# Relationship history for MSHA mine 4103113

Current hierarchy: **Hughes Tool Company; W R Grace & Company → Hughes Drilling Fluids → Sheldon Road Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** W R Grace & Company et al → Sheldon Road Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hughes Drilling Fluids → Sheldon Road Plant; 1981-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** W R Grace & Company et al → Hughes Drilling Fluids; 1981-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hughes Tool Company et al → Hughes Drilling Fluids; 1981-10-01 to current/open; source msha-controller-operator-history