pipes

[hammers4spanner]

Anyone know if its ok to connect low carbon to medium iron on heat circuit ? Have been dropped on it via another plumb and have a speed vs time issue so obviously mapress gets it done quick .

So linking on iron corrosion or not ?

 

[SimonJohns]

I wouldn't use mapress on heating unless you have to.

If you have to use mapress use stainless steel

There is too much corrosion risk with galv mapress

 

[hammers4spanner]

Cheers fella it was on my mind

 

[Scott_D]

I have used carbon steel mapress on heating many times. I cant think what other use it has?
You could always check with the manufacturer if your concerned.

 

[SimonJohns]

Hi Scott

In my experience of galv mapress. It's fine and fit for purpose

BUT

If its not a system you know well

Or a system that may not have correct dosing. It can fail prematurely.

I'm. It saying dont. But my best advice due to not knowing the system stainless will not corrode or fail like galv will

 

[Scott_D]

Have you found the pipe or fittings to fail?

 

[SimonJohns]

Have you found the pipe or fittings to fail?

The material fails.

And quite comman. Not the pipes fault. But dosing issues.

Either too much inhibitor or incorrect chemicals

 

[hammers4spanner]

Inhibitor reacting to the carbon chemical breakdown ??

 

[SimonJohns]

No. An overdose of inhibitor will actually become corrosive

Leave some steel in inhibitor for a while and watch it fall apart

 

[SimonJohns]

Just done a little homework

Inhibitor has a ph of 6.5. And this contributes to metal corrosion

Have a look at the sentinal data sheet and then google 6.5ph metals

 

[hammers4spanner]

Never knew that so most od the big stuff thats going on now is a future costly error

 

[SimonJohns]

Routine GOOD maintenace will prevent this

 

[Ermintrude]

6.5 is fairly close to 7. If system is sealed you will reach equilibrium, a point at which the oxygen required is balanced by the hydrogen produced.
Le Chatelier's Principle dictates how the system would corrode . Think most inhibitors work on this principle . If system open or oxygen can enter system you would need a significantly higher dose or to add every year as the ph would drift back to water ph ?

 

[SimonJohns]

Yes your right

But mapress is usually found on commercial installations

Overdosing can occur quite easily

There is more than just 1l being added in a commercial system

The corrosion is not occurring because of the presence of oxygen

 

[mutley racers]

Very interesting

 

[Ermintrude]

No but corrosion occurs at significantly lower rates without oxygen. If an inhibitor existed to reduce the dissolved oxygen in water to almost zero and there was a partial pressure of hydrogen, no oxidation ( corrosion) could occur. Iron changes from Fe to Fe 2+ and Fe3+ .

 

[SimonJohns]

No but corrosion cannot occur without oxygen. If an inhibitor existed to reduce the dissolved oxygen in water to almost zero and there was a partial pressure of hydrogen, no oxidation ( corrosion) could occur. Iron changes from Fe to Fe 2+ and Fe3+ .

I think your a fool!

Do you work ok commercial ?

You do not have to have oxygen for corrosion. The corrosion is takin place because its got a ph of 6.5

The corrosion is not RUST. It is just purely the pipe being dissolved by the liquid

What is your back ground even?
I can give you firm evidence as to systems failing due to an overdose of inhibitor

 

[Ermintrude]

possibly a well educated fool studied pipe corrosion, system mechanics and fluid mechanics, process pipe work, materials science, metals and chemistry for about a week or two.

Corrosion is liquid dissolving pipes?

4Fe + 3O2 = 2Fe2O3

Anion and nucleate chlorides and calcium salts have a lot to answer for.

Dissolving the pipes is oxidation - the metallic crystalline structure disturbed by oxidising agents.

 

[SimonJohns]

I don't care what you think

I know inhibitor destroys pipework in high concentrations

You can try and appear smart. But regardless of the fact that I have alot of experience with this very issue

What do you do as a plumber?

Are you Dom com or industrial?

 

[Ermintrude]

Most of my time is spent on controls and programming works. Appreciate that experience can and does outweigh knowledge. As said above its correct inhibitor / fluid additives which make the job? If systems all one material inhibitor should protect that type? Stainless will react very differently to galv if in same system. They corrode differently. From a chemistry point of view ?

 

[Ermintrude]

Most of my time is spent on controls and programming works.

 

[hammers4spanner]

Back to billy basics does iron and lcs clash ? Nevermind inhibitors ph levels etc etc

 

[SimonJohns]

Not really