BRAKEGLEN LIMITED   REFRACTORY CONSULTANTS   THE CAUSES OF REFRACTORY FAILURE   Poor workmanship. Sub-standard materials. Wrong material selection. Incorrect dry out & cure. Faulty installation. Suspect specifications. Maloperation. Poor design.   In the event of refractory failure, or when faced with an unacceptable level of maintenance, there are several factors to consider. Experience has shown some causes of failure and short service life to be considerably more prevalent than others; Sub-standard Materials: The incidence of problems arising from poorly made materials is relatively rare. Most refractory manufacturers now hold quality assurance certification which has lessened what has always been a relatively low area of concern. Refractory manufacturers have for the most part always made good refractories. There has, of course, been the odd classic exception.   Poor workmanship: While the availability of skilled and experienced tradesmen is something of a problem in the industry, the incidence of failure due to poor workmanship is lower than many would suspect. The incidence should approach zero if the designer takes into account the quality and class of labour locally available before deciding on the type of materials and construction technique. Incorrect dry-out & cure: There have been problems on this front but again the incidence of failure is relatively rare. Some materials are more critical than others and a select few are super-critical with regard to dry-out and cure. For the most part, refractory manufacturer’s heat-up schedules are conservative with a certain amount of in-built leeway. Maloperation: Relatively rare and becoming rarer. Improved instrumentation adopted in recent years in the drive to improve operational efficiency has also improved overall safety and reduced the incidence of furnaces "running wild". The biggest problem in this general area are furnaces which have been upgraded to operate beyond their original design capacity. Refractory linings are rarely upgaded to meet the increased duty. Suspect specifications: These occasionally lead to catastrophic failure but more often give rise to excessive maintenance cost and lengthy downtime. Some classes of furnace continue to be built with refractory specifications which are 30 years old. The incidence of this is fairly high in some industries where certain classes of vessel are just accepted as “high maintenance cost designs”. This, of course, need not be so. Wrong material selection: Here the incidence of failure increases due to using the wrong material in the first place. It can vary from a fundamental error of choosing the wrong class of material to selecting the wrong grade within a correct class of material. Poor design: Here we have the most common cause of failure. Mention was made earlier to the shortage of skilled and experienced tradesmen to install refractory linings. The shortage also extends to knowledgeable, experienced and qualified designers. Refractory design is too frequently left to a draughtsman whose expertise and experience on the subject is limited. Needless to say that design weaknesses are a fundamental flaw which cannot be negated by the use of either superb materials or excellent workmanship.