Galvanized Flange Face

What fluid, what temperature and what pressure?

<... very urgent...>

"Urgent" is Operations. Engineering is "considered".

Why did the contractor clean the galvanising off the flanges if the NFPA standard says otherwise?

What remedies are available along the lines of dismissal of the contractor?

What section of NFPA Standards states that Galvanized must be used? Check the appropriate standard (see standards index in books, there are 11 or 12 books) to see what they say. Often times there are many misconceptions, here say, old wife's tales about these standards. Likewise most of them are updated approximately every 5 years but the changes are not announced or publicized unless your are a NFPA member.

What is the material being extinguished? This determines what foam mixture is used. Is it an inductor system or a CAFS (Compressed Air Foam System)?

Most of the foam systems, especially CAFS, I have been involved with are either all plastic, especially the storage tanks and the piping with the metering pump made of Stainless steel. Older inductor systems have had a chrome plated brass inductor placed in the pail and plastic tubing connecting them. Since clean water is fed into the inductor the foam is suctioned out of the pail, mixed with water in the inductor and discharged through the outlet to the hose and nozzle. All of these components are thoroughly rinsed and cleaned shortly after use.

In summation, this is a brief description of the common systems, the COMMON systems. It should in no way be taken as your system. If you want a good answer you must give a good description with much more information than you have. In my days iti was called GIGO, Garbage In- Garbage Out! If you want a better answer give better information.

Good Luck, Old Salt

Fire fighting foam is a mixture of several items which together act as a surfactant. This is especially true of Class A foams (wood, cardboard, etc.). These are the type that most fire engines carry in the larger quantities on there vehicles unless there are special circumstances.

The sample composition of one of these is: Water, proprietary mixture of synthetic detergents, 1,1, Propanediol, (2-Methoxymethylthoxy) Propanol, and a propriedty mixture of corrosion inhibitors. They are like synthetic detergent! Like liquid soaps they usually, but not always, have a pH of 7.0-8.0, slightly basic. Eye tears are 7.0 so they are not very basic. These are so ecologically safe that it will not usually harm (only very sensitive plants) vegetation. It is not uncommon for fire depts. to practice with one type of delivery (compressed air foam system) and completely "shaving cream" or "snow" a tree. This is the foam you usually see firefighters covered with in pictures after a house fire or similar. It is not uncommon for firefighters to clean themselves up by taking some of the foam and "wash" themselves with it.

Class B foam is for oil and petroleum based fires. This is mostly used in large quantities at refineries, airports, gasoline tanker fires and other similar petroleum fires. It is very similar to class A but also provides a vapor barrier to prevent air from getting to the fire. That is why it is sometimes placed on a runway for a landing plane if fire is suspected as it lands. If you are in this foam it is usually possible to breath it you don't get it into your lungs (hold a handkerchief on your nose). These have a similar but slightly different composition: Water; Diethylene glycol monobutyl ether; Polysaccharide gum; hydrocarbon surfactants; and florosurfactants. It also, is basicall a surfactant or soap. Likewise the pH is usually 7.0-8.0, very harmless.

The only time that these liquids usually become a problem is when the their "use by date" has expired. At that time the usual problem is that some formulas, especially when two brands are mixed together, is that they form what is commonly (slang) called "snotts" as in nasal discharges. I have been told that this is due to polymerization but I personally don't know and will not endorse that reason. It is a real bother to remove since it clogs the metering pump and must be removed by hand or wide clearance pump. Only near the bottom, when little is left, can you discharge it as a foam/water mixture through the hose and nozzle.

OK, why this dissertation? The pH is near that of water, it is not harmful to skin unless exposure is extremely long as in days or weeks, it is basically a soap (vegetable oil is no longer used), and there is no unusual history of reaction to people. You can almost breath the stuff, in a really bad situation go ahead.

This stuff isn't bad chemically. Is galvanized used because it is the cheapest material available that won't leave unsightly rust stains? I don't know for sure but it seems likely. As a volunteer firefighter, I have had it on my skin, immersed my hands and arms in it, washed my hands and arms off with it as a soap, breathed air contained in the foam, stuffed my bare hand over 2" openings on the plastic drums or pails (the usual container) while switching containers and numerous other activities with it.

Is the reason for galvanized's use economic and not chemical resistance?

Good Luck, Old Salt

I'll weigh in on this, as another poster pointed out the OP has not checked in, so we can only speculate what his actual condition is.

We do special hazzards fabrication for fire suppression systems, and almost all of our pipe spools will be installed outside (LPG plants, tank farms etc), that is the purpose of the galvanizing to protect piping from the external outdoor elements.

My bet is this could be the OP's case.

Pipeit-

Sounds Good! I have done the same in the past for mostly water piping. If suitable, PVC or CPVC was also a choice. If the pipe was going through a nasty area then we used St. Stl. to prevent any leaks and resultant toxic spills. This was a good investment since the loss of business, lost production cost, lost time accidents, etc. made it a bargain.

Good Luck, Old Salt

"These are the type that most fire engines carry in the larger quantities on there vehicles unless there are special circumstances."

So, nowadays, they're carrying large quantities right there on their trucks...(?) COOL!!

OK, OK. I admit it. I was much better in math and science in high school than I was in English Composition and diagraming sentence's. Give me a good piping, electrical or electronic diagram anytime.

Also my keyboarding ain't worth a cr_p. When I learned the best thing you could type on was a "Royal" office typewriter. This was prior to the IBM ball type. Now even this "natural hand position" keyboard doesn't help that much. Wife won't type for me, I have to type for her sometimes, so I ain't got no choice!

Thanks for the help. In between your assistance, just feel sorry for an old bodied guy with a young spirit. I also learned how to use the abacus. That was prior to $0.59 pocket calculators. In my time they cost $89.00. Just found out that this keyboard doesn't have a "cent" character on it! You have enlightened me more than you will ever know!

Good Luck, Old Salt

I don't get the english teachers/NS who have to play the english/diction edit cards.

I'll take the "Old Salt" types to war with me anytime, and let the NS/ET stay home with the kids.

Wait for it: NS your serve:

Anonymous Poster #1

Thank you for your corrective comment. I will be sure to keep it in the frontal lobes of my mind at all times. It is very sound advice for me. I never was a good speller until reaching adulthood when I heard some people ask how to spell words that were downright simple. So simple that I think my dog could spell them if I gave him a milk-bone! Maybe this durn kid ain't dat dumb as he thout!

In the words of an infamous Fire Chief "Get that da_n class A on the engine. I don't give a flying f__k about what you think. We're going to fight a structure fire so get rid of that class B sh_t? I want as much of that stuff on the pumper as you can squeeze in your big fat a_s? Get it right next time rookie, we're here to put the wet stuff on the red stuff!"

For some reason those words seem somewhat familiar to me. I think I heard them once in training and they were so familiar that I might have imagined me saying them.

Thank you for your sound advice,

Good Luck, Old Salt (Ex-Fire Chief)

Are you sure that the flanges were hot dipped galvanised. By experience hot dip galvanise does not come out by cleaning even with emery paper or hard brush. Probably your supplier welded CS flange to GI pipe and painted with Aluminium paint. This can easily come out when cleaned.

It is possible to hot spray Zink on the flange after abrasive cleaning same either using mechanised wire brush or sand blasting. There is standard equipment for hot Zink or Aluminium metal spray. Metal to be coated is melted using Oxy Acetylene torch which melts the metal and sprays on the part to be coated.

Both Zink and Aluminium are Electro-negative and protect the steel galvanically. Al is coated on Carbon Steel pipes and stacks which are subject to high temperatures. Zn coating is to protect Carbon Steel at normal temperature.

Pl note that we an not mix both Al and Zn in your case. One of two (probably Al) is more electronegative and will be eaten by Zn. Hence you should try to protect the exposed surface by Zn spray only.

Cold Zink sprays (Colloidal Zn Spray) are also available in small handy cans. But is not effective as the spare does not have good adhesion and would come out like the paint had come out. It is OK to use cold spray to protect small patch of weld on GI.

Best regards,

Ramesh

The brand name of the material that we used to coat the welds when fabricating chain link fence gates made from galvanized pipe was called "Galvaloy", which was purchased in 1/4" square x 18" lengths. It was heated with a torch, covering the welded joints as it melted. It held up much better than any type of paint that we found.

No idea how suitable it would be for an application related to life safety or NFPA codes. You might check with the authority having jurisdiction in your area. (Fire Protection Engineer)

The original poster has disappeared, it seems, leaving many questions unanswered in the wake.

It would still be valuable to know the name of the operation carrying out this installation so that it can be avoided by others commercially in the future.

Hmmmmm... ["Key"]..... "if there is no galvanizing layer on flange face then face doesnt have any protection and may be corroded due to corrosive fluid."

The "galvanizing" consists of zinc, yes?

Zinc is "amphoteric", yes? (meaning it survives WELL in neutral pH environments, but, will corrode FASTER when put into EITHER alkaline OR acid environment).

[[ The above defines WHY galvanizing is unsuitable for tanks, conveyors etc for cementitious materials, which are generally alkaline in nature...]]

The KEY Question(s) here might BE : WHY is the 'fluid' considered "corrosive"...???

Hand-in-Hand (as already asked) : under WHAT Pressure is the system operated, AND, what is the specified GASKET material...?

This could be the "DOH!!" answer, as to why the galvanizing was removed by the contractor...

You really have to know the breakdown of the fluid. For instance muriatic acid will virtually dissolve commercial grade, hot dipped galvanizing in very short order. Marine diesel fuel tanks are not galvanized internally because it can dissolve the zinc coating. Perhaps the contractor is smarter than we think. If cathodic protection is needed on the flange, one could always install a sacrificial anode and have it attached to the metal to be protected. That is all your galvanizing is doing in reality.

Galvanizing is, in fact, affording the protection that it does, by virtue of the fact that it IS "sacrificial" in nature (with respect to carbon steel).

It affords that "type" of protection far better than (sacrificial) primers such as "cold galvanize", 'Zinga', etc.

However, galvanizing cannot "throw" its protection *any* distance; thus, once a fairly broad holiday occurs in galvanizing, protection is LOST there.

(see another post I made on galvanizing HERE)

Adding an "anode" to this system would do NO good whatsoever.....unless it were put on the INSIDE of the piping....

" We have designed the piping system for Foam-water fire fighting system with corrosive chemical foam "

This should explain it all.....

They designed it yet don't know what the ramifications of an alteration will do???

Really??

Next time consult someone who has done this before, PRIOR to manufacturing!! They may have said "Ummm, This should be STAINLESS STEEL, not Galvanized steel.

Dear all!

Thank you so much for your valuable help/advise and i apologize for my late response due to trip to where internet is not accessible.

Here is information:

1. Fire fighting foam concentrate 3% (Profilm AFFF 3%), pH:6-8

2.Design pressure 16.5 bar. Operating pressure 15bar

3. I dont remember NFPA code number but NFPA just generally say galvanized material shall be used.

4. Gasket is Spiral Wound gasket, ss316 winding

The issue is when we received flange at site for construction most of flange are rusted due to unknown reason from Subcontractor, but there are still have flanges remained in quite good condition with galvanize on faces, and Contractor decided to clean rust on flange faces. They said there is no international standard for galvanize on flange faces that why they just clean the flange faces with wire brush to bare carbon steel. My concern is since they clean the faces, galvanize is gone then what is corrosion might be on face during operation. They try to apply cold galvanize as spraying but our Painting specification does not allow to apply any spray/paint on faces to avoid over spray at site. Contractor keep saying due to Flange Supplier procedure, after hot dip galvanize flange faces will be machined and all galvanize is gone, but they can not explain why some flanges we received still in good condition with galvanize on face, note that all flanges pass inspection before shipping.

My question is what is final condition of galvanized flange, including flange faces, shall be after manufacture and ready to use, will galvanize will be removed after machining since normally hot dip galvanize will give 40-50 micrometer thick and ASME b16.5 requires roughness of face is Ra 3.2-6 micrometer. Can Contractor clean the face to bare carbon steel when their engineering design follow NFPA requirement such as Galvanized Material shall be used? The practice is flange face is always same material with pipe internal.

Contractor say their experience is all galvanized flange faces will be cleaned at site prior installation

Please advice!

Thank you so much

Napka-

Very good question. I will only answer part since I only feel confident with answering that much.

When the contractor cleans or turns down the galvanizing on the face it is no longer galvanized faced, very simple for the contractor to understand. Spec says galvanized so he must either not clean or hot dip galvanize them after cleaning.

Contractor does it the way specified in the contract or to a standard referred to in the contract or he doesn't get paid. Money Talks!

Take the NFPA code as being the "Bible" of all things that it pertains to. It is the industrial standards making organization for fire. Everyone else is going to go by it when necessary.

In the future, if any liability is concerned, the first question asked will be "Were NFPA standards complied with?" second question "Why not?"

Spec only clean galvanized flange faces. If necessary, because of a schedule, state that all faces must be cleaned without compromising the galvanizing, no brushing or machining. There are ways that this can be done, maybe not cheap but it can be done.

pH shouldn't be a problem since that is what most foams are. They are similar to soap or fat. That is what the old ones were made from.

Contractor can refer to all the experiences he has had but you are the ones paying the bill. Remind him of that!

Good Luck, Old Salt

"Fire fighting foam concentrate 3% (Profilm AFFF 3%), pH:6-8"

Your pH range is very neutral, Corrosive for me means something in the 3-4 pH range or lower. It doesn't seem as there is much of a problem as long as the foam is rinsed off with clear water after dispersal.

Original MacGyver-

Good Answer!

This is the normal procedure for operators/drivers of fire trucks whenever foam is used "the foam is rinsed off with clear water after dispersal". For CAFS (compressed air foam systems) this is done plus the rinsing of hoses, the metering pump and all piping that can be rinsed (usually excludes the piping from the foam tank to the metering pump. For aspirated systems the aspirator, foam hose and the fire hose are rinsed. This is somewhat easier than the CAFS system because it is normally an external system vs. the internal systems of the CAFS.

Ex-fire Chief, now Firefighter,

Good Luck, Old Salt

Thank you all!

My intention is trying to comply with NFPA otherwise as sir Oldsalt said there are only 2 questions comply? and why?. Since explanation from Contractor is just their experience which can not answer the question comply or not to standard that why i can not accept. However this is also my first case then just want to know the actual practice. Thank you for your support, i got the idea.

Best regard!

Old Salt

To tell you the truth, I'm not an engineer.

I have worked with machinery of all types over the course of my life, even designing and building a few automated machines myself.

The industries I've worked in is quite varied, from delivering newspapers on my bike as a kid to working in the Nevada water quality industry.

In this forum I see a lot of great "common sense" answers, and a few "you've got to be kidding me!!" comments.

I'm able to filter out the garbage and get to the root of the issue.

Sometimes it does take asking a "dumb" question to point me in the right direction and save me time and embarrassment.

I know what I know and I enjoy learning new things every day. I will never stop the learning process, it just takes a bit longer at my age!!

Original MacGyver-

Excellent Post! Common Sense if the most useful problem solver in the world. Add to that some experience and the desire to learn and you have the right tools to succeed in life. Maybe not monetarily, but a better goal- to enjoy your life! I feel that we should make the world a better place while we are here before we go to see our maker, Some people might disagree with me, there are always some of those, but that has worked for me.

I too enjoy working with machines. Sometimes easier to talk with them than certain people.

Check your private mail.

Good Luck, Old Salt