8 February 1999

ARTICLE FOR ASI JOURNAL: FEBRUARY 1999 ISSUE

Familiar they may be, but the British Standards covering plastic underground drainage, soil and waste, and rainwater products are on their way out. A new wave of Euro Norms (ENs) is heading this way. Frank Jones, Director of the British Plastics Federation (BPF) Pipes Group, introduces ASI Journal readers to these friendly invaders.

Specifiers of plastic drainage, rainwater and soil and waste pipes and other associated products do not need to be convinced of the material’s benefits – it is easy-to-handle, simple to install, durable and cost-effective. This explains why plastic has taken the plumbing and drainage markets by storm over the last 20 years, coming to dominate the market. In the UK, PVC now accounts for around 90% of the rainwater market and 50% of the underground drainage market (75% of the 110mm pipe market). It seems that the practical and competitive UK building industry puts cost and performance first and this is where PVC wins hands down.

Those same specifiers and installers are also familiar with the British Standards governing the myriad products in these categories. But a whole raft of new European standards will be phased in over the next few years to replace them. And so it is vital that architects and surveyors know how these standards work if they are to receive the same high quality plastic products that they have come to expect, and comply with British Standard Codes of Practice.

The new Euro Norm - BS EN 1401-1: 1998 - covering PVC underground drainage pipes and fittings in sizes from 110mm to 1000mm is already in effect. It was introduced in the summer of 1998 and is being phased in by the manufacturers, stockists and users of the products over the next eight months. Anybody unsure of how it affects them can contact the BPF Pipes Group. We have prepared a number of informative and straightforward guides to the changes that the new EN is bringing about.

ENs covering soil and waste will be introduced in the spring, with rainwater products following down the European path early in the millennium. Once again, there will be no major or fundamental difference to the dimensions or performance of products complying with the new ENs. For example British Standard Code of Practice elements such as swept entry fittings, bosses, large radius bends and inch-based dimensions have also been kept, sitting happily with metric measurements.

The basic message for underground drainage is that the new BS EN 1401-1 1998 actually means relatively little change. It replaces parts of the existing British Standards BS 4660 and all of British Standard BS 5481. Pipes and fittings manufactured to the new standard will be completely interchangeable with old products in terms of dimension.

One possible area of confusion is that different grades or stiffnesses of pipes and fittings all technically comply with the new standard. Stiffness Class 4 products are exactly equivalent to British Standard BS 4660 for 110mm and 160mm pipes, and BS 5481 for 200mm, 250mm, 315mm, and 400mm. But BS EN 1401 does allow the use of a thinner grade of pipe, with reduced stiffness

(Stiffness Class 2) in pipes with diameters of 160mm and above than was permitted under the previous British Standards. But the areas that these can be used in are limited and the BPF Pipes Group strongly recommends the specification of Stiffness Class 4 products in all installations.

The reason that applications for Stiffness Class 2 products are limited is that, for the first time ever, the new EN stipulates the specific application areas where certain pipes can and cannot be used. It states that Stiffness Class 4 or Stiffness Class 8 pipes and fittings must be used if an installation is to comply with BS Codes of Practice and resist long-term deformation. The BPF Pipes Group strongly recommends that specifiers continue to specify Stiffness Class 4, since Stiffness Class 2 pipes will need to be subjected to complex structural design load calculations before installation. They could also cause costly delays and problems on site because they require much more preparation and bedding to give the same performance, even though they do technically comply with BS EN 1401-1.

The two separate application areas and the type of pipes and fittings that can be used in each:

U: application area code for areas more than one metre away from the building to which the buried pipe system is connected

D: application area code for the area underneath and within one metre from the building where pipes and fittings are underground and connected to the soil and waste discharge system.

All pipes and fittings manufactured to BS EN 1401 will be marked with these codes. Since Stiffness Class 4 or 8 pipes are suitable in both cases, they will be marked ‘UD’. The new European standard states that Stiffness Class 2 (SN2) pipes are totally unsuitable in areas where hot water discharge

occurs (area D applications) and strongly recommends the use of Stiffness Class 4 or 8 pipes in these applications.

Specifiers of PVC underground drainage systems can start using the new EN with immediate effect, retaining reference to the existing standards until the changeover is completed in October 1999. The new standard refers to all PVC underground pipes and most fitting from 110mm to 1000mm. Access fittings and gullies will continue to be covered by a revised
BS 4660.

The BPF Pipes Group is made up of the UK’s leading PVC pipe and fitting manufacturers and covers rainwater, soil and waste, and underground drainage products. The group was set up to promote plastic and educate the building and construction industries about the benefits of using plastic pipes. It is issuing a series of technical bulletins outlining the changes that the new standards will bring about and what specifiers and contractor need to know about them.

For further information please complete our contact form.

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