Large steam system problems (hr)

Brad White_28

Edge of my seat...

hr

A new building

that is having water hammer issues in the condensate piping.
My local B&G rep is involved and claims the 4" welded steel condensate lines are jumping 2 feet off their supports in the tunnels below the building!

So far the engineers, installers and reps are at a loss.

About an 8 story building, four 40 million BTU steam boilers.

Way out of my league, any wallies want to take a look at this system?

hot rod

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Boilerpro_3

I suspect...

principals are the same, so why not take a look. So the return lines are 4 inch instead of 1 1/4....everything is the same, just bigger.....much bigger!

Boilerpro

Brad White_27

Was this after a long shut-down?

Just started up? Cold system slugging w/o warm-up?

What transpired since the building was last heated (normally without incident)?

Too many variables: Trap leak-by, flashing (low pressure or something higher?) water hammer. Steam and condensate fighting for space and supremacy of course. Condensate pump switch on/off points too close together? Both pumps fighting if a duplex ("fail to second pump on" situation)

What is the source of the steam? HPS from a remote plant via a PRV? LP boilers in the building?

Interesting..and freaking dangerous too.

oil-2-4-6-gas

where is it located?

hr

I've not been

to the jobsite. Not sure I want to be in a room with pipe that size, or any size, that jump 2 feet in the air.

I have little to no experience with steam, and this doesn't sound like a good place to get my feet wet. Or steamed

I be glad to put you in touch with my rep friend that is in the middle, between the designers and installers.

The job is in Springfield, Missouri

hot rod

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gerry gill

seems to me,

that there is steam were there should be only water..i've seen big condesate reciever tanks walk around the floor cause steam got into pipes it shouldn't be in..

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Brad White_27

Thinking Out Loud Here

Four 40MM BTU boilers?- Assume an N+1 arrangement and input is what is given. The three boilers on-line (if this is what it is) work out to 96 million BTU's. 8 stories? Sure this is not the Pentagon? Sounds like a huge building, well over a million SF of laboratory or something with a high ventilation load.

If it is handling 96 million BTU's (100,000 PPH) that is 200 GPM condensing rate.

Does the 4 inch line handle all of it or is it just a branch I wonder?

For pumped "net" load it seems OK, but if gravity return seems way too small...

If as most condensate pumps are sized at 3x the condensing rate, (600 GPM in this example) it is at least a size too small.

Christian Egli_2

Just the tool you need...

Following another thread I just read, I want to say this is nothing you can't fix with a few clip ties... to keep that monster return from even budging. You've got some success with those clips, don't you, HR?

All sounds like collapsing steam induced water hammer caused by a combination of trespassing steam and non properly draining condensate lines. Are all the pipe hangers still hanging in there?

Springfield is far away, but would be a nice visit. Best wishes.

Mad Dog_2

Gerry and Steve are the closest.................................

They will consult, travel, fix. If they are not avail. , Me and steamhead are ready willing and able. The BIGGER THey come the harder they fall! Mad Dog

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Unknown

If I can help, Hot Rod,

Give me a shout. The big buildings aren't harder, just bigger, to troubleshoot.

Try This. I wrote this for someone else, but it works for anyone...


There is a certain minimum amount of maintenance required on all steam systems, weekly and periodically. Steam traps usually find themselves in the periodic category. Unfortunately, periods can be quite long, and viewed as an "all or nothing" venture. They get deferred frequently. There can be other alternatives to this, however.

There is nothing as easy as deciding to change every single trap and calling it cured, except not doing anything. Those are usually the two choices presented. The third choice is pretty labor intensive. It involves identifying exactly what is installed in the building, what is wrong with it, what it would take to fix it (broken down in stages), and what order to do it in, and what each stage would accomplish and cost.

This would chip expectations down to manageable and budgetable projects, and might give incentives to combine steps where it would save money to do so. It would help project for future budgets what the actual maintenance costs are on a large building with a seventy five year old heating system. It would maintain fuel consumption at predictable levels.

It would show how thrifty it is to keep up with steam trap maintenance. I'd like to help discover how to do this in layman’s terms. My experience is with four story brick residences with various vapor systems from 1910 through the 1960s. These were mostly two pipe vapor systems.

The very first thing to do is to identify the individual steps in an outline form that will bring the system back to working properly. Identify the system from trap names, unusual items in the returns or near the boiler, supply valve names, something to date the system with. This helps a little. Identify the height above the boiler water line to the lowest horizontal piping in the whole system that is above it. This is a B dimension, and is most important if there isn't a vented condensate tank or boiler feed tank. It defines what pressure the system was meant to be run at. Identify what vent is on the system and if it works, and at what rate it vents.

The first thing to address on the outline would be venting, as it has the biggest payback to cost ratio. Simply size the vent properly for the load and pipe lengths, and make sure it vents when it is cold, and it shuts when it gets hot. Make sure it is back from the end of the main about a foot or two, or more. It can even be right after the last radiator connects to the return main. There is likely to be a crossover pipe between the supply main and the return main there, with a radiator trap as the union and elbow on the return end. This is the supply main's air vent into the return. This flow is from supply to return to air vent. To keep the air and condensate all flowing the same way, the vent will be downstream and downhill from this crossover connection.

The next item on the outline will be to crank the pressure down to the pressure just above what it takes to get the main air vent to close. Identify that the control on the boiler might eventually need to be replaced with the one required to run this particular system at the design pressure. More on this later.

The next item to successfully tame the system is going to be insulation on all of the pipes. It simply must be in good shape to deliver all of the steam that they were designed to carry. If the steam condenses within the mains, the cross section of the pipe becomes reduced and the mains cannot carry the steam that they need to at reasonable velocities. The speed picks up and the water starts flying around, the noise goes up, the cost to run goes up, the vents and traps get hammered into little crumpled balls of metal inside. The insulation is mandatory. The mains are actually TWO pipe sizes too small, if the pipes are bare.

Along with insulating, the boiler piping must be right before the insulation gets applied. The first thing to do is to determine what the boiler needs to do, and if it will. We finally have come down to measuring the load connected to the boiler, and the size of the boiler, and to actually verify the firing rate and combustion efficiency. A filthy oil boiler that had been downfired beyond reason won't show up from a peek at the rating plate. It might make sense to look at the boiler size itself and it's piping, and start from scratch. It might be fine. Be sure the boiler piping matches the manufacturer's instructions, to the letter. Undersized piping might be the problem. Now is the time to decide.

If you have come this far, and have a working system to evaluate the steam traps with, you can move to the next step on the outline. You need a trap survey; a document that you make that shows what each trap model number is, and what room it is in. You need to group them by which branch of the RETURN main that they empty into. The return mains are groups of traps to be maintained and troubleshot as a group. It helps to begin thinking of them that way early. Along with this list of traps, a piping plan would be wonderful. These documents should be filed in a way that they outlast you on the job.

Once you have identified a return main, and have the steam pressure cranked down as low as it will go, start the system up cold and see if the return main becomes steam hot at the vent, up on this end of the return. Since only air is supposed to be there, and cooler condensate, it should remain open and not be steam hot. If it gets hot within minutes, you have a trap blowing steam through. On a system with working steam traps, and on ALL pumped condensate systems, the vent isn't needed. It only sees steam if a trap lets steam through. An open pipe could serve as the vent.

Take it out, if it isn't too much trouble, while you troubleshoot. It will speed up the whole process. The way that we are going to discuss checking traps isn't the only way, by any means. My focus is on cost of materials, but admittedly it is very labor intensive. This isn't developing a free estimate for repairs, this is actually a very valuable part of DOING the repairs, and should be thought of this way. The reason for the trap survey in advance is, in part, so that some repair parts for traps can be brought in and kept on hand. This enables repair as the testing evolves.

The premise of this method of testing is to follow the steam as it expands into cool piping in the supply mains, and detect, by external pipe temperature, where the traps let steam pass through. I started by using my hands, but years later, infrared thermometers with laser pointers came along, and they cut the time in half.

Start up the boiler until you detect steam in the returns someplace. Shut off the boiler and follow the hot pipe back to it's source. You'll get near it easily enough; close radiator valves off to eliminate their traps; identify how the steam is blowing into the return. Shut the boiler off often because once everything in that return main becomes hot, the information to be gained is very diluted. Keep everything cool, and squirt steam through by firing the boiler once in a while to keep the path hot. This is more art than science.

After the return main stays cool, because all of it's traps are fixed and holding, or shut off from steam, open up radiators one at a time with the steam on. As you open a radiator, check the return for live steam. Condensate dripping into the return will warm it up. Steam blowing into it will make it a blistering 200° F plus, right away. Shut those back off. Mark those for repair.

Here's another note. On a return that you know has steam blowing into it, shut the boiler off with hot mains, and let the vent pipe draw air in until it stops. With all of the radiators and valves open, start up the system again. As soon as the system vent pipe gets hot, go through the building and find HOT HOT traps on radiators that have COLD or cool sections right next to the radiator trap. This will tell you two things. One, there is obviously steam in that return. Two, THIS TRAP IS WORKING!!! It won't let the air from the radiator into the return, which has an open vent on the other end. It is keeping the radiator from venting. Write this one down on your trap survey as good. Look for more. Cool it down and start it again. Check again. Shut some off in a pattern that makes sense along the return, to determine where the steam is moving around. Some of the radiator valves won't hold steam all the way off, but that's OK. As long as the radiator condenses what it does get, and the last section doesn't get steam hot, you'll be OK. The room will use that heat, anyway. It's temporary. Leave off whatever it takes to keep the returns from having steam in them. For temporary heat, crack open radiator valves to allow half the radiator to get hot, but NOT THE TRAP!!!! Fix the crossover traps and the F&T traps on the mains. Get your vent to be cool while the system runs.

Now make a list of the traps on radiators that are shut off. These are what you need to replace. Leave the radiators with bad traps off in the meantime, or mostly off, to save the remainder of the working traps. Budget your replacement costs, but remember that more will fail as time passes. It will often be fewer than expected, though.

Now that the system is tame, and half shut off, the boiler waterline will be pretty wild, due to overfiring. Get the traps fixed to get the load back on the boiler, and troubleshoot from there. Have a very clean system with clean water. This is a whole different subject, but very important.

If the system floods after it runs, or if it runs out of water and shuts off, suspect plugged returns that are below the water line. Don't waste any time on them, replace them. Pipe them so that you can remove an air vent and flush them with a hose to a drain valve that you put in at the boiler end. Use mud legs to collect debris.

Once you get an intimate knowledge of the system, a loving pat on the air vent while it's running will tell you if you need to check your traps again. It should run at virtually the same temperature all of the time, a little hotter in very cold weather.

If you want real economy, buy a vaporstat that operates from 0-1 PSI, and is graduated in ounces. Install it at the boiler, or even better, at the end of the steam supply main. Wire it to break one leg of the thermostat wire through it, and leave the pressuretrol as is, as a high limit. Set the vaporstat as low as you can and still heat every radiator.

All of this would be done with the service person AND the weekly operator. The more involved with the system that the operator becomes, the more known and less costly will be the maintenance plan.

Along the way, you'll both learn the system. You'll find that return that's ALWAYS hot, no matter what. It'll drive you nuts, looking for the cause. Eventually, you'll find the crossover trap in the wall at the end of the main in the finished basement. It'll be behind a wall hung radiator.


You'll find the F&T trap that works, but it has a 3/4" bypass around it with a very painted plug cock in it; wide open.

You search the building and find two more. Guy's have been rebuilding these traps for 90 years, yet the bypasses never were closed. Originally, this system made heat and electricity by coal, the bypasses are from those days.

I want to close with a story. It is very relevant, and it was costly. It was a four-story residence, and the bottom floor was four feet in the ground. The returns ran around the bottom floor ceiling with the supplies, until they were pitched down to a point 30" above the floor, then the return split into a high and a low return back to the boiler room, the same on both ends of the building. The west end had steam in the front return, as a door on the ends of the building split the returns into a back and a front on each end of the building.

This front, west return had steam in it near the boiler end, the low end. The rooms all had thermostatic radiator valves on the radiator inlets, so each had control. The front door entry was always cool, and the radiator always hot. The next room had his thermostat off, because his room was hot enough, and the trap was hot and the radiator burbled steam into it through this hot trap. The radiator would fill with condensate until the system satisfied, when everything would cool off and drain back to the boiler. He opened and closed his window for temperature control.

The next room had the same hot trap and shut-off thermostat, but he was roasting. He NEVER closed the window. He went away every chance he got. One weekend when he was away, it was very cold. The whole weekend never saw above zero temperatures. The guy in the end room by the door called for no heat. Even with the valve open, no heat would come from the radiator. His walls were FREEZING. The hallway wall, the entryway wall, the outside wall, and the room next-door wall.

The radiator was full of water. No steam could get in. Draining it by shutting off the boiler got the radiator to heat but the room didn't heat well.

The wall to the next room was freezing. Uh - oh. In the maintenance guy went, to check on it. Everything was frozen. Bottles on the dresser had broken. The window was open. The radiator had exploded. He shut it off, shut the window, left the door open and went to call in some help. He was gone for a short while.

The frozen and split 1" sprinkler had thawed out while he was gone. The whole time he was gone, a 1" sprinkler pipe filled the west half of this building. About 11 people lived in the lower level, and they were displaced. The water was a few feet deep. Several people on the next level were also displaced to hotel rooms, until the building was renovated.

The steam traps were repaired right away. The rooms were comfortable, after that.

Noel

hr

Thanks everyone!

I'll pass along all this info to the "players"

This is a brand new system. An energy system for a large medical facility. The boiler capacity is sized for future additions, although the facility currently covers a city block.

The chilled water side has 36" piping with a 36" RollAirtrol. I hope to get a tour when things simmer down Thanks

hot rod

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[Deleted User]

Excellent article Noel....

Your writing skills have improved significantly! Keep up the EXCELLENT word work. I'll be printing this and distributing it amongst my steam members.

Thanks for the education.

ME

[Deleted User]

This guy will go...

for a price, I'm sure. I've been following this guys career for a few years. He is A STEAM HAMMER EXPERT.

Wayne Kirsner

http://www.kirsner.org/pages/forensicResAlt.html

Good Luck

ME

Anna Conda

What pressure is the system running at? How big are the supply mains? Has anyone checked to see if there is condensate backing up into the supplies? What kind of traps are installed on the system? And how far apart are the traps?

Tony Conner

They haven't done something like install inverted bucket traps on vacuum return system, have they? The water hammer from that particular installation boo-boo can be as spectacular as you describe.

In any event, the only circumstance I can think of that would result in the water hammer events you're talking about is something is allowing large steam bubbles into a line flooded with condensate. The steam bubbles condense, collapsing into virtually nothing, and leaving a vacuum behind. The in-rush of water filling this void can create some very impressive shock waves/pressure spikes. This can happen even at very low steam pressures.

Tony Conner

Hammer Time

I've seen water hammer issues because lines weren't sloped properly. There are LOTS of guys out there who are great PIPE fitters, but they're not STEAM fitters. I know of another at a hospital where they'd used inverted bucket traps for the new section and tied them into the existing vacuum return system. (Inverted bucket traps + vacuum return = bad news.) The water hammer was so bad the maintenance guys wouldn't go down there - and I didn't blame them. They swapped the buckets for another style, and the problem went away.

Steamhead (in transit)

\"The boiler capacity is sized for future additions\"

might be at least part of the problem. Check the boilers' output against the connected load that's there now. If it's oversized, try isolating one or more boilers to match the load more closely, and see if that helps.

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Brad White_28

If it is a high pressure plant

would the boilers not have stop-check valves, Steamhead? Hence automatically isolate upon pressure drop. Or maybe that is the problem- they do not have stop-checks... fair call to ask.

Wethead7

HR

The size should not matter.

This might be a high pressure system that needs time to warm up. How are they starting it?

I would set the boiler presssure low and then watch what happens. Do not forget to think like steam. The problem is most likely to be in a different place than the effected parts.

I could and would check it out if you need help. You can leave a message on the wall or you do have my e-mail.

Mike