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 » Thu Oct 19, 2017 3:34 am

"2x Malleble 4" Elbow"

Do you knowthe specification for those screwed fittings, and are those rated for the same Pressure/Temperature of the boiler to witch they will be connected?
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Thu Oct 19, 2017 3:49 am

150 PSI 350F

I cannot start transfer until the boiler is 150PSI or less was the plan.

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

Post by DetroiTug » Thu Oct 19, 2017 3:05 pm

It's going to behave like a boiler. Liquid level will have to be kept in the 70 -80 % max of total volume or there will be carry over from flash boiling rising water level on demand. The biggest issue is going to be transferring boiler water to a cold vessel on such a small scale, most of the energy is going to be lost just bringing it up to temperature. Calculate that water volume to the inside surface area of the vessel, then upscale that to Locomotive size and you'll see why it doesn't scale down well, they probably only lose a few percent, on small scale it will be much greater. It may need to be filled once, dumped and then filled again for use. Remember temperature and pressure go hand in hand, temperature or heat is the work available :) To help maintain the temperature, you could put a circulating coil on it with a fire under it?...

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

Post by cyberbadger » Thu Oct 19, 2017 4:30 pm

I'm planning a heat soak phase before transfer which is basically what you are describing.

There is going to be a drain on the one end. I plan to leave this somewhat open during this heat soak, I'll have to get a feel for it - but I'm going to let condensate have a place to exit out this drain.

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

Post by fredrosse » Sat Oct 21, 2017 3:57 am

What geometry are you contemplating for this Kayak Pressure Vessel (KPV)?

In keeping with your original question in this thread; "What are the concerns/safety of an unfired >100C vessel"

Your intent is to only charge the KPV when your big boiler is below 150 PSI, because this is the maximum allowable working pressure of your screwed fittings? 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. Administrative controls (promising to always remember, and not to do something which could easily cause a potentially dangerous overpressure) are generally prohibited wherever possible. Even an automatic pressure reducing valve between the big boiler and the KPV would only be permitted if an appropriately sized safety relief valve were fitted downstream to protect the KPV in the event of the pressure reducing valve failing open.

I think we can all agree with the absolute rule that there can be no isolation valve between a boiler and its safety valve, even if the boiler operator promises to keep that valve open whenever the boiler is in service. This is a similar situation, where a broken, or forgotten, promise might cause much danger.

"To help maintain the temperature, you could put a circulating coil on it with a fire under it?..." Yes, that could be done, but then it becomes a fired pressure vessel (a boiler), where cast iron pressure retaining parts are prohibited if one is following code rules.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sat Oct 21, 2017 5:51 am

Fred,

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)

I'm not going to have any sort of heating going on for simplicity and safety sake, it's not a boiler.

Shape all in 4" 36" pipe-90elbow-close-90elbow-36" pipe

So take that and it can be a u-tupe lying flat, a 36" on a side L shape or any angle in between.

I'm leaning toward an L. You've got a natural steam dome.

I was trying to draw something but it's late. Basically I will have gauge, safety, valve on either end, and probably a trycock.

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

Post by fredrosse » Sun Oct 22, 2017 5:42 am

"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??
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Sun Oct 22, 2017 3:53 pm

fredrosse wrote: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. P
lease 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??
I appreciate the offer and would like to take you up on it, but I'd prefer to have you only you do it once, so lets talk a little first.

I'll try to explain what's fixed and what I haven't decided yet.

The MAWP for Nyitra's Boiler is 200 PSI.

I was intending on drawing water from the bottom of the boiler.

I don't have the removeable handholds, just 4 large NPT threaded half couplings for inspection/cleaning purposes. If I bush one of these down to a small pipe and use it for this filling purpose, is that against the ASME code?
There are also two main drains right now with large ball valves, but I would rather use those for blowing down and draining.

I have different options for flexible lines.

Hmm - Just looking online. One of the options I have is steamking hose, but look at this:

"CAUTION: DO NOT ALTERNATE USE BETWEEN STEAM AND WATER."
http://www.gates.com/products/industria ... -steam-250

I would like to know why because I'm sure sometimes it might end up being a mixture....

The connection might be swagelok, but I had been using AN 37 deg flare. My buddy was trying to convince me to use these instead of swagelok but I'm not sold either way. I like the flare, but I think I remember those threads can jam from thermal expansion.

-CB

P.S. Yuck. I can say that I am guilty of violating this rule but have not had the negative consequences:
From the Gates Steam King Safety Guide
Rule:
ALWAYS drain steam hose when not in use.

Reason:
Water remaining in the hose may be absorbed by the tube. When the hose is then reheated and still under low pressure, the absorbed water may change to steam and “popcorn” or expand and explode the tube. Popcorning can weaken and destroy a hose.
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Re: What are the concerns/safety of an unfired >100C vessel

Post by cyberbadger » Thu Oct 26, 2017 6:50 am

Fred,

Looking at 54875K15 for the hose
Extra-Flexible Extreme-Temperature Hose
24" 321 Stainless Steel with 1/2 x 1/2 304 Stainless Steel NPT Male Fittings
ID: 1/2" OD:7/8"

Probably shooting for 1/2" ID the whole way.

Again MAWP of boiler is 200PSI. PV will only be rated for 150PSI. I don't anticipate or really have any interest in trying to start a transfer more then 150 PSI. I
should make my own Tag for the PV.....

However it occurs that I have no forced circulation in the boiler, and taking water from the water legs is the potentially the hottest water. I don't know if that will be noticeably different in PSI or not. I think it will be hard to really even tell with the condensation happening during the heat soak phase of the PV.

I will need to have at least one vent valve to purge pressure from the hose before disconnecting.

Attached is an image of the safey valve I have. I also have available - but it's not set for anything right now an adjustable single spring ATAM 15mm relief valve.

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

Post by fredrosse » Thu Oct 26, 2017 11:52 am

That safety valve is somewhat small for the 1/2 inch ID connection, I would use 1/4 inch ID connection.

The Swagelok vs 37 degree flare? That is like comparing a modern BMW to a model T Ford in terms of performance. I hope some of our experienced steamboaters on this forum can chime in here and verify what I am saying. The Swagelok fitting can take 3000 PSI with many many connect/disconnect cycles.

The 37 degree flare may crack open and leak, possibly catastrophically, with potential serious injury to those close to the connections. Others have commented on the failure issues with flare fitting. Do you remember some very recent posts on this issue?
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