Presentation on theme: "Proposed Joint Industry Project - ULTIMATE STRENGTH LIMIT STATE CRITERIA for SHIP-SHAPE FPSO NEW-BUILDS & CONVERSIONS and SHUTTLE TANKERS by Dr Paul A."— Presentation transcript:
Proposed Joint Industry Project - ULTIMATE STRENGTH LIMIT STATE CRITERIA for SHIP-SHAPE FPSO NEW-BUILDS & CONVERSIONS and SHUTTLE TANKERS by Dr Paul A Frieze PhD, CEng, FRINA, MIStructE, MSNAME, ACIArb PAFA Consulting Engineers Hofer House 185 Uxbridge Road Hampton Middlesex TW12 1BN UK
INTRODUCTION 1.ISO/TC 8/SC 8 Ship Structures has just voted affirmatively on a New Work Item to develop an ISO Standard on Guidelines for the Ultimate Strength Limit State (ULS) Assessment of Tankers, Bulkers, and related ship structures. 2.The strength formulations will apply to ship structure components plus the hull girder and will allow for the effects of corrosion, fatigue cracking and damage due to accidents. They will not deal with other relevant limit states such a fatigue and serviceability. 3.The Standard will address the common forms of overall and local loading, namely, wave bending and still water loads, bow and bottom slamming, greenwater, cargo, thermal and sloshing. It will also address finite element modelling issues.
INTRODUCTION - II 1.The Project Leader is Professor Jeom Paik, Pusan National University, Korea, who also prepared the proposal. Professor Paik is the author of a recent book on Ultimate Limit State Design of Steel Plated Structures. 2. Professor Paik will prepare most of the draft on the strength formulations and will draw heavily on his book for this. He has set himself a target of six months to complete the first draft. 3.Professor Paik has requested PAFA Consulting Engineers to assist in drawing up the requirements for slamming, greenwater and sloshing based on PAFA’s work for UK HSE and its involvement in SafeFlow.
INTRODUCTION - III 1.Currently, ISO Standard 19904, Floating Structures for Petroleum & Natural Gas Industries, is being finalised, under the auspices of ISO/TC 67/SC 7/WG 5, by an Editing Panel (Bob Wolfram, Andrea Mangiavacchi & Paul Frieze) and is scheduled for issue as a Draft International Standard (DIS) in September ISO deals with FPSOs (includes FPSs, FSUs, etc), spars, TLPs and semi-submersibles. It assumes Class Rules are used for sizing FPSO scantlings. 3.ISO should be in a limit state format but cannot be, in full, because of, generally, the Working Stress Design basis of Class Rules. 4.Class Rules cannot deal readily with damaged or corroded ship structures and thus are not generally suitable for application in the case of Conversions.
JIP OBJECTIVES 1.To develop ISO Standard Guidelines for the Ultimate Strength Limit State Assessment of a) FPSOs and b) Shuttle Tankers. 2.For b) Shuttle Tankers, to achieve this by actively participating in the ISO/TC 8/SC 8 Work Group on ISO Standard Guidelines for the Ultimate Strength Limit State Assessment of Tankers, Bulkers, and related ship structures to include: i)loadings due to greenwater, wave slam and sloshing, ii)derivation of load and resistance factors
JIP OBJECTIVES - II and introducing requirements peculiar to shuttle tankers, eg, iii)normal loadings due to hawser and/or flexible hose connections to FPSOs, dynamic positioning, or other arising from interactions with FPSOs during offloading and related activities iv)potential accidental loadings peculiar to shuttle tanker/FPSO operations.
JIP OBJECTIVES - III 3.For a) FPSOs, to achieve this by (re)activating the ISO/TC 67/SC 7/WG 5 Panel on Structural Strength and including: i)normal loadings peculiar to FPSOs such as a basic 100-year return period design event and consistent side structure and transverse structure events, effect of prolonged ‘head to seas’ exposure, heavy and concentrated topsides loads and/or restraints, offloading, and connections to shuttle tankers. ii)potential accidental loadings peculiar to shuttle tanker/FPSO operations.
JIP OBJECTIVES - IV iii)components peculiar to FPSOs such as turrets iv) achieving compatibility/consistency with the requirements of ISO Floating Structures v) derivation of the load and resistance factors, of which the latter may differ depending on whether they relate to New Builds or Conversions.
SCHEDULE & COSTS The support effort for the workings of ISO/TC 8/SC 8 and the parallel complementary work on shuttle tankers needs to put in motion shortly in order to comply with the timetable set by ISO/TC 8/SC 8. The major effort on this should be completed this year. A preliminary estimate for the cost of this phase is £30,000 $48,000. The significantly more intensive effort required to adapt the Guidelines to FPSO New Builds and Conversions will take place in 2004 and is expected to cost some £125,00 $200,000.
DELIVERABLES The prime Deliverable will be an ISO Standard on Guidelines for the Ultimate Strength Limit State Assessment of FPSO New Builds & Conversions that: a)deals with all standard ship structure components as well as the hull girder plus those components peculiar to FPSOs such as turrets b)allows for the effects of corrosion, fatigue cracking and accidental damage. c)accounts for normal ship overall and local loadings but set in a 100-year return period framework plus loadings peculiar to FPSOs (head to seas, heavy concentrated topsides, shuttle tanker interactions)
DELIVERABLES - II FPSO New Builds & Conversions Standard (cont.) d)identifies relevant accidental loads (shuttle tankers) e) addresses finite element modelling issues f)specifies appropriate load and resistance factors differentiating between New Builds & Conversions as necessary.
DELIVERABLES - III The secondary Deliverable will be an ISO Standard on Guidelines for the Ultimate Strength Limit State Assessment of (Shuttle) Tankers, Bulkers, and related ship structures that deals with standard ship structure components and hull girders and their loadings as well as: g)addresses normal and accidental loadings due to shuttle tanker/FPSO interactions h)provides partial load and resistance factors relevant for shuttle tankers.
BENEFITS OF PARTICIPATION The ISO Standard Guidelines will provide hull girder and component (including side and transverse structure) strength formulations that are: *In a ULS format *Account for typical aging and accidental damage *Applicable to FPSOs year return period events, head to seas, heavy/concentrated topsides loads, wave slam, greenwater, sloshing, offloading, connections to shuttle tankers - accidental loadings peculiar to shuttle tanker/FPSO operations - both New Builds and Conversions
BENEFITS OF PARTICIPATION - II *Applicable to shuttle tankers - relevant loadings as above - loadings due to hawser and/or flexible hose connections to FPSOs, dynamic positioning, other interactions during offloading - accidental loadings peculiar to shuttle tanker/FPSO operations *Load and resistance factors appropriate to FPSOs & shuttle tankers *Independent of class rules *Consistent and compatible with the safety format and levels in ISO Standard Floating Structures for Petroleum & Natural Gas Industries.
NEXT STAGE A Preliminary Draft of the Proposal has already been issued to a limited number of potentially interested parties for their views and comments. Most of these have now been received. The Proposal will be revised to take account of these and and any further comments /views that might be expressed here today or following this meeting. The revised Proposal will be formally issued.