How to choose your plumbing fittings?

How to choose your plumbing fittings?

Jeremy, construction site supervisor, Cardiff

Guide written by:

Jeremy, construction site supervisor, Cardiff

131 guides

Welded and olive fittings for copper pipe installations, compression screw fittings for polyethylene, push and sliding fittings for PEX pipes and adhesive fittings for PVC: read our advice to become a home plumbing pro!

Important features

  • Type of fitting
  • Copper
  • PVC
  • PER
See our plumbing fittings!

What are the main types of plumbing fitting?

To get stuck in, copper pipe fittings are brazed and require specialized plumbers' tools to install; olive joints, on the other hand, allow you to connect copper pipes without having to do any welding – brilliant! Screw fittings incorporate teflon or hemp fibre as a seal; specific PEX fittings are needed for a PEX installation and PVC fittings, for pressure or wastewater pipes, are glued. 90% of plumbing installations nowadays use copper pipes, so depending on how you rate your skills you'll need to use olive fittings, screw fittings and PVC fittings – typical for the wastewater side.

Welded fittings

Copper fitting


alt

Copper fittings are connected to copper pipes via welding or brazing – a specialized welding technique which can either be 'strong' (hot water and heating pipes) or 'cold' (cold water pipes). Brazing is done with a blowtorch or flame welder and a filling metal chosen to suit the welded material. The fittings are sized to match the pipe and come in a variety of forms to suit your needs (elbow, T-joint, sleeve, etc.).

Making connections without welding

Screw fittings


 width=

Screw fittings are of course connected via a screw thread, with a seal formed of teflon or oakum (hemp fibre). Often used in domestic plumbing applications, they are made of brass or galvanized metal and are available with different types of screw thread with sizes expressed in mm or inches. Screw fittings can be male, female or male-female and come in the form of elbows, T-joints, sleeves and bungs and sometimes require washers.


alt

Bicone or 'olive' fittings

A bicone fitting also allows two copper pipes to be connected without welding and is the quickest, easiest solution. Their working principle: a ring deformed by the screwing action forms a seal between the fitting and the pipe. Perfect if you don't have a welder or blowtorch.

PEX fittings


 width=

PEX is an abbreviation for cross-linked polyethylene, with specialized fittings for building plumbing installations. It makes a flexible pipe useful in renovation as well as new-build water and heating installations and, again, not requiring welding. There are four main types of PEX fittings: compression fittings, push fittings, sliding fittings and automatic fittings.

Compression fitting


alt

As the name suggests, a seal is formed by compressing the pipe around the fitting. This is achieved with a nut, so all you need in terms of tools is a flat spanner of the right gauge.

Push fitting 


 width=

A little more complex than the compression type, here a seal is formed by forcing the fitting onto the end of the pipe. This may require the use of a pair of crimping pliers.

Sliding fitting 


alt

This is the most reliable type of PEX fitting. It is used in heating applications, among other uses, where the seal must be perfect and durable. Fairly complex to assemble, you'll need some knowhow and the relevant equipment – flaring pliers and a specialized PEX crimping tool.

Automatic fitting


 width=

Similar to a compression fitting, the automatic type requires no prior knowledge or specialized equipment to assemble. The seal is formed by a clip activated by turning a nut. Easy to use, but unfortunately the least hardwearing of the PEX fitting options.

Adhesive fittings

PVC wastewater pipe fitting


alt

Wastewater PVC isn't designed to support significant internal pressure; so the water is discharged under gravity. This type of PVC is commonly found in sink and washbasin outflow pipes, showers, baths and toilets.

When constructing an evacuation network, there are various types of PVC fitting at your disposal: elbows, T-joints, sleeves, reducers etc. in a range of diameters. These fittings are assembled with adhesive (specialized PVC glue), ensuring a robust and watertight seal.

PVC pressure fitting


 width=

Unlike wastewater PVC, pressure PVC (as the name suggests) supports a certain level of internal pressure; so it can be used on the supply side.

When constructing a pressure PVC network, there are also several different types of fitting to choose from (elbows, sleeves, Ts, reducers, scew fittings, ball valves, one-way valves, etc.).

These fittings are assembled either with adhesive (in the case of a M/F joint) or screwing where some kind of valve or a union joint is involved.

Explore the ManoMano catalogue
Valve

Properties and uses of plumbing fittings

Type of fitting

Material

Diameter

in mm

Diameter

in inches

Uses

Welded

Copper / brass

10-64

-

Water / heating

Screw

Brass / galvanized steel

8 (13)

12 (17)

15 (21)

20 (27)

26 (34)

1/4

3/8

1/2

3/4

1

Water

Bicone / olive

Brass

8 (13)

12 (17)

15 (21)

20 (27)

26 (34)

1/4

3/8

1/2

3/4

1

Water

PEX

Brass

12 (15/21) to 20 (20/27)

1/2 to 3/4

Water / heating

Compression polyethylene

Brass

12 (15/21) to 20 (20/27)

1/2 to 3/4

Water

Adhesive wastewater PVC

PVC

32 to 500

-

Wastewater evacuation

Adhesive pressure PVC

PVC

16 to 630

-

Water supply network

A typology of plumbing fittings

Shape of fitting

Uses

Sleeve

Connects two pipes in a straight line

Elbow

Alters pipe direction by 27°, 45° or 90°

T-joint

Connects three pipes in a 'T' shape

Reducer

Connects two pipes of different diameters

Bung

Stops the end of a pipe or other component

Culotte

Connects three pipes in a 'Y' shape

Inspection cover

Point of access for inspecting / repairing a network

How to choose your welded sockets?

Types of fitting

Elbow


alt

You can get elbow joints in various angles, but the most common are 27, 45 and 90°. These are flared to allow copper pipes to be inserted and welded in place. For ease of assembly, copper elbow joints are mainly used in renovation and repair work; in new-build settings it's easier and more reliable to bend the copper pipe itself – using annealed copper, it can be wrought into the desired elbow shape with a roll bender. Elbows maintain the same pipe diameter.

T-joint


alt

A T-joint is a fitting in the shape of a 'T' which allows three pipes or other components to be fitted together. This can either connect three elements of the same diameter or incorporate a reduction.

Screw fitting with beaten collar


alt

This type of fitting lets you attach a rigid copper pipe to another element or screw fitting. The term «beaten collar» refers to the end of a rigid pipe onto which the screw fitting is connected – requiring a joint which is located on the flat part created by the collar.

Sizes and uses

Size in mm

Uses

8 x 10

WC supply pipe

10 x 12

Sink, washing machine, dishwasher

12 x 14

Sink, washing machine, dishwasher

14 x 16

Shower

16 x 18

Bath

20 x 22

Water heater

26 x 28

Central heating

30 x 32

Wastewater evacuation

38 x 40

Wastewater evacuation

Explore the ManoMano catalogue
Roll bender

How to choose your screw fittings?

Material: brass or galvanized steel?

Galvanized steel offers an impressive level of resistance to oxidation, superior mechanical resistance to abrasion and better shear-resistance and tensile strength. It's not recommended in close proximity to non-galvanized steel elements or in damp areas due to the galvanic corrosion that can occur. It can be used both in drinking water and heating circuits (≤ 60°C); brass is more malleable and offers high corrosion-resistance in damp settings.

Types of fitting

Elbow


alt

An elbow allows you to change the direction of a pipe by a set angle: 27°, 45° or 90°. Like a sleeve fitting, they can be male, female or male/female and can incorporate a diameter reduction.


alt

Reducer

A reducer is a straight fitting that lets you connect two pipes of differing diameters, male or female: M20/27-F15/21; F12/17-M15/21, etc. The two diameters can only differ by one or two sizes.

Bung


alt

A bung lets you end a pipeline or block off a component. It can be male or female, depending on the component it's attached to.

What's an 'olive' fitting?


alt

A bicone fitting is a copper fitting that doesn't require welding. A seal is formed by turning a nut, which deforms the pipe inside the fitting. The main advantage is its ease of use: it can be installed with a simple flat spanner and doesn't require any specialist knowledge; you just need the right diameter for your pipe and you can go straight ahead.
This type of fitting doesn't require welding, adhesive or teflon (or indeed, oakum) and is specific to rigid copper pipes (not the annealed type). These fittings can only be used once: If you unscrew them again once installed, they lose their seal and you'll have to change the ring – which can be tedious.

Sizes and uses of bicone fittings

Type of fitting

Diameter

Thread & diameter of pipe

Uses

Straight fitting

8/13 – 8mm

12/17 – 8mm

12/17 – 10mm

15/21 – 12mm

15/21 – 14mm

15/21 – 16mm

20/27 – 18mm

20/27 – 22mm

Combi fitting used to connect a screw fitting to a copper pipe

Equal union joint

10mm

12mm

14mm

16mm

18mm

22mm

Lets you connect two copper pipes of the same diameter

Reduction union joint

10 – 12mm

12 – 14mm

14 – 16mm

Lets you connect two pipes of different diameters

T-joint

10mm

12mm

14mm

16mm

18mm

22mm

Lets you connect three elements of the same diameter

Elbow (M/F)

15/21 – 12mm

15/21 – 14mm

15/21 – 16mm

Lets you make a 90° joint between a copper pipe and a threaded fitting

Elbow (F/F)

15/21

15/21

15/21

Lets you make a 90° joint between two threaded elements

What's a PEX fitting?

PEX installations 

As we saw above, PEX is a plastic used to make plumbing circuits, both for water supply and heating, and it can be more or less flexible.

Anyone can work with PEX with no specialist knowledge or particular flair for plumbing. There's no need for welding, and not much equipment is required.

Types of PEX fitting

Sliding fitting


alt

This type is principally used in heating installations, since it's highly reliable in terms of robustness and minimizing leaks. The sliding fitting  does require a little bit of technique to assemble, as well as a few bits of equipment – flaring and crimping pliers.

Push fitting


 width=

Push fittings allow for very thorough assembly of PEX components. The fitting actually deforms under the action of crimping pliers and becomes an integral part of the installation.

Automatic fitting


alt

This is the easiest type to assemble, but also the least reliable! Looks very similar to a compression fitting apart from the fact that the connection is achieved via a special clip mechanism. This is also controlled by a nut.

PEX fitting characteristics

Type of fitting

PEX pipe diameter

in mm

Diameter

in inches

Compression

12

12

16

20

25

3/8 – 12/17

1/2 – 15/21

1/2– 15/21

1/2 – 15/21

3/4 – 20/27

Automatic

12

14

16

-

-

-

Sliding

12

16

25

3/8 – 12/17

3/8 – 12/17

3/4 – 20/27

Push

12

12

16

16

3/8 – 12/17

1/2 – 15/21

3/8 – 12/17

1/2 – 15/21

Explore the ManoMano catalogue
The sliding fitting

What's a polythene compression fitting?


alt

There is an alternative to metallic fittings for assembling HDPE pipes (high-density polyethylene): polyethylene compression fittings.
They work just like other compression fittings, but the seal is obtained by screwing. Generally they're only used in larger diameters (from 16mm up to 90mm). They're often found in water mains supplies for large buildings.

Diameter and uses

Shape of fitting

Diameter in mm

Uses

Straight sleeve

16 - 90

Lets you connect two pipes of the same diameter

Reducer sleeve

20 – 16

25 – 20

32 – 20

32 – 25

40 – 25

40 – 32

50 – 32

50 – 40

63 – 40

63 – 50

90 - 75

Lets you connect two pipes of different diameters

Straight fitting

16 (1/2") to 90 (3")

Lets you connect a pipe and a threaded component

Elbow

16-16 to 90-90

Lets you connect two pipes of the same diameter at a 90° angle

Male elbow

16 (1/2") to 63 (2")

Lets you connect a pipe and a threaded component at a 90° angle

Female elbow

16 (1/2") to 90 (3")

Lets you connect a pipe and a threaded component at a 90° angle

16-16-16 to 90-90-90

Lets you connect three elements of the same diameter

Bouchon

16 - 90

Lets you close off a pipeline

Valve

20 to 40

Lets you stop and start flow in a pipeline

Explore the ManoMano catalogue
Polyethylene compression fittings

What's a PVC fitting?

PVC pipes: wastewater vs pressure


alt

Basic PVC as used in wastewater evacuation is a plastic material which doesn't hold up under pressure. Flow in a PVC wastewater network must therefore occur under gravity. It can be used for any domestic wastewater evacuation (sinks, washbasins, showers, baths, rainwater, etc.). It is recognizable by its light grey colour.

Pressure PVC has to be highly resistant, and is therefore much thicker than the previous type. As a result it can be used for water supply pipes (i.e. necessarily pressurized). It can be use to supply drinking water, water for pumping, etc. It is recognizable by its darker grey colour.

Explore the ManoMano catalogue
Washbasins

Installing PVC wastewater papers


alt

The whole of your household water evacuation network (kitchen, bathroom, etc.), sewage (i.e. toilet outflows) and rainwater piping can be made of PVC - with a few caveats.

The vast majority of this network will be assembled using adhesive fittings as described above. A minimum gradient needs to be incorporated so that evacuation flows smoothly and to prevent solid waste from causing blockages. All the wastewater pipes are combined into a storage tank before leaving your household water system (i.e. a septic tank), or are pumped directly into the public sewer system.

Rainwater can be distributed, captured, stored or evacuated via a network, an underground tank or an above-ground collector.

Diameters and uses

Diameter in mm

Uses

32

Kitchen and bathroom wastewater

40

Kitchen and bathroom wastewater

50

Bathroom, including toilet macerator

80

Combined interior pipe (kitchen + bathroom + appliances) or rainwater

100

Toilet(s), wastewater and / or rainwater

Types of PVC fittings

Fitting

Type

Uses

Sleeve

Straight male-female

Connects PVC pipes of equal diameter

Elbow

15, 27, 45, or 87.5° M/F or F/F

Connects PVC pipes of equal diameter at an angle

T-joint

M/M/F

F/F/F

Connects three PVC pipes of equal diameter (one positioned at 90°)

Culotte

F/F/F (two positioned at 30°)

Connects three PVC pipes of equal diameter (one at 30°) or two of equal diameter and one different

Inspection cover

Usually screw-fit (male element glued)

Allows you to inspect the evacuation network

Ground siphon

Vertical or horizontal outflow

Lets you collect runoff (from garage, utility room, etc.)

Reducer

M/M

M/F

F/F

Connects two pipes of different diameters

Pitting

90° (usually male)

Lets you connect a second pipe partway without cutting.

Learn more about DIY topics...

To find out more about DIY topics, follow our editors' advice and check out their other guides:


How to braze copper pipes?
How to choose your flame welding equipment?
How to choose your flame welder?
How to heat your home?
How to choose your spanners?
How to choose your boiler?
How to choose your toilet?
How to choose your glue, mastic and resin?
How to connect a washing machine or dishwasher?
How to connect your electric water heater?
How to choose your bathroom heater?
How to choose your shower cubicle?
How to choose your pump hose and accessories?
Shower or bath: which is best?
How to choose your freestanding toilet?
How to choose your septic tank?
How to choose your rainwater collector?
How to choose your macerator?
How to choose your spanners and sockets?
How to choose your bathroom sink?
How to choose your bathtub?
How to choose your shower column or set?
How to choose your bath drainage kit?
How to choose your shower drainage kit? How to choose your sink drainage kit?How to choose your plumbing tools?How to choose your locks?How to choose your sink?How to choose your kitchen taps?How to choose your ladders, stepladders and scaffolding?How to choose your hammer?How to connect PVC pressure pipes?How to choose your lawnmower?How to choose your trailer?How to choose your angle grinder?

See our plumbing fittings!

Guide written by:

Jeremy, construction site supervisor, Cardiff, 131 guides

Jeremy, construction site supervisor, Cardiff

Electrician by trade, I first worked in industrial estates where I installed, wired and fixed a large number of electrical installations. After this, I managed a team of electricians for this type of work. 10 years or so ago, I turned to building and construction. From the modest family home, to gyms and theatres; I have been able to coordinate, audit and organise all sorts of construction sites. for 4 years now, I am restaoring and bulding an extrension to a bungalow in the heart of the welsh countyside. My experience in manual work and my knowledge means I am proud to be of service. Terraces, interior design, roofing, plumbing, electricty, anything goes! We have, my wife, daughter and I, built almost everything we have from scratch! So to answer all of your questions, and to orientate and advise you on coosing your tools? Easy!

The products related to this guide