Mountain Valley Pipeline LLC (MVP) operator Equitrans Midstream Corp., seeking to complete construction of its controversial natural gas conduit after a long delay, has agreed to additional steps to address safety concerns raised by the Pipeline and Hazardous Materials Safety Administration (PHMSA).

Equitrans would follow a number of additional safety measures in completing construction of the 303-mile, 42-inch diameter MVP, including engaging with a third party to assess the effectiveness of its pipeline coating, according to the terms of a consent agreement published Tuesday.

The agreement, which resolves an August PHMSA order that raised various potential safety issues related to MVP’s construction, also details requirements for preventative measures. These include inline...