Project Report - 9 April 2016

A fair bit has been going on with the S class since the last update.

Boiler Preparation For A Hydrostatic Test

Now that the tubes have been installed, the boiler needs to hydrostatically tested, our friends at Wikipedia explains;

A hydrostatic test is a way in which pressure vessels such as pipelines, plumbing, gas cylinders, boilers and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection, and pressurization of the vessel to the specified test pressure. Hydrostatic testing is the most common method employed for testing pipes and pressure vessels. Using this test helps maintain safety standards and durability of a vessel over time.

So the next step was to seal (plug up) all the other holes in the boiler so the vessel could be pressurized. The holes were in the form of washout plug holes and boiler fitting mounts such as safety valves and clack valves.

The washout plug holes are a tapered threaded hole of which a bronze (Leaded Gunmetal) tapered plug is fitted. Some of the threaded holes required cleaning up to ensure a good seal is formed when the plug is fitted, to do this washout plug taps were borrowed from Bennett Brook Railway and Ian Willis, we are extremely grateful for the loan of these. Once the threads were restored, the plugs were sorted for the correct size and refitted.

WAGR drawing of a washout plug

Washout plug tap

For the boiler mounts, special blanking plates were required. Each mount was measured, drawn on AutoCAD, cardboard templates produced to test to ensure the dimensions were correct and then subcontracted out for manufacture. The blanking plates were manufactured by Pressform using a CNC (Computer Numerical Control) mill to ensure accuracy. Unfortunately on a couple of mounts the pitch between studs varied slightly and the plates for these required some fine tuning by Kirk with a KOHF (Kirk Operated Hand File). A gasket was also required between the blanking plates and the mounts, John manufactured these out of rubber insertion. The plates and gaskets were then fitted and the securing nuts and washers tightened up.

Blanking plates fitted to the safety and clack valve mounts

As the boiler required to be pressurised a pump was necessary to carry out this task, luckily enough there was one in storage. John took on the task of getting the pump operating; new fittings and pump to boiler hose acquired to ensure there were no leaks for the test.

The last task was to replace the fusible plug leads, these are a safety device in the event of the water level in the boiler dropping below the firebox crown, the leads melt and the pip drops out allowing the steam to put the fire out minimizing warping the firebox shell and other damage to the boiler.

Fusible plug assembly as fitted 

Fusible plug mounting nut with conical plug removed 

There are four fusible plugs fitted to the S class locomotives, roughly one in each corner of the firebox. They consist of a mounting nut, conical plug with the fusible lead and a pip (tapered brass plug) fitted.

The conical plugs were removed and the leads/pip (gently) punched out, the lead is then gently knocked with a hammer to stretch/deform it, allowing the lead to slip off the pip. All parts were then cleaned up to remove any contaminants. A replacement lead was then slipped onto the pip and then fitted into conical plug and then firmly knocked into position to seal. The conical plugs were then refitted into the mounting plugs.

Fusible plug assembly,
Left - water side - showing the pip & lead
Right - fire side showing removal socket

Fusible plug assembly
Left to Right - Conical Plug, Pip, Fusible Lead
Rear - Completed Assembly

Upon completing the sealing up of the boiler, the plan was to carry out a trial a low pressure hydro test to ensure any slight leaks could be rectified prior to calling the boiler inspector. We did this and unfortunately the studs that were fitted in the steam dome that hold the dryer and steam pipe in position leaked. The studs were removed by Dom and with assistance from John Wearmouth drawings were located of the originals. Dom arranged to have replacement studs manufactured by Verriers Engineering in Bassendean who generously offered to provide at no cost, thanks Verriers.  www.verriersengineering.com.au The new studs were then fitted by Dom and the blanking plates reinstalled.

A trial low pressure hydro test was then carried out and the studs sealed this time. The tubes were inspected and only one weaped slightly at the smokebox end. The pressure was dropped and the tube was lightly re-expanded, finally we're ready for Doug (Boiler Inspector) to run his eye over her. Doug was contacted and arrangements were made to carry out the hydrostatic test on Saturday 9 April.

Saturday, 9 April - The team started early to ensure the area was set-up, Doug arrive around 10am and the tap was turned on to allow water off the mains pressurize the boiler, this took the boiler up to around 75psi in pressure. Doug then started his rounds, in the firebox, in the smokebox, along the sides and no leaks were found. OK let's start the pump and get the pressure up to operating pressure of 190psi which took around half an hour, still no major concerns. The pump was again turned on and the pressure increased to a higher pressure above the normal operating pressure (safety margin) to ensure the vessel would be sound in its normal operating condition. The pump was turned off and Doug again carried out his rounds.

Finally, all good was given by Doug and the pressure was slowly released. Now for the next step, put her back together again.

Other Works in Parallel

Whilst the work in preparing the boiler was going on, other work was being carried out in parallel.

Boiler Mount Gaskets - Following the Hydro test, the locomotive and all its fittings need to be reassembled, the fittings will need a gasket suitable for steam and as John had already made the rubber gaskets for the hydro test, he went on to source the steam gaskets also. Several companies were contacted and their products reviewed against our requirements, Novus Sealing Pty Ltd was selected as the supplier with their product Novus 30. Brett Mohen, Novus's Technical Sales Representative was extremely helpful as he had first hand experience in steam requirements as he is also a volunteer at the Hotham Valley Railway and knew exactly what we needed, thanks Brett.

Boiler Surface Preparation - Twenty five plus years ago, the boiler was sitting on sitting on specially built stands off the engine, the decision was made to sand blast the exterior surfaces and paint in a zinc rich primer. It actually held up quite well in some area's but not in others over the years since it was initially done.

We didn't have the luxury of sand blasting it this time due to concerns in getting the abrasive sand into the operating equipment of the locomotive, not worth the risk. John and Alec researched a rust converter and top coat for the boiler and two products were selected, Fertan Rust Converter and a high temperature zinc rich primer.

Firebox with Fertan applied

Firebox with the High Temp Zinc Rich Primer applied

John and Andrew then proceeded to remove any loose scale and surface rust and coat the surface with the converter, after the recommended period for the converter to do its work, the top coat was then applied. Andrew had the task of doing the area underneath the boiler barrel, between the frames, nice and squeezy, well done Andrew. The boiler where completed to date looks as good as new and should see it protect the boiler for the next twenty five plus years, well done guys.

Painted Boiler - Looks like new

Steam Regulator Overhaul - John Wearmouth has taken on the task of overhauling the steam regulator valve. Basically this valve is operated by the driver and when opened by him, steam is delivered to the cylinders making the engine go forward or backwards, a very important valve. John's father had previously overhauled the valve as part of the original restoration of the locomotive 20+ years ago. The parts have now been cleaned up and repair requirements noted, some new components will need to be manufactured.

Crinoline Bar Replacement - Crinoline bars are what support the exterior cladding or clothing away from the boiler shell, initially it was thought that the 70 year old items would make do for another 10 years, we were kidding ourselves. The original bars had corroded to the point that in sections were only a couple on millimeters thick, they were loose on their brackets due to the thinning of material and the threaded holes used for bolting the cladding to were void of any thread at all. Time for replacements. The existing bars were then removed by John, Greg and Kirk however the mounting brackets now require drilling out and re-tapping, Dom is in the process of carrying out this work.

John and Greg removing the Cowling Crinoline Bars

Kirk marks the Crinoline bar for tracability

A busy few months indeed, stay tuned for more updates shortly. If you would like to be informed when there is an update, simply follow by email located on the right hand side of this page. Thanks for your ongoing interest, we are looking forward to seeing her in steam once again.