Plastics piping Systems in Polyethylene (PE) for the supply of gaseous fuels


5a

In the 60s of XX century, plastic pipes had begun to be introduced in some areas of Catalonia and Andalusia using rigid PVC pipes. At that time natural gas was still not and gas distributed (“city” gas or “manufactured”) it was locally manufactured from petroleum and in some cases still from coal.

On the other hand, in America and some European countries, there was already some experience in the use of polyethylene. Its success United States was due, in great part, to the existence of manufacturers capable of supplying complete systems (pipes and fittings) covering the needs of gas industry.

In Europe, the center European countries were inclined to the use of high density PE (HDPE) while in the UK, were they started using the American system, it was preferred to develop a resin which combined the long-term mechanic strength with the slow crack resistance, thus giving rise to medium density PE (MDPE). Subsequently it was called “second generation”, compared with the HDPE, which was the “first generation”.  In Spain, probably because at that time there was a very strong UK influence in some gas Companies, the British model was followed.

5c

One of the reasons which motivated to take PE in consideration as the pipe and fittings new material was the need to reduce cost without reducing pipeline safety.

Although at first, the cost of PE pipe was relatively high and did not allow cost savings, it allowed itself to provide laying cost reduction due to advantages such as:

–       Reduction of trench dimensions

–       Tightness

–       Flexibility

It also had advantages from maintenance point of view, by removing problems caused by metal materials corrosion.

From the first quarter in 1980 PE was starting to be used systematically for natural gas distribution in Spain. “Networks Policy and gaseous fuels rush” in 1974 already considered it one of the possible use materials up to 4 bar Maximum Operation Pressure (MOP).

It can be said that in the 1990s, already 98% of the new network being installed for pressure distribution was 4bar PE80 pipe.

In 1988 the resins third generation appeared in the market, which later was named and classified by the corresponding Norm ISO 4437 as PE100. This material advantage versus PE80 is basically MRS providing greater and greater resistance to both slow and fast fracture propagation. Therefore, this material allows the use PE pipes for gas distribution at pressures higher than 4 bar.

The first country to use this material for gas distribution at pressures above 4 bar was Belgium (5 bar since 1988) followed by UK (7 bar since 1989). Then followed by other countries such as Germany (with some installation designed 10 bar) and also France (8 bar since 1990). During year 1995 was done in Spain, the first experience with PE 100 pipe free of cadmium and in the early 2001 was regularly.

In Spain has now been adopted the PE 100 as material for networks distribution at pressures up to 4 bar in diameters 20, 32 and 40 in SDR 11 and in diameters from 63 to 315mm, with thicknesses corresponding to SDR 17.6 and yellow-orange colour.

Likewise, PE 100 pipes are used in black colour with yellow-orange bands in the series SDR 11 for distribution to a maximum operating pressure (MOP) including up to 10 bar, although some countries keep the 8 bar.

The Norm UNE-EN 1555-2010 for the first time includes co-extruded, multi-layer, peel -able pipe with PP outer layer or with one or more layers, and when the layer is interior, the yellow-orange bands can be external. In some of these types, the interior or intermediate layers are also manufactured with Natural PE 100. The peelable pipes are usually manufactured with PP outer layer.

In NO-DIG (no trenching) installations the material can be PE 100 RC (Cracking resistance).

In any case, it will be either the distributor Company or the responsible for gas distribution network which ultimately will approve or not the installation of these type of pipes in their network.

5d

a) Withdrawn Norms History

UNE 53333:1977 EX            

Plastics. Medium and high density polyethylene pipes for underground networks in the gaseous fuels distribution.  Features and test methods.

 UNE 53333:1980            

Plastics. Medium and high density polyethylene pipes for underground networks in the gaseous fuels distribution. Features and test methods.

UNE 53333:1990  

Plastics. Medium and high density polyethylene pipes for buried pipelines in the gaseous fuels distribution. Features and test methods.

 UNE 53333/1M:2000   

Plastics. Medium and high density polyethylene pipes for buried pipelines in the gaseous fuels distribution. Features and test methods.

 UNE-EN 1555:2003

Plastic material pipeline systems for gaseous fuels supplying. Polyethylene (PE).

 b) CURRENT NORMS:

UNE-EN 1555:2011

Plastic material pipeline systems for gaseous fuels sypplying. Polyethylene (PE). Parts 1 to 5.

 UNE-CEN/TS 1555-7:2004

Plastic material pipeline systems for gaseous fuels supplying. Polyethylene (PE). Part 7: Guidelines for Conformity Assessment

SEDIGAS, the Spanish Gas Association, is a non-profit organisation established in 1970 on the initiative of Spain’s piped gas companies, and groups together all corporations, bodies and individuals committed to the development of the piped gas industry.

REFERENCES:

This post is based on the article published by Jordi Canet and Juan Miguel Solis from the Technology and Environment of Natural Gas SDG, S.A. within the “Quality Brand Information Campaign from AENOR for Plastic Products” which took place between October 2002 and April 2003 where I had the honor to be a coordinator.

>>> Do you want to say anything else about the PE pipes for gas pipelines?

1 Comments

April Cook
Reply 19 July, 2016

It never crossed my mind that the gas industry would be limited by the pipe systems that were available to transport the gas. I can see how flexibility would be an important trait for a pipe to have. It would be dangerous to have gas flowing through pipes that would break instead of adjusting to their surroundings. Thanks for sharing this information!

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