Pivot failure in ICCG solver in a transient thermal analysis (ANSYS)
 

I am trying to model a welding bead on a pipe in ANSYS transient thermal. Double ellipsoidal model has been used for moving heat source and element birth and death technique for filler metal deposition (EALIVE, EKILL and SOLVE commands). Convection has been applied on all the bodies as boundary condition. Mesh of both pipe and bead, have been made coarse through a body sizing control, resulting into a total of 8000 elements, approx. But, the solver returns the error: pivot failure in ICCG solver (Plz see pics for reference).

Thanks in advance!