near boiler piping ruins steam boiler, P. Linhardt

Dale

About all that can be done here is safety checks, not that that isn't important. It's definately buyer beware in the states as far as correctly installed. In my state only boilers in commercial buildings are govt. inspected and that is for installed to pressure test, and relief valves, low water cut offs ect. Strangely in the states the large boiler gas train components are determined by whatever insurance company you have, or if on a federal govt. job. A guy I know worked for the HSBIC a major US boiler inspection service, he had a large steam fired packing plant in KY where he spent his 3 days working in a rain coat to protect himself from the overhead pipe leaks, but, the relief valves did test OK.

patrick linhardt

near boiler piping ruins steam boiler

Sometimes you don't realize how bad it is until you do the math. The boiler was partially apart when I got there, a big commercial twelve section Weil-McLain 88. The scale build-up was falling out of the bottom nipple port, big chunks the size of peanut brittle. The contractor says the owner used 11,000 gallons of water last year, that wasn't hard to believe. The building has some underground returns, so I was suspecting a major leak down under the floor. I looked at the near boiler piping out of habit, because I find it interesting how the piping is almost never to the manufacturer's recommendations in some way. I didn't have the installation guide with me, but I knew what I was looking at was wrong. This is a 3,700,000 btu boiler, a big fellow. But three 4" risers were piped to a 4" header, without swing joints or an equalizer! At that size of boiler, I'm usually looking at a 8" or larger header. Now, this building has a downfeed piping system, meaning the steam main leaves the boiler room in the basement and travels up vertically two floors to the distibution piping that is in the attic. From there, risers carry the steam down to the radiation.

The contractor with me, not the one that piped it, was speculating that steam velocity created by the undersized near boiler piping was causing water to be carried out of the boiler, up the main, down the risers, and backing up in the wet returns, which looked original. The boiler feed unit would pump water into the boiler, but if the wet returns were clogged by years of debris, the boiler feed unit would have to feed in new water. Eventually the condensate would return, but by then it would flood out the vent/overflow of the boiler feed unit. Enough cycles of this, and you use 11,000 gallons of water. Needless to say, this much fresh water is going to leave a lot of mineral and lime deposits in the bottom of the boiler. And of course, this leads to boiler failure.

When I got back to the shop, I looked up what pipe sizes should have been used. The risers were supposed to be at least 5", and the header 8". I decided to check the velocity of the steam as it left the boiler piped incorrectly. This is where I found out how bad it can be when you do the math. When I did research for my book, I found that the old timers liked low exit velocities to assure dry steam, some as low as 10 feet per second (FPS) and up to 30 FPS or so. Modern manufacturers range between 30 to 60, most below 50 FPS. The bad piping on this job had the three 4" risers going at 78 FPS, while that 4" header was screaming along at 236 FPS. It was probably pulling water up out of the boiler faster than it could be pumped back in. Remember that they also didn't pipe an equalizer, so all that water had no where to go but up the main as very wet steam. Oh by the way, the building owner was also complaining of high fuel bills. Could you see that one coming?

Alan(CaliforniaRadiant)Forbes

Steam Speed

Thanks for letting us in on that, Patrick. It's wonderful how simple physics can be with a good explanation.

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patrick linhardt

speed kills

Hi Alan,

It is an extreme case of mis-piping, thought I would share.

Best regards, Pat

[Deleted User]

Reminds me of

a conversation I just had w/ the lead man for the new rigging company we are using. He was cutting out a steam boiler. I asked him why he was not cutting the discharge where I had marked it, rather than at the risers off the boiler. He said, "I thought you were going to use the header over again. Everyone else does."

Enough said.

JackEnnisMartin

Steam header installation

Hello Pat
I can only say one thing about this installation and it is simply --- people who are in the trade should have to be trained and certified. In Canada, a boiler of that size would have to be certified correctly installed by our Department of Labour. All the inspectors who come out are professional engineers or First Class Stationary Engineers with at least twenty years of time in the trade. We would have been told to do the job over again and until it met the specifications we would not be given a permit to operate the heating plant. I have to ask in your part of the world are heating plants such as this inspected or do you do you not have to be licensed to run the plant? The same goes for all welded joints on any pressure application such as heating,refrigeration , process piping etc. I am curious to hear how it is done in your area.

All the best and keep writing.

Jack Ennis Martin

gerry gill

bad piping drives me nuts,

and it drives me nuts even more so, when it doesn't break the boiler..to bad there is not some rule of nature that says ''if you pipe a steam boiler badly, it breaks''..did you take pictures of that boiler before they took it out? would be a great training picture.

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patrick linhardt

no pix yet

Hi gerry,

The boiler has the first few sections removed at this time. The "header" is still in place. I will try to get stop by to get some pictures.

Best regards, Pat

patrick linhardt

rules and regulations

Hi Jack,

It sounds like you folks in the great white north are once again ahead of us. I'm sorry to say that although this is an extreme case, it is not uncommon to find steam and hot water boilers piped improperly. Inspections that are performed do not include near boiler piping, or even satisfactory operation. Most inspections seem to focus on safety controls, relief valves, and gas valve venting.

This installation is a low pressure steam boiler below the size level that requires an operator. I am not familiar with the regulations for high pressure in this area.

Thanks for posting your comments.

Best regards, Pat

Tony Conner_2

I'm Guessing...

... that you're in Alberta. I suspect that the only ones to look at a low pressure boiler like this in Ontario would be the TSSA fuel safety guys, who would check the burner controls, and maybe that there was a relief valve, but that's about it. The insurance company inspector might look at the boiler, but typically they don't even glance at the piping. (If they don't insure it, they don't look at it.) The kind of outfit that would have installed it here? At least an even chance that it would have been a millwrighting or sheetmetal outfit. Steamfitter? What's that?

Even on higher pressure boilers, the piping will only be inspected from a code perspective, and they won't really care whether or not something works from an operational point of view. If you should have an 8" line, and you're only running a 4", they won't know, or care.

The rules here will match the rules almost anywhere in North America. Enforcement of the rules??? Not so much. Alberta puts FAR more emphisis on this stuff than Ontario. It's a long way from being "homogenous" boiler-piping wise, here in the Great White North.