Welded v/s Single body Tubular Mandrels

[metboss]

Hi All,

We have ordered one Drilling Tool (Whipstock) which should be made of single piece Tubular mandrel. But supplier has come up with a deviation request that the supplied Tool will be of welded type instead of single body type due to concave curvature configuration & associated machining difficulties. . In this case, the two sections of steel plates will be rolled & welded together (butt weld) to form a single assembly.
We requested for additional documents such weld map, WPS and NDE procedures.
Considering design changes (single piece v/s welded), do need to request for any design analysis documents (ex: FEM analysis) or MOC to mitigate any risks in drilling wellbore condition?
Thank you in advance.

 

[Tmoose]

https://www.esimtech.com/what-do-you-know-about-whipstock-drilling.html

Will the mandrel transmit torque/drilling forces?
Will be forced into a curve while rotating ? ( to be a bending fatigue/endurance tester)

 

[metboss]

Mandrel will not transmit any torque/drilling force and also, not subjected to any rotational force. It will be lowered and anchored at pre-defined depth and Drill bit will be passed through its concave curvature (hole) for directional drilling. It will be subjected to only Drag force while running (lowering) into well bore as it carries some heavy other BHA components.