Immediately after brazing the front head

(sorry about the camera jitter - that thing was still searing hot

and the radiant heat on the camera and my face was tremendous!)

 

 

Silver brazing - isn't it beautiful!

 

 

 

ACID ROCKS!

 

 

I just use ordinary citric acid because...

1. it doesn't burn my clothes                                                      
2. it is reasonably safe in most respects                                   
 3. it is also gentle - but I can easily spice it up by heating it.      

 

 

On March 26 2009 this boiler passed a milestone

 

The hydrostatic test was conducted on the pressure vessel assembly Thursday night (Mar 26).  It was filled with water at 240 psi (16 bar) of pressure and held it at that level for the recommended 30 minutes.  This is double the designed maximum working pressure (in this case 120 psi) as a proper test for copper boilers requires.  In practice, I usually run steam only at 60 psi for most of my models, but want to be able to safely use more for operating expansion engines.

 

'Nary a drop of water escaped from any of the 139 silver brazed joints - nor did anything deform.  It looked every bit as benign under that pressure as it does right now, sitting on the desk in front of me - dry as a bone with all of the ten threaded plugs removed.

 

Now I will be able to turn my attention to the marriage of the boiler enclosure and pressure vessel, with thoughts of the burner, stack and tanks not far down the road.

 

 

They say a picture's worth a thousand words ...

 

 

The boiler is 100 percent full of water in this view

 

At last it is now safe to clean off all that red and black firescale :-)

 

 

By standing it on end, if any drop of water should leak out, it will travel down and be visible on the stainless steel sheet under the boiler...

 

You can see how much leaked:

 

NONE - not a single drop in thirty minutes.

(the boiler is still under full 240 psi pressure in this shot)

 

 

 

 

 

Here is a close-up showing the vessel being tested to 240 psi (1,654 kPa)

 

 

 

 

 

110 F (43.3 C)

In this case the temperature required for the test was quite low

- not enough to obscure the evidence of leaks by evaporation

 

Stamped for maximum working pressure of 120 PSI

 

 

 

 

The steam pressure vessel in front of my computer monitor

- it is now ready for mounting in the steel enclosure

 

(Yes - I have two widescreen monitors here as well, but it is not a very useful format for most pictures)

 

 

Ready for the installation of baffle plates to direct the hot gases

 

 

It is not easy to see from these photos that there are

actually four rows of tubes in the convection section

 

 

 

 

 

 

Beginning the marriage of the pressure vessel and boiler casing

 

 

Drilling for steam nozzle, safety valves and the vent valve

 

 

 

 

The lower portions of the safety valve bodies will be under the roof

(for a better scale appearance)

 

 

 

Next problem: to make a coverplate to match the front gauge and pipe connections

 

 

 

 

 

Why use one pencil when five will do!

 

 

The pencils are stuck in each of the ferrules to create a paper template 

 

 

 

I knew that ancient pile of fanfold printer paper would come in handy some day...

 

 

 

 

 

Copied on to sheet steel and drilled

 

 

 

 

Cut out

(but not yet cleaned up!)

 

 

 

 

Bending a piece of old packaging strap to make a hole liner

 

 

 

 

Test fitting - it is ready for brazing

 

 

 

 

 

Prepared to mount the plate with stainless screws from the inside

 

 

 

 

 

Inside view with back removed showing cooling tube loop for the furnace viewing port

 

 

 

 

 Davidson aluminum 35 mm slide frame

an easily replaceable solution for the view port glazing

 

 

 

 

The two glass sheets are each less than 1mm thick

the foil-covered paper mask leaves a tiny insulating air space

 

 

 

Two simple clips hold it in place

the insulating blanket will cover all but the round porthole

 

 

 

 

 

A 12L14 steel ring in the back plate completes the job

 

 

 

 

On the outside looking forward toward the burner firehole in the front plate

(insulating blanket will also cover the inside of the front plate)

 

 

 

I knew that drill press table was good for more than just drilling!

(put to good use in holding the pressure vessel down inside its casing via two

blanking plugs screwed into the safety valve holes on the drum top)

 

 

The objective was to hold two cork protectors between the bottom drum

and the cradle while a high temperature adhesive set.

 

 

 

Hoisting lugs have been added at the balance point

 

 

 

 

 

Adding the heat-reflecting aluminum

 

 

 

 

Better than black steel sheet

 

 

 

 

 

Note the top of the flue gas outlet frame is contoured to clear upper drum

 

 

 

 

 

A lot of tricky things to get around on the front plate

(and the back was a more difficult job with the glass slide)

 

 

 

 

I think it will reflect heat alright!

 

 

 

 

Silvering completed.

(note the right hand wall is not fully seated in this posed shot)

 

 

 

 

Waiting to attach the Cerablanket and rigid Cerrafelt

 

 

You are on Part 6

Part 1 (casing)

Part 2 (drums)

Part 3 (tubes)

Part 4 (tube brazing continued)

Part 5 (forming the drum heads)

Part 6 (vessel testing and silvering the casing)

Part 7 (insulating the casing)

Part 8 (stack and economizer)

Part 9 (burner windbox)

Part 10 (methanol fuel tank)

Part 11 (fuel tank fittings)

Back to the D-boiler first page

or

Return to ModelEngines.info homepage