Conditions of design or Operation consitions

I want to know its opinion with respect to a subject that has a little to me complicated.

When analyses of flexibility of pipes are made, generally conditions of Operation are used, (temperatures and pressures of operation); nevertheless much with other specialists has been discussed who the conditions that would be due to use are those of design, since they are conditions you criticize.

Although all we know that the conditions of design always for being very happened through limit of the real thing (Process men) wanted to know that they think with respect to this

Thanks and I wait for its commentaries

Mr. Shrimp