The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community
Issue link: http://sea-technology.epubxp.com/i/344822
32 st / July 2014 www.sea-technology.com pate trouble areas, with an eye on all of the industry common failure modes. Connector Design The result of the aforemen- tioned analysis has been the de- velopment and introduction of a new dry mate connector that complies with the relevant standards and has innovative, up-to-date features that reset the design bar for underwater dry mate connectors. AMETEK SCP's new Elite Series Dry Mate Connector includes the following attributes: design life of 25 years; ISO/API compliant design; 316SS standard, Ti Gr 2, 5 available; dual O-ring seals at all points of sea- water entry; O-rings captured for retention; fully modular design; 19 positions for electrical or optical contacts; indus- try standard mounting interface; APC contacts available for fber-optic version permits very low back refection; cable termination or PBOF designs available; glass sealed electri- cal version available; and open-face pressure rated (as well as reverse). The nominal termination design for this connector is a connection to a PBOF hose or mechanical feld install- able and testable assembly (FITA) type termination. While the technology can certainly be offered in an overmolded backshell design, the user would need to be aware of the life considerations consistent with an overmolded design (for example, with a polyurethane overmolding approach). The modular design and the ability to confgure the con- nector quickly with either electrical or optical contacts are highly desirable attributes. In addition, since the connector is designed from the outset to be compatible with today's oil and gas PBOF cable systems, today's oil and gas system de- signers will have a dry mate connector choice that fts their design needs immediately, with no modifcation to an older design needed. Another desirable attribute that will save precious repair dollars is the ability of the Elite series to be rebuilt. In an overmolded plug design, the backshell of the cable-ended plug can, in theory, be recovered. However, anyone who has done the cost-beneft analysis of this repair quickly real- izes that the cost of the repair (carving away all of the old polyurethane material and recovering the shell) usually ex- ceeds the cost of a new connector. With the Elite series, the connector can be easily disassembled and rebuilt, as the Requirements Analysis The design effort that supports a new product should come from both a technology gap assessment and a re- quirements analysis. Currently available dry mate con- nectors were found to fall short of full compliance to application specifcations. AMETEK SCP has developed a dry mate connector that is compliant with these industry standards, and includes a number of enhancements that will be wel- come to users of dry mate connectors. From a requirements point of view, a new dry mate product would logically be designed to accommodate all available existing specifcations, if at all possible. Relevant industry specifcations that were examined included Mil-C-24231, API 16A Specifcation For Drill Through Equipment, API 16D Specifcation for Control Systems For Drilling Well Control Equipment and Control Systems for Diverter Equipment, API 17E Specifcations for Subsea Umbilicals, ISO 13628-6 Petroleum and Natural Gas Industries, Design and Operation of Subsea Production Systems, Part 6: Subsea Production Control Systems, and STATOIL TR2390 Electrical/Optical Connectors and Jumpers for Subsea Control Systems. Failure Mode Effects And Criticality Analysis An additional activity that is extremely valuable in terms of reliability is to conduct a failure mode effect and criticality analysis (FMECA). A thorough FMECA is an essential part of requirements analysis. The analysis that was conducted fol- lows the methodology as described in both MIL-STD-1629A and API 17N: Recommended Practice for Subsea Production System Reliability and Technical Risk Management. In mechanical design, the essence of an FMECA is to ex- amine all failure modes and to mitigate both their likelihood as well as their impact should they occur. In the parlance of the MIL-STD-1629A, probability ranges from frequent to extremely unlikely, and the consequences range from minor to catastrophic. Note that in a new design, when specifc parts confgura- tion or failure data rate are not yet available, a qualitative approach is utilized. Failure modes identifed in the FMECA are assessed in terms of grouped categories. Thus, the FME- CA analysis of failure modes for both plug and receptacle included the following: main shell assembly, coupling ring (plug), electrical contacts and optical contacts. The value of an FMECA during the design phase is that if done effectively, failure modes can be identifed and then mitigated with thoughtful design. Therefore, a more reliable product can be developed and offered to the market. All possible failure modes for key components were identifed, and then examined for probability of occurrence as well as impact. An example of the value of this analysis is a design choice that incorporates two seals to each point of seawater entry. Although many connector manufacturers might claim that in some cases one seal might be good enough, it is also true that O-rings can be damaged during assembly, fall out of position or extrude at high pressures. For these reasons, a second seal serves as a backup and can mitigate the effects of issues with one seal. The result of the FMECA analysis on the new dry mate connector allowed the designer to antici- Dual seals on both shell and contacts.