Lead to Copper – Connecting or Capping a Lead Pipe

Lead used to be used fairly extensively in plumbing but once the potential health risks associated with lead were understood, moves to change to alternatives were made. Nowadays lead is not allowed to be used for drinking water or, to use its formal description, potable water. However, old lead pipes still exist in many buildings. If you have old lead pipe, the best solution is to remove it and replace it with copper. But, this is not always practical or possible.

There may be situations where you need to make a connection to a lead pipe. You may have a leaking joint or fitting, or there may be an old lead pipe that needs to be capped off.

The old practice of wiping lead joints to connect to copper on a potable water supply is no longer used as it is not permitted under the Water Regulations. There are two main alternatives which can be used if you need to connect to an old lead pipe

Lead Lock Compression Fitting

These lead lock compression fittings are readily available. They allow a connection between lead and copper to be made by means of a rubber O ring being compressed against the outer surface of the lead by a gripper ring and friction ring, and held in place by the compression nut.

A common difficulty with this fitting is establishing the size of the lead pipe so that the correct connector can be bought. Lead is generally referred to by weight as well as diameter. So, you will find the following sizes:
3/8” 5lb
1/2” 6lb
1/2” 7lb
1/2” 9lb
3/4” 9lb

When buying a lead lock fitting you will need to know the diameter of the lead pipe to which you are connecting. The easiest way of course is to take an offcut of the lead with you to the plumbers merchant but, that’s not always practical. The simplest way to measure is using a length of cotton. It’s easier that using string as the cotton is so thin you don’t have to worry about the thickness of it. Wrap the cotton around the lead pipe and cut where it joins itself. Undo the cotton again and measure the length. Then, remembering your maths from school days, divide by 3.142. This will tell you the diameter. Some people wrap the cotton round a couple of times to make it more accurate and then divide by 6.284

Connecting a Lead Lock Fitting

Choose a straight section of the lead pipe and, with the water turned off and the pipe work drained, cut the lead pipe ensuring that this is square and clean. If there are any markings on the lead at this point you will need to carefully file them off so that the size is not distorted.

Now, assemble the joint. Place the compression nut over the pipe with its open side facing the end. Slide this along and follow it with the gripper ring then friction ring. Lastly, push the rubber O ring onto the lead pipe before mounting the coupling itself on the end of the pipe. Make sure that the lead pipe fully engages into the fitting body. Pull the rubber O ring and other components down to the fitting and hand tighten the compression nut.

Now, tighten the nut with a wrench. Hold the body of the fitting with a second wrench to prevent it turning. This fitting will need to be done up very tight to ensure that the O ring seals against the lead pipe, and that the gripper ring is moulded to the pipe shape fully. The friction ring prevents over tightening and crushing or mis-shaping the pipe out of shape.

You can now fit the other side of the coupling to copper in the normal way for a compression fitting. Once the work is complete, switch the water back on gently at first to ensure there are no leaks.

Philmac Universal Transition Coupling

A popular alternative to the lead lock is made by Philmac. Their UTC or Universal Transition Coupling is designed to fit onto many different materials including lead. One of the significant advantages of this fitting is that it accommodates a greater tolerance regarding the pipe diameter making selection easier. It is also readily dismantled and refitted if required.

Select the appropriately sized fitting – each is designed for a specific range of diameters that it will securely connect to. Choose a straight section of the lead pipe and, with the water turned off and the pipe work drained, cut the lead pipe ensuring that this is square and clean. If there are any markings on the lead at this point you will need to carefully file them off so that the size is not distorted.

The fitting does not need to be dismantled. Ensure that the locking nut is open and that you can see three turns of the threaded section. Hold the fitting next to the pipe with the pipe end against the stop flange. Mark the pipe at the end of the fitting. This serves as a guide so that you will know that the pipe is fully inserted to the correct depth inside the fitting. Push the fitting onto the end of the pipe and up to this mark. Hold the body of the fitting with a wrench to prevent it turning and tighten the compression nut with a second wrench. Ensure that the joint is fully tightened.

Once the work is complete, switch the water back on gently at first to ensure there are no leimaks.

Philmac say that their Universal Transition Coupling can be used on a live pipe but wherever possible it is easier (and drier) to switch off the water and drain down first.

Examples of Use of Lead to Copper Fittings

You may have an old wiped joint which has deteriorated and begun to leak. Being able to cut out the failed section and reconnect to the copper is a typical example of using these connections. If you are relocating the incoming mains stop valve and this is fitted to an old lead pipe, you can cut back the lead to a suitable point and connect to copper or plastic first, then fit the new stop valve on the copper or plastic pipe. It is sometimes necessary to cap off and old lead pipe and the simplest way to do this will be using one of these connectors and then fitting a capped end on the copper.

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