What are the concerns/safety of an unfired >100C vessel

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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fredrosse
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Re: What are the concerns/safety of an unfired >100C vessel

Post by fredrosse » Sat Oct 28, 2017 9:45 pm

See my 1st post on 14 October 2017 21:32, these are my opinions here.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sun Oct 29, 2017 12:01 am

Fred,

I'm not understanding this at all. There are no opinions on this thread for that date of the 14th from you.

I am trying to work under your guidance on this PV.

I am refering to this from you...
fredrosse wrote:"Fair enough. I have an ASME relief valve that is set at 125 for cap 790 #/HR Aquatrol that I will put on (no valve in between it and the PV)"

OK, that can be configured to meet the safety rules. One facet of this is the pipe size and length between your big boiler and the PV. That line must be small enough to assure that the safety valve is not going to be overloaded. To determine that, we need to know the MAWP of the big boiler, and if you will charge the PV from a steam line or a bottom blow line from your big boiler. I have the software to make these determinations and will calculate for you if you wish. Please also define the line size and configuration for the connection. I am guessing small ball valves (rated for the big boiler MAWP) and stainless braided flex connection, similar to McMaster Carr 5301T41 x 18 inches long, with Swagelok connections at each end??
Later you said 1/4" for the aquatrol.

Is just not appropriate for this PV? Or just restrict it to 1/4"?

-CB
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Sun Oct 29, 2017 1:32 am

Quote: ""An unfired pressure vessel for the service you want simply needs to be rated for at least the maximum operating pressure of your boiler. ASME rules require a relief valve on a pressure vessel IFF it can potentially be charged above its design pressure, so just design for, say 250 psig, and have three connections:

Top steam off-take to the small engine.
Try cock which assures no overfilling to a water level too high
Bottom connection to receive steam from your big boiler, and to drain the vessel when desired.
I would do all these connections in 1/4 inch OD tubing if powering a kayak. ""

He said if you design for a higher pressure than you need, it doesn't need a relief valve.

-Ron
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sun Oct 29, 2017 5:20 am

I have to use the safety valve as Fred said later:
fredrosse wrote:That operating philosophy would never be permitted within my employer's safety review, and they would require a safety valve on the KPV, set at or below 150 PSI, with sufficient capacity to protect the KPV from maximum connection flow (depending on connection size) from the big boiler at its MAWP. .
So I am taking a non reply to this to mean that I should reduce this Aquatrol to 1/4" inlet per your quote from Fred.

-CB
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Sun Oct 29, 2017 12:59 pm

He said his employer would never allow it.

If you want to build it to code, put a relief valve on it, use A106 seamless , radiograph for A53 etc. It's something to play with, if your waste steam is 150, build for 250 MAWP with appropriate hydrotest and play with it.

As long as there is no fire, the pressure can never be higher than when first charged with waste steam, thermal loss is going to result in a steady drop in pressure. How it would blow off on it's own after charging??? Lightning strike? :) As long as you're going to use it as you're implying in this discussion, you don't need a relief valve.

Now if someone there has a eureka moment involving hydrogen peroxide or Calcium carbide or as I joked a few pages back,add a small coil and fire to minimize the loss, then you need a relief valve.

-Ron
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sun Oct 29, 2017 2:15 pm

What are talking about, where was it said what you are saying - QUOTE IT otherwise I cannot follow it!

Look at what I quoted!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
fredrosse wrote:That operating philosophy would never be permitted within my employer's safety review, and they would require a safety valve on the KPV, set at or below 150 PSI, with sufficient capacity to protect the KPV from maximum connection flow (depending on connection size) from the big boiler at its MAWP. .
How am I supposed to secretly heat anything with fire that's already painted - are you looking at the photos on this thread I am posting?

The worry is the heat from the boiler with a higher MAWP!

If you think I am being deceitful, I have no interest in doing so and am not that kind of person.

I maybe impatient, but if I say I'm going to follow Freds guiddance at the time on this then I bloody well will!

But I cannot do that unless it's from Fred and it's quotable.

So unless Fred says otherwise to this thread, or you can faithfully quote him.
1) In my case with my large boiler MAWP and the pipe that was purchased it is required
2) 1/4" reduction for the safety valve

-CB

P.S.Those elbows are each more expensive then the 3 feet of 4" pipe. That's the limit for this design. And no I'm NOT welding a boiler. They are about 2-3x more in price at the 4" size to get that extra 50PSI rating.
Last edited by cyberbadger on Sun Oct 29, 2017 2:50 pm, edited 1 time in total.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Sun Oct 29, 2017 2:45 pm

I don't see how you're misunderstanding this??

If you have no plans of heating the vessel, all you need is three outlets: Filler, trycock and steam out. NO RELIEF VALVE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :)

He went on to say his boss would never allow that in a professional application. YOU DON'T WORK FOR HIS BOSS!!!!!!!!!!!!!!!!!!!!!!!!!!!! :)

Yes, I've looked at the painted pipe, an external coil would not burn the paint off of that, Google Lamont or Clayton type boilers.

Quote: "The worry is the heat from the boiler with a higher MAWP!"

Your vessel should be equal in MAWP. Temperature and pressure go hand in hand. Why would you want to put higher pressure steam than the vessel is designed for? I think when the transfer is made, the pressure is going to drop considerably due to the temperature difference.

If you're still misunderstanding this, I implore you to hold off another few years with the experiments until you have a better grasp of what you're working with. No offense intended, but I get the idea from this subject and others posted here, that you don't fully understand how steam behaves. I don't either, but I'm learning.

-Ron
Last edited by DetroiTug on Sun Oct 29, 2017 3:04 pm, edited 1 time in total.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sun Oct 29, 2017 2:58 pm

I'm not going to cheat on what Fred said, because I'm not comfortable doing it.

I'm not putting any heat into other then what comes from the 200MAWP boiler.

The elbows are so expensive, and I'm limited to that because I'm not welding a boiler or PV. 50 extra PSI rating is double or triple the cost.

-CB
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Re: What are the concerns/safety of an unfired >100C vessel

Post by DetroiTug » Sun Oct 29, 2017 3:08 pm

Oh I see, you want to use a vessel, that is under rated and rely on a relief valve to make it safe. :shock:

Read my comment above about holding off a few years with the experiments. Again, I intend no offense, but you are grossly underestimating the potential hazards.

-Ron
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sun Oct 29, 2017 3:13 pm

Last Fred said was that a safety valve was required for this PV because of the elbow MAWP and the big boiler MAWP, I see nothing in what you are saying that convinces me Fred is wrong on this point.

-CB
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