Dear all,

In our company, stress analyis engineers have been taking Xmas Tree vertical displacements (for oil and gas wellheads in onshore installations) in doing analysis. The value taken is normally 50mm upwards. Due to this movement, we have to give spring support at very first support near the wellhead. What is the source of this 50mm displacement, nobody knows.

Recently a question was raised, why this vertical movement? What is the basis? How can we calculate the Wellhead Christmas Tree displacement? And should we consider any displacement at all?

One of my seniors who has very good experience in off-shore piping, says it is not required at all. Please give your opinion or share your experience with us on this.