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Regulators in Taper Barrel Boilers

Reuest to share information about design of steam regulators in taper boiler barrels

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Bruno Taylor13/02/2018 10:02:45
48 forum posts
14 photos

Following the recent thread on What Regulator Type l thought l would ask opinions on a related subject.

The boiler of my current project (LBSC Princess Marina but with piston valves) is tapered. This means that the smokebox steam pipe flange is lower than the backhead regulator flange.

So far l have thought of three options.

1. Do no nothing and hope it doesn't leak too much.

2. Provide a suitable joining piece below and fixed to the top feed bush in the boiler.

3. Put a joggle in the steam pipe so that both regulator assembly and steam delivery pipe are perpendicular to their respective flanges.

Any advice gratefully recieved.


David Wasson14/02/2018 03:19:44
145 forum posts
42 photos

What is wrong with the regulator specified in the drawing?


Bruno Taylor14/02/2018 10:56:18
48 forum posts
14 photos

There is nothing wrong with the regulator on the drawing per se, but l have chosen the screw down type. However the issue is the steam pipe connecting the regulator to the smokebox flange plate bush. Curly simply did not include it on the drawings or accompanying text. Leaving constructors to work out their own.


Nick Hughes14/02/2018 11:34:50
243 forum posts
141 photos

Hi Bruno,

It's usual to put a Joggle in the steam pipe as per your third option.

There is also an alternative method of sealing the steam pipe at the smoke box end, that eliminates the need for two threads of equal pitch and instead uses an "O" ring seal. Discussed here:- **LINK**


Edited By Nick Hughes on 14/02/2018 11:49:50

David Wasson15/02/2018 20:23:56
145 forum posts
42 photos

Not included in the drawing? Sorry about that!

Yes, I have seen some folks complete the connection from the regulator tube to the smokebox bush by having a "joggle" in the tube that goes into the smokebox bush.

The above mentioned link is for the connection of the small tube of the regulator to the smokebox, The method described in the article works well. I have used the compressed O ring method for this connection using a Viton O ring. It has the highest temperature rating.

Attached should be a photo of the smoke box of my boiler that uses this type of connection to the regulator tube. You can just see the end of the tube in the center of the bushing. The gap between the tube and the bush is where the O ring goes. This entire assembly slides into the smoke box end of the boiler. The four small holes in the part that compresses the O ring are for the screws that pull the assembly together.

The threaded fitting out of the side is for the snifter valve connection.

Below that is the wet header, the super heater elements and then the hot header. On the left side of the hot header you can see just a little bit of the pipe that feeds the cylinders.


dscn1439 - reduced 4.jpg




Edited By David Wasson on 15/02/2018 20:25:15

Matt Harrington11/09/2019 17:43:51
135 forum posts
6 photos


How are you progressing with your Princess Marina?


Bruno Taylor22/09/2019 17:52:10
48 forum posts
14 photos

Hi Matt

Thanks for asking. In short very well. Last Friday successfully passed Steam Accumulation test so now fully ticketed. Couple of tweaks to sort out and finish spray painting the boiler/firebox cleading. Then handrails and heat cladding and job done. I will try to post some pictures shortly.


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