PVC Pipe and Fittings FAQ:

These three terms are, as far as rigid pipe is concerned, interchangeable. The "U" stands for "unplasticized", which in layman's terms means rigid. For example, a flexible hose or tarpaulin would have plasticisers added to the PVC compound to make it flexible. Rigid pipe doesn't need these, hence the terms UPVC and PVCU. Over time, however, users have got used to referring to this type of pipe as just PVC. As long as it's rigid and not floppy, uPVC, PVCu and PVC all mean the same thing.

Most of the world uses one or the other, but in the UK we like to be different and have ended up using both! For new systems, we would recommend using metric as there is a larger range of fittings and sizes available. It also tends to be cheaper than inch.

Both our inch and metric PVC pipe systems conform to all relevant standards and specifications.

Yes. Nearly all pipe and fittings in both our grey PVC systems are WRAS approved. This is mentioned in the product description.

There are some more specialist items such as flowmeters and diaphragm valves that are not WRAS approved, but this doesn't mean they are of lower quality, just that the complexity and high costs of the approval process is not warranted for the numbers manufactured/sold.

The term "food safe" is a very ambiguous one as there are all sorts of chemicals that are present in foods that could react with any pipe material. The WRAS approval (above) demonstrates that it is safe for drinking water, but for highly concentrated, oily or aggressive ingredients we suggest you refer to our chemical resistance table.

Yes, it is; however, we recommend that you allow 24 hours for the cement to cure fully and that all pipe and fittings are flushed out with non-aquarium water before being put into use. Note that when allowing to cure, you should ensure the ends of the pipe system are open for airflow.

This can be tricky for the first-time or amateur installer. We suggest looking online for similar systems to the one you are building or call us for advice if you are still unsure. If a pipe is too small, it can restrict flow and increase pumping costs. If it is too large, you are spending more than you need and also running the risk of solids build-up due to low velocity in the pipe. To check your pipe size, use our simple Headloss Calculator.

PVC pipe systems are used for a myriad of different applications, including industrial process lines, swimming pools and spas, agriculture, irrigation, and biogas processes, to name a few. If you are unsure of the suitability for your process, please refer to the table below or contact us for advice.

Compressors - PVC pressure pipe should NEVER be used with compressors. This is because if there is a break in the pipe, it can shatter, causing shards to fly out. ABS pipe is a much safer option as it splits rather than shatters.

Blowers - PVC pipe can be used with low-pressure blowers at pressures under 0.5bar.

Inch pipe sizing is based on a system originally designed for metal pipes in the 1800s. The stated size relates to the "approximate" or "nominal" bore of the pipe. For example, a 2" pipe has an approximate bore of 2", which gives it an outside diameter of 60.3mm. So, confusingly, neither the inside nor the outside measures exactly 2"!

The outside diameter of metric pipe is the stated dimension. For example, 63mm metric pipe measures 63mm outside diameter.

Our inch (imperial) PVC pressure pipe is generally supplied in 5m lengths or divisions of that length (2.5m, 1m) with plain ends. Some more specialist sizes are supplied in 3m or 6m lengths. The table below shows the different wall thicknesses and internal bores.

Our metric PVC pressure pipe is generally supplied in 5m lengths or divisions of that length (2.5m, 1m) with plain ends. Some more specialist sizes are supplied in 3m or 6m lengths. The table below shows the different wall thicknesses and internal bores.

The pressure rating of PVC pipe reduces with increasing temperature. Multiply the pressure rating of the PVC pipe by the ′De-Rating Multiple′ to get the actual pressure rating at that operating temperature. For example, a 9 bar pipe operating at 30°C will be 9 x 0.8 = 7.2bar.

These spacings between pipe clips are given on the assumption that the PVC pipe is carrying water at 20°C and 40°C. For lighter loads, the spacing could be extended, and for heavier loads, the pipe clips could be positioned closer together. Be sure to provide additional support either side of elbows, bends and in sections of PVC pipe with heavy items such as valves, flange sets etc. At 60°C, continuous support is necessary.

Ratings are given in terms of the suitability of PVCU pipe to carry a specific chemical. For some chemicals no reliable data is available and so no data is given.

Please note the following:

• The effect of any chemical on PVC pipe systems may be dependent on factors such as temperature, pressure, concentrations and abrasiveness. Materials should be tested under actual conditions to determine the suitability for a specific application.
• This information has been supplied to Plastic Pipe Shop Ltd by its suppliers and from other reputable sources. The information should only be used as a guide.
• The ratings for each chemical are based on a period of 48-hour exposure of the PVC pipe.
• Plastic Pipe Shop Ltd does not guarantee (neither express or implied) that this information is accurate or complete. Further Plastic Pipe Shop Ltd does not by way of this information make any recommendation that any material is suitable for any purpose.

Plastic pipe is much more prone to expansion and contraction with changes in temperature than metal pipes such as copper and steel.

In situations where there are long pipe lengths being installed, it is necessary to ensure that precautions are made to allow for contraction and expansion. A failure to consider this can result in the PVC pipe becoming stressed as it tries to expand or contract, but the installation will not allow it. By clipping the pipe hard, you will not stop the expansion or contraction, you will merely direct the forces of it to a different section of the pipe which can sometimes result in breakage of the pipe.

By following the points below, you can avoid issues with contraction and expansion on PVC pipe lengths of over 5m:

• Use pipe clips that allow the pipe to slide through (not rubber lined types)
• Ensure both ends of the pipe are not bolted hard to a wall or other stop point. The pipe needs somewhere to expand to
• If your pipe is going to be exposed to extreme temperatures and sometimes lie empty or static, think about insulating your pipe
• Be conscious of whether you are fitting your pipe in an unheated building during winter, or if the building is going to be warm or hot when completed, such as in some aquaculture and horticulture situations

The coefficient of linear expansion of PVC pipe is 7.8 x 10-5m/m.°C. This is nearly twice that of copper and three times that of mild steel. Using this value, a 20m length of pipe will expand 4mm with a 25°C rise. This may not sound a lot, but if the pipe is clipped hard at either end the expansion power has to go somewhere!

The calculation for this can be found at The Engineering Toolbox.