Report - Kennington Oval Gas Holder, London, October 2013

[GAJ]

Gasometers, you may love them or hate them, but there is absolutely no denying these things are iconic urban structures that we have all become used to seeing in towns and cities across the UK and beyond. They're big, dirty, sometimes imposing structures that have been around since the 1800s and were still being built right up to the 1980s. So, lets have a bit of a history lesson..

A gas holder (commonly known as a gasometer, sometimes also gas bell, though that term applies to the gas holding envelope alone) is a large container in which natural gas or town gas is stored near atmospheric pressure at ambient temperatures. The volume of the container follows the quantity of stored gas, with pressure coming from the weight of a movable cap. Typical volumes for large gasholders are about 50,000 cubic metres, with 60 metre diameter structures. Gasholders tend to be used nowadays for balancing purposes (making sure gas pipes can be operated within a safe range of pressures) rather than for actually storing gas for later use.

Origin of the name "gasometer"

The term gasometer was originally coined by William Murdoch, the inventor of gas lighting, in the early 19th century. Despite the objections of his associates that his so-called "gazometer" was not a meter but a container, the name was retained and came into general use. The word is also used to describe a gas meter (a meter for measuring the amount of gas flowing through a particular pipe). The term "gasometer" is discouraged for use in technical circles, where the term "gasholder" is preferred.

Gas holder types

Gas holder schematic

There are two basic types of gasholder, rigid waterless and telescoping. Rigid waterless gas holders were a very early design which showed no sign of expansion or contraction. There are modern versions of the waterless gas holder, e.g. oil-sealed, grease-sealed and "dry seal" (membrane) types.

Telescoping holders fall into two subcategories. The earlier of the telescoping variety were column guided variations and were built in Victorian times. To guide the telescoping walls, or "lifts", they have an external fixed frame, visible at a fixed height at all times. Spiral guided gasholders were built in the UK up until 1983. These have no frame and each lift is guided by the one below, rotating as it goes up as dictated by helical runners.

Both telescoping types use the manometric property of water to provide a seal. The whole tank floats in a circular or annular water reservoir, held up by the roughly constant pressure of a varying volume of gas, the pressure determined by the weight of the structure, and the water providing the seal for the gas within the moving walls. Besides storing the gas, the tank's design serves to establish the pressure of the gas system. With telescoping (multiple lift) tanks, the innermost tank has a ~1 ft wide by 2 ft high lip around the outside of the bottom edge, called a cup, which picks up water as it rises above the reservoir water level. This immediately engages a downward lip on the inner rim of the next outer lift, called a grip, and as this grip sinks into the cup, it preserves the water seal as the inner tank continues to rise until the grip grounds on the cup, whereupon further injection of gas will start to raise that lift as well. Holders were built with as many as four lifts

Gasometers, a British invention, first appeared 180 years ago and quickly caught on as an effective means of storing large amounts of gas at low pressure.

The most recent gasometers, built 16 years ago, abide by the same, basic mechanics - as gas is fed in from a pipeline it pushes up each of the individual storage chambers one-by-one, to accommodate the exact amount. The more gas, the bigger the holder - hence the name.

The rim of each chamber is sealed by water and with no room for air inside, the holder prevents gas from igniting.

Gas historian Brian Sturt says in their pre-War, pre-nationalisation heyday, gasometers were everywhere.

"There were over 1,000 gas companies before nationalisation. Just about every town had its own gas works and the gasometer was the central focus," says Mr Sturt.

Natural gas was still a thing of the future, and instead households and industry relied on town gas, which resulted from carbonising coal.

While holders were never conventionally beautiful, in the early days at least, they exhibited a fair degree of decoration.

"They were cast iron at the start but steel sections came later, in the 1880s. The ones still standing at St Pancras and Bromley-by-Bow in London carry a Grecian-type finish," he says.

"The style was dropped because it required a lot of maintenance."

Unfortunately, since 1999 there has been a structured plan to dismantle many of the gas holders around the country to save the money being spent on maintaining them in a safe condition.

Advances in pipepline technology and smoothing out demand mean there is no longer any need for the massive storage cylinders.

Their passing is unlikely to provoke howls of protest - most urban dwellers will be glad to see the back of these graceless, imposing structures. Think of gasometers and you can't help but conjure up images of grey skies and drizzle.

It's no secret that I've had a bit of a fascination with these things since childhood and have made several attempts to actually sit on the top of a piston as it slowly rises. This is something I have yet to manage, and the chances are I never will. In the meantime, however, I have been climbing as many of them as I possibly can, some on live gas sites and others that are completely disused with the gas holders ready for dismantling. Whilst some people may view these as big derps, I can assure you that quite a few of these things are secured as well as any site you can think of.

Which brings us nicely to this gas holder.

The gas holder at Oval is probably the most famous one in the UK, and due to it's position next to one of our premier cricket grounds, it is likely millions of people have seen it at one point or another.

In addition to this, it is on a live gas site so the owners really don't want you pissing about anywhere near it, and certainly not on it, for obvious reasons and the security in place reflects this. When I first had a go at this place a couple of years ago, I had to GTFO very very quickly as I had tripped one of the many motion sensors around the site and there was a response within 10 mins. I tried a second time a few months later, and pretty much did the same thing all over again. Clearly this wasn't going to be an easy one..

Fast forward 2 years and I'm having a discussion with fellow gasophile Keïteï about gas holders we want to hit and, unsurprisingly, this is one of them. Ironically, Keïteï had suffered pretty much the same fate as me attempting this place a while back, even using the exact same access route so we really did have a problem to solve. And so it was, we decided on a day to really have a proper crack at this place and I brought everything I could possibly think of to get us in. We warmed up like true urban athletes by walking through a sewer, complete with a very public exit, then headed over to Kennington to work this thing out.

The first thing we worked out was that if caught we would both use our phone call to ring work and inform them we were so ill we couldn't make it in The next thing we worked out, was that our original access was a little bit impossible so we had to try something else. After totalling my hoody, we were in and it became obvious this thing was ridiculously well secured so our journey to the top still wasn't easy. But make it to the top we did, and it was one of the nicest gas holders I've been on top of as it actually had a view worth looking at. Just a shame we didn't have someone on hand in the ground to flick the lights on for us as it was a bit dark. Still, you can just about make it out in the shots.

It was a long journey to get here, but it was definitely worth it.

Big thanks to Keïteï for being on this gas adventure too, and also for the bourbon creams back at the car Let's go hit some more