Unit 04 Common processes and techniques
LO 2 Quick recap – types of domestic plumbing and heating pipework and their jointing techniques
Because this has been a really, really long session, we have included an extended re-cap here to make sure you are keeping up to speed with everything that we have covered.
Before we move on, let’s have a quick look back on what we covered in LO 2. We looked at all the different pipework materials and sizes, you’ll recall we covered:
Copper . R220 soft coils . R250 half hard lengths . R290 hard lengths
Low carbon steel (LCS) . Medium grade
Plastic pipework (hot, cold and heating) . Polyethylene . Polybutylene
Plastic pipework (sanitary) . PVC-U . Polypropylene . MuPVC . ABS
Next we looked at methods of joining pipework to lead pipe. We said it’s illegal to install lead pipe from scratch now, but there may be circumstance where it’s necessary to connect to a lead pipe for a repair for example. Two methods mentioned were Lead Lock and the Philmac couplings.
And don’t forget we talked about the health and safety precautions associated with lead pipework and with working with lead.
We moved onto identifying fitting types used in dwellings and focused on Couplings Elbows and bends Equal tees Reducing tees Reducers Tap connectors Flexible connectors Manifolds Tank connectors.
Unit 04 Common processes and techniques
Starting with copper, we said these fall into four main categories, can you remember? Have a go at completing the list, we’ve given you the first letter to start you off: C C P P There are two types of capillary fitting, end feed and integral solder ring and two types of compression, type A and B. Which type of compression fitting was suitable for underground services?
We completed copper fitting types by looking at push-fit and press-fit fittings before seeing examples of the actual fittings, i.e. elbows, tees, reducers etc. under each type.
After copper it was LCS. We mentioned that the most popular fitting for domestic plumbing was malleable cast iron, what were the typical sizes used in domestic plumbing?
Of the two jointing techniques we said that threading was probably the most popular for domestic plumbing; the other method being the use of compression fittings. In terms of threaded joints, you should know the difference between a male and a female thread.
Like with copper joints we showed you a range of malleable cast iron fittings. Here’s one, can you remember what it’s called and why it’s used?
You’ll probably recall that there are loads of plastic fittings and these are determined by the pipe material and the jointing techniques used, which may be solvent welded, push-fit or compression. We produced a table to summarise this information.
We then considered materials for hot, cold and heating pipework and for this we looked at:
Polyethylene (MDPE) Polybutylene (PB-1)
Polyethylene included compression fittings made from brass or plastic, as shown, or push-fit fittings made of plastic. With the compression fittings, it’s important to make sure the pipe insert is used.
Polybutylene can be jointed using push-fit or type A compression fittings and again we showed you a range of fittings.
Sanitary pipework next, can you remember the group of plastics used here? Have a go at completing the list below. Unit 04 Common processes and techniques
P P Mu A
We said that we could group these materials together as soil, vent and waste pipes are the same size, are interchangeable, and can be jointed using push-fit or solvent welded jointing techniques. Then we gave some examples of soil and vent pipe fittings, followed by waste pipe fittings.
We also showed a range of overflow fittings for solvent weld or push-fit jointing techniques, as well as some compression fittings and traps for sanitary appliances.
After types of fittings we considered the various methods for actually jointing the pipework used in dwellings. So, having given you all the various fittings used on the various materials we followed a stage by stage process of how to actually complete the joints.
Copper jointing; integral solder ring and end feed is all about cutting, preparation and then carrying out the jointing process using a blow torch, making sure the pipe is deburred, cleaned and/or fluxed.
De-burring the outside of the pipe when using a hacksaw enables the fitting to go onto the pipe easily, whilst inside prevents small particles of copper filings going into the system.
De-burring on the inside of the pipe when using pipe cutters removes the ‘lip’ caused by the cut, which can have an effect on the flow of water in the pipework.
Compression for copper pipe included type A and B.
Unit 04 Common processes and techniques
Type B is where the end of the pipe has to be opened out to receive the adaptor. Push-fit fittings are relatively straight forward, again make sure the pipes are cut straight, de-burred and that the depth of the fitting is marked on the pipe.
Finally, press-fit fittings require the use of a specialist tool. Hopefully, you viewed the videos we provided via the link to the Peglar Yorkshire site that showed the various jointing processes
Jointing LCS pipe requires either threading or compression methods. Threaded joints are produced by using a manual ratchet threader or a power portable threader, in both cases stocks and dies are used in the process.
The dies being the tools that actually cut the threads and the stocks that provided a casing for the dies. We also showed you a powered threading machine Again we gave you an opportunity of seeing the actual threading process via a video link. Compression fittings for LCS, enables mild steel pipework to be joined without the need for threading, but these types of fittings tend to be more expensive.
Finally we looked at how to join plastic pipes and established that these fell into four main categories:
Push-fit Compression Solvent weld Proprietary – copper and MDPE.
Then we summarised the jointing techniques under.
Polyethylene (MDPE) PVC-u Polypropylene (PP) MuPVC ABS.
We did a recap before for joining plastic pipes, but here’s a quick reminder. MDPE pipe for domestic plumbing is mainly used for underground water services and can be joined by either brass or plastic compression fittings. The important thing to remember is to make sure the pipe support liner is inserted.
Unit 04 Common processes and techniques
Polybutylene pipe is used on hot, cold and central heating domestic water services, with barrier pipe being used on central heating systems. You may recall that we looked at two jointing methods:
Push-fit fittings Type A non-manipulative compression fittings
For the push-fit we showed the jointing techniques for Wavin’s Hep20 using a step by step guide. One thing to remember is not to cut the pipe with a hack saw but to use cutters that are recommended by the manufacturer.
We provided a link that reinforced the jointing process, as well as showing how the fittings can be demounted.
We moved onto the standard type A non-manipulative compression fitting. Can you remember the important component that must be used on the plastic pipe? Yes, it’s the pipe insert, needed to support the pipe wall during the jointing process.
Remember, push-fit and compression fittings can be used to join copper to plastic.
We grouped PVC-u, Mu-PVC and ABS pipe together as these can be joined using both push-fit and solvent welded techniques.
The process is relatively straight forward for both and it’s important that pipe ends are cut square and de-burred.
If you’re using push fit, you need to chamfer the end of the pipe, which makes it easier to push into the fitting and avoids dislodging the neoprene ‘O’ sealing ring; pipe and fitting should also be lubricated. A 12mm allowance should be made inside the fitting to allow for expansion.
Solvent welded fittings and pipe should be cleaned using solvent cleaner and then the solvent weld cement applied by a brush. Make sure the work area is well ventilated.
We rounded off with polypropylene, which is mostly used on waste pipes and uses push-fit jointing techniques.
The final session was about methods of bending pipework used in dwellings. Here we looked at:
Copper machine bending . 90o bends . Sets and offset bends . Passover bends
Copper spring bending . 90o bends . Sets and offset bends Unit 04 Common processes and techniques
LCS hydraulic machine bends . 90o bends . Sets and offset bends . Passover bends
Plastic pressure pipe . Spring bend . Cabling technique . Cold forming bend
Copper pipe can be bent either by machine or by hand. For most domestic plumbing we’re talking pipe diameters of 15, and 22mm so machine benders are likely to be the hand held lever or scissor type. Remember this type of bender can also be held in a vice, which gives it greater stability.
We also showed you the hand held ratchet bender and a tribender. Can you recall what the tribender is used for? Domestic plumbers also work with pipe diameters of 28mm so the free standing bender would be a better choice for that size and we showed you all the component parts of the machine.
Next we showed you how to carry out the following bends in copper using the machine bender:
90° or square bend Sets and offset bends Passover bends/sets
Once we’d completed machine bends we looked at bending copper pipe by spring and in particular how to set them out. Do you remember that there is an apparent gain of the material when the bend is formed and this should be allowed for when setting out; the bend should also be pulled in the right position in relation to the fixed point.
LCS pipe is bent using a hydraulic bending machine, due to the strength of the material, and the thickness of the pipe. For domestic systems we’re looking at bending ½”, ¾” and 1” pipe. We went through the process of forming:
90o bends Sets and offset bends Passover bends
Finally for copper and LCS we set an activity based on a pipe work layout and asked you complete a list of activities for doing the job.
Unit 04 Common processes and techniques
We completed the section on pipe bending with plastic and here we listed the following techniques. Can you remember what they were; have a go at completing the list.
S C C
Spring bends are used on plastic pipe to form tight radius bends; the spring preventing the pipe wall from collapsing, you can bend plastic pipe without a spring but they have to be large radius bends, which if in view can look unsightly.
Cabling techniques are used when long lengths of coiled plastic pipe is threaded through pre-drilled holes in the centre of joist to supply hot, cold and heating systems in dwellings.
Finally we showed examples of cold formed bends where a metal former is fixed in the positon where the bend is required and then the pipe is clipped in position.
OK that’s the recap over; it’s time to move on to LO 3, site preparation techniques for plumbing
and heating work.
Unit 04 Common processes and techniques
LO 3: Understand site preparation techniques for plumbing and heating work
At the end of this session:
You will understand site preparation techniques for plumbing and heating work
To achieve this, you will be able to:
State work methods for preparing and protecting the building for installation work
Identify the pre-existing damage checks to the building fabric or customer property before the work commences Describe the methods of safe storing of tools and equipment Identify sources of information for carrying out preparatory work
So far in this unit we’ve looked at the range of hand and power tools that plumbers’ use to carry out their various plumbing tasks; then we had a large section about the types of domestic plumbing and heating pipework and the pipework jointing and bending principles.
In this next section we are going to consider site preparation techniques for plumbing and heating work, starting with session AC 1.
AC 1 State work methods for preparing and protecting the building for installation work
First of all then, what do you think we mean by work methods? Bear in mind we’re talking about work methods that are associated with preparing and protecting the building for installation work and not the installation work itself. So start by thinking along the lines of how we get pipework from A to B through various types of building materials such as walls and floors.
We’ve prepared an activity to see what you think.
Unit 04 Common processes and techniques
Activity 20
We’ve compiled a list of bullet points and given you the first three work methods; we would like you to have a go at completing the bullet points and.
Making holes in masonry surfaces, use of hammer and chisels, large power drill Making good to masonry surfaces Lifting and replacing timber flooring materials
How did it go? Not an easy activity if you’re just starting out in the industry, but we’re going to look at the various work methods in a bit more detail shortly.
Before we get into the detail, let’s explore what we mean by ‘work methods for preparing and protecting the building for installation work’.
We keep saying that the plumbing industry is quite varied in that plumbers’ will work in a number of different types of building, even with domestic plumbing, and they also work on new building projects or in existing properties carrying out refurbishment or repairs and maintenance.
On new work some of the work methods mentioned such as lifting and replacing floor materials won’t be necessary and things like cutting chases in floor and wall surfaces may be done by other trades.
It’s really when working in existing properties where the plumber is expected to carry-out a range of associated building tasks. As such, you’ll need to learn some additional skills to carry out your work effectively.
You’ll need to run pipes under timber floors, so that will involve notching joists (cutting openings or holes in timber joists for pipes to pass through).
In existing properties, gaining access to carry out work under the floor will mean lifting floor surfaces so you’ll need to know how to do that. Often, both on new work and maintenance work, you’ll be required to cut or drill holes in brickwork, block work, concrete and timber so we’ll cover that here as well.
Unit 04 Common processes and techniques
Holes in masonry surfaces, use of hammer and chisel or large power drill
For cutting holes in brick, block and concrete, hand tools will consist of: Cold chisels Brick bolster and club hammer.
Typical situations where a plumber will need to cut holes in masonry surfaces include holes for pipework to pass through walls or floors.
So for example, a waste pipe may need to pass through an external wall from a kitchen sink to the waste gulley outside. As shown in the example to the right.
A hole can be cut through the internal and external wall surfaces using either a cold chisel or bolster chisel together with a lump hammer
Care must be taken only to cut out the minimum of material for the passage of a pipe in order to keep making good to a minimum. Other examples include cutting out larger holes to accommodate flue pipes from domestic gas boilers or soil pipes from a WC outlet.
Whilst plumbers still use hand tools for cutting holes in masonry, a popular choice is the use of power tools, particularly as these can be used with large diameter hole saws.
The drill shown is a 1350 watt combination hammer drill and is capable of drilling up to 48mm diameter holes in concrete and a 115mm diameter hole in masonry when using a core bit.
Unit 04 Common processes and techniques
The core bit, shown with the drill, is diamond tipped which prolongs the life of the cutting teeth. These bits range in size from 28mm to 150mm for domestic applications.
Masonry bits are also available for larger diameter holes; these have tungsten carbide tips for longer life and are for use with rotary or percussion drills. Typical sizes are 16, 20 and 24mm.
What do you think are the advantages of using power tools and large diameter hole saws or drills have over hand tools?
Two main things really, power tools have the advantage over hand tools in providing a much neater finish to the job, which means less making good. It’s also a lot easier physically to use power tools!
Making good to masonry surfaces
This will involve making good to brickwork, blockwork and concrete. For most jobs a mortar mixture of 4 parts sand to 1 part cement will be adequate for pointing any brickwork joints that may be disturbed whilst doing the job, and for making good the gap around the pipe penetration.
There are also a number of branded ready-made mortar mixes on the market. Expanded foam filler is also available for larger holes. This can be used on wood or masonry inside or outside and takes around 1 hour to dry, then it can be cut, sanded, plastered and painted.
Note: all metal pipes that pass through wall structures must be sleeved, with an approved material.
Why do you think it’s important to ensure that masonry surfaces are made good?
Firstly, it’s important that any unsightly holes or gaps are made good to create a neat and tidy finish to the job. The other reason, particularly where pipework is being installed from the inside to the outside of the building, is to prevent any heat loss through the gaps around the pipework.
Lifting and replacing timber flooring materials
It’s possible to lift sections of floor boards using hand tools, but this is a time consuming process when compared to using an appropriate power saw. Powerful battery operated versions like the one shown here are ideal for this type of task.
Plumbers’ have to lift single floor boards to run pipework through timber joists, or they may have to cut a section of floor to run pipe between joists or to install a plumbing component below the floor, such as central heating pump (though this should always be made accessible for maintenance purposes).
Unit 04 Common processes and techniques
Using the power circular saw
Check-list
Use an 110v or 18v cordless model Make sure the tool is in good condition and has an in-date PAT test certificate (battery operated power tools don’t need PAT testing but their battery chargers do) The depth of the cut must not exceed the depth of the floor board A guard must always be fitted to the saw blade Use a cable/pipe tracer to make sure there are no hidden cables or pipes in the areas where the saw will be used Make sure you’re wearing appropriate PPE
Taking up a single length of floorboard Once the length of board to be removed has been determined, it will be necessary to remove the tongue and groove joints on either side of the board and then make cuts across each end of the board being removed.
The cross cuts should be located over the joists, making re-fixing easier, if not you’ll have to fix timber cleats to support the end of the joists. The joist can be located by finding the nails fixing the floorboards to them. Sometimes it’s possible to lift the board from its natural joint, if not, the board will have to be cut. The saw can be used to cut down the full length of the tongue and groove on each side of the board. The cross cut is made, again over the joist, making sure that the blade doesn’t hit the nails.
The nails holding the floorboard to the joist should be punched through the floorboard using a nail punch which is best practice, or alternatively, the board can be lifted using a bolster chisel or nail/crowbar and the exposed nails tapped back through the board ready for re-fixing the board. (Never leave the floorboard with the nails through the board and the pointed end exposed).
There may be occasions where it’s not possible to use a power saw and hand tools have to be used. A floor board saw should be used to do the cuts across the floor board with a hammer and a 100 or 150mm bolster chisel used to chop through the tongue and grooved joint.
Cutting traps in floor boards
This uses the same methods as for removing a single floor board, either using hand or power tools. It’s just that there’s more boards to cut, although in shorter lengths.
Unit 04 Common processes and techniques
Replacing floor boards and traps
The floor board length or trap should be screwed back into position to make future inspection or maintenance easier; this should be done using countersunk wood screws. When re-fixed over pipework, the board surface should be marked accordingly, e.g. water, heating or gas pipework.
Where it’s not been possible to find a joist to refit the board or trap to, cleats must be used to support the board end. The illustration below shows a trap or board replacement over joists and use of cleats.
Removing and replacing chipboard
This can be a more difficult job than lifting floor boards, as it’s laid in wider sheets. The best way to remove it is by using a circular saw - like floor boards, the same rules apply. If a power supply is not available, a section of board can be cut using a floor board saw.
The section of board to be removed needs to be marked out across the board so you have guidelines to follow for the cut. If using a pad saw to make the cut, it’s helpful to drill holes in each corner of the area to be lifted in order to start the cutting process. Using this method will mean replacing the removed section with a new piece of chipboard.
Unit 04 Common processes and techniques
Replacing the chipboard
Below is a typical detail for re-fixing chipboard.
Like the floor boards, the chipboard should be screwed back in position.
Use of pipe guards
As we mentioned earlier, pipe runs under floors should be marked. A more effective way of protecting pipes which pass through joists is the use of pipe guards. The illustration to the right shows a typical example.
Notching or drilling holes in timber floor joists
It’s inevitable that a joist will have to be drilled or notched to permit pipe runs under timber floors. The preferred method would be to drill the joist in the centre of its depth as this is where there’s least stress.
In practice, apart from when using plastic heating, hot and cold water supply pipe, this tends to be
impractical.
The main thing to remember then, for either notches or holes, is to make sure that the joist is not weakened. This also applies to the distance from the wall where the joist is notched or drilled. Think about the consequences for the customer of having joists Example of pipework passing through holes drilled that have been significantly weakened. in the joists Unit 04 Common processes and techniques
The Building Regulations set out the requirement for notching or drilling joists.
Notches Should only be made in the top edge of the joist Should be no deeper than 0.125 times the depth of the joist Should be no closer to the support than 0.07 times the span and no further away than 0.25 times the span
Here’s an example calculation for determining the distances from the support for a 3m joist:
Length of span = 3m 0.07 times the span = 3 x0.07 = 210mm 0.25 times the span = 3 x 0.25 = 750mm
Holes Should only be drilled on the centre line of the joist Should have a diameter no greater than 0.25 times the depth of the joist Should be no closer together than 3 times the larger diameter Should be no closer to the support than 0.25 times the span and no further away than 0.4 times the span
Again for the distance from the support hears a calculation for a 3m joists:
Length of span = 3m 0.25 times the span = 3 x 0.25 = 750mm 0.4 times the span = 3 x0.4 = 1200mm
Requirements for joists
Unit 04 Common processes and techniques
Activity 21
Using the specifications for notches and holes work out the following for a 200mm deep joist:
1. The notch depth 2. The hole diameter
When notching, ideally the joist should be drilled at the correct depth using a wood bit then the sides cut down to form a notch which is rounded at the bottom. However, the joists are normally cut manually using a power, hand or floor board saw. Once cut to the required depth and width, the timber notch is removed using a hammer and sharp wood chisel.
The width of the notch should be large enough to give freedom of movement, in order to allow for expansion and contraction, particularly for hot water supply pipework.
Power drills are commonly used for drilling joists and where space is limited between joists, drills, such as the one shown on the right, are particularly useful.
Plumbers may be called upon to drill holes through other timber components such as the side of kitchen units or cupboards for storage vessels or cisterns. Again cordless power tools are used, but a brace and bit can be used as an alternative.
Wood bits are used to drill holes and typical sizes include, 12, 16, 18, 20, 22 and 25mm and are useful for drilling holes in joists, or other timber constructions for the passage of pipes.
Hole saws are also available for timber; size range: 19, 22, 29, 38, 44 and 57mm. These are handy when drilling through kitchen units in order to pass installation pipework or waste pipes through the side or back of cabinets. (They are also used to drill holes in plastic cold water storage cisterns.)
Cutting chases in in wall and floor surfaces
It may be necessary to cut chases in walls to conceal pipework, e.g. plastic heating pipework, particularly in older properties that are constructed with plaster on solid internal masonry walls.
Concealing pipework in wall and floor surface surfaces is permitted providing they are adequately protected, but the Water Regulations do not permit fittings to be embedded in wall or floor surfaces.
The most common method for cutting chases is the use of an angle grinder; 18v cordless or 110v grinders are available. The intended chase should be carefully marked out using a straight edge and then the lines followed using the grinder. Unit 04 Common processes and techniques
In walls, the depth is important; horizontal chases should be no more than 1/6th of the thickness of the wall and for vertical chases not deeper than 1/3rd the thickness of the wall
Once the grinder has done its work, the chase can be made using a hammer and bolster to remove any plaster or masonry.
Walking boards
Walking boards are used mainly to allow access onto fragile roofs. We covered working at heights and on fragile roofs in the health and safety unit so it may be worth revisiting that for a recap.
Dust sheets
Dust sheets are an essential requirement when working in occupied properties to protect customer’s furniture and floor coverings. Many of the tasks carried out by plumbers can generate dust or small pieces of debris, such as drilling and cutting materials such as timber and masonry. Other activities, such as the removal of pipework and components may also run the risk of spillages.
Occupied premises are likely to have carpets or other floor coverings so dust sheets should be used to protect floor coverings from foot traffic, although many employers provide boot covers for this purpose. Branded plastic sheeting is also available as an alternative to dust sheets.
Activity 22
Time for a bit of research; we’d like you to investigate the options that are available for plumbers in terms of protecting the work area, including dust sheets, plastic sheeting and foot covers.
Removal of personal property
This is particularly important when working in occupied premises and relates to the occupiers’ personal property such as valuables. Never work in occupied premises where the owner/occupier or their representative isn’t present as this leaves you vulnerable to accusations should any personal property go missing.
It’s also important to move any personal property away from work areas that may be liable to get damaged.
End of extract If you’d like to discuss this material in more detail, please e-mail Steve on: [email protected]