1850.] Encrustation of Steam Boilers in India, 419 



On the Encrustation of Steam Boilers and Pipes in India. — By Dr. 

 Geo. Buist, Bombay. 



A very serious source of annoyance to the Steam Engineer in India 

 is the extreme rapidity with which encrustations collect in the recesses 

 of flues, and around the tubes of steam boilers. These often accu- 

 mulate in parts of the boiler difficult of access, to the thickness of an 

 inch in the course of a year — they intercept heat, diminish the genera- 

 tion of steam, and by permitting the temperature of the iron outside 

 to get high, with a non-conducting substance, rapidly cause oxidation. 

 The crust generally consists of sulphate and carbonate of lime, with a 

 large portion of dried sea salt. The greatest inconvenience is felt 

 with tube boilers. I have known the whole of the tubes burnt out in 

 six months' time, and have seen them, when placed too close to each 

 other, cemented into a solid mass, with the stony matter between. 

 The stony matter consists of sulphate and carbonate of lime, with a 

 very large proportion of sea salt, hardened by the great heat of the 

 flues and tubes when the boiler is emptied too soon after the fires are 

 drawn. 



The remedies proposed for this unfortunate state of things are very 

 numerous ; none of them have, I believe, proved so successful as might 

 have been desired. 1 have suggested the expediency of running off 

 the brine leisurely, and filling up the boiler either with sea water not 

 concentrated by boiling, or with fresh water, where this was accessible, 

 so as by these means to get rid of the soluble part of the crust, when 

 the earthy portion, deprived of this, would become so friable and 

 spongy as to drop off. 



Dr. Giraud has suggested hanging portions of broken crust in bags 

 inside the boiler, in hopes of affording a nucleus of depositure prefer- 

 able to that provided by the tubes or the boilers themselves. 



The Engineers get quit of the crust when it is thin by running off 

 the boilers, and allowing the encrustation to become perfectly dry. 

 When cold, a sudden blaze of chips is lighted in the furnace, by which 

 means the crustings inside crack and drop off. When they grow thick 

 and troublesome, workmen are sent inside the boiler to chop them off. 



