Why are allowable component loads often given in three directions only

[SverkerO]

Hello,

Often I get in to discussion with suppliers of components about allowable component loads. The supplier often has the opinion that we piping engineers only produce bending moment and axial force at the interface to the component. Does anyone know the background to that?

I always ask for allowable for torque and shear forces to, so I can fulfil them for my own peace of mind.

 

[BigInch]

Do you often have problems with shear stresses?

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[SverkerO]

Thanks for the reply, Just back from a nice vacation.

No I do not have problems whith shear stresses. I guess thath the reply implies that if the piping can whithstand the shear stresses then the component can whithstand the corrosponding reactions. But as the component often is a black box I cant know that for sure.

Is there an understanding that I have not yet heard of that if no limits is put on the shear forces than the component can whitstand them if the pipe can?

 

[micalbrch]

If you talk for example about nozzle loads of a pump's discharge connection what other allowable loads do you need than the 3 directions you usually get?

 

[SverkerO]

If I get allowable forces and moments in three directions I would be satisfied. I’m talking about those times when I only get two bending moments and an axial force as allowable.

 

[BigInch]

Others would be 0 implied.

"The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward X-CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[JStephen]

Make sure that you are asking the right question.

In our applications, the allowable load in one direction is reduced by the applied loads in other directions. Applying an axial load produces transverse deflections and vice versa, and there are deflections indendepent of the attached piping. If someone then asks for the allowable load in each direction, but hasn't thought to ask for the flexibility or the other deflections essential to a meaningful analysis, it comes across as a fairly pointless question, and the response will oftentimes not be overly useful either. It can easily turn into a "How long is a piece of string" question.