30 / 32
28
Set Double Block
and Monitor Tool
at location
BY THE
NUMBERS
Offshore pipeline maintenance typically falls into one of four categories:
valve replacement, tie-in, riser repair, or heavy lift protection.
During these types of maintenance, operators rely on non-intrusive inline
isolation methods to protect their people, achieve compliance, and mitigate
reductions to production. The most common isolation is the DNV-certified
double block and monitor method, as seen here.
DNV-Certified Double Block
and Monitor Isolation Method
1
2
3
4
5
HIGH
LINE PRESSURE
ANNULUS PRESSURE
Monitoring and
Tracking Module
Plug
Module #1
DNV Recommended Practice for Pipeline
Subsea Repair Criteria (DNV-RP-F113/3):
. Each barrier must be able to retain full line pressure
. Independent locking system
. Seal must be independently tested
. Ability to monitor line integrity
. Seals must be independent
from each other
Through the use
of independently operated isolation
barriers and continuous monitoring,
the system allows high-pressure
pipeline operators to carry out remedial
pipeline work in a safe, controlled, and
monitored environment.