Hi All,
My build is getting to the point that I need to be thinking about piping, valves etc. I am running a Tiny Power M 3x4 simple engine, rated at ~ 5 hp. I could use help with the following questions:
1. What size pipe should I use for the main steam connection to the engine ? I am planning to use a leg of braided stainless in the connection, but need help with sizing.
2. What is the appropriate size pipe for the feedwater circuit ? There was an entry in SBMSL that said it was important to have the discharge side of the water pump larger than the intake. Do I need to follow that protocol ?
3. I read in either SBMSL or the UK steamboating guide that it is a good idea to oversize valves since they can unduly restrict flow. It was suggested that larger valves be used and bushed down to the diameter of the pipe. Are people doing that ?
4. I understand there are a couple of different types of check valves. Which type should I use ? Do I oversize these too and bush them down ?
5. Is there a functional benefit to the angled blowdown valve ? Is there any reason I cant use a regular valve If I am blowing off through the hull ?
6. Is there a reason to use globe valves for specific applications or can I go with all ball valves ?
7. How do I make sure that I buy the right blowoff valve. I know the popoff pressure is specified, but I am worried about theegree of blowdown, the possibility of blowing off too much before it re-seats. How do I know that I am buying the right one ?
8. I intend to use copper for the exhaust /condensation loop. Do I need to silver solder the joints on that loop or will I be OK with regular solder given the lower pressure and temp.
9. Where in the feedwater circuit should I have a pressure relief valve ?
thanks in advance for the help.............
jon
Plumbing Questions
-
fredrosse
- Full Steam Ahead
- Posts: 1925
- Joined: Fri Nov 20, 2009 5:34 am
- Boat Name: Margaret S.
- Location: Phila PA USA
- Contact:
Re: Plumbing Questions
This should be moved to Technical – Engine & Boilers
You will probably get some differing answers for these questions, here is what I think is OK for your 100 – 150 PSI steam launch setup:
1. What size pipe should I use for the main steam connection to the engine ? I am planning to use a leg of braided stainless in the connection, but need help with sizing. ANS: At 100 psig or greater, about 200 PPH steam flow, 1/2 inch schedule 80 is ok for the main steam line to the engine. 3/4 is OK too, perhaps proper if the steam line is more than a few feet long.
2. What is the appropriate size pipe for the feedwater circuit ? There was an entry in SBMSL that said it was important to have the discharge side of the water pump larger than the intake. Do I need to follow that protocol ? ANS: Feed discharge, 3/8 inch pipe is big enough, 1/2 is OK too. I use 1/2 inch outside diameter copper, 5/8 OD is OK too, use type “K” tubing, not “L” or “M” if you use copper. Copper piping should be sil-brazed, or pipe thread, or unions or flared fittings for 100-150 PSI service. Compression fittings are not considered as reliable, but I typically use these for high pressure cold water service. Swagelok compression fittings are the best, and will take high pressures very reliably. Discharge side larger than suction – not correct, the suction to the pump should be one size larger. I use 3/4 inch copper Type "L" suction piping, and automotive radiator hose to join suction piping sections together.
3. I read in either SBMSL or the UK steamboating guide that it is a good idea to oversize valves since they can unduly restrict flow. It was suggested that larger valves be used and bushed down to the diameter of the pipe. Are people doing that ? ANS: no need to do this with the sizes outlined above.
4. I understand there are a couple of different types of check valves. Which type should I use ? Do I oversize these too and bush them down ? ANS: Brass swing checks or lift checks are OK. Oversize - no need to do this with the sizes outlined above.
5. Is there a functional benefit to the angled blowdown valve ? Is there any reason I cant use a regular valve If I am blowing off through the hull ? ANS: any valve rated for main steam temperature/pressure is OK, angle valves tend to hold up a little better in this service, but I think it does not matter much. I use 1/2 inch ball valve, followed by 1/2 inch angle valve for blowdown. Two valves in series is required on each blowdown.
6. Is there a reason to use globe valves for specific applications or can I go with all ball valves ? ANS: You can use all ball valves, but be sure the rating for steam is defined. Stay with USA name brand ball valves that are steam rated. Globe valves are said to provide better regulation (throttling), but ball valves work OK.
7. How do I make sure that I buy the right blowoff valve. I know the popoff pressure is specified, but I am worried about theegree of blowdown, the possibility of blowing off too much before it re-seats. How do I know that I am buying the right one ? ANS: I think you intend to buy a Safety Relief Valve. Get an ASME stamped valve, it will have the pressure setting and blowdown (how much lower pressure falls before the valve reseats) marked on the valve, and it will have sealed wires that must be cut if someone fools around with the valve settings. The valve must have the lock wires and seals intact. 5 to 10 % blowdown is typical.
8. I intend to use copper for the exhaust /condensation loop. Do I need to silver solder the joints on that loop or will I be OK with regular solder given the lower pressure and temp. ANS: I use copper, put together with ordinary automotive radiator hose and hose clamps for atmospheric pressure exhaust. Portions are silver brazed together, but ordinary solder would work OK for this service. Note that an automotive radiator cap on older cars acts as a pressure relief valve for overheating automotive engines, and automotive radiator hose is good for a few PSI pressure, boiling water.
9. Where in the feedwater circuit should I have a pressure relief valve ? ANS: on the pump discharge line, with no isolation valve between the relief valve and the pump discharge. In general, you need relief protection for any piping or pressure retaining component that could be exposed to pressures exceeding the design pressure of the piping or component. That usually means a feed pump relief valve if reciprocating pumps are used, and a boiler safety valve. If an economizer can be isolated from the protection afforded by the main boiler safety valve, then this section of piping needs its own relief valve, with no isolation valve capable of removing the protection of relief. If your exhaust piping can be isolated from atmospheric vent, then this piping would also need a relief valve, again with no intervening isolation valve.
I use 1/4 inch OD copper tubing for piping drains and cylinder drains, also for my bilge eductor, which has 5/8 OD copper discharge piping, 3/4 copper suction.
You will probably get some differing answers for these questions, here is what I think is OK for your 100 – 150 PSI steam launch setup:
1. What size pipe should I use for the main steam connection to the engine ? I am planning to use a leg of braided stainless in the connection, but need help with sizing. ANS: At 100 psig or greater, about 200 PPH steam flow, 1/2 inch schedule 80 is ok for the main steam line to the engine. 3/4 is OK too, perhaps proper if the steam line is more than a few feet long.
2. What is the appropriate size pipe for the feedwater circuit ? There was an entry in SBMSL that said it was important to have the discharge side of the water pump larger than the intake. Do I need to follow that protocol ? ANS: Feed discharge, 3/8 inch pipe is big enough, 1/2 is OK too. I use 1/2 inch outside diameter copper, 5/8 OD is OK too, use type “K” tubing, not “L” or “M” if you use copper. Copper piping should be sil-brazed, or pipe thread, or unions or flared fittings for 100-150 PSI service. Compression fittings are not considered as reliable, but I typically use these for high pressure cold water service. Swagelok compression fittings are the best, and will take high pressures very reliably. Discharge side larger than suction – not correct, the suction to the pump should be one size larger. I use 3/4 inch copper Type "L" suction piping, and automotive radiator hose to join suction piping sections together.
3. I read in either SBMSL or the UK steamboating guide that it is a good idea to oversize valves since they can unduly restrict flow. It was suggested that larger valves be used and bushed down to the diameter of the pipe. Are people doing that ? ANS: no need to do this with the sizes outlined above.
4. I understand there are a couple of different types of check valves. Which type should I use ? Do I oversize these too and bush them down ? ANS: Brass swing checks or lift checks are OK. Oversize - no need to do this with the sizes outlined above.
5. Is there a functional benefit to the angled blowdown valve ? Is there any reason I cant use a regular valve If I am blowing off through the hull ? ANS: any valve rated for main steam temperature/pressure is OK, angle valves tend to hold up a little better in this service, but I think it does not matter much. I use 1/2 inch ball valve, followed by 1/2 inch angle valve for blowdown. Two valves in series is required on each blowdown.
6. Is there a reason to use globe valves for specific applications or can I go with all ball valves ? ANS: You can use all ball valves, but be sure the rating for steam is defined. Stay with USA name brand ball valves that are steam rated. Globe valves are said to provide better regulation (throttling), but ball valves work OK.
7. How do I make sure that I buy the right blowoff valve. I know the popoff pressure is specified, but I am worried about theegree of blowdown, the possibility of blowing off too much before it re-seats. How do I know that I am buying the right one ? ANS: I think you intend to buy a Safety Relief Valve. Get an ASME stamped valve, it will have the pressure setting and blowdown (how much lower pressure falls before the valve reseats) marked on the valve, and it will have sealed wires that must be cut if someone fools around with the valve settings. The valve must have the lock wires and seals intact. 5 to 10 % blowdown is typical.
8. I intend to use copper for the exhaust /condensation loop. Do I need to silver solder the joints on that loop or will I be OK with regular solder given the lower pressure and temp. ANS: I use copper, put together with ordinary automotive radiator hose and hose clamps for atmospheric pressure exhaust. Portions are silver brazed together, but ordinary solder would work OK for this service. Note that an automotive radiator cap on older cars acts as a pressure relief valve for overheating automotive engines, and automotive radiator hose is good for a few PSI pressure, boiling water.
9. Where in the feedwater circuit should I have a pressure relief valve ? ANS: on the pump discharge line, with no isolation valve between the relief valve and the pump discharge. In general, you need relief protection for any piping or pressure retaining component that could be exposed to pressures exceeding the design pressure of the piping or component. That usually means a feed pump relief valve if reciprocating pumps are used, and a boiler safety valve. If an economizer can be isolated from the protection afforded by the main boiler safety valve, then this section of piping needs its own relief valve, with no isolation valve capable of removing the protection of relief. If your exhaust piping can be isolated from atmospheric vent, then this piping would also need a relief valve, again with no intervening isolation valve.
I use 1/4 inch OD copper tubing for piping drains and cylinder drains, also for my bilge eductor, which has 5/8 OD copper discharge piping, 3/4 copper suction.
- Attachments
-
- piping.jpg (86.13 KiB) Viewed 6179 times
-
daysaver1
- Steam on Deck
- Posts: 49
- Joined: Thu Dec 10, 2009 11:21 am
- Boat Name: No Boat Yet
- Location: Livermore, CA
- Contact:
Re: Plumbing Questions
I'll take a stab at this list:
1. What size pipe should I use for the main steam connection to the engine ? I am planning to use a leg of braided stainless in the connection, but need help with sizing.
I think 1/2" is about right based on your engine.
2. What is the appropriate size pipe for the feedwater circuit ?
1/2" inlet and 3/8" outlet makes a good feedwater pump. This combination allows plenty of water into the pump at no pressure and plenty of cross section to keep your boiler level up.
3. I read in either SBMSL or the UK steamboating guide that it is a good idea to oversize valves since they can unduly restrict flow. It was suggested that larger valves be used and bushed down to the diameter of the pipe. Are people doing that ?
Assuming this question referres to the feedwater pump and given the sizes recommended in #2 above I don't think oversizing from that is necessary.
4. I understand there are a couple of different types of check valves. Which type should I use ? Do I oversize these too and bush them down ?
Again, if we're still talking about feed water, you want a check valve with zero back pressure on the inlet side, say a lift check with spring removed. To use this type valve you need to ensure the valve is in the upright orientation. I like a ball check valve for the outlet from your feedwater pump as it's nice and compact and pretty darn dependable.
5. Is there a functional benefit to the angled blowdown valve ? Is there any reason I cant use a regular valve If I am blowing off through the hull ?
Since blow down is normally done with plenty of boiler pressure you want something that is quick like a ball valve...say at least 1". Antoher thought on blow down is attempt to mount the hull hole five or six inches below water surface so you can actually see when clean steam is.
6. Globe valves
Old guys will tell you globe valves "look right". In the days before stainless balls in bronze seats its understood that globe valves can be "easily" re-seated making them last almost forever. Yes a globe valve is important for your throttle control, but for something that likes a quick action, use good quality ball valves. Shy away from nylon seats in steam lines.
7. How do I make sure that I buy the right blowoff valve. I know the popoff pressure is specified, but I am worried about theegree of blowdown, the possibility of blowing off too much before it re-seats. How do I know that I am buying the right one ?
As mentioned in #5, by watching the steam blowing out just below water surface as soon as the steam turns from brown to white you'll know to shut the valve and head off for a day's running. Remember the best time to blow down is in the morning after the boiler has had a night for the crud to settle. Build a fire and when you have 100 lbs or so, dump the crud and have some fun.
8. I intend to use copper for the exhaust /condensation loop. Do I need to silver solder the joints on that loop or will I be OK with regular solder given the lower pressure and temp.
If you plan to trailer your boat over roads that may not be very smooth, I would never recommend soft solder for anything on the boat. Silver solder is just too easy (albeit expensive) not to use it for your condenser.
9. Where in the feedwater circuit should I have a pressure relief valve ?
Just ahead of the ball valve at the surface of the boiler.
1. What size pipe should I use for the main steam connection to the engine ? I am planning to use a leg of braided stainless in the connection, but need help with sizing.
I think 1/2" is about right based on your engine.
2. What is the appropriate size pipe for the feedwater circuit ?
1/2" inlet and 3/8" outlet makes a good feedwater pump. This combination allows plenty of water into the pump at no pressure and plenty of cross section to keep your boiler level up.
3. I read in either SBMSL or the UK steamboating guide that it is a good idea to oversize valves since they can unduly restrict flow. It was suggested that larger valves be used and bushed down to the diameter of the pipe. Are people doing that ?
Assuming this question referres to the feedwater pump and given the sizes recommended in #2 above I don't think oversizing from that is necessary.
4. I understand there are a couple of different types of check valves. Which type should I use ? Do I oversize these too and bush them down ?
Again, if we're still talking about feed water, you want a check valve with zero back pressure on the inlet side, say a lift check with spring removed. To use this type valve you need to ensure the valve is in the upright orientation. I like a ball check valve for the outlet from your feedwater pump as it's nice and compact and pretty darn dependable.
5. Is there a functional benefit to the angled blowdown valve ? Is there any reason I cant use a regular valve If I am blowing off through the hull ?
Since blow down is normally done with plenty of boiler pressure you want something that is quick like a ball valve...say at least 1". Antoher thought on blow down is attempt to mount the hull hole five or six inches below water surface so you can actually see when clean steam is.
6. Globe valves
Old guys will tell you globe valves "look right". In the days before stainless balls in bronze seats its understood that globe valves can be "easily" re-seated making them last almost forever. Yes a globe valve is important for your throttle control, but for something that likes a quick action, use good quality ball valves. Shy away from nylon seats in steam lines.
7. How do I make sure that I buy the right blowoff valve. I know the popoff pressure is specified, but I am worried about theegree of blowdown, the possibility of blowing off too much before it re-seats. How do I know that I am buying the right one ?
As mentioned in #5, by watching the steam blowing out just below water surface as soon as the steam turns from brown to white you'll know to shut the valve and head off for a day's running. Remember the best time to blow down is in the morning after the boiler has had a night for the crud to settle. Build a fire and when you have 100 lbs or so, dump the crud and have some fun.
8. I intend to use copper for the exhaust /condensation loop. Do I need to silver solder the joints on that loop or will I be OK with regular solder given the lower pressure and temp.
If you plan to trailer your boat over roads that may not be very smooth, I would never recommend soft solder for anything on the boat. Silver solder is just too easy (albeit expensive) not to use it for your condenser.
9. Where in the feedwater circuit should I have a pressure relief valve ?
Just ahead of the ball valve at the surface of the boiler.
Co-Captain...S.L. Reward
-
JonRiley56
- Full Steam Ahead
- Posts: 340
- Joined: Sat Oct 08, 2011 12:58 am
Re: Plumbing Questions
Hey Guys,
Thanks for all the replies !
jon
Thanks for all the replies !
jon
-
fredrosse
- Full Steam Ahead
- Posts: 1925
- Joined: Fri Nov 20, 2009 5:34 am
- Boat Name: Margaret S.
- Location: Phila PA USA
- Contact:
Re: Plumbing Questions
Judging from the post time for both my reply and daysaver1's reply, they were probably thought out completely independent of each other, but are remarkably similar in many respects.
That is a good sign.
That is a good sign.