Butterlfy Valve Double Flanged Bolting

[MatiasMech]

Good morning,
Im currently installing a 10'' Butterfly Valve (Triple Eccentric, Doubled Flanged).
Most of the bolting required is already installed, the bolts missing are the ones that have the stem in the way. This arent supposed to go through the hole, according to what i understand.
The question is, what kind of bolts are they?
Are there any standard table for bolting of this kind of valves?

Thank you.

 

[TBP]

As always, what does the manufacturer's literature say? Nobody is manufacturing a commodity valve that uses different sizes/types of bolts for some bolt holes. Nobody would buy it.

 

[bcd]

It is common on some butterfly valves to have different bolting at the flange holes near the stem(s). This is because the stem diameter being close the space between t flange bolt holes. Usually, these are drilled and tapped and use stud bolts. The manufacturer should provide a table with recommended fasteners to install the valve.

 

[Nick_Gray_88]

Hopefully the valve is to API 609 and not a commodity valve as it is a triple-offset.
API 609 requires the bolts to be the relevant flange bolting and threaded to a minimum depth, you should be able to use standard flange bolting to complete the joint even with these holes being threaded/studded.