CUSTOMER STATED: Thermal expansion tank is leaking. TECHNICIAN NOTES: Out to the residence today for the concern of the thermal expansion tank above the 50 gallon natural gas water heater. Thermal expansion tank is leaking and needs to be replaced. Homes water pressure is within code testing at 60 PSI from boiler drain on water heater. Existing water heater is 18 years of age and is showing severe signs of corrosion, mainly near the hot side water heater nipple. Metal of water heater tank around hot side nipple has become brittle amd will break down if you barely apply pressure to the metal. Water heater is not leaking at this time. Therefore, I have only recommended to replace the leak in the thermal expansion tank on the water heating system to rely home warranty. Choice home warranty has denied the claim to replace the leaking thermal expansion RESOLUTION/RECOMMENDATIONS: No repairs made today. Customer has requested that we send all recommended service estimates to thei