Literature on Ofeldts?

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dampfspieler
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Re: Literature on Ofeldts?

Post by dampfspieler » Fri Jun 30, 2017 6:18 am

Hi Tom,

for coal firing i prefer a thre-drum-boiler. They have a bigger water-capacity than the ofeldts with vertical drum (up to three times).

There are a lot of designs for a three-drum different from yarrows like roberts or STUART Mandip (Kelly built such one for his RECIPROCA).

Here is one of my boilers built for a STUART 6a. The superheater and the feedwaterheater can be installed in the boiler so the plant is small enough for a little boat.
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Best Dietrich
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Re: Literature on Ofeldts?

Post by Akitene » Fri Jun 30, 2017 6:19 pm

Good evening Dietrich,

Very nice & interesting boiler. What are the dimensions of its main drum (especially its wall thickness)? What are the test pressure and the working pressure? Image

Thank you in advance.

-Christophe
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Re: Literature on Ofeldts?

Post by TriangleTom » Fri Jun 30, 2017 8:03 pm

dampfspieler wrote:Hi Tom,

for coal firing i prefer a thre-drum-boiler. They have a bigger water-capacity than the ofeldts with vertical drum (up to three times).

There are a lot of designs for a three-drum different from yarrows like roberts or STUART Mandip (Kelly built such one for his RECIPROCA).

Here is one of my boilers built for a STUART 6a. The superheater and the feedwaterheater can be installed in the boiler so the plant is small enough for a little boat.

Best Dietrich
Dietrich,

Thanks for the advice. I'm planning on running at 300 PSI, so I've been drawn more to the Yarrow than to the Roberts and the like because of the Yarrow's ability to handle higher pressures. I'm not aware of any Roberts installations above 220 PSI.
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Re: Literature on Ofeldts?

Post by RGSP » Fri Jun 30, 2017 8:29 pm

TriangleTom wrote:
RGSP wrote:If it's for a steamboat, and you're coal firing, go for the Yarrow. They're somewhat bigger and heavier than the Ofeldts for the same steaming capacity, and the time to reach pressure is a little worse, but the real point is that Yarrows are very easy for external tube cleaning, which you'll need to do fairly regularly, and for tube replacement, which you shouldn't have to do very often.

Yes, I know, steam lances are quite good at tube cleaning, but having used one quite a lot, they do have their limitations, whereas brushing always works.
Thanks for the advice. Do you know of anywhere that sells plans for a Yarrow?
I think there are a couple in the Steam Boat Association "approved design" library. Kevin Slater at Steamwell Boilers (Manor Farm Engineering) would know of others, and would be worth talking to anyway

By the way, if you want to go to 300 psi, then copper is certainly taboo in the UK, regardless of tube wall thickness, and I suspect knowledgeable insurers in the US won't accept it either. The problem with copper is that its creep strength drops quite rapidly over 200C, and for any tubes or drums exposed to full furnace heat, you need quite an allowance above the saturated steam temperature. For new build (as opposed to historic boiler maintenance) I don't think boiler inspectors will accept copper much above 120 psi. I think you'll probably need to go to steel, though 10% Cunifer might be OK for 200 psi.
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Re: Literature on Ofeldts?

Post by TriangleTom » Fri Jun 30, 2017 10:20 pm

RGSP wrote:
I think there are a couple in the Steam Boat Association "approved design" library. Kevin Slater at Steamwell Boilers (Manor Farm Engineering) would know of others, and would be worth talking to anyway

By the way, if you want to go to 300 psi, then copper is certainly taboo in the UK, regardless of tube wall thickness, and I suspect knowledgeable insurers in the US won't accept it either. The problem with copper is that its creep strength drops quite rapidly over 200C, and for any tubes or drums exposed to full furnace heat, you need quite an allowance above the saturated steam temperature. For new build (as opposed to historic boiler maintenance) I don't think boiler inspectors will accept copper much above 120 psi. I think you'll probably need to go to steel, though 10% Cunifer might be OK for 200 psi.
Thanks for the information. As for materials, I'm planning on going all overbuilt, with schedule 80 pipe for the steam and mud drums and schedule 40 pipe for the water tubes. I really don't care about weight much for such an important component, so I'm aiming for a safety factor of 10, and hydrotesting at 1200 PSI on each part of the boiler.
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Re: Literature on Ofeldts?

Post by cyberbadger » Fri Jul 07, 2017 1:31 am

The Ofeldt boiler like Ron made - can they work with solid fuels? Anybody done or tried that?

-CB
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Re: Literature on Ofeldts?

Post by fredrosse » Fri Jul 07, 2017 5:28 am

"As for materials, I'm planning on going all overbuilt, with schedule 80 pipe for the steam and mud drums and schedule 40 pipe for the water tubes. I really don't care about weight much for such an important component, so I'm aiming for a safety factor of 10, and hydrotesting at 1200 PSI on each part of the boiler."

Beyond using Schedule 80 drums and Schedule 40 pipe for your boiler, the materials also should be considered here. As mentioned previously, Copper, even in the heavy schedules you mention, would be unsuitable for high temperature service. The ASME Boiler and Pressure Vessel Code limits use of Copper boiler pressure parts to 406F, corresponding to 250 PSIG saturated steam service.

If you are using steel pipe components, the ASME Code also prohibits using ASTM A120 steel water pipe, the most common water pipe in the USA, usually what is available in box stores. This pipe is not considered suitable at any boiler service condition. The ASME Code lists several available steel grades that are suitable for boiler fabrication.

If building a new boiler, I would recommend at least using the materials that are Code compliant for the pressure retaining parts, and why not use real boiler tubes (ASTM A178 material) rather than Schedule 40 pipe for the water tubes? Currently real boiler tubes cost less than the Schedule 40 pipe sold at Home Depot, and that stuff is real low specification steel, probably manufactured in China.
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Re: Literature on Ofeldts?

Post by TriangleTom » Sat Oct 28, 2017 6:06 am

fredrosse wrote:"As for materials, I'm planning on going all overbuilt, with schedule 80 pipe for the steam and mud drums and schedule 40 pipe for the water tubes. I really don't care about weight much for such an important component, so I'm aiming for a safety factor of 10, and hydrotesting at 1200 PSI on each part of the boiler."

Beyond using Schedule 80 drums and Schedule 40 pipe for your boiler, the materials also should be considered here. As mentioned previously, Copper, even in the heavy schedules you mention, would be unsuitable for high temperature service. The ASME Boiler and Pressure Vessel Code limits use of Copper boiler pressure parts to 406F, corresponding to 250 PSIG saturated steam service.

If you are using steel pipe components, the ASME Code also prohibits using ASTM A120 steel water pipe, the most common water pipe in the USA, usually what is available in box stores. This pipe is not considered suitable at any boiler service condition. The ASME Code lists several available steel grades that are suitable for boiler fabrication.

If building a new boiler, I would recommend at least using the materials that are Code compliant for the pressure retaining parts, and why not use real boiler tubes (ASTM A178 material) rather than Schedule 40 pipe for the water tubes? Currently real boiler tubes cost less than the Schedule 40 pipe sold at Home Depot, and that stuff is real low specification steel, probably manufactured in China.
I was planning on using 304 stainless, however per your advice I've moved towards ASTM A178 pipe. I'm still waiting to hear back from the SBA on a copy of the standard design library catalogue, so until then I'm focusing on engine design in my free time.
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Re: Literature on Ofeldts?

Post by dampfspieler » Sat Oct 28, 2017 6:46 am

Hello Christophe,
What are the dimensions of its main drum (especially its wall thickness)? What are the test pressure and the working pressure?
back your pardon for the late answer.

The boiler is desgned for a working pressure of 8 bar, it is tested with 12 bar cold water.
The Dimensions are:
- main drum 108 x 2,5 x 500 mm
- mud drums 64 x 2 x 500 mm,
- all watertubes 15 x 1 mm.
- total heating surface of the shown vessel 2,1 m².

The driven engine is a STUART 6a at 750 rpm.

Best Dietrich
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Re: Literature on Ofeldts?

Post by marinesteam » Sat Oct 28, 2017 1:54 pm

TriangleTom wrote:
fredrosse wrote:"As for materials, I'm planning on going all overbuilt, with schedule 80 pipe for the steam and mud drums and schedule 40 pipe for the water tubes. I really don't care about weight much for such an important component, so I'm aiming for a safety factor of 10, and hydrotesting at 1200 PSI on each part of the boiler."

Beyond using Schedule 80 drums and Schedule 40 pipe for your boiler, the materials also should be considered here. As mentioned previously, Copper, even in the heavy schedules you mention, would be unsuitable for high temperature service. The ASME Boiler and Pressure Vessel Code limits use of Copper boiler pressure parts to 406F, corresponding to 250 PSIG saturated steam service.

If you are using steel pipe components, the ASME Code also prohibits using ASTM A120 steel water pipe, the most common water pipe in the USA, usually what is available in box stores. This pipe is not considered suitable at any boiler service condition. The ASME Code lists several available steel grades that are suitable for boiler fabrication.

If building a new boiler, I would recommend at least using the materials that are Code compliant for the pressure retaining parts, and why not use real boiler tubes (ASTM A178 material) rather than Schedule 40 pipe for the water tubes? Currently real boiler tubes cost less than the Schedule 40 pipe sold at Home Depot, and that stuff is real low specification steel, probably manufactured in China.
I was planning on using 304 stainless, however per your advice I've moved towards ASTM A178 pipe. I'm still waiting to hear back from the SBA on a copy of the standard design library catalogue, so until then I'm focusing on engine design in my free time.
Triangletom,

The advice from this group is good but several of your comments (plan to hydro to 1200psi, safety factor of 10, overbuilt with schedule 80 pipe, etc) make me think you should be consulting with a professional engineer knowledgeable in the boiler code before proceeding any further.

The SBA boiler archive (I have a copy) is a great resource but the designs are approved for use in the UK. The designs and calculations do need to be reviewed before they can be applied in the US.

The statute from your state (OK) states....
The definitions, rules and regulations so formulated for new
construction shall be based upon and follow generally accepted
national engineering standards, formula and practices related to
boiler and pressure vessel construction and safety. The
Commissioner of Labor may adopt an existing American National
Standard known as the Boiler and Pressure Code of the American
Society of Mechanical Engineers, with the addenda and code
cases, and may also adopt subsequent
revisions in the form of
addenda and code cases of that standard provided such revisions
are acceptable to the Commissioner. When so adopted, the same
shall be deemed incorporated into, and to constitute a part of
the whole of the definitions, rules and regulations of the
Commissioner of Labor
Requirements for new installations
Except for State of Oklahoma authorized owner/user Inspection
Agencies, the installer must notify the Bureau of Boiler Inspection prior to
installation. No boiler or pressure vessel shall hereafter be installed in this
State unless it has been constructed in conformity with the ASME Code and
installed in conformity with the requirements of this Chapter except:
The maximum allowable working pressure of a non-standard steel or
wrought iron heating boiler of welded construction shall not exceed
15 psig for steam. For other than steam service, the maximum allowable working
pressure shall be calculated in accordance with Section IV of the ASME Code,
but in no case shall it exceed 30 psig.
I don't want to place a damper on your enthusiasm. It's also great your asking questions here and the group is always willing to share but it would be a shame to put the time and money into building a boat that can only be used on your own private property due to a non-conforming boiler. Unless that is your intent, I would seek professional assistance in the design and build, get some advice from your local boiler inspector and do a lot more research before touching torch to steel.

Ken
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