When considering weld repairs within the chemical industry it is important to remember the rapid changes in engineering steels recently. Where AISI 316 stainless steel was undoubtedly a major barrier against corrosion as little as 20 years ago, it would be safe to say it has been surpassed by the superalloys such as Inconel, Hastalloy and Nimonics in recent times. Similarly the days of carbon steels has been updated by the use of modern day materials such as carbon manganese steels and low alloy steels such as 1% Cr/Mo and 2% Cr/Mo.With this in mind it is important we do not fall into the trap of assumption. Always ascertain which materials are to be welded before making a final decision.