Seen and unseen - Utilities

13 March 2024

The aim of the Seen and unseen exhibition is to show objects that are we perhaps don’t see even though they might be right in front of us, we don’t notice them or pay them much attention.  It also has objects that are literally part of the hidden infrastructure that we don’t see because it is under the ground or buried in walls.  The case I am highlighting in this blog post is entitled Utilities and is a theme which exposes some of the hidden objects linked to our homes and some which are used as part of our everyday life.

For the purposes of this blog post I am going to concentrate on two of the objects on display - a section of blue pipe and a section of yellow pipe.

A close up at the cut end of a blue water pipe.

MDPE water pipe, AIBDC : 009716


Utilities, such as water, gas, electricity, sewerage, and telecommunications, come into and out of our homes through pipes like these.  These particular pipes are made of medium density polyethylene (MDPE) but pipes have traditionally been made of a number of different materials from wood from elm trees, terracotta, cast iron, copper, and lead.

The first HDPE drainage pipes were introduced to the UK in the 1950s. The 1970s saw rapid growth in the use of PE by both the water and gas industries. Improved grades of PE with different densities were introduced in the 1980s along with the blue coloured pipe for UK water supply.  In the same decade twin-walled pipe, like the yellow gas pipe on display, were launched and offered a good performance with less material and, therefore, less weight.

A close up at the cut end of a yellow gas pipe.

MDPE gas pipe, AIBDC : 009715


MDPE pipes can suffer from deterioration caused by UV light they are generally used underground.  The flexible pipe created can be used in challenging locations, it can flex with ground movements which means that will not crack and cause leakages.  It is resistant to chemical damage and can withstand a range of temperatures and pressures.  Because plastics can be integrally coloured rather than needing a surface treatment, the pipes can offer colour coding which will not be accidently removed.  The blue pipe, on display, is used to denote incoming water and the yellow pipe is for service and mains gas. Other colours include black - domestic mains electric cable, low voltage; red - high voltage electric cables; green - broadband, telephone, and non-motorway CCTV cables; grey - BT or telecommunications cables; purple - motorway service cables for speed cameras, traffic cameras, emergency phones etc; and orange - street lighting and traffic signalling cables.

Louise Dennis, Curator of MoDiP