Development of ROV Replaceable Control Valves
Authors: Jolly R.D. , Langen M.G. , Hewlett C. 
Published: October 2008

ABSTRACT
As the development of deep water production systems becomes more common, cost effective maintenance through sub sea intervention becomes an increasingly important design goal.
One method of accomplishing this goal is the use of ROV replaceable control'alves. These'alves offer an attractive alternative to permanently installed sub sea control'alves by providing readily replaceable/ interchangeable control components for a'ariety of applications. As part of an ongoing developmental program, a prototype 10,000 psi ball'alve has been designed and tested. The results of these tests have shown the effectiveness of the overall design and the feasibility of developing additional'alve types.

INTRODUCTION
As more deep water production systems enter into the development phase, cost effective maintenance through sub sea intervention takes on an increasingly important role. An integral part of the maintenance solution is the replace ability of sub sea components. In keeping with this philosophy, ocean systems Engineering has instituted a program to develop a line of ROV replaceable sub sea control'alves (ROVSERT). This product will offer a cost effective means of maintaining and replacing sub sea control'alves, especially in control circuits that are not retrievable or where retrieval is cost prohibitive.
The control'alves can beimplemented in a'ariety of applications including control line isolation'alves (ie: SCSSV control line isolation) and chemical injection lines. In addition, the availability of'arious types of control components will allow subsea control circuits to be reprogrammed. That is, it will be possible to change the use of a previously installed control circuit to suit new conditions or production requirements.
This paper describes the design, development and testing of a prototype ROV replaceable control'alve. It will also discuss further developments now in progress and potential applications for ROV replaceable control'alves.

DEVELOPMENT OF A PROTOTYPE VALVE
Once the need for ROV replaceable'alves was established a developmental program was instituted. The objective of this program was to design a prototype'alve that would fully demonstrate the capability of the concept. It was determined that the best way to meet this goal was to produce a'alve that would encompass the maximum demands of a number of possible usage scenarios while maintaining simplicity in the design. with these criteria in mind, a 10,000 psi, 1/2 inch ball'alve was developed.
The utilization of a ball'alve for the prototype model was an attractive choice for two reasons. First, ball'alves are used in a wide spectrum of sub sea operations and therefore would be most apt to be deployed in a retrievable mode.
Second, the actuating mechanism of a ball'alve often requires high torques to operate, especially when used in high pressure applications. The use of this'alve class in the prototype permitted determination of a key requirement for ROV operation; the forces required to open and/or close a'alve subjected to pressure.
The overall design of ROV replaceable'alves is centered around packaging the'alve components in a pressure balanced stab to facilitate ROV deployment and retrieval.
Extensive experience in the design and use of pressure balanced hydraulic connectors on sub sea equipment has proven the reliability of this design.
Operational experience has also established the'ersatility of the equipment when used in conjunction with remote work systems.
The'alve consists of two main assemblies; the male'alve body (pressure balanced stab) and the female receptacle (see figure 1). All moving parts (re: failure p