Bolts for removing stucked blinds

[hakkik]

Hi,

One of our customers wants "jack screws"(how they call but i am not sure that is the correct wording for.)on blind flanges of an U stamped PV. Blinds are varying 3" to 30" and all CL900(RTJ). But they don't provide any details except attached sample.

If i understand correctly, these bolts used to losen stucked blinds easly.

I'm not able to find any info about sizing and placing of these bolts on books, spesifications, google etc. So here is my last resort. Also i want to know, whether drilling these holes is a violation of the code(Asme B16.5 or BPVC)or not.

Any information will be extremely hepful,

http://files.engineering.com/getfil...-9d82-8bf5cdfabb61&file=Jack_Screw_Detail.PNG

 

[DSB123]

hakkik,
Jack bolts are normally used to separate flanges when you want to swing spectacle plates or when you want to change spec blinds out. They are normally used on the larger size pipes where "breaking" the flange joint takes more effort. On smaller lines 1" to say 12" they are rare.

 

[pennpiper]

Hakkik,
Jack Screws are common on Orifice Flanges. If you want to see what they are, where to place them, the proper size "Jack Screw" for a given flange size, etc. then pull out an Orifice Flange catalog and look for the one that fits your situation.

 

[eadwine]

They're called "jack screw" or "jack bolts". Nothing exotic here, they're just a hex-hd capscrew placed between the bolt holes of the Flg. at 180 deg. apart. See the detail of an orifice flg.. Some owners spec's require them at every blind location.

 

[unclesyd]

They are usually laid out as the ones in your print so you cna drop out a gasket without having to pull the flange. In your case the ring will dropout at the bottom with removal of a few studs and backing off of one jack bolt.
One thing that I've found that for larger blind flanges the weight of the flange is generally enough to break any seal. Some times it might take a little nudge with a 4 pound hammer.

I don't recall ever seeing any prohibition of using them in a flange. You can have as many bolt Holt holes as you want as long as the flange will calculate out for the conditions.