... are used for start-up of the boiler load (with/without variable speed pump).Operation Conditions The main Feedwater Control Valve is ... startup feedwater valve is installed parallel to main feedwater valve with cavitation trim. The most common problem is selection of ... , ASTM A276 420, 440C, 630 Stainless steel, 316,316L with Stellite, or other materials provided according to customer's requirements ...