Dripping a steam main high in the air

Joe Lambert

I believe you are correct to locate the traps at grade level, and this is how it is done in many industrial locations throughout the country. Most installations will include a shut-off valve at the drip leg up in the piping and an additional valve at grade level before the strainer.

If the trap is working there is no chance of freezing if you pipe everything with a gravity drain. I am not a big proponent of disc traps and prefer to use thermostatics, but both will work draining to grade. It is important to orient the strainer so the 'Y' part is not facing down as this will be a leg that will collect liquid, face it at 3-O'Clock so it will be self draining.

The MOST IMPORTANT THING is to minimize the piping AFTER the trap. I have seen this piping freeze even though the system is hot and the trap is working, as there is such low condensate flow rates from drip lines. The safest way to do this is have NO PIPING WHAT SO EVER after the trap and have it just discharge to grade.

If you are still worried about freezing, I do not recommend electric tracing, but rather there are mechanical freeze protection devices on the market that will drain a line based on either pressure or temperature. Sarco, Ogontz, and Gestra make such devices, and these are installed upstream of the trap in such a way that gravity can drain any condensate without the steam pressure.

As for placement, every 100' is excessive. the rule of thumb is every 300' or before elevation changes in the steam line.

Chris Gerrits

Help on steam drip

I am designing a new 16" 60# steam main that will be 50' in the air. I am planning 8" drip legs every 100'. I would like to have the traps accessible from the grade and not from 50' in the air if possible. Are there considerations that have to be made for the inlet piping to the trap? I would guess that size would be a concern. I am calculating a 1/2" thermodynamic trap, but am planning to route a 1" line to the trap. I am also planning to have the manual blow down valve also at grade.

I have looked at some of the "hook up" details published by the trap manufacturers, but nothing seems to be helping me. I just don't want to make a critical mistake here. I can install the draps at the higher elevation to make sure the system works, but would like to make start up access and trap maintenance easier.

Help!

DanHolohan

I don't see a problem, Chris,

as long as you don't create any pockets before the traps. Good plan to get them where they can be serviced.

chris smith_2

sir

i think you are and engineer a guy could work with i service so many steam traps 20-40 feet in the air its crazy
thanks for looking out for those of us that come after the install kudo's

chris smith

paradise porter maine

Tony Conner

What About...

...the condensate system? What elevation does it run? Are you dropping through the floor to the next level, or is it up near the steam line? If you're pushing condensate up 50 feet, you'll have condenate backing up into the header any time the steam pressure is below about 25 PSIG (like on start-ups). Even slightly above that pressure, you won't be moving much condensate through the traps.

If you can run a forward slope, you can likely go 300 feet or more between drip legs. Remember to allow for expansion in the steam main, and on the little trap & condensate lines. When the main expands or contracts, those 1/2", 3/4" and 1" lines won't hold it back. I've seen a few hundred feet of 10 PSIG 6" steam line put an amazing kink in 1/2" condensate piping off a drip leg, when the main heated up and expanded 3 or 4 inches.

I see people do this all the time with heat exchangers. They locate them chest high, because it's easy for installation and service. However, at low loads, the temp control valve throttles-in, the steam pressure falls, and...it's hammer time.

Unless there's some special consideration, I'd put the traps farther apart than 100 feet, and locate them up near the drip legs in spots where they can be accessed with manlift.

DanHolohan

Good point, Tony

I was assuming that he was dropping into a condensate return line that was lower than the traps. Thanks for bringing this up (no pun intended).

Eric

Pipe Rack

Its going to cost a pretty penny to install 16" piping 50' in air with insulation, hangers,expansion loop/connector, siesmic, welding, ect. Sounds like its going a couple hundred feet. May be the cost of catwalk not much of an adder.

If outside on pipe rack, long condensate drops could be prone to freezing.

tp tunstall

where is the

return line (condensate line) located? above or below the trap? that'll help the selection process.

Chris Gerrits

Steam line at 50' - (I know this is bad) No condensate header

I will draining these drips to grade. This whole installation is outside on a new pipe rack. The total length of pipe on this rack is 700' and we have some under rack clearances that are code required (we are crossing RR area). This rack also goes through an area where there are no services at all. Also, I was instructed to not install a condensate collection header, therefore, I came up with the idea to make the traps easy to maintain.

The concern about freezing is a good one, but this installation will be in the NW about 20 minutes from the ocean. Freezing is a concern, but not a huge one. Plant personnel say snow sticking on the ground is not normal. Maybe electric heat tracing on these lines. However, if the traps are in working order, that line should be hot right?

If I size the traps properly, there should be less than 3' of condensate in the vertical drops to the traps (I think). The only concern would be on trap failure in a cold snap. With the traps discharging to a gravel pit, a trap failure should be easy to spot.

Am I way off base here?

tp tunstall

traps...

if the installation was inside a heated space, the best trap would be an f&t ,eventhough your running 60psi, as they have constant discharge of condensate as it accumulates. being outside, you don't want to have any place for the condensate to collect...even the 3 feet in the leg. the thermodynamic is best suited for an outdoor application as they actually spit or discharge steam or flash steam when they cycle and the body has no room for the condensate to collect. remember you're dealing with "mother nature". suggest you use some type of electric tracer in case of steam supply failure.