PSSL ROV Intervention UI 2007
PSSL ROV Intervention UI 2007
PSSL ROV Intervention UI 2007
1
The Norwegian NORSOK U-102 and U-007 The absence of a standard definition for the fish-tail
standards provide valuable additional definition but handle doesn’t help.
are regional.
The T-bar style is not as easy to use as its widespread
THE STANDARD ROV use would suggest. The T-bar sits in grooves in the
parallel jaw but it needs the manipulator to grasp
There isn’t one! An area that remains undefined at within ¼” to properly swallow the bar into the slots.
present is what space should be allowed for This is quite difficult to do. An easier handle
workclass ROVs to pass into subsea structures. The interface to grip is the “paddle” which is fabricated
table of ROVs in API 17H Annex A has widths from from plate but with a round bar on the outer edge -
55” to 77” but it is relatively common to encounter but this is not part of any standard.
subsea structures with gaps around 60”. Length is
usually less significant but height is often critical
where ROVs have to pass under BOPs to position
tools. There isn’t an easy answer on this as vehicles
have had to become much larger to accommodate the
larger thrusters, power packs and buoyancy packages
for deepwater applications.
FLUID CONNECTIONS
2
TORQUE TOOL INTERFACE
LINEAR OVERRIDE INTERFACE
There are usually more torque tool interventions than
any other. API 17H figure 18 classes 1-4 are the The Type A interface is commonly used for override
most common. They are also the source of most of powerful valve springs. This can be for
interface problems. The standard defines the operational reasons where the normal fluid control is
receptacle interface. The receptacle ought to be +/- not functioning or where a valve has to be locked
0.02” on all dimensions but this is often not properly open for a downhole intervention.
controlled. In addition, the buckets are usually cast
and some suppliers fail to clean-up the cast surfaces.
The thickness of paint is often ignored but obviously
affects the tool fit: in one project the interface was
0.15” undersize on the main bore diameter.
3
ROV WEIGHT, PAYLOAD, FRAME LIFT interface, can make a major difference to the offshore
operations.
These simple terms are universally understood
among ROV suppliers but often misunderstood This starts with correct use of the interfaces. 3-D
elsewhere. computer models can be built and operations
rehearsed using ROV simulators. (Perry Slingsby
Weight. ROVs have to fly at near-neutral weight in Systems now provides this facility with its ROV
water. Any weight it picks up has to be counteracted systems). With the latest “physics” software engines
by the vertical thrusters. High vertical thrust stirs up giving objects weights, stiffnesses and full ocean
the seabed. As a rule of thumb, large work class environment simulation the experience is as realistic
ROVs can pick up tooling objects of up to 100 lbs as possible without the consequences of errors!
(weight in water) and readily fly and maneuver them
using manipulators. Lighter is always better. As
weights approach 200 lbs, thrust becomes excessive
and special planning is required.
REFERENCES
1. ISO 13628-8:2002 Remotely Operated Vehicle (ROV) Interfaces on Subsea Production Systems
2. ANSI/API Recommended Practice 17H, 1st Edition, July 2004
3. NORSOK U-102 Remotely Operated Vehicle Services, Rev 1, Oct 2003
4. NORSOK U-007 Subsea Intervention Systems, Rev 2, June 1998