Used Type M - Mistake?

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Old 12-21-13, 10:59 AM
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Used Type M - Mistake?

My husband plumbed a water softner yesterday. Without thinking we used Type M copper 3/4". In total theres about 2 ft. of pipe.

Did I make a mistake doing this?
Is this flirting with disaster?
 
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Old 12-21-13, 11:13 AM
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A plumber once told me type M pipe is good for 20 years, and type L is good for 50 years. It will depend how corrosive your water is.
 
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Old 12-21-13, 11:17 AM
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More than likely it will be fine for a good long time. Type M is commonly used in residential, but due to the minerals present in the water it is not usually recommended for potable water. It will probably last 50 years instead of 75. You'll probably be long gone by then.
 
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Old 12-21-13, 11:30 AM
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I agree with X. Type M was originally developed for use in hot water radiant heating systems. Way back then it was not uncommon for municipal water utilities to supply water to residential properties at pressure in excess of 100 psi with no local pressure reducing valves. The house where I grew up had about 103 psi and I have seen as high as 130 psi. At these pressures the type M was not approved so either type L or type K was used.

However, for several decades it has been recommended that residential water pressure be no higher than about 75 psi and 50 to 60 is most common. At these pressures type M is commonly used.

In other words, you are fine.
 
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Old 12-21-13, 11:36 AM
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I've done various minor copper plumbing repairs from time to time over the years, fixing pinhole leaks and on all the repairs I have done, the pinhole leaks always occurred at 90 elbows, not on the straight pipe. Not that it doesn't happen, but I'm sure it probably has something to do with the way the pipe wears. I've seen more problems with pipes splitting since Type M is not as heavy it can't withstand freeze/thaw cycles as well as Type L or K.
 
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Old 12-21-13, 11:39 AM
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OK thanks for the explanations! I was just in the basement trying to bend some scrap pieces by hand... I thought it might have been the stuff used for refridgerator water lines or condensate lines but only larger ID. FWIW, I cant bend it by hand

So are the fittings type L or M?
 
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Old 12-21-13, 05:49 PM
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mummy I think you should check with your local authority because I believe in some localities M is not allowed. In fact I heard somewhere that in the east thats mostly the case. But I dont know that for a fact. I know you can always find M in the Home Centers here in the east near where you and I live, if thats means anything. LOL (btw - I just use L).

The different copper tubing sizes M, L, and K vary in the pipe wall thickness but the O.D. is the same for all three. The O.D. is 1/8 larger than the nominal pipe size. So a pipe has a 7/8 O.D. A pipe has a 5/8 O.D. etc. (The wall thicknesses for M, L, and K are set by a standard.)

So for example if you look at a copper fitting, the inner diameter of that fitting will be 7/8 so it can slip over the O.D. of the pipe, that is, so it can slip over a pipe with a 7/8 O.D. Confusing isnt it? LOL (IMHO Start looking at the myriad of fittings and material and standards that need interoperability and you can see why plumbers make a lot. lol There is a whole bunch to it and thats just the tip.lol)

I believe the wall thickness of the fittings are set by a separate standard (ASME something or other) and is not meant to match tubing wall thickness.

I believe all the above is factual.

p.s. I came across an argument somewhere (I think from a plumber) that said if your water is aggressive you shouldnt be using copper in the first place, however if its not aggressive then type M should last longer than the house. I dont know if thats right but sounds good to me. LOL, and I also dont know why some authorities wont allow M ?
 
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Old 12-21-13, 06:15 PM
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I also dont know why some authorities wont allow M ?
I think they simply believe that thicker pipe is better and longer lasting. But I thought this was an informative article on the subject- especially the quote: "If there is something eating the copper pipe from well water or another source, the problem should be fixed rather then postponing the inevitable with a thicker walled pipe."

Makes sense to me!
 
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Old 12-21-13, 06:20 PM
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I cant bend it by hand
MBT is the type you can bend... Thats a lost art though... I used to bend to save on fittings back in the day...

I am on a well and repiped my whole house in L... It will out live me....Most of the M in the homes here has not lasted 20 yrs...( PH issues)...

When I added bath upstairs I wnet with pex......

In total theres about 2 ft. of pipe.
I would not worry about it.... When it fails replace with L............
 
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Old 12-21-13, 06:32 PM
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"If there is something eating the copper pipe from well water or another source, the problem should be fixed rather then postponing the inevitable with a thicker walled pipe."

Makes sense to me!
Yes I totally agree. I had a low ph (5.5) that was eating the h### out of my copper pipes. I finally bit the bullet and put in a neutralizing filter. Sleep better now.
 
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Old 12-21-13, 06:37 PM
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lawrosa-

...I am on a well and repiped my whole house in L...
Wow. We know you aren't a cheapskate!LOL That had to be a ton of money.
 
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Old 12-21-13, 06:44 PM
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5.5??? That's crazy acidic!
 
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Old 12-21-13, 06:54 PM
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5.5??? That's crazy acidic!
Oh yea, bad news! LOL But that is the true number. I guess back in 1967 pex and other stuff wasn't around? Only thing I can figure because it really seems copper was not appropriate in this house.

(i think previous owners had a chem injection system, that's why the pipes aren't destroyed)
 
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Old 12-21-13, 06:58 PM
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a chem injection system
i.e. Milk of Magnesia LOL!
 
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Old 12-21-13, 07:01 PM
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i.e. Milk of magnesia lol!

lol..............................................
 
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Old 12-21-13, 07:36 PM
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Wow. We know you aren't a cheapskate!LOL That had to be a ton of money.
Fell off a truck...............

Im a 5.5 or so too... Depends on the time of yr... (shallow well)..

I have a calcite filter that does well...
 

Last edited by lawrosa; 12-22-13 at 10:33 AM.
  #17  
Old 12-22-13, 09:41 AM
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I have a calcite filter that does well...
Me too! Great minds think alike! LOL
 
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