THECUB A REVIEW 31 



HOW TO BUY PIPE COVERING 



By D. J. Lewis, Jr., M. E., New York 

 [Special Contribution to The Cuba Review] 



The question of buying insulating material for high pressure hot surfaces is one 

 requiring considerable attention, especially in these days of high pressure steam. 



During the last 20 years the writer in course of his practice of conserving steam 

 waste in manufacturing plants has made a vast number of condensation tests, and in 

 addition to measuring the condensation has made note of the material and condition of 

 the insulation, which has been good, bad and indifferent, mostly the latter, the method 

 of installation and its condition, paying special attention to the time it has been in use. 



We have been much surprised at the indifference shown to the actual results given 

 by the different coverings by the managers and engineers of the many plants examined. 

 The kind and method of insulation depends mostly on the price and the ability of the 

 covering salesman to convince the purchaser that he has the best covering. No results 

 are as a rule asked for or required. The specifications generally call for some make 

 or its equal. On sugar plantations tnany managers think because the run is a short one 

 and fuel is cheap that the pipe covering question does not interest them, and in numbers 

 of plants we find bare pipes carrying steam up to 125 lbs. Now, even if the question of 

 fuel did not cut any figure the quality of steam does in the manufactured product. 

 Where the pipe is uncovered the steam becomes saturated and carries along with it 

 a lot of water which really acts as a cooling medium instead of one for heating. 



For example, to show the amount of heat lost, we find that from a bare 4-inch pipe 

 line 300 feet long carrying steam at 125 lbs. pressure with a temperature of the air at 

 90 degres F. would require 105 tons of coal for 300 days a year. To make up for 

 the loss of heat, this means considerable, even with cheap fuel. 



Another matter to be considered is the finish outside of the covering. We find with 

 the same covering condensation will vary as much as 20 per cent whether regular 

 pasted canvas and bands are used or some special finish. The results vary also with 

 the different material used for the insulation. 



Managers and engineers should give this considerable thought, as it is one of the 

 great savings that can be made in industrial plants, and all live steam pipes should be 

 properly insulated so as to prevent condensation from taking place. 



El articulo siguiente es una traduccion de una communicacion muy importante de 

 Mr. D. J. Lewis, perito muy conocido, que no dejara de interesar a todo duefio de ingenio 

 de azucar, pues da a conocer la iinportancia de conservar el desperdicio de vapor. 



El asunto de comprar material aislador para las suferficies calientes de alta presion 

 es cosa que requiere una atencion considerable, especialmente en esta epoca de vapor 

 a alta presion. 



Durante los ultiinos veinte anos el que suscribe, en el curso de su practica de con- 

 servar el desperdicio de vapor en las instalaciones manufactureras, ha llevado a cabo 

 un gran numero de ensayos de condensacion, y ademas de anotar la condensacion ha 

 hecho apuntes del material y el estado del aislamiento, el cual ha hallado ser bueno 

 en algunas casos y en otros malo e indiferente, este ultimo en la mayor parte de los 

 casos, asi como el metodo de su instalacion y su condicion, fijandose especialmente 

 en el tiempo que ha estado en uso. 



Nos hemos sorpendido mucho a la indiferencia mostrada por los encargados e in- 

 genieros de las muchas instalaciones examinadas respecto a los distintos forros en uso. 

 El metodo y clase de un aislamiento depende en su mayor parte en el precio y en la 

 habilidad del vendedor de forros en convencer al comprador de que dicho vendedor 

 tiene el mejor forro. Por regla general no se requieren ni se exigen resultados satis- 

 factorios. Las cspecificaciones generalmente se concretan a una marca dada 6 a su 

 cquivalente. En los ingenios de azucar muchos encargados creen que porque el fun- 

 cionamiento es de corta duracion y el combustible es barato el asunto del forro de 

 la tuberia no les interesa. y en bastante numero de instalaciones hemos hallado tubos 

 desnudos conducicndo vapor hasta una presion de 125 libras. Ahora bien, aun supo- 

 niendo que el asunto del combustible no sea de importancia, la calidad del vapor si lo 

 es en lo que se refiere al producto manufacturado. Cuando la tuberia esta desnuda 

 el vapor se satura y lleva en si una cantidad de agua que verdaderamente hace las veces 

 de enfriador en vez de servir de calentador. 



Por ejemplo, para nostrar la cantidad de calor perdido, hallaremos que un tubo 

 desnudo de 4 pulgadas de diametro y 300 pies de largo conducicndo vapor a una presion 

 de 125 libras a una temperatura atmosferica de 90 grados Fahrenheit requeriria 105 



