We must have had a good job, as only a couple of the rivets had to be taken out and replaced due to looseness. After the rivets cool we go around with a small hammer and tap to find loose ones. We have found that loose rivets cannot be made tight enough to be steam tight. However, tight rivets that leak or drip during hydrostatic testing can usually be caulked shut with specially formed caulking tools in a small air hammer.

The last step of this project was to replace all the staybolts. As I noted earlier, the holes for the staybolts were put in prior to installing the sheets in place. With this done it was only necessary to tap the holes to accept the new stays. Of course I make it sound easy, but it must be remembered that there are 64 stay-bolts in the mudring area plus the four in the crown sheet patch. The stays that Paul made were cut to length and screwed into the mudring sheets, leaving about to 3/8' extending past the sheets. With a large sledgehammer used to buck the other side, an air hammer with a special rivet set was then used to form the heads. This work was done cold and in some ways was much harder than driving the rivets. The staybolt set we used created a head that matched the one that Case used very closely. Lastly, we had to caulk the seam at the base of the mudring. This was done with a round nose tool in a small air hammer. No welding joined the plates at the bottom so caulking alone was used to create a steam tight joint.

Finally it was time to fill the boiler with water for the hydro test. Throughout the project we had much doubt as to whether we could ever get it sealed up again to be steam tight. We had essentially used the same construction methods as when the boiler was built in 1919, much of which we had to learn as we went along. But as the project came closer to completion it became obvious that the care we had taken would pay off. With hand hole plates back in the boiler after two years, we slowly began to fill it with water. Everyone there was pleasantly surprised that, contrary to predictions, the water did not flow out the bottom as fast as we put it in the top. In fact, with the boiler full we only had some steady drips; these could, we hoped, be sealed up by caulking.

This boiler is allowed 100 P.S.I. in Illinois, so the hydrostatic test given was 150. As the pressure rose, some of the drips became sprays, but with careful caulking we were able to slow them down enough that the pressure test was deemed a success. The final inspection was done by our inspector several days later. He found everything to be in order and a certificate was given to operate the boiler at 100 P.S.I. After all the long hours we had spent on this job we were all very pleased that it had turned out so well. After reassembling the engine the big day came when we could finally steam the boiler up for the first time in several years. Under pressure we only had a few small leaks and the job was declared a success.

In closing I would like to say a bit about our antique hobby boilers. Many of these boilers are now reaching an age when they will soon require some type of heavy repair to remain safe to operate. Others, however, are in excellent condition and with proper care will be safe for many years to come. Each boiler must be evaluated on its own merits. It simply is not fair or accurate, as some will do, to declare all antique boilers unsafe due to their age or supposed engineering flaws. Most of the boilers being exhibited today represent many, many years of engineering knowledge. Don't forget that in the 19th and early 20th centuries some of the best and brightest engineers dedicated their entire careers to perfecting the steam boiler. The traction engine boiler built in 1920 represents 100 years of refinement. Any machinery that is used, however, is subject to wear and will require repair to extend its useful life. It is becoming fairly routine to hear of front tube-sheets, crown sheets and even barrels or fireboxes being partially or totally replaced. There is an extensive network of people out there dedicated to preserving our industrial and agricultural heritage. If this work is done in a safe and proper manner by qualified workers the life of these boilers can be extended many years.