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Ardeer, Ici Works, Pentaerythrite Tetranite (Petn) Plant

Explosives Factory (19-20th Century)

Site Name Ardeer, Ici Works, Pentaerythrite Tetranite (Petn) Plant

Classification Explosives Factory (19-20th Century)

Alternative Name(s) Nobel's Explosives Factory

Canmore ID 89473

Site Number NS24SE 47.10

NGR NS 28894 40903

Datum OSGB36 - NGR


Ordnance Survey licence number 100057073. All rights reserved.
© Copyright and database right 2017.

Digital Images

Administrative Areas

  • Council North Ayrshire
  • Parish Stevenston
  • Former Region Strathclyde
  • Former District Cunninghame
  • Former County Ayrshire

Archaeology Notes

NS24SE 47.11 28894 40903

General Details of Plant

1. Most of plant made of stainless steel

2. Process involves nitrating Pentaerythrite (imported from Sweden) in Nitrators by adding 98% strength Nitric Acid, and passing the resulting PETN down to a Nitration Filter, via a Diverter, which can divert the mixture to a drowning tank if there is any problem. The process of nitration is exo-thermic, producing heat. The greatest danger is that the heat from the reaction will accumulate, causing a fire or explosion. The Nitrator is therefore cooled by brine circulating at -10'C. The reaction takes about 30 minutes.

At this stage, the PETN is acid wet, and a water wash, followed by a sodium carbonate and then another water wash ensues. The residual acids are removed by dissolving the PETN in Acetone, after which the acetone is recovered and recycled, and the PETN re-crystalised in Granulators, before being fed down to the Product Filter, and on to the Distributor, from which it is packed into blue plastic barrels (if dry), or into sealed fibre-board drums (if wet) for export.

3. The PETN Plant Main Building is TA12, and comprises a 13-year old complex protected on the rear side by turfed earth mounds, and at the front by 18' thick Chilworth Mounds, clad with crimped steel (as opposed to corrugated iron). Separate baffles (also clad with crimped steel) protect the entrances to the plant, the interior building being entirely steel-framed. Ancillary buildings immediately outside the front of the Main Building are steel-framed and crimped-steel-clad rectangular and windowless, and house the control room, compresed air and hydraulic plant. Nearby are associated acid storage tanks, and an effluent treatment plant.

4. When first opened, this was the first computerised explosives plant in the world.

5. Gary Hemingway and Jim Moffat estimate that the plant produced about 3000 tons of PETN in its 13 years of production. The plant closed down in June 1995, and is currently mothballed. Production has been transferred to ICI plants overseas.

6. PETN stands for Pentaerythrite Tetranite, an explosive widely used in "Initiating Systems" (ie detonators). Other uses include primers for explosives, and the core of "Cordtex" and "Superflex" fuses, which are made in neighbouring buildings at Ardeer.

7. The neighbouring buildings associated with PETN include drying stoves (TS5) and detonator cord spinning (in TL6).

8. PETN manufacture was originally an entirely manual process, and many buildings associated with this era survive (although their demolition is likely in the near future). The manual process was replaced by a Biazzi system, and then the new computerised plant in c.1980.

Visited by RCAHMS (MKO) August 1995.


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