Intercrystalline Cracking in Boiler Steel

Abstract

In 1934, Powell (1) estimated the cost of repairs and replacement on boilers damaged by intercrystalline cracking or embrittlement during the preceding four years at approximately 200,000 dollars per year. In spite of this outlay no extensive experimental work was in progress on this specific problem, although a related investigation concerning the solubility of sodium sulphate in boiler water salines was under way at the Bureau of Mines. This situation existed because many operators believed a satisfactory solution to the difficulty was available if conditions believed to be correct were maintained in boilers. These conditions which had been accepted as correct involved principally the maintenance in the boiler water of such concentrations of sodium sulphate and alkalinity that the ratios suggested by the A.S.M.E. for the prevention of embrittlement were satisfied. These ratios it will be recalled were based upon data gathered from boilers throughout the country and were later supported by the important pioneer work of Parr and Straub. On the other hand many competent engineers believed that the use of sodium sulphate for protection was based on contradictory operating data. The solubility studies at the Bureau of Mines under the auspices of the Joint Research Committee on Boiler Feedwater Studies attempted to establish an accurate basis for the use of sodium sulphate