Experiences With Hydrogen Embrittlement in the Consolidated Edison System

Abstract

Boiler 40 at Astoria developed brittle failures in about 3-months operation. Feedwater was pH-adjusted and deaerating condenser and heater were in operation, but no oxygen scavenger was used. Boiler water was maintained on no-solids basis. Some condenser leakage occurred. After six months, the boiler was put on coordinated phosphate control and a pronounced hideout condition was disclosed. After about nine months of operation, brittle failures occurred in the nose tubes to the extent that replacement of the entire nose section was made. Boiler 70 at East River developed brittle failures after about 8 years of service. Feedwater pH was adjusted by cyclohexylamine. Boiler water treatment for the first 5 years was low NaOH + Na3 PO4 , and the last 3 years coordinated phosphate. A hideout condition also exists in this boiler. Factors of chemical control, cleaning, operation, and design are discussed. Many variables can be eliminated by comparison with other units in the system. Some factors remain unanswered. Consideration is given the fact that both boilers disclosed a considerable hideout condition when operating on coordinated phosphate treatment.