flanges with threaded holes

[engahmedbahgat]

Hello all,

I have a strange case, please help me with:

I received a new equipment (gas turbine meter) with flanges connection, but the holes of the flanges are threaded ??

and the flange welded to the pipe is a normal ansi flange (b16.5), so when installing the turbine-meter, the bolt suppose to be connected with the pipe flange with nuts as usual, and connecting with equipment flange(flange with threaded holes) without nut because both bolt and flange holes are threaded

is that a standard piping connection way in a high pressure gas (about 20 barg) ??

thank you in advance

 

[LittleInch]

I've seen it before, but never really liked it.

You need to be very certain that the flange types are the same, but look very closely at the drawing supplied by the vendor for the item to see exactly what it says. Integral flanges can be screwed to accept stud bolts, but the thread length needs to equal or exceed the nut length on the other end.

The flange codes don't specifically say there are allowed or not allowed as far as I can see.

Given the propensity to get the threads crossed or galled, they are not a great idea.

a picture or drawing would help.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[racookpe1978]

In a perfect world, where threads never galled and studs could get carefully and beautifuly and miraculously professionally ALWAYS screwed in by hand without ever getting dirty or cross-threaded or wrenched with a pair of pliers and the studs would never need be replaced or scarred when the pipes and flanges are disconnected ..... (Robt dreams on) ..... the threaded-in studs might make sense.

But not in the real world: Also, when the nuts are removed from one end, the studs still stick out of the threaded flange, so the fitting/valve/instrument in the middle STILL can't get lifted out or moved. It has to be slid off of the studs to the side to get lifted up by the crane or man. More chances for damage and much slower.

 

[LittleInch]

One the one's I've seen the equipment supplier also supplied the studs and did so with hex nut inserts in the end of the stud so that you could unscrew then from the flange and remove the item.

racoope is still right though - Unless you can't get a nut in behind the flange then I can't see why they've done it - a drawing or picture would help....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[KevinNZ]

Tapped flange bolting is common on API wellhead equipment.