Down Hole Safety Valve.
Source: Norwegian Oil and Gas Association, Guideline No. 135, Recommended Guidelines for Classification and categorization of well control incidents and well integrity incidents, Rev. 4, 27 June 2017, National or Regional Standards
Source: NOGEPA Industrial Guideline No. 41, Well Construction Process Checklist, Drilling Best Practices, Netherlands, Version 0, December 2011. Global Standards
Downhole safety valve.
Source: 117 OLF, Norwegian Oil and Gas Association recommended guidelines for Well Integrity, No. 117, Revision No. 4, June 2011. Global Standards
Source: API STD 689, Collection and Exchange of Reliability and Maintenance Data for Equipment, First Edition, July 2007. Global Standards