Welded steam headers

Tony Conner

... no doubt you've seen CI boilers crack, but can you definately point to the welded piping as the cause? I'm not saying it isn't, I'm interested, because the coefficient of expansion for CI and steel is virtually identical, and the lengths of the boiler and near boiler piping is really pretty short, in the grand scheme of the things.

I very much agree that most welders are NOT steam fitters. Some are, but that's not very common. To me, a steam fitter is somebody who understands steam, and the characteristics the piping needs to have - size, slope, traps, expansion etc, to make it work properly. A pipefitter, on the other hand, is somebody skilled in installation or direct replacement work. A good pipefitter can show up, get the print & material list (somebody else has put these together), and slam that piping up in short order. It'll be true, plumb, square, sloped as spec'd and assembled out of the materials listed. It'll be beautiful. However, they typically have no idea about WHY things were laid out as they were, how to size pipe for different services, or why the specified material was chosen. So, in spite of being beautiful and going up in record time, if you let him do the design bit, it may not work very well. Most pipe welders are usually pipe fitters. Unless you've done a lot of background design work, and have a layout ready for them, you'll need to have somebody on site with them who does. Usually, you need a second guy to help fit up and for firewatch anyway. It just can't be the labourer kid - it's gotta be somebody who understands how it works.

thfurnitureguy_4

welded steam headers

I was talking to a local steam guy who mentioned welding sections of iron pipe to fabricate a steam header. He new of a company that did this. Any body hear of this? It sounds like a neat way to make a dropheader without all the hi dollar fittings (4" and 6" stuff). Better yet why dosn't Burnham or others, manufacture a tuned header for the boilers there selling. Like headers on a car. I picture a heavy iron pipe with tank like ends and nipples out the top for the conection to the boiler. A sweep down for the equalizer with a nipple welded for a union to the return and a couple of nipples out the top for the supply risers. all neat and clean mig welds painted blue with a big fancy logo on the side. Let the installer pick and cut the piping length for the install.

JackFre

Welding headers

You can weld a steam header. Just make sure you accomodate the expansion co-efficient and incorporate swing joints.

Tony Conner

Welding...

... of steel piping sytems is routine at industrial plants, especially for 2-1/2", and up. Every job is different, though, so don't just look at the cost of the screwed vs welded fittings, consider the whole package.

One of the big advantages to welding, is (assuming you get a professional pipe welder) zero leakage.

thfurnitureguy_4

what is required for a swing joint? is a union or elbow in rotation good enough? If you welded a chamber for your dropheader and attached to it with elbows off welded in nipples would this alow for enough swing?

gerry gill

it should

then work.

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clammy

swing joints and companion flanges

I'm not a big fan of steel welded header i've had a few which when where installed lacked swing joints or compaion flanges and of course they did crack the boilers .Just remenber that a weld may think he is a pipe or steam fitter they ain't .Every large residental boiler that i've worked on was steel screw fitting originally then some replaced them and made a welded header all probalby by the same guys no companion flanges and not designed properly and it seemed on every one the drop for the equalizer was reduced from 4 to 2 of course these new header didn't help things ended up with a cold spot in the equilizer because the pipe was not large enough .I feel alot of guys push the welded because they don't have the equiptment to thread 2 1/2 to 4 or 6 so welded header sound great maybe to them but not to me i'de stick to screwed header but i'm a idiot peace clammy

clammy

alot

Tony not to start anything but in alot of cases i can point it to hte welded header in all the cases i have seen the boilers cracked in the upper part of the sections and all the welded joints did have intinal stress cracks at the welds plus they did not have proper swing nor enough companion flanges to allow for expansion .It wasn't to funny that all these welded jobs where all in one gated community and all looked to suffer the same promblems bad near boiler piping from not reading the installation instruction nor having sized the equilizer correctly or doing the hartford loop correctly .These where i would gather at the time big buck jobs but all died at the tender age of 10n to 14 years old .Most where wiels 76 and 78 sereis from 6 to 8 section oil fird boilers i really hated to see them go and some where a horror to remove and of course it was mighty cold and they where very very long nites no stopping till we had them up and running just me and one othe rmech .peace clammy

don_171

Could

companion flanges take the place of swing joints?

don_171

Thats

what I've seen to Clammy..that why I ask about the flanges.

I have a couple welded jobs with the flanges..the header and
near boiler piping is correct and their still seperation at the section.

Tony Conner

I'm Not ...

... throwing rocks - I just want to understand what's happening. Why wouldn't the relatively thin walls of the CI pipe fittings fail before the boiler? I've seen expansion on long runs of pipe (over 100 feet) crack CI fittings.

I normally don't get involved in boilers this small or made of CI, but I'm aware that there are some subtle differences in what has to be considered for relatively small steam systems as compared to big ones. In bigger systems, it's a code requirement to check the piping flexibility. There are calculations, but the concept is pretty much common sense. A 2" sch 80 shoulder nipple isn't going to bend very much. 10 feet of sch 40 1/2" will flex all over the place. The larger the pipe diameter, the heavier the wall, and the shorter the run, the stiffer it will be. If the boilers you mention had been correctly piped from the start, would welding have been a non-issue?

Do any manufacturer's talk about welded piping in their installation instructions? I would think that copper piping for steam would be far FAR worse for this - the coefficient of expansion for copper is much larger than for CI or steel.

Tony Conner

I'm Not ...

... throwing rocks - I just want to understand what's happening. Why wouldn't the relatively thin walls of the CI pipe fittings fail before the boiler? I've seen expansion on long runs of pipe (over 100 feet) crack CI fittings.

I normally don't get involved in boilers this small or made of CI, but I'm aware that there are some subtle differences in what has to be considered for relatively small steam systems as compared to big ones. In bigger systems, it's a code requirement to check the piping flexibility. There are calculations, but the concept is pretty much common sense. A 2" sch 80 shoulder nipple isn't going to bend very much. 10 feet of sch 40 1/2" will flex all over the place. The larger the pipe diameter, the heavier the wall, and the shorter the run, the stiffer it will be. If the boilers you mention had been correctly piped from the start, would welding have been a non-issue?

Do any manufacturer's talk about welded piping in their installation instructions? I would think that copper piping for steam would be far FAR worse for this - the coefficient of expansion for copper is much larger than for CI or steel.

clammy

to tony

I'm not doubting what you are stating but it just seems that with welded headers for large residental steam systems that promblems do occue maybe in commericaland industral jobs the boilers are usually always on line and don't much see the heating and cooling of the piping as much as a residental system does plus i believe that on most commerical jobs they pay alot more attention to water quality issues and they have a clue about the ph and the amount of fresh make up water there systems are taking in besides the fact that every year there drain and inspected thgere system as required by the stae unlike most residental jobs .It just seems to me that most of the boiler that i have replaced that did crack had functional lwco and unclogged returns and besides the boiler the systems where in good shape .I have very rarely seem boilers crack with screwed headers while with welded i've had at least 6 in recent years.In most cases wheather it was the welder or the guy there layin it out there near boiler piping left alot to be desired besides the system take off in the wrong spot they all seemed to lack a swing jhoint or proper offset for the equilizer which after alot of thought was probaly putting some stress on the return tapping .As memory serves most seemed to be cracked on the top with not much seperation on the section .Most also still had water in them when the rip out time came and most had not seen alot of maintance on the water side of the system only the occasinal firesde cleaning .It's ahard sale for water side cleaning i quess they only believe you after the boiler cracks from waterside passage blockage and after the replacement bill they really don,t want to see ya again and as time goes by they forget any advice you have given them or they feel that your thrying to sell them something they don't need .Peace clammy

thfurnitureguy_2

Clammy once gain the voice of experiance. There is usually a reason why we see thing done the way they are. Even if it is not obvious at first glance. My thinking was to weld a 6" chamber and install threaded (on one end) nipples that would be welded into the chamber (on the other). The atachment of the boiler to the chamber would be with pipe fittings as always. Basically use the design for a drop header and replace the drop part with the welded chamber. you could attach to the boiler with unions and to the equalizer as always. The real thought is for the MFG to produce a factory "robo"welded version at about 1/2 the price of fittings. If built to their own spec. attaching the supply pipe would be an easy job. Your right that the tools to do 6" pipe are not in everybodys box. It seems odd that the near boiler piping being the root of success for efficiency of operation for many systems, that it would not be an integrated part of the boiler. As you have seen, it is often done wrong. What if you could screw your wet return into the side of the box, attached you supply risers to the top of the box, attached the oil line, hooked up the flu and screw on the stat wire and flip the switch. All inside a neet insulated box. Why all the magic? A hand built car is nice just like a stick built home, but in todays world these things are becoming out of reach. Besides the Ford will still get you there just like the Bently. Just thoughts from the ignorant I'm sure there are lots of things I'm not considering. Thats why I'm the wood guy. Take care All, T.

RonWHC

Been welding headers

on small to medium size commercial C/I boilers since late 60's. Weil 84, 86, 88, 94, 73, 76, 78, 80, & Smith 19 & 28. Have never seen a crack on our boilers attributable to header expansion. Rotted out (86 & 76), horizontal cracks in the lower wall (86 & 88), cracks around the rear door (94), & the mysterious 78 cracks around the top draw rod, on water & steam, yes. Smith had a period years ago when a 28 section that did not leak was the exception.

A properly DESIGNED, INSTALLED, & SUPPORTED, welded header works. Rejecting a proven installation method because some folks don't read, or follow, manufacturers' instructions makes no sense. On our next 28-16 steamer, you can furnish the 8" pipe machine & fittings.

Dick_3

My experience mirrors Ron's, if the welded header is designed, installed, and supported properly it will not cause problems with the boilers on residential, commercial, and industrial jobs. As stated above the co-efficient of expansion is the same for screwed or welded pipe and fittings.

The only reason older jobs, 1960 and older, are installed in screwed pipe on larger diameter piping is that weld technology wasn't advanced enough and cost effective.

To install screwed pipe in diameters of 2 1/2'' and over, other than a final connection, you would have to hate yourself. Why risk a leak and the additional cost.

Seen some residential heating guys using larger diameter screwed pipe, but being true to the trade a steamfitter typically welds anything over 2''.

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Dick_3

My experience mirrors Ron's, if the welded header is designed, installed, and supported properly it will not cause problems with the boilers on residential, commercial, and industrial jobs. As stated above the co-efficient of expansion is the same for screwed or welded pipe and fittings.

The only reason older jobs, 1960 and older, are installed in screwed pipe on larger diameter piping is that weld technology wasn't advanced enough and cost effective.

To install screwed pipe in diameters of 2 1/2'' and over, other than a final connection, you would have to hate yourself. Why risk a leak and the additional cost.

Seen some residential heating guys using larger diameter screwed pipe because they know no better, but being true to the trade a steamfitter typically welds anything over 2''.

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