[Steam-engine] boiler feedwater injector conection

[Richard Strobel]

Interesting EJ.  The expanding/contracting metal which causes feedwater 
leaks is most interesting.  Would this also pertain to feedwater being 
injected at the mudring?  Seems to me that the outer shell would be cooler 
down there and this expanding/contracting condition wouldn't be quite so 
bad....but that's just a newbee speculation.

  Also if one were to inject between the sheets, how would one NOT shoot it 
against a tube?

  I'm not asking you specifically, but invite any and all comments.

Thanks much for the post!!

RickinMt.


----- Original Message ----- 
From: <EJHottel at aol.com>
To: <steam-engine at lists.stationary-engine.com>
Sent: Saturday, November 05, 2005 10:05 PM
Subject: Re: [Steam-engine] boiler feedwater injector conection


Here is some info that may be pertinent. It is exerpted from the 2002 
Pawnee
Steam School Text. It refers to Traction & Portable boilers, but I  can't 
see
why it would not be applicable to Stationary also. There is lots more  good
advice. You might want to obtain a copy.


•RossStaggs instructor
Boiler Piping continued:

We will now  discuss a fitting you must make if you need an extension 
nipple,
It is a nipple  with an extension, usually about one (1) inch long with a
diameter that will  just slide inside the threaded pipe hole the nipple is 
to
screw into. This  special nipple is used where the feed water enters the 
boiler,
Using a lathe,  chuck a coupling and screw about a 3 or 3 1/2 inch long 
nipple
into this  coupling. Bring your tailstock up to support the outer end of the
nipple and  turn off the threads to about .015 to .020 below the roots of
threads. You might  check here to see if it will pass through the threads in 
your
boiler. Next set  your lathe up and cut the threads. Set the center line of
the threading tool at  right angles to the center line of the pipe and not 
to
the taper of the thread.  This makes a nice looking job.
These extension nipples can also be made  without a lathe. You will need
either a nipple chuck or I use old or dull hand  expansion reamers for a 
nipple
chuck. They work better than the regular tool  and, being centered on both 
ends,
can be used to an advantage with a lathe. Even  with a broken or missing
blade, these old reamers work good. With the reamer now  turned into a 
nipple
chuck and tight in the nipple, put the square drive end in  a vise and you 
are
ready to cut threads fhrther up the nipple. Your die should  be set for a
standard thread and the dies advanced until they are beyond the end  of the 
nipple to
a distance of 1/8 inch less than the distance you wish the  extension to
protrude into the boiler. Extension nipples should only be made  from 
schedule 80
pipe.
Piping a Traction or Portable Engine
We will start  our piping at the point where the feed water enters the
boiler. Remove the old  fittings and inspect the threads. They should be 
sharp and
at least three (3)  continuous threads. The curvature of the boiler will 
reduce
the number of  continuous threads available for sealing, but this will not
materially reduce  strength or “shear” as the partial threads are still
effective.
At the point  where the feed water nipple enters the boiler we often see
leaks. This is caused  by cold or even warm water being used as feed water. 
This
contracts the nipple  and even with all precautions it will leak. This is 
where
the extension nipple  comes in, but cannot be used in every case. ‘Where the
nipple will come in  between two rows of tubes or the row of tubes is on a
level with the nipple, but  inside the boiler shell by at least 1 1/2 inches 
an
extension nipple can be  used. Do not make the extension of such a length as
will put the discharge point  closer than about 1 inch from a boiler tube
directly opposite.
The principle  of the extension nipple is that the extension projecting into
the boiler will  carry heat to the threaded portion of the nipple and keep 
it
from contracting to  a point where it will leak. Any amount of extension 
will
help but there is no  advantage to making it longer than one pipe diameter.
Beyond this point the  solids in the water will form incrustations (lime up) 
and
choke  delivery.
With the nipple in the boiler we are now ready for our first  fitting. Screw
the run of a forged steel tee on the outside end of the nipple.  The branch
should beheaded toward the source of water feed. The outer end  of the tee
should be plugged with a brass pipe plug having the square wrench  pad. This 
plug
is essential for cleaning out the nipple as it tends to lime up.  This is
especially true where an extension nipple is used.
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