ANSI API RP 17M-2004 pdf download.Recommended Practice on Remotely Operated Tool (ROT) Intervention Systems.
3 System selection 3.1 General The design, configuration and operation of the ROT intervention system impacts directly on the LCC for the entire SPS. In order to obtain an SPS design providing safe and cost-effective intervention operations, it is important to obtain a closed loop between SPS design and intervention system design. See Figure 1 . An ROT intervention system typically comprises the following: a) ROTs for dedicated intervention tasks, b) deck handling equipment, c) ICS, d) deployment/landing equipment, e) ROV spread interfaced with ROT systems. An illustration of the main features of an ROT intervention system and associated equipment is shown in Figure 2. The breakdown of the ROT intervention system into sub-elements and components as presented in this part of ISO 1 3628 should not pose limitations on the selection of new intervention concepts whose functionality and reliability can be documented. Configurational options for the ROT intervention system and interfacing equipment, such as intervention vessel and ROV systems when used, are shown in Figure 3. ROT intervention systems shall be evaluated for all phases of an intervention operation, which typically are: ? mobilization (specific issues at the location in question), ? deck handling and preparation, ? launch, descent and landing, ? intervention task, ? testing, ? complementary tasks, ? retrieval, ? demobilization, ? contingency. During the evaluation, consideration shall be given to reasonably foreseeable misuse of the ROT intervention system.
3.2 Deck handling equipment Deck handling equipment and launching techniques shall be selected to ensure that a wide range of vessels can be used. Flexibility shall be provided without compromising safety and reliability of the work, both on surface and subsea. Main issues are: ? means of moving intervention equipment on deck (skid systems vs. use of vessel cranes); ? means of deploying and landing ROT systems (winches and simple mobile A-frames vs. use of complex, purpose-made heave-compensated systems); ? means of installing on and removing from the intervention vessel. The selection of equipment shall be dictated by the nature of the intervention task (e.g. tie-in operation, module replacement), environmental considerations affecting the operation and time available to carry out the required operation. 3.3 Intervention control system (ICS) The ICS shall be designed for control and monitoring of a) ROT function testing on deck, b) ROT status during running, if required, c) ROT functions during the intervention task. These control functions may be provided either through ? ROT function testing on deck, ? a dedicated system for the ROT, ? an ROV control system, or ? a combined ROT/ROV system. Main issues with respect to selection of the ICS configuration are ? complexity of the subsea work, ? cost and manning for a dedicated control system, ? level of modifications to a standard ROV control system, ? flexibility of the ROV during the subsea work, ? reliability and suitability of the subsystems within an ROV spread. See Figure 4, which is meant to highlight the interrelationship between ROTs and ROVs and related interface requirements.
4 Functional requirements and recommendations 4.1 General This subclause contains general functional requirements and recommendations for the elements within the various options of ROT intervention systems and interfacing equipment. a) The ROT intervention system shall be designed to be as small, simple, reliable and robust as possible, to ensure safety of personnel and to prevent damage to the intervention system, the SPS and/or the environment. No single failure should result in reduced safety for the involved personnel, or cause damage to involved equipment and/or the environment (consider redundancy in order to minimize the probability of failure). b) The ROT functional requirements shall reflect its multiple use over the design life of the SPS. c) The ROT intervention system shall be designed to allow for safe and easy operation, maintenance, repair and replacement of components. d) Operations of all functions in the ROT intervention system shall be optimized with regard to duration. e) Priority should be given to reduce the time required for mobilization/demobilization onboard the intervention vessel. f) Functionality and operability of new ROT intervention concepts shall be documented in design and by testing under realistic conditions. g) All intervention tasks shall be possible to suspend in a safe manner. It shall be possible to resume a task suspended due to equipment failure or adverse weather conditions. h) All ROT operations should be fully reversible at any stage. i) All tool functions, which upon failure may prevent retrieval of the ROT system to surface, shall have override features. These shall include release from both the permanently installed subsea systems as well as from sealines and replaceable components. j) In case of a vessel drift-off, a weak-link or safe disconnection/release method shall be installed between the ROT system and the liftwire/umbilical.