Steam & Excursion > Northern Pacific 924 Update!!!!!!!

Howdy all,

This fall has been a busy one at Northwest Railway Museum!  We have installed several new machine tools, continued work on our core project rebuilding NP 924 to service, operating steam with Santa Cruz Portland Cement 2 (THE CHIGGEN), and major vestibule rehabilitation on SP and S coach 213.  This update is also available on our blog located at www.trainmuseum.org.  

In September 2015 another major milestone was passed in the rehabilitation to service of Northern Pacific Railway steam locomotive 924.  

In November 2014, the boiler tubes were removed from the locomotive and a preliminary engineering package was created based upon the thicknesses and geometries of the existing vessel.  During this time, a complete ultrasonic thickness grid was laid out and measured from the water and fire side of the boiler sheets, and the results were more than encouraging.  However, for the locomotive pressure vessel to be legal under the regulations of the Federal Railroad Administration (“FRA”), the exterior jacketing and lagging had to be removed.  This allowed for a visual inspection and for documentation of the final ultrasonic thickness measurements of any critical areas that were not possible to reach from the inside of the boiler.  So following the abatement of the asbestos lagging in late July and early August, it was time to finalize the form 4 engineering package, external visual inspection, and ultrasonic grid. 
 
Preparing the pressure vessel for an external inspection and for ultrasonic measurements involved a variety of tasks. First, the boiler shell was stripped of rust and scale, as well as any other appurtenances that obstructed the exterior of the boiler.  Then, a grid pattern was laid out with data points polished to bright steel so as to allow the ultrasonic transducer to couple with the material and give an accurate reading. Any areas found to exhibit additional pitting or deterioration were also tested to find the thinnest points in each boiler component. 
 
Preliminary calculations indicated the pressure vessel to be in good shape, especially following the installation of new firebox side sheets in January.  However, visual inspection found questionable rivets and some cracking present in the steam dome barrel near these rivet holes.  The original design of the dome also included a longitudinal lap seam, which although legal to remain in service, would require additional inspection and care in service. The dome ring at the top of the steam dome was also found to be cast iron, which was not a good choice for pressure vessel use due to its lack of ductility and low tensile strength.  Curator Stathi Pappas made the decision to replace the steam dome with a new fabrication using A-516-70 steel and butt strap riveted construction to provide for both safety and longevity of service. 
 
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At this point, Curator Pappas brought in friend and colleague Jon Brewster - who is an expert in boiler calculations - to run the final numbers and determine the health of the pressure vessel with the alterations and repairs as noted above.  Although locomotives may operate with severely derated boiler pressures, these locomotives are often but shadows of their former selves in capability, power, and economy.  In order to be true living history, philosophically, locomotives should be rebuilt to behave as they would have in their period of significance.  This being the case, Northwest Railway Museum is pleased to announce that NP 924 will once again be legal for her original full working pressure of 180 psi, just as Rogers intended!!!
 
Following this achievement, no time was wasted in beginning the construction of the new steam dome.  A new upper ring was machined on the Museum’s 48” Bullard Spiral Drive vertical turret lathe from a 5.5” thick plate of A-516-70 steel to match the original.  This machine was able to bore the center hole removing up to 1” of material in one pass.  Now that is mid-century American machine tools being used as intended!  At the same time a new dome barrel was rolled by Liberty Metal in Portland, Oregon out of A-516-70 steel.  By mid September, the new ring and rolled round were fitted together and welded preparatory to riveting.  Although the rivets are more than strong enough to support the joints in this new dome, Curator Pappas (who is a certified 6G welder) welded the dome for additional strength, prevention of leaking seams, and dimensional stability during the riveting process. By using appropriate riveted construction and welding, this dome may even outlast the rest of the pressure vessel.  During this time, the old dome was removed and all rivets from the dome saddle removed preparatory to installation of the new dome. 
 
Fall 2015 will see the completion and installation of this new dome on the 924. Following this achievement, the stay bolt work on the new side sheets can them be completed, tube sheets prepped, and the vessel will be ready for tubes and a hydrostatic pressure test. 
 
I would like to take this opportunity to invite you all to come see our operation and museum.  We are running my personal Santa Cruz Portland Cement 2 (THE CHIGGEN) Oct 24, 25, and 31, and Santa Train tickets are on sale at www.trainmuseum.org.  Get them while you can, we sell this event out!  So until next time, I hope to see you all in Snoqualmie!

Best

Stathi

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Efstathios I. Pappas, MS
Curator of Collections
Northwest Railway Museum

Photo Credits Richard Anderson, Zeb Darrah, Stathi Pappas

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Keep up the great work. Stathi your work is always first class.

Posted from Android

I really enjoy seeing your progress and pictures of your work.  Outstanding job.  Wish you weren't at the other end of the country.

Just out of curiosity Stathi, I see in the third picture some wasted rivets, how does a form 4 account for such wastage? Do they affect strength and is there any benefit to replacing them?

Posted from iPhone

Rivets are allowable if 60 percent or better of the head remains. I think what you are referring to are the countersunk flush head rivets on the dome collar riveted on the barrel which are common in this location. In fact, all the rivet heads on this locomotive are in quite good shape considering the age and long term exposure this locomotive saw.

Best,

Stathi

Posted from iPhone

Lathe is a little more modern than the one at Carson City that I saw about two months ago. They are quite the machine and not all that many know of them at all. Would love to have been able to help out on that machine job.

Having been a controller (head accountant) for a machine shop for many years I can appreicate the brand names of those machines as they truly say American made. And they really lasted a long time. There at the last, many of the new lathes and CNC machines had Oriental names...

Victor A. Baird
http://www.erstwhilepublications.com



Edited 3 time(s). Last edit at 10/20/15 15:42 by wabash2800.

I appreciate the information about all the steps in the process of the restoration of a steam locomotive. This is very interesting, and I look forward to hearing more as the work continues. 
You are doing good work and making lots of progress. 
Thanks for the information and photos. 

John

Stathi.

Thanks for taking the time to keep us all informed on the progess on the 924.  Keep up the good work!

Pete