Galvanized pipng for gas

The Steam Whisperer (Formerly Boilerpro)

Hi,  I was taught this is bad news.  Apparently our local gas company, Nicor, is planning on starting to use it.  Any comments?

Tinman

I was taught the same thing

and I believe it's because the coating on galvanized tends to flake and potentially clog orifices, etc.

Techman

Gas pipe

Hi! I was taught galv pipe outside, black or galv inside.lol

Bob Harper

gas codes

Both the IFGC and NFGC allow galvanized steel pipe where the gas contains less than 0.3 grains of hydrogen sulphide per 100 SCF. Around Philadelphia PECO requires galvanized steel pipe outdoors and penetrating the wall. FYI, this requirement also applies to copper.

Gordo

Galvanized Piping and Fittings

 I have a plumbing book from 1918 that recommends galvanized fittings for gas because the zinc coating on the fittings will cover over any sand hole leaks. 



And those were good ol' 'mercan sand holes, too!  The Middle Kingdom back then was still in the middle ages.



In my house, built in 1968, the gas fittings are galvanized.  It was local code by then that you MUST used galvanized fittings. Now, it is condemned. Or so it seems.



I worry not that the zinc flakes will cause problems.  Should I worry?



Can anybody -anybody- quote a study showing where a zinc flake caused a problem with a gas valve? 



Where did that idea come from?



Please tell me.

icesailor

Galvanized Gas:

In 1967, when I was taking study courses for my Massachusetts Journeyman's License, the instructor told us "No Galvanized On Gas". For the very reasons you listed. That it would cover up sand holes in gas fittings. And gas pipe because if there was a leak, it was usually on the Skelp of the pipe. The instructor, a UA member and a Voke Plumbing teacher, also said that you had to be aware of hackaroos using electrical conduit for gas pipe. And if anyone has ever used HW conduit on water pipe, it leaks like a squirt gun because the skelp isn't pressure tight from the inside out. Its only to protect the wires, inside.

FWIW.

Henry

Code

NFPA54 as well as B149.1 permits any ASTM A 53 or ASTM A 106 steel pipe  black or hot-dipped zinc coated pipe. Your AHJ can decide otherwise.

Jack

In my apprenticeship

we were instructed to avoid it due to flakes getting lodged in the gas valve. Using galvie fittings to "cover up" a sand hole? I think I would prefer to have the sand hole make its presence known right away other than 30 days after I am gone.

Gordo

Sand Holes

The reference I quoted for using galvanized fittings for gas pipe because it seals the sand holes is from 1918.  It was quoted for informational purposes only. 



I was trying to show some history as to the whys and wherefores.



I am NOT advocating their use or condemning their use for that purpose.



My point is, other than quoting "in my apprenticeship course we were instructed...",  I would like to know of any authoritative, scientific reason that can be given for NOT using galvanized fittings?



I too, was told the same thing about the galvanized flake theory in my apprenticeship course.  Is it true? 



I think it might be a bunch of hokum.



I have asked this question several times on this board and no one yet has provided a hint of a good history of any gas valve leaks or failures that can be laid at the feet of zinc particles.



We just today took apart some old gas pipe, mostly galvanized fittings, that was going to a stove on the second floor of an old house.



There were no zinc flakes.  Why?  Because the old gas fitter had re-used fittings from a domestic water supply and were full of rust!  He is now beyond our justice.



The old steel piping was free of rust, so it wasn't "wet gas". 



I would say rust flakes were and still are a bigger issue than the possibly mythical zinc flakes.



 

Bob Harper

then vs now

Back in the day, when the gas was not as well refined as it is now (wet gas), the impurities, especially hydrogen sulphide, caused some corrosion associated problems. With the advent of the EPA and other regulatory agencies, the gas has been scrubbed rather well. Still, private wells abound so you can encounter wet or sour gas. It's always best if you have a laboratory analysis to confirm it but not too many techs carry a gas chromatograph on their vans.

I would be more concerned about lousy gas with copper tubing because the potential to form copper sulphide flakes. This stuff is often referred to as "black dust" or "black flakes" and yes, it can and has clogged gas valves. These clogs have lead to explosions, delayed ignition, sooting,  carbon monoxide production, etc.

Most of the things old timers were taught were based upon actual conditions, rumors, urban legend and just plain falsehoods from generations before. Yet once something gets into the codes, its there to stay. For instance, draft hoods made sense to the great minds of the world 80 years ago when houses leaked like a sieve. Today, we don't know how many people die or get sick annually thanks to these contraptions but they should have no place in modern weatherized buildings. Unfortunately, they tend to work as designed.

When a local gas utility REQUIRES galvanized steel pipe, that ought to tell you something.

Gordo

Thank You, Sir

Does hydrogen sulfide attack zinc?  What is the result?



Years ago, our local AHJ forbade copper for gas due to the evils of hydrogen sulfide. Than it was allowed, mostly to allow builders to put in cheaper 2 pound gas systems with small diameter soft copper before CSST became common.



I have seen old steel gas pipe almost totally occluded with fine dust rust, so I can well imagine the vile black dust of cupric sulfide clogging gas valves.  You make it very vivid.



Again, I am not so sure that a flake or two of zinc could cause the same havoc.



Am I wrong? 



Your comment about urban legends and so forth is so true.



I well remember being told by a master plumber, who is now a Dead Man, that galvanized fittings were used with black steel pipe because it made identifying gas lines easier!



"See? It's like a zebra. There. Black. White. Black. White. That's gas pipe right there."



I'm not making this up.



It is only years later I found out it was to reduce leaks from sand holes.



And your comment about draft (death) hoods is also right on the mark!



 

Techman

Galvanized pipe

If not for gas, then what is galv pipe and fitting used for? We also were taught that copper had no place in gas systems.

Bob Harper

chemistry 101?

I am not a chemist and don't play one on TV but here is my rudimentary understanding: For hydrogen sulfide to react with the zinc in galvanized steel, several things have to happen. The most important, as I understand it is moisture: the H2S needs to get into a solution form of sulfuric acid in direct contact with the zinc: >zinc sulfate and hydrogen. Next, anything that scratches or degrades the surface of the zinc  to allow an entry point of the acid to really set up shop. The third is time. Lastly, is the condition of the zinc--a coating of zinc oxide is totally different from bare zinc and react differently. That forms zinc sulfate and water. If you don't have moisture in the pipes, then it becomes hard to get corrosion for any reason. This is why they had "drip legs" in buildings. A drip is NOT what everyone else erroneously calls it at the appliance. That is a "sediment trap". A drip should be located as a gravity sump right where the gas enters the building. It is much larger than a sed. trap at an appliance and, like a sed. trap, must be "accessible" to unscrew the cap, drain the condensate and inspect it. Some systems actually pitch the entire system back to a drip, just to keep the moisture and condensate out and away from the appliance.

As for copper, this is probably your best resource as it is written easy to understand:  http://www.copper.org/applications/fuelgas/pdf/Official_Copper.pdf 

I will dispute their claim about the low incidence rate of gas valve problems. I work in product liability and litigation support. I know of a number of cases where copper sulfide was found to be the culprit. Thus, for a long time, special internally tinned copper tubing was available for use with NG or LPG that was suspected of containing too much H2S.

Galvanized steel pipe should be fresh so there's not a lot of zinc oxide coating on the inside to flush downstream. If you keep old fittings, as I do (yes, I do gas piping), I run a baby bottle-type brush through all galv. nipples and fittings. Use clean, fresh gas cocks and never reuse regulators or flexible appliance connectors.

HTH

Gordo

For Your In-Depth Response

I thank you. This is good info.

 

I've seen those "sediment traps" on some really old parts of the gas grid here in Baltimore.



I was told by the "old timers" that used to haunt BGE that they would have to empty those traps periodically and the stuff that came out was pure evil. 



I've been told that they used to shoot steam into the lines to add moisture to keep the hemp seals on the cast iron hub joints moist and juicy.  I don't think that do that any more.  I think because of all the ground water leaks into the system that works pretty well in keeping the hemp moist and leak free. Well, mostly leak free.



I have seen them pump out the sumps in low points in the grid that collects gallons and gallons of ground water seeping in through 100 year old leak repairs.



So dry gas is good gas.  Dry gas without H2S is even better. 

Techman

Black pipe

How rusty will black pipe and fittings get when used outdoors for 1 year, for 20 years? Real good info guys and Bob Harper!

Bob Harper

other gases

Before WWII, much of the gas was "manufactured gas" or "city gas". You'll see old energy company names such as "XYZ Gas Works" or "XYZ Electric and Gas". Well, the *gas* back then was probably made by the gasification of coal--not natural gas or propane. There are gobs of different types of mfd. gas and they became known by where they were produced. The Gas Engineers Handbook is full of tables on these various gases, their chemical analysis and properties. You had all sorts of names for them such as "water gas" where steam was indeed injected to names like "blue gas". One of the common constituent gases was carbon monoxide. There were all sorts of other nasties mixed into these gases.

 If you watch old pre-WWII melodrama's on TV, you might see a scene where someone was asphyxiated by turning on the kitchen range. Well, NG and LPG are not toxic directly. They do displace O2 but otherwise are not poisonous. CO certainly is and that is how a lot of murders and accidental poisonings happened before NG. What is interesting is how many appliances are still out there with rating plates stamped into them indicating the appliance was set up for "MFD Gas" and never modified. These boilers and furnaces are major safety concerns. Combustion analysis will undoubtedly reveal very lousy combustion and often very hazardous. I always red tag and lock out these appliances when I find them. They are almost always sooted up. Even where someone did some sort of conversion, there are questions.

Yes, those drips were rather large and often full of *stuff*.

jumper

galvanized on outside?

Is that what we're talking about?

icesailor

Galv. Fittings & Manufactured Gas:

Where I worked, when I grew up and then started, they had Manufactured Gas in the town. Anything outside was LPG. Any other gas in other areas that had piped gas was probably Natural Gas. The MFGas was made by a process of burning Naptha or Hexane, I don't remember which. I never worked in the gas plant, just the electric generating plant. They used high pressure steam for the heat to get the liquid extremely got, then burned it in a "gas maker" where they burned off the carbon and it was trapped in the "maker". Then, they ignited the carbon and injected air into the furnace which created the gas. It was very low BTU output (350 BTU per Cubic foot?). The company sold gas and electric appliances. A selling point was that ALL gas appliances had to be heavily modified. Like comparing LP to Nat gas. Only the increase was 2X larger than the Nat Gas.

As far as the Galvanized Fittings and leaking through sand holes, they are cast. I have never seen a galvanized fitting leak through a sand casting pin hole. But I have seen MANY black Malleable fittings leak through sand holes when I tested them. 

After having many sand hole leaks on Malleable fittings and having a hard time finding them, I started testing to 100# air pressure. Then having the test with my 5# gas gauge. I remembered about the galvanized fittings.

A local LP gas distributor that does installs, had so many leaks from rust corrosion on black pipe or nipples. Even though they painted all their pipes that are outside. So, they switched to brass pipe, nipples and fittings. They have had problems with bad Chinese pipe and some nipples with leaking Skelp joints.

They use Galvanized piping on fire sprinkler systems where the piping is outside.

Its like a saying my grandmother had. "What we hold in memory, is ours forever".  Like bogus code rules. Once there, no matter how stupid, it's there forever.

Jean-David Beyer

The MFGas was made by a process of burning Naptha or Hexane, I don't remember which.

I suppose it could be done that way. But when I lived in Buffalo, N.Y., from 1942 onward, the gas supplied as manufactured gas was made in the steel mill coking ovens. They need the coke that they made by heating coal in an oxygen deprived furnace. The coke was the desired product, but they got coal tar used in the chemical industry (now mostly replaced by petroleum derivitives) and carbon monoxide, methane, etc. Instead of burning off the gasses, they purified them slightly, pressurized them and distributed it throughout the city. After World War II, natural gas became more plentiful and the steel manufacturing business started its decline in the Buffalo area, and later the whole country. So less manufactured gas was available, and more natural gas was plentiful. In fact, about the same time, coal declined greatly as a fuel for residential heating, replaced mainly by natural gas. By 1950 or so, the city refused to pick up the ashes anymore, so people had no choice but to convert to natural gas. I suppose heating oil was an option, but I cannot remember anyone in the city using it. Perhaps in the suburbs.

icesailor

Either or:

I lived in a place where transportation was the issue. It came by barge. Along with the #6 and diesel oil to start the generators that ran  on Bunker C to run but needed Diesel to start and stop. Gasoline, Kerosene and fuel oil all came by barge. It was nasty Naphtha. I think that Hexane was interchangeable or the same thing. Your description on how it was made. It was explained to me about 40 years ago, but I didn't understand. I guess they used the heat from high pressure steam to boil off the Naphtha and leave the carbon behind. Then. they would fire it off and the result was a gas. It was really hard for them to maintain a consistent BTU level.

Bob Harper

history of mfd gas

http://en.wikipedia.org/wiki/History_of_manufactured_gas

This explains what constitutes "manufactured gas" and some of its main derivatives along with the history. You will see the bulk of it up until the mid-20th cent. was derived from coal. There was a brief period where various hydrocarbon species were also employed The use of "naptha", which is a generic term covering dozens of various hydrocarbons, was not to burn it to form another combustible gas. If you burn naphthalene (moth balls) you get: C10H8 + 12O2 = 10 CO2 + 4 H2O + 5154 kJ  The point is, combustion of it once cannot be piped off and burned again. Yes, there was some blending of all sorts of aliphatic and aromatic hydrocarbons. It was Katie bar the door until the petro-chemical industry figured out how to make money off the previously thought of waste. A prime example of this was gasoline. It was initially a waste product from the production of kerosene to light America's homes until Edison came along. Then Ford found another use for it and the rest is history.

Yes, we are discussing using galvanized steel pipe when directly exposed outdoors but not buried. The inside and the outside of the pipe gets coated with zinc but threading removes this protection so you must apply paint, oil, dope or some other protectant to exposed threads. You can use galvanized steel indoors if it is otherwise approved for use in that jurisdiction (see my first post). It's just overkill in most cases. If you pipes are rusting indoors, fix the humidity problem.



Back to the mfd. gas; back then if a heater gunked up with soot or backpuffed into the home, it was not something you sued anyone over. It was your misfortune. A lot of homeowners owned brushes and swept their boilers and chimneys regularly themselves because there weren't any chimney sweeps. The houses leaked like a sieve so any fumes flushed out quickly and every lived with various forms of soot, dust, dirt, etc. We didn't have forced air ventilation systems for the most part until into the 1950s. So, as people became aware of the waste from coal gasification plants polluting their neighborhoods, the fumes poisoning their families, the homes become nicer with white wall to wall carpet, the homes being built like mason jars thanks to the Yom Kippur War, and litigation becoming the fastest growing livelihood in the US coupled with the delivery of much cleaner and cheaper NG ran mfd gas out of business. However, those old appliances set up to burn that junk are not suitable or compatible with burning NG. Moreover, a heater that old is grossly inefficient by today's standards and is highly suspect at having multiple failures in the heat exchanger, burner compartment or producing high levels of CO. Those units also were typically attached to undersized chimney flues which would work back in the day but not anymore. These aren't "Ozzie and Harriet" houses anymore and neither should their heaters be vintage.

Tim McElwain

You guys sound

like a bunch of old gas men. That was when men were really men.

Techman

Dear Tim

I am" a bunch of old gas men". LOL