I am a young engineer at a power plant, and we have an odd application that I wanted to get some advice on.
We have an aluminum bronze piping system that can have either aluminum bronze flanges (SB-169 CA-614), or carbon steel flanges (SA-105). We need to specify material requirements for cap screws being used with stainless steel (SA-240 Grade 316; SA-351 Grades CF8M, CF8, CF3M or equivalent) valves. The cap screws pass through the flange and screw into the valve body.
I am considering specifying the following:
"For stainless steel lugged wafer butterfly valves, SA-193 Grade B6 cap screws may be used. If the adjacent flange is aluminum bronze, no insulating kit is required. Insulating sleeves and washers are required when being used with a carbon steel flange."
Does this sound reasonable? Is there a better option that I am overlooking?
Will Grade B7 cap screws experience galvanic corrosion if they are screwed into our stainless steel valves? I ask because right now our specification says that if Grade B7 studs are used to bolt aluminum bronze and stainless steel flanges together, insulating kits are needed.
I appreciate any help, advice, or other bits of wisdom that you could pass onto me. I am always grateful when more experienced engineers pass on knowledge to the younger generation of engineers… I am not sure if they are doing it to be helpful, or because they don’t want our mistakes to negatively affect something they will use after they retire. Either way, I will take what I can get.
We have an aluminum bronze piping system that can have either aluminum bronze flanges (SB-169 CA-614), or carbon steel flanges (SA-105). We need to specify material requirements for cap screws being used with stainless steel (SA-240 Grade 316; SA-351 Grades CF8M, CF8, CF3M or equivalent) valves. The cap screws pass through the flange and screw into the valve body.
I am considering specifying the following:
"For stainless steel lugged wafer butterfly valves, SA-193 Grade B6 cap screws may be used. If the adjacent flange is aluminum bronze, no insulating kit is required. Insulating sleeves and washers are required when being used with a carbon steel flange."
Does this sound reasonable? Is there a better option that I am overlooking?
Will Grade B7 cap screws experience galvanic corrosion if they are screwed into our stainless steel valves? I ask because right now our specification says that if Grade B7 studs are used to bolt aluminum bronze and stainless steel flanges together, insulating kits are needed.
I appreciate any help, advice, or other bits of wisdom that you could pass onto me. I am always grateful when more experienced engineers pass on knowledge to the younger generation of engineers… I am not sure if they are doing it to be helpful, or because they don’t want our mistakes to negatively affect something they will use after they retire. Either way, I will take what I can get.
