The big shutdown

May 6 2008 Evening Gazette

TEES CHEMICAL firm SABIC shuts down production on the 223-acre site tomorrow as it launches a year of major investment beginning with a multi-million pound overhaul of the Olefins 6 cracker at Wilton.

A major piece of engineering, which will see an additional 1,500 staff brought on site, the £35m project will be followed over the next 12 months with a similar scale investment in plant to boost production of key products, ethylene and propylene.

A significant public relations campaign to make both domestic and industrial neighbours aware of the importance of the programme to the Teesside process industry, which will involve a noticeable amount of flaring as the plant is taken off line on Wednesday, is under way.

Several dozen North-east companies will be involved in the six-week project, which marks the end of the longest period of uninterrupted production at the £200m plant since it was commissioned 29 years ago. The usual period between overhauls is five years. This will be the first shutdown since 2002 and was two years in planning.

Other elements of the awareness programme include putting information in local community calendars and working with pupils at Wilton Primary School in Lazenby - situated next to the Wilton Site - on the design of safety posters to encourage safe working by contractors.

The Olefins cracker complex at Wilton is, in effect, three plants in one. It uses feedstocks ranging from a light fraction of crude oil called naphtha to natural gas liquids, such as propane and butane, which are heated in an industrial sized pressure cooker to achieve “cracking”. At that point big molecules are broken apart into highly valuable products, such as ethylene and propylene. After heating, the gases are chilled to temperatures as low as -170 degrees C to separate the molecules.

Stripping down the plant involves inspecting and cleaning millions of components. The two landmark distillation towers alone involve more than one million parts between them.

While the majority of the site produces ethylene and propylene, the butadiene plant manufactures rubber products and there is also a gasoline treatment unit.

Chemicals produced at the site are used to make everything from toothbrushes and toiletries to car parts and packaging.

The complex was completed in 1979 at a cost of £200m and operates 24 hours a day, year-round.

Flaring - a sign that the maintenance project is under way - is normally avoided because it involves burning off valuable gases.

It is an essential part of the cracker safety system. When pressure builds up a valve releases gases to the flare stacks where steam is injected to make the flare burn cleanly and reduce pollution to the atmosphere. It is the act of injecting the steam at high rates that causes the most noise.