Assuming you are dealing with the API codes, X60 comes from API 5L. The "60" indicates it has a yield strength of 60ksi. The usual welding code would be API 1104.

I would look into whether or not supplemental requirements are imposed. Oftentimes the pipeline owners add the requirement to qualify the wps with notch toughness testing.

Generally we would use E7010 for the root and hot pass and E8018-C3 for the remaining passes (all SMAW). If you want to do the root and hot pass with GTAW, use E70S-2; followed by E8018-C3 for the rest.

API 1104 allows you to qualify the WPS on X60 and use it on any materials between X46 and X60.

Charles