Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 144,977 pages of information and 230,624 images on early companies, their products and the people who designed and built them.
Clydach Ironworks, near Abergavenny, Monmouthshire
Established in the 1790s with coke-fired blast furnaces
1793 & 97 Two square blast furnaces were constructed
1820 Advert: 'To Smiths, Dealers in Iron, &c.
Edward Frere and Co. of the Clydach Iron Works, respectfully inform the Public that they have established a Depot for the sale of IRON of every description, in the City of Oxford, and have appointed Mr. EDWARDS, the firm of BROWN and HOWARDS, their sole Agent for the City and Vicinity of Oxford ; who has been in the constant habit of vending, as well using it in large quantities for the last Eighteen Years.
N.B. A trial will prove its superior quality.
Premises wanted for an Iron Warehouse, near the bottom of the High-street.'
1826 A third circular furnace was constructed
1830 Frere and Co operated 3 blast furnaces.
1833 Partnership dissolved: Edward Frere and John Powell, ironmasters, Clydach Iron Works, Breconshire, 17th Jan. 1832 — Debts J. Powell 
By 1841 the works employed over 1,350 men
1842 A fourth furnace was constructed.
1869 Joshua Llewelyn Morgan became manager of the works
1877 production ceased.
In 1986 the site was excavated and partially restored but it was subsequently abandoned. The exposed remains include three furnaces and one charging house, together with the pit for a 12.8m (42ft) diameter cast-iron water-wheel. The air blast for the original furnaces 1 and 2 was provided by the waterwheel; air for furnaces 3 and 4 being provided by a steam engine. 
The site is accessed by Smart's Bridge, spanning the Clydach River, which is a cast-iron structure of lancet tracery dated 1824.