How to correct misaligned flange with torque wrench 1

[ElCidCampeador]

Hi,

my client is contesting me a vessel that I built (pressure vessel acc. to ASME VIII Div.1) because he is not able to connect correctly it to his piping line.

Here below what my client has measured (different height gap about 3mm):

I ask you if it's possible to fix it by pullings tie rod of flange with a different torque depending of the position of bolts, so that flanges will have a side more compressed than the other (reducing this gap).



Thank you

 

[LittleInch]

No it isn't.

You will induce large bending moments in either your nozzle or the pipe that is connecting to it.

Cut off the flange and reweld.

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

 

[r6155]

Alignment of flange face of nozzle shall be within 1/2 DEG of specified plane.

Where was the inspector during construction?.



Regards.

 

[desertfox]

Hi ELcidampeador

I agree with others it can’t be done with a torque wrench for sure, why can’t the flange be removed and another flange be welded on?

However I am curious as to whether or not you have verified this discrepancy for yourself and if it is out of align as shown, how did it pass inspection prior to delivery?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[r6155]

You can use the same flange with simple repair of bevel.

Regards

 

[Gr8blu]

Devil's advocate here. Which piece aligns with the specified plane? Is it the nozzle flange (done correctly) or the user's (piping) flange face? Just because there is a 3 mm / 3 degree difference in coplanarity does not mean only one of the two flanges didn't meet code.

Converting energy to motion for more than half a century

 

[ElCidCampeador]

Flange can't be cut because vessel is already in the plant.

Problem has come out as soon as they try to connect this flange to another one, which belongs to a vertical line from below and they notice an incomplete contact between the 2 flanges.

 

[r6155]

Modify the piping to the nozzle.

Regards

 

[LittleInch]

Which is easiest as r6155 says.

Cut the flange off the vessel or cut the flange off the pipe? Then re weld so that the two mate.

Will look bad if its the pipe flange but might be the easiest todo

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

 

[r6155]

Several times I have seen, at different manufacturers, heating and rapid cooling to reduce misalignment. But I don't agree with this practice on pressure components.

Regards

 

[ElCidCampeador]

My client could also put an additional gasket below one of the external saddle in order to correct slope of flange. In this case vessel would be slightly inclined from the vertical, but if the lower connection is the only one of concern, well I think it could be a solution (considering that the scope of this vessel is a sort of spare).

Several times I have seen, at different manufacturers, heating and rapid cooling to reduce misalignment. But I don't agree with this practice on pressure components.

I'm not aware of this "exotic" trick, could you explain me how could you do that? Do you have to heat only one part of the flange or the entire? I suppose that there could be problems related to changes of grain dimension, including the risk of local deformations.

Please note that materials of this connection are stainless steel (austenitic).

 

[LittleInch]

Think he means the pipe where you heat up one side and then cool it rapidly to bend the pipe so that the end flange is more at 90 degrees. But then you have a bent banana shaped pipe.....

Just cut the flange off and reweld it at 90 degrees to the pipe and stop fannying around trying all sorts of ridiculous solutions that look terrible and will create problems long term. You know it is the right thing to do so just do it. IMHO.

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

 

[3DDave]

If there is any cutting and welding the unit needs to be pressure tested again and he doesn't want to pay for that. He wants to keep the test results and make a customer over-stress the part and then they are responsible if it blows out or leaks. Which is why the customer has, apparently, refused to install the item.

 

[LittleInch]

Wouldn't this be external piping and just do it a a golden weld?

Or you can hydro just that weld with plugs and flange testers.

Far better than the alternative.

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

 

[r6155]

Structural integrity is not affected, so hydrostatic testing is not required.

Regards