Mt Rainier Scenic Railroad News

Having just barely stopped working on our Baldwin 2-8-2 #70, we have already begun the task of returning our ALCO 2-8-2T #17 back to serviceable condition.  This locomotive was our primary motive power until January, 2010, when it was taken out of service in accordance with the federal steam locomotive regulations.  These regulations state that the boiler must be recertified for service after 1472 days of service, or 15 years, whichever occurs first.  Since the #17 had last been rebuilt in 1995, the locomotive had seen 15 years of operation.  Performing what is known as a ”1472-day” inspection of the locomotive involves any number of items depending on the overall condition of the locomotive, but is primarily a boiler inspection.  The steam pressure vessel must be inspected inside and out which means most everything is removed to expose the exterior of the boiler, and most (if not all) of the boiler tubes and flues are removed.  The boiler barrel, tube sheets, firebox sheets, interior braces, riveted seams, staybolts and such are all visually inspected for flaws and erosion.  Ultrasonic thickness testing of all sheets is also performed to determing the extent the boiler sheets have eroded from their original thicknesses.  Sometimes x-rays are taken of certain locations as well.  Many dimensions are taken from the boiler, then an engineer takes all of the dimensions and thickness data and plugs it into various mathematical equations to determine the boiler’s maximum allowable operating pressure (MAWP)(this is all part of creating a document known as the FRA Form 4, which describes exactly the condition of the pressure vessel and proves its ability to operate safely at the arrived pressure).  Depending on the condition of the boiler, the MAWP may be the same as when the boiler was built, or if it may have to be lowered.  Certain repairs can be performed to correct defects or eroded areas in order to maintain the as-built MAWP.  In the case of our #17, we are performing the repairs required to maintain the boiler’s MAWP of 190 psi.

MRSR’s volunteers began the process by removing everything from the exterior of the locomotive that was required to remove the water saddle tank.  The interior of the cab was also stripped of all plumbing and fixtures to expose the exterior firebox sheets.  Inside the firebox, all fire brick was removed and the sheets were thoroughly cleaned.  Lastly, CMO Stathi Pappas spent a full day cutting both ends of all boiler tubes and flues, then spent another day inside the boiler barrel cutting the 5-3/8″ superheater flues into short sections so they could be removed through the steam dome opening.  The 2″ diameter boiler tubes were taken out through the larger flue openings in the front tube sheet.

(Photo 1)  Rikki Burchett and Brian Bundridge spent several days removing all of the brick inside the firebox.  The bottom pieces had been in there since 1995 and were firmly encased in carbon.

(Photo 2)  The 2″ boiler tubes are being removed through the larger superheater flue openings in the front tube sheet.

(Photo 3)  CMO Stathi Pappas inside the #17’s boiler barrel, cutting the 5-3/8″ diameter superheater flues into short chunks so they can be removed via the steam dome opening right above his head.

(Photo 4)  Craig Magnuson launches the shortened superheater flues clear of the #17.

(Photo 5)  The #17 inside the shop at Mineral where volunteers have been working diligently to get the interior and exterior surfaces of the boiler clean and ready for inspection and testing.

After ultrasonic thickness testing of the interior firebox sheets had been performed, our engineer was able to tell us just how thick the sheets needed to be in order to operate the boiler at the desired 190 psi.  With that number in mind, we marked out all of the portions of the sheets that needed to be replaced.   The bottom 1/3 of both side sheets had to go, as well as the bottom 8″ of the door sheet at the back of the firebox.  The throat sheet, at the front of the firebox, was ok, but we knew that we were going to have to replace all of the flexible staybolts in this area due to corrosion, so we decided to replace the inside throat sheet as well.  We also decided to remove most of the riveted seam above the firebox door opening as it was riddled with past repairs that did not meet our standard of quality.

(Photo 6)  Volunteer Jason Hill gets a lesson from CMO Stathi Pappas in how to properly remove a portion of the right side sheet in the firebox. 

(Photo 7)  The upper portion of the door sheet was removed in order to eliminate a major portion of the riveted seem that had seen many small repairs over the years.

(Photo 8)  CMO Stathi Pappas is welding the removed portion of the door sheet to steel supports so that it cab be used as a pattern for forming the new door sheet.  A new steel plate will be secured over the form, then heated white hot and beat down over the old sheet with very large hammers.

Stresses caused by the heating and cooling of the boiler sheets, and the motion of cooler water circulating inside the boiler, can cause various problems in different parts of the boiler.  One type of problem is “grooving” of the inside of the steel where a sheet bends around a corner (typically called a “knuckle”).  The juncture of the boiler barrel to the front of the firebox is particularly susceptable to grooving at the knuckles.  When the grooves get to a certain depth, cracks can form.  Such was the case with the #17’s boiler and upon visual inspection of the knuckles at the left and right ends of the throat sheet we decided to have them x-rayed to determine the extent of the problem.  The x-rays confirmed that we would need to replace both knuckles so the affected zones were cut out.

(Photo 9)  The knuckles at both sides of the firebox throat sheet were x-rayed to find out how bad they really were.  The short white marks are cracks inside the steel.

(Photo 10)  Here is the left side knuckle after the affected zone was cut out.  The horizontal bars you can see inside are the flexible staybolts that hold the inside throat sheet parallel to the outside throat sheet.  Just above those are the short “T” shaped braces that support the bottom of the rear tube sheet to the boiler barrel, and above that you can see the cut ends of the boiler tubes that have not yet been removed from the rear tube sheet.

(Photo 11)  Here’s Stathi using a grinder to prepare the edges of the left knuckle opening.

(Photo 12)  After the inside portions of the firebox were removed, the remains of all of the staybolts that were connected to those portions also have to be removed.  Here Stathi is cutting out the staybolt ends in the outer firebox sheet.  Once he’s removed most of the center of the bolt, a pneumatic gun is used to push the red-hot remains through the hole.

Just this past week we had our local FRA inspector come out and perform the required internal inspection of the boiler.  He did not find anything that concerned him, so we can proceed with performing most of the firebox repairs (the knuckle repairs require us to submit paperwork to be approved by the FRA before we can have the new pieces welded in).