Railway Preservation News

Injector Fun on K582
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Author:  softwerkslex [ Mon Jan 11, 2016 11:27 am ]
Post subject:  Injector Fun on K582

As part of winter overhaul we pulled the injectors off of DSB K582. This was three hours of work for two guys. These injectors are in impossible to access locations with no room to swing a wrench. And for some annoying reason, they use coupling nuts on the supply and overflow lines, but they use bolted flanges on the steam and suction lines. Engineer's injector is right up against screw reverse, and one bad move with the wrench and you smash the speedometer. And all the nuts are gummed up and tight requiring wrench removal all the way.

Why couldn't they use coupling nuts all the way around?

p.s. and somebody assembled them with three different bolt head sizes

File comment: Where they came from
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File comment: Injectors on the workbench
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Author:  Frisco1522 [ Mon Jan 11, 2016 11:56 am ]
Post subject:  Re: Injector Fun on K582

Murphy works in mysterious ways.

Author:  Dave [ Mon Jan 11, 2016 12:56 pm ]
Post subject:  Re: Injector Fun on K582

Just think about how you can improve it when you put it all back together again.

Author:  softwerkslex [ Mon Jan 11, 2016 1:25 pm ]
Post subject:  Re: Injector Fun on K582

Just think about how you can improve it when you put it all back together again.

Diesel on board power unit, electric pump.

Author:  Dave [ Mon Jan 11, 2016 1:51 pm ]
Post subject:  Re: Injector Fun on K582

No, bigger cab with more room for everything. Speedometer? Really? Just time the mileposts as they go by.

Author:  dinwitty [ Wed Jan 13, 2016 12:27 am ]
Post subject:  Re: Injector Fun on K582

ever work on a mini-sports car...to get to one thing you have to remove this then remove that then that piece and on and on...everything packed in....

I've had nuts in tight places, 1/2 quarter turn, release, re-adjust, maybe somebody needs to invent some air pin spin hammer nut remover for tight places, I'd be rich...

Author:  softwerkslex [ Wed Jan 13, 2016 7:39 pm ]
Post subject:  Re: Injector Fun on K582

Well, we are inspecting and cleaning the injectors.

What do your injectors look like after 30 days of service? After 300 days? Are they coated in calcium and lime? If they are, does this mean your water treatment is not adequate?

How are you cleaning your injectors? Are you soaking them in vinegar?

Our injectors are original to before restoration. The cones now look like rough castings. Did water erosion do this? Or excessively acidic cleaning?

Materials: all the photos I have seen of injectors show them made in bronze. Why not stainless steel? Would it last longer? We will probably have to machine new cones. We do not have a stock of spares.

Author:  10stewi [ Wed Jan 13, 2016 8:29 pm ]
Post subject:  Re: Injector Fun on K582

Here are photos of the now "rough castings". I am very interested in what could have caused the perpendicular deep gouge marks in the cone! Thankfully, its not the worst thing in the world to make from scratch! The second injector's cone is not gouged, but shows more pitting in the metal.

Very annoying when you stock loads of spares....but they are all for the injector model 1 size smaller!

4.042-6 - Strålerørskruestykke for injetkor nr. 10.pdf [82.22 KiB]
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Author:  Dave [ Wed Jan 13, 2016 9:34 pm ]
Post subject:  Re: Injector Fun on K582

Yes, they are steam pitted and cut from years of service. This is not unusual and reflects why they were common consumable replaceable components back in the day. Some modern replacements are made of stainless rather than steam bronze - I'm not sure what grade is best, never having made steel tubes and nozzles. I do know that if you can find or generate good drawings, they can be manufactured using programmable tools rather than the old custom tapered and curved reamers necessary in the old days.

In general, the cleaner the water, the better everything works, boiler included. Test the water and treat and blow down to the test results. If you don't know that your treatment is good, why are you using it?

I've seen much less damage make injectors fail before - yours seem very forgiving.

Author:  10stewi [ Wed Jan 13, 2016 10:03 pm ]
Post subject:  Re: Injector Fun on K582

I would seriously not be surprised if it didnt work any longer. The calcium build up was so thick that completely filled all of the pocketing and gouges, along with reducing the diameter of the cone by about a millimeter!!! The past two years have shown the injector to be worn, the most obvious sign being that the injector would prime in different handle positions over small pressure differences

Author:  JJG Koopmans [ Thu Jan 14, 2016 8:41 am ]
Post subject:  Re: Injector Fun on K582

There is a fair chance that the pitting is caused by cavitation. The implosion of tiny cavities in the flow causes metal fatigue in the surrounding metal. If you replace by bronze, make sure that it is of ship propeller quality. I am not so sure about stainless steel in an old bronze housing, what about the voltage range?
kind regards
Jos Koopmans

Author:  Overmod [ Wed Jan 20, 2016 4:01 pm ]
Post subject:  Re: Injector Fun on K582

I have little doubt that Jos is right on both counts -- the cavitation, and the danger of galvanic interaction between a new stainless cone and the bronze body. I do not know if it would be possible to use something that would electrically insulate the new cone at its mounting points - but I'd also be concerned with cavitation damaging a replacement preferentially, especially if it is 'harder' than the original. (I am assuming you treat the feedwater to knock down any chloride).

I also wonder whether some of the cutting is enhanced by solids coming out of solution as the water passes through the injector -- if you see deposits plating out on a location where there is high flow, there may well have been more 'solid' nuclei being drawn across internal surfaces. This in turn might lead to rethinking some of the water treatment...

I'm tempted to have you see whether some rather simple ultrasound frequency detector (basically a glorified high-frequency microphone) might be bonded to the injector body, which would pick up any distinctive cavitation signature during operation that could give you a guide when operating in the 'wrong' way...

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