Dear group members,
I am little confused about following question on external bolting selection for girth flange (w.r.t to flange material / sour service / temperature / Allowable stress and Flange design)
1.Currently we are using SA 193 B6 bolt (13%Cr S41000) for SA 182 Gr.F6a (13%Cr S41000) Flanges to match bolt material with flange material… but for high pressure (320 bar), Carbon Dioxide (CO2) service electric heaters. Due to high pressure bolt size is coming very high (3" to 4") and equipment is in sour service so hardness can be the issue to comply NACE MR 0175 hardness requirement.
Please highlight any issues face in past with B6 material and what alternative can be use
2.General practise is to use LAS bolting with SS flange however in which case we need to go for SS bolting for SS flanges??
3.In case of using alloy steel bolting with Stainless Steel Flanges, What are the hidden problems like galvanic corrosion and differential thermal expansion??
4.What are other problems of going with SS bolting??
5.For stainless steel, Which are acceptable bolting material grade grades as per NACE MR0175 as NACE does not specify the acceptable grades for SS bolting like B7M and L7M is specified in part-2.
Please share your views.
I am little confused about following question on external bolting selection for girth flange (w.r.t to flange material / sour service / temperature / Allowable stress and Flange design)
1.Currently we are using SA 193 B6 bolt (13%Cr S41000) for SA 182 Gr.F6a (13%Cr S41000) Flanges to match bolt material with flange material… but for high pressure (320 bar), Carbon Dioxide (CO2) service electric heaters. Due to high pressure bolt size is coming very high (3" to 4") and equipment is in sour service so hardness can be the issue to comply NACE MR 0175 hardness requirement.
Please highlight any issues face in past with B6 material and what alternative can be use
2.General practise is to use LAS bolting with SS flange however in which case we need to go for SS bolting for SS flanges??
3.In case of using alloy steel bolting with Stainless Steel Flanges, What are the hidden problems like galvanic corrosion and differential thermal expansion??
4.What are other problems of going with SS bolting??
5.For stainless steel, Which are acceptable bolting material grade grades as per NACE MR0175 as NACE does not specify the acceptable grades for SS bolting like B7M and L7M is specified in part-2.
Please share your views.
