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#6954 - 08/20/01 05:59 AM Vessel/Nozzles centerline direction cosines
Yoshida,Gilberto Offline

Registered: 08/20/01
Posts: 7
Loc: Brazil
I'm having some difficulties to run wrc 107 program in coadecalc when entering the loads from Caesar II global coordinates, so I hope somebody could give me some tips.
The problem is the following:
When I enter the loads in the wrc 107 convention I don't get the stress summations, so I'm entering the loads in global coordinates. But the problem is that I'm not felling confident of entering the direction cosines rigthly since I didn't understand the convention described in the user's guide.
I just know that the nozzle vector is always defined to point to the centerline of the vessel. But what is the convention I have to use, for instance, when analying a horizontal vessel with a nozzle on the shell?
And another situation is when I have a nozzle on the head. What is the vessel direction cosines?(I know that it can't be colinear with the nozzle centerline.)

Gilberto Yoshida
Construtora Norberto Odebrecht

#6955 - 08/21/01 09:42 AM Re: Vessel/Nozzles centerline direction cosines
Mandeep Singh Offline


Registered: 12/15/99
Posts: 600
Loc: Houston, Tx, USA
The direction vector for a nozzle is along the nozzle centerline pointing towards the vessel. For a cylinder or a cone, the direction vector is along the vessel centerline. The +/- direction does not matter, as it will only have the effect of switching the location of the A, B points.

For a spherical vessel the direction is tangent to the vessel at the nozzle-vessel junction. Since WRC-107 only addresses 90-degree nozzles, hence the nozzle and vessel direction vectors will not be collinear.

It helps to draw the vessel, axis, nozzle and the loads all on 1 page and then figure the direction vectors from there.

Program converts the global loads to the WRC system before doing the stress computations. A good check is to check the loads in WRC convention from the output.

Best Regards,
Mandeep Singh
CADWorx & Analysis Solutions
Hexagon PPM


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