# Copper to Cast Iron



## dcspector (Feb 20, 2010)

What I have here is a threaded copper connector for a fixture trap arm to a cast Iron DWV stack. I thought it had to have a brass transition. :?  Note, this is new construction.


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## peach (Feb 20, 2010)

Re: Copper to Cast Iron

2006 IPC Section 705.18 has several scenarios:

Copper or copper ally TUBING to cast iron hub pipe

Copper or copper-alloy TUBING to galvanized steel pipe

Cast-iron pipe to galvanized steel or brass pipe.

Plastic pipe or tubing to other materials

Lead pipe to other piping materials

Borosilicate glass to other materials

Stainless stell drainage systems to other materials.

What's tubing and what's pipe?


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## Uncle Bob (Feb 20, 2010)

Re: Copper to Cast Iron

Greg,

Peach gave you the section.

Copper or copper-alloy to cast-iron; the joints between copper or copper-alloy tubing and cast-iron hub pipe shall be made with a brass ferrule (adapter) or compression joint (no-hub).  The copper or copper-alloy tubing shall be soldered to the ferrule (adapter) in an approved manner, and the ferrule shall be joined to the cast-iron hub by a caulked joint or a mechanical compression joint (no-hub).

Note: apply pipe-joint compound or tape to the male threads only.

Correct; brass ferrule (adapter) required.

Uncle Bob


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## RJJ (Feb 20, 2010)

Re: Copper to Cast Iron

UB: Glad you cleared up the part about the tape to the male thread! I have been struggling with the opposite for years!


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## dcspector (Feb 20, 2010)

Re: Copper to Cast Iron

So in summary one must use brass regardless between the Copper and Cast Iron? Or are you saying use the copper to Cast Iron with teflon tape it or dope it up?


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## Uncle Bob (Feb 20, 2010)

Re: Copper to Cast Iron

Greg,

BRASS; you must use BRASS adapter;  and then apply pipe-joint compound or tape to the male threads.

How did they hook you into inspecting plumbing?  You don't even like the stuff.    

Uncle Bob


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## dcspector (Feb 20, 2010)

Re: Copper to Cast Iron



			
				Uncle Bob said:
			
		

> Greg,BRASS; you must use BRASS adapter;  and then apply pipe-joint compound or tape to the male threads.
> 
> How did they hook you into inspecting plumbing?  You don't even like the stuff.
> 
> Uncle Bob


Long story Bob. :shock:  I really appreciate the info it seems the PC's around here have been getting away with it untill I brought it up on Friday "Large Grocery Store Chain".

Thanks again Bob. You now are my Plumbing go to guy.


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## peach (Feb 21, 2010)

Re: Copper to Cast Iron

copper.org has a lot of interesting information and links to even more interesting information like this:

http://www.copper.org/Applications/plum ... stems.html

I hate beating a nearly dead horse.. but we have to cite code.. not the way "we've always done it"...


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## Uncle Bob (Feb 21, 2010)

Re: Copper to Cast Iron

Peach,

"I hate beating a nearly dead horse.. but we have to cite code."

2006 IRC, 705.18.1 Copper or copper-alloy tubing to cast-iron hub pipe.

picky, picky, picky.   

Uncle Bob


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## peach (Feb 21, 2010)

Re: Copper to Cast Iron

If the dimensions are such that it's "pipe" and not "tubing"?

It's an apple or orange question, I think.  Orange - tubing:  the code is clear.  Apple - pipe: not clear...


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## Uncle Bob (Feb 21, 2010)

Re: Copper to Cast Iron

Peach,

The important issue with pipe is the interior diameter; and with tubing it is the exterior diameter  (nominal size included).

Here is a more indepth explaination;

Pipes

The purpose with a pipe is the transport of a fluid like water, oil or similar, and the most import property is the capacity or the inside diameter.

For a ASME/ANSI B 36.10 Welded and Seamless Wrought Steel Pipe the inside diameter - ID - of a NPS 2 inches pipe with

•schedule 40 is 2.067"

•schedule 80 is 1.939"

The inside diameters are close to 2" and the nominal diameter related to the inside diameter. Outside diameter are 2.375" for both schedules.

Since the outside diameter of a single nominal pipe size is kept constant the inside diameter of a pipe will depend on the "schedule" or the thickness of the pipe. The schedule and the actual thickness of a pipe varies with the size of the pipe.

It is common to identify pipes in inches by using NPS or "Nominal Pipe Size". The metric equivalent is called DN or "diametre nominel". The metric designations conform to International Standards Organization (ISO) usage and apply to all plumbing, natural gas, heating oil, and miscellaneous piping used in buildings. The use of NPS does not conform to American Standard pipe designations where the term NPS means "National Pipe Thread Straight".

Nominal Bore (NB) may be specified under British standards classifications along with schedule (wall thickness).

The tolerances are looser to pipes compared with tubes and they are often less expensive to produce.

Tubes

The nominal dimensions of tubes are based on the outside diameter. If we look at Copper Tubes - ASTM B88 the outside diameter of a 2" pipe is 2.125", relatively close to 2".

The inside diameter of a tube will depend on the thickness of the tube. The thickness is often specified as a gauge. If we look at Copper Tubes - ASTM B88 the wall thickness of 0.083"of a 2" pipe is gauge 14.

The tolerances are higher with tubes compared to pipes and tubes are often more expensive to produce than pipes.

In other words; pipe sizing is based on interior diminsions and tubing sizing is based on exterior diminsions.

Hope this helps,

Uncle Bob


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## peach (Feb 21, 2010)

Re: Copper to Cast Iron

What I'm getting at is this:  the code doesn't address copper _*pipe *_to cast iron.. it's not in there.

I can take a caliper to the jobsite in question to make the determination (before the contractor starts to scream)... since it's in the drain system, I'm pretty sure I'm going to find pipe.

I'll enforce what the code says.. now I'm just really corn-fuzed..

thanks UB


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## dcspector (Feb 21, 2010)

Re: Copper to Cast Iron

Great info Bob. I wonder why this is not addressed in the IRC. I have a similar situation with boiler loop lines.....copper to Iron.


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## Uncle Bob (Feb 21, 2010)

Re: Copper to Cast Iron

Peach,

No, you don't need calipers; look at the application and the joint adapters.

The reason the term "copper pipe" is not used is because, copper pipe is not used in sanitary drains; copper tubing is used in sanitary drains. The exterior diameter of copper tubing is more important than the interior diameter.

Example: Picture a P-Trap arm that slides into the drain opening under your kitchen sink.  The P-trap arm is (1 1/2") tubing and the drain opening is (1 1/2")pipe.  A 1 1/2" P-trap arm is sized to be inserted inside a 1 1/2" pipe.  The nominal size of the tubing exterior is designed to be inserted into the interior nominal size of the pipe.  This is because the trap needs to be easily removed (slip-joints) to provide access to the drain for cleaning the drain, or the inferior trap arm tube needs replaced.

There are adapters/fittings; that are designed to join tubing to pipe in cases like Greg described; like a male thread copper tube adapter (brass in this case) to join to a threaded female cast-iron opening; where removal for servicing is not an issue.

Hope this helps,

Uncle Bob


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## jar546 (Feb 21, 2010)

Re: Copper to Cast Iron

Oakum and lead


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## Uncle Bob (Feb 21, 2010)

Re: Copper to Cast Iron

Greg,

Keep in mind that when working with water or gas lines you may be working with required interior pipe diameters; or not; depending on the application and capacity requirements.  Also, with regard to fuel gas; there other requirements that must be adhered to.

Well, busy, busy, busy; I need to go get my sunday newspapers.

Uncle Bob


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## dcspector (Feb 21, 2010)

Re: Copper to Cast Iron

Bob I think I will stick to the NEC.....Less confusing..... :mrgreen: Enjoy that time with the Sunday Paper.......Iam sure plumbing will be involved in the end "if you catch my drift".... :mrgreen:


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## Moscow (Mar 1, 2010)

Re: Copper to Cast Iron

I am know I am in the discusstion late but in the UPC 2003 section 705.2.3 Joints between wrought iron,steel,brass,or cooper pipe and cast iron pipe shall be either caulked or threaded joints made as provided in section 316.1.1 (wich is a section on wiped joints) or 705.1.1 (wich is a section on caulked joints) or shall be made with approved adapter fittings.

Approved adapter fittings is the big one, there are so many approved out there that have been tested for the the joint between copper and cast. What I see here is a (I will miss spell this so please bare with me) a diolectric nipple.

Justin


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## peach (Mar 6, 2010)

Re: Copper to Cast Iron

If they are threaded connections with pipe dope of some type on them?

Assume we're using the IPC, not UPC here.

The big issue here is... some project require copper drain lines (because of the historic significance of the building)...  frequently it's copper to copper.. what happens (that we can't see).. is the building drain or sewer .. which may be cast.. it may be terra cotta.

I'm looking for a really good argument to give to the Contractor (and the AHJ)..

Thanks


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