Steam Pressure Reducing Valve Replacement

Gordo

In the basement of the Zion Lutheran Church in downtown Baltimore (where services are given in German), there lurks a three zone manifold for their steam system.  It used to have five zones way back when (in the 1950s ?).



The main Church building was built in 1809, just outside the then city limits.  Now, City Hall is just across the street.



Sometime around 1909, that building had a one-pipe steam system installed.  Previously, if you wanted to stay warm while you attended services, you rented an enclosed pew and picked up a large heated brick from the furnace at the entrance.



The zone that needed work this time was for the social/classroom areas.



This zone was put in sometime around 1912 (?) and was a two-pipe/air vent system.



Sometime in the 1950s the whole system was put on the district steam system, then owned by Baltimore Gas and Electric.

gerry gill

Thats some cool stuff there..

They got the right crew for that job! I like the cribbing holding up the valve. So i gather they use a different reducer for each zone??

MikeyB

Spence

Nice work guys, gotta love the Spence valves over the Leslie GPK's, no air station needed

MikeyB

Spence

Nice work guys, gotta love the Spence valves over the Leslie GPK's, no air station needed

Gordo

Yes, each zone gets a PRV

All Steamed Up, Inc replaced the Church Zone first back in 2008.  The valve we removed had failed open.  It was line-sized at 3", or about 8X the output needed.  The replacement valve is now 1-1/4" and there is no more water hammer for the first time in 50+ years on that zone.



A few years later, the next zone we replaced was the "Office" zone.  The old valve was 1-1/4" .  It is now 1/2".



A few weeks ago, the 2" "Social" zone failed stuck open like the others.



These valves were all doomed to premature failure because they were massively over-sized and of the wrong type (type E3 as opposed to just type E).



Type E-3 Spence valves are designed for low pressure differential, max. 15 psi.



The "city steam" is supplied at 35 psi, and we reduce it to about 2 psi.



Thanks as always for your comments and questions!

gerry gill

Gordo, do you do

your own welding or do you sub it out? I've been thinking of venturing in that direction myself..haven't struck an arc in twenty plus years, but used to do boiler pipe and submarine hull welding in the navy..i think it would come back to me.

Gordo

Spence Valves

MikeyB, thanks for your kind words!



Yes, Ol' Spence has been around since the '20s I believe, and they pretty much got the design of their PRVs right the start.  They've had very few design changes since.



I'm not at all familiar with "Leslie GPK ".  Pray tell, what is it?

Gordo

Welding

Although I have an old Lincoln "buzz box", we sub out our welding jobs, especially for high pressure steam.  Liability and certificates and such.



The first zone we did for this Church, we had a welder.  



With your experience, I don't think you'll need much practice!

Hap_Hazzard

Have you tried

any of these newfangled wire welders? I always sucked at stick welding, and was mediocre with a torch, but last year I picked up a flux-core wire welder for under $100, and one of those quick-change welding masks.



Although they're technically arc welders, they give the impression of using a torch because of the way they feed the wire into the weld. You just point it at the joint and spray burning steel at it.



If you get a chance you should try one.

Henry

Protecting the PRV

On our instals, we always put a Y strainer before the PRV and use an IB steam trap on the Y strainer. This prevents condensate from forming. If this is not done (BTW recommended by the PRV manufacturer), erosion of the seat can occur.

 

Dave in QCA

Looks Great!

All these PRVs remind me of my old hospital days.  We had a series of attached buildings all fed from a central attached boiler house. Two of our PRV stations were 1/3 -2/3 duplexed Fisher valves.  There was also a Boyleston set up for 10 PSI and another smaller Boyleston set up for 30 psi for the kitchen.  Boilers were 338 HP Kewanee Scotch Marine type, modulating burners, maintained pressure at 60 PSI minimum.  One boiler was sufficient to carry the load, always have to have a redundant backup, and one to operate when the other is down for service and inspection.

Gordo

Strainers and Drip Traps Before the PRVs

are the way to go, no question.



However, when this PRV station was installed 50+ years ago, no provision was made to add these components.  There is no space that we can see.



We are going to try to get the steam utility to add these components on the upstream side of the Church's main valve.  They have agreed to replace the failing 3" gate valve.  Thank you and wish us luck.

Gordo

Any excuse to buy a new toy

...er, I mean, tool!  Yes, I'll try one.

Gordo

Thank You, Sir

High pressure steam is really something, isn't it?  It must be treated with respect.



With residential and even light commercial boilers,  the output is noticeably limited and it takes a finite amount of time to get the heat out to the system.



With District steam, when you turn on that valve..... Here's Your Steam. RIGHT. NOW!

Dave in QCA

Ouch!

You know, that steam is hot!

I was wondering what kind of pressure that the district steam runs at.

crash2009

Gordo, First of all

 I wanted to thank-you for sharing with us, some of these amazing projects you guys get to work on.  I would imagine there was a whole lot of troubleshooting going on before you targeted the PRV. 

How did your troubleshooting lead you to the PRV?

I had a couple questions about district steam also.  You said previously the district pressure was 35psi.  Where and how big is that boiler and how does it get the condensate back?

Thanks

Gordo

There are two

parallel line service pressures that "Small-t-more's" district steam lines provide.  One is about 130 psi and the other is about 35 psi.



The steam utility is slowly doing away with the 35 psi service and converting it to the higher pressure.



On this system in question, the presure comes in the building at 35 psi, their so-called "low pressure" service.



This system is also unusual in that the supply line almost immediately splits at a bull head tee and one outlet of that tee goes to the church's zone manifold a few feet away and the other outlet goes to a line that snakes it's way through the basement of the church complex, through crawl spaces, etc., etc.,  and into the headquarters of the Baltimore City Fire Dept. situated hard against church property. (please see the picture above in an earlier post).



The BCFD took the land from the church years ago to build their headquarters just because.

Gordo

You are Welcome

This board gives me a lot, so I try to share.



Trouble-shooting a stuck open steam PRV is not that hard...the building overheats.  But the Church now can shut off the steam to any failing zone relatively easily.



With the previously oversized PRVs,  it was a nightmare!  There was sooo much steam, that it would back-feed through failed traps and get into the dry returns and heat up shut-off zones and radiators.  And I'm talking about zones that had been shut off for 20 years!  The water hammer was amazing. 



Persistence pays.



The district steam system in Baltimore is fed by several boilers in several locations scattered about downtown.



The only one I've seen was years ago.  It is not owned by the steam utility per se, but sells steam to it.  It is used as the City's main trash incinerator plant.  The boilers are HUGE.  You need to take an elevator up several stories to read the sight-glass.



The condensate is dumped into the storm drainage system and not sent back to the boilers.  Attempts at condensate return in the past  has been a maintenance horror for district steam.  What tends to happen is the lines will fail at uneconomic rates and they are underground and difficult to repair.



As the water bleeds from these leaking lines, it migrates over to the steam lines and boils off, melting the streets above. 



The utility has enough on it's hands just keeping their boilers, steam lines, traps and PRVs intact, let alone any rotting condensate lines.



Before the condensate is dumped, it is metered so the utility can bill the customer.

All this condensate being dumped  is why the inner harbor of Baltimore never freezes over.

Dave in QCA

Very Interesting

yes, Very Interesting Stuff!!!

Gordo

The Spence E Main Valve

is normally closed.  The pilot  valve attached to it is normally open and is used to control the E valve.  Downstream pressure is fed back to the pilot valve and as this pressure reaches set-point, it acts to close the pilot valve and thereby allows the main valve to cycle closed.



The pilot valve with the yoke and spring on top to control the downstream pressure is called a type D.



In order to convert it to work with the lever and weight mechanism, we have to remove the spring and yoke and install the old lever from the old pilot.



The Spense pilots that are operated by a lever and weight are called type W and are no longer made.



There are 12 1/4"-28 NF bolts on this thing.

Gordo

And Now

the new PRV assembly has been installed.  It heats the zone with much less noise, as the steam is not being slammed into the pipes as before with the old over-sized zone valve.



The pilot is opened by a Honeywell motor linkage that looks to be 50+ years old and is labeled "the electric janitor".  It must have been a really good product; they've stopped making it.

Mark Eatherton

Great job guys. Got a question...

What temperature does the condensate flow back into the city sewers at?



Here in Denver, the city requires that the condensate be cooled with straight cold water to dilute it to less than 140 degrees F.



I've done snowmelt systems that utilized the hot condensate (FREE BTU'S) for doing snowmelt on large parking lot structures. We not only saved a butt load of steam $, but also the wasted cold water AND provided perfectly dry sidewalks.



I also see an opportunity to do DHW preheat using the same tactics.



Working on city steam systems makes my sphincter do the momba. Lots of power there.



ME

Gordo

The Temperature of The Condensate

that goes down the drain at the Church.... varies. 



First, because there is a high pressure steam line (35 psi) that snakes it's way through the basement of the Church on it's way to the Balto. City Fire Dept. Headquarters,  there are at least three high pressure traps on that line that drip it, and the discharge of those traps go back to a drain under one the Church's kitchen sinks.



At least that condensate is not metered.  But it is VERY hot.  And, no, it is not mixed with cold water first.  Who pays for the water?



I would love to run that through a heat exchanger to to pre-heat domestic hot water for the Church, but getting approval to get paid is an issue.  They've got at least a dozen traps that'll need to be rebuilt first.



 And then there are the uninsulated pipes....lots and lots...that basement gets hot.



That meter water measuring the condensate is a cash cow for the steam utility.



Oh, boy, do I know what you mean about the power in those lines!  When I hook up and turn on that shut-off valve, it's like I've tapped a little 5mW electric circuit directly into Almighty G-d!

Dave in QCA

Great!

It is great to get to see more of the church building where the Pressure Reducing Station is located.  Also, nice to see the American Radiator Florentine radiator.  A close-up of the end panel would show an angel in the pattern.  That radiator is a "flue" type, and has higher EDR than a standard 3 column model of the same dimensions, not to mention that the Florentine models are heavier as well.

Gordo

Heavy Indeed!

As you can see, it was set up as a two pipe air vent system, but traps were added in the basement to the return line in the 50s.  The air vents are now gone.



When we first got there, some the Church's radiators had been leaking so long at the union nuts and packing nuts that they had rotted through a 2" floor and rusted out the 2" wrought iron supply pipe.  THAT was a heavy radiator.





And here are the shots of the PRV and main steam piping  taken with a FLIR



Thank you for your comments and info!