Steam Coil Leaks!!!

Bryan_Morris

This is the first steam system I have had the pleasure to work on, and it's an industrial one! The issue is that they have leaks everywhere in this plant. I've found schedule 60 90 deg fittings with holes blown right through them and Copper Tube Aluminum fin coils patched so much that less than 50% of the coil is operational.

So let me start with the system layout. We have 3 massive steam boilers unsure of Btu/h output but they are supplying the main header for the plant with 110 psi steam at 350+ degF. This is being fed to headers that have pressure reducing valves to unknown steam pressure and temp (gauges on system don't work, I only found working gauges on condensate that was reading 30-40psi). This header feeds ovens that are in rows of usually 10-15 ovens are on a single header. This is where all the leaks are happening. So off of the main steam header we have threaded black iron pipe a mix of sched 80 and 60 due to repairs over time that feed into the steam coils in the ovens.

Over the last few weeks I have observed that the majority of leaks are in the bottom passes of the coils, on the condensate line leaving or worse low points on the steam piping to the coil where condensate has pooled. When we are given an oven to repair, we usually go up to it, open the valves and just look for the leak. A lot of the leaks have been water shooting out of the coil or fitting. It is my understanding that in a steam system there should be steam all the way to the steam/condensate trap, any water before that should be minimal at best. My best educated guess it that we have water in the coils and fittings where we only want to see steam, the water at high temperatures is eating away at copper tubes and black iron pipe until we have leaks.

To fix this I believe that we need to 1. repair all steam traps and ensure that they are not bypassing. 2. ensure all piping slopes from the steam solenoid to the condensate trap.

I have been a Dan Holohan fan for a few years. I was introduced to him in my Advanced refrigeration training course and I fell down a rabbit hole of hydronics heating and cooling. I purchased and crushed Pumping Away in 2 days while in Advanced training and I purchased A Pocket full of Steam Problems and the lost Art Of Steam Heating today before making this post. So Hopefully between this post and those 2 books I can narrow down the cause of this issue to a point where I can confidently quote an extremely large repair at this site. But instead of putting Band-Aids on it every day i hope to make a real repair that will last.

Attached are photos of the fitting that I found yesterday on the steam line feeding a coil. You can clearly see the corrosion line in the fitting where condensate was pooling on it's way to the steam coil. The wife is better at taking pics than myself so that's all her handy work.

DanHolohan

Are there control valves for the coils?

EBEBRATT-Ed

@Bryan_Morris

Sounds like you got a big mess on your hands... Job security

Good luck

I would start with trying to get any information on the original system design......IF available.

Who knows what has been monkeyed with.

I would start with traps and prvs...make sure they are right. Fix leaks as you go. Maybe a good water treatment guy (if there are any good ones)

retiredguy

You need to get a better handle on the whole system before you try to fix the the leaking piping and coils. You need to identify the cause of the deteriorated system so I recommend that you start in the boiler room and work out from there. What type and style of boilers are these; water tube, fire tube and how many passes. What fuel are they using and what is their input or steaming capacity. If there is a tag on the boiler that shows any type of boiler capacity or any information that may be helpful list it and/or post a picture of it here. How much make-up water are they using in gallons per hour or per day and is it treated or softened, and do they have a deaerator. What are they using the steam for? You said ovens, what type.

I have to ask a personal question; how experienced are you with high pressure steam systems or steam in general. You said that this is your first steam system. If it is, it may be wise to consult someone with way more experience than you have before you make a fatal mistake. I am not questioning your ability just trying to provide a little safety.

JUGHNE

You mentioned Sch 60 a couple of times....do you mean Sch 40?

ScottSecor

Not that it really matters,  but the elbow in the photo appears to be 'regular old" schedule 40 black malleable.   Schedule 60 is not something I've ever seen.

As you've probably already read, most steam system piping fails where  "hot" steam hits meets with "cool" condensate.  As others have suggested,  I'm guessing there are steam trap issues that are passing live steam into the condensate lines.  Without any gauges or thermometers your simply guessing 

DanHolohan

If there are control valves, there must be a vacuum breaker after the control valve and before the coil. Without it, the coil won’t drain through the trap. Water hammer hits the coil the next time the control valve opens. Goodbye coil.