Steam test 2021

Northern Pacific Railway steam locomotive 924 was fully rehabilitated and restored over a period of five years.  It made its debut on 1 November 2020 with passenger runs from Snoqualmie and North Bend.  Yet with any steam locomotive, maintenance and inspection are ongoing responsibilities.  

Steam locomotives require an annual inspection and test of the boiler.  This work includes a series of visual and other non-destructive tests, followed by a hydrostatic test of the boiler at 125% of operating pressure.  Then a steam test is performed during which the safety valves must demonstrate that they lift and seat at the required pressures.

The 924 received its annual test in April 2021, and a portion of the test was witnessed by an inspector from the Federal Railroad Administration.  There were no anomalies reported, and the locomotive boiler was declared fit for service.  This was also the first time the complete new locomotive jacketing was displayed; continuing tests and rehabilitation did not allow the new jacket to be installed until this past winter.  The jacketing project was funded in part by the Northern Pacific Railway Historical Association; the Museum is grateful for their support.

Pandemic-era restrictions are particularly difficult for steam trains  because of the higher operating costs.  Fewer passengers places the cost per passenger much higher that normal. Notwithstanding, the Museum has committed to operating steam trains on at least two upcoming weekends: Mother's Day Weekend and Father's Day Weekend, when they will operate on two hour return schedules, and include a brief visit to the Train Shed exhibit hall.  

Do you want to see the 924 continue to run?  Please consider a Give BIG! 2021 donation now or on May 4 & 5 to the Northwest Railway Museum to help support operating of the Museum and the 924 during the pandemic.

Hydro-static test

Locomotive 924 circa 1908

Northern Pacific Railway steam locomotive 924 has been undergoing restoration in the Conservation and Restoration Center.  This 1899-built Rogers locomotive served the Northern Pacific Railway until 1924. It is a King County and City of Snoqualmie Landmark, with project support from many individuals, foundations and public agencies including 4Culture, Washington Heritage Capital Projects, the Northern Pacific Railway Historical Association, the Emery Rail Heritage Trust and more.

Fire in the 924 firebox

For the last several years a variety of project work has been underway, but the most important division of work has been on the boiler.  The boiler is where water is heated and converted to steam, usually with an oil, coal or wood fire.  The boiler must withstand high temperatures and considerable pressure.  

Locomotive 924 is filled with water, 

and then the water is lightly heated so

as to reduce the strain on the boiler 

when it is pressurized.

For the general public, a little known fact about locomotive boilers is that they must be designed to withstand four times their operating pressure.  So an operating pressure of 180 psi requires the boiler be designed to withstand 720 psi.  This is called the factor of safety, and must consider any wasting or other deterioration of the boiler that occurred since it was built.

FRA inspector Brandon King witnessed
the 924's official hydro-static test.  He
found no exceptions, which is the best
possible outcome.  This means the
inspection found that the Museum
is complying with the regulations.

After measurement, analysis and calculations demonstrate that the boiler construction is capable of withstanding 720 PSI, a non-destructive test called a hydrostatic test is performed.  This test is performed by the locomotive owner, but is witnessed by an inspector from the Federal Railroad Administration.  During the test, the boiler is filled with water, lightly heated, and pressurized to 125% of its stated operating pressure.  

Kyle I. operated the hand
pump.

It was a beautiful morning on Thursday, September 5th when Museum volunteers and staff arrived to "fire" the boiler on locomotive 924.  Recycled wood logs and waste wood were used as fuel, and the temperature was brought up to 100 degrees.  At that point, the fire was dropped and a hand pump was used to bring the pressure up to 225 psi. Visual and aural inspections were all positive - just some light weeping from a handful of rivets.  Most impressive to the Museum volunteers and staff was how tight the boiler was.  One stroke from the hand pump every 15 or so seconds was sufficient to maintain 225 psi.

Kyle and David remove the steam dome
lid and throttle to allow an internal
inspection.

Upon completion of the hydro-static test, the boiler was drained.  After this 125% test, an interior inspection of the boiler and hammer testing of the stay bolts was required.  For the interior inspection, the steam dome lid and throttle was removed so an inspector could enter and crawl along the top course of tubes.

The Northern Pacific Railway steam locomotive 924 rehabilitation and restoration project continues to progress.  The hydro-static test brought great news so now the next phase - steam plumbing - can begin.  Donor support remains critical to the ultimate success of the project; your support really makes a difference.  Please consider a making a donation on the Museum's web site: Donate Now

Thank you for your support!

Back in the boiler

Steam locomotive 924 is a former Northern Pacific Railway switch engine that operated in the Seattle area from 1901 until 1924.  It is listed on the King County and City of Snoqualmie Landmark Registers, and is a property truly representative of our collective history in the settlement and development of the region.

The 924 has been undergoing a major rehabilitation and restoration inside the Museum's Conservation and Restoration Center in Snoqualmie, WA.  Despite several unanticipated setbacks in the project, it has moved forward and real progress is becoming evident.

This past week, the last major known work on the 924's boiler was performed.  Seattle Boiler Works visited the Museum to remove the portion of the throat sheet that supports the blow down valve.  A patch had been installed here with patch bolts at least 70 years ago, and the "new" material had wasted in places almost 50% of its original thickness.  So replacement was definitely warranted.

The original patch was removed, which also required three rivets in the mud ring to be cut out.  Then the affected area was cut out, and the perimeter was beveled to allow for welding.  A dye penetrant was used to check for cracks and other flaws.

Seattle Boiler Works installed a flush patch and welded a coupling for a new blow down valve.  The process involved a full penetration weld, and preheating of the native material to about 350 degrees.  Repeated passes, grinding, welding, and continual evaluation took a full day, but the results are impressive.

Up next: three replacement rivets, two new stay bolts, and more.