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1.0IntroductionDescribe the purpose of the report.

2.0BackgroundProvide limited detail on the project background and identify why these calculations are required. Be specific to the structural scope of work only, dont clutter the report with superfluous information on drilling, pipeline, reservoir data etc

3.0External Design Constraints

3.1Site and PhysicalNote any external constraints which have an effect on the design. This may include geotechnical restrictions such as soft soil, allowable bearing pressures, areas of special interest (protected sabeleria tube worms), fishing area restrictions. Client restrictions on the design, such as no site welding or the need to be dismantled and stored. Road transportable design (cut in half and bolted/welded). Vessel restrictions, deck space, crane capacity, deck strength. Diver or ROV access. Clear access points. Large buttons or handles. Weight restriction. Installation restrictions in terms of vessel, method or crane. Hook height

3.2Existing StructuresNote any adjacent structures. This could be topside work such as access restrictions, limited height and working area or subsea pipelines, crossings, work in side other manifolds, retrofitting

3.3Specific Plant and EquipmentIf the structure is design to accommodate certain items of plant and equipment provide details of these. Sizes, weights, fixing details, supplied by who. Specific vendor requirements, access to certain areas of equipment. Items used on previous projects, corrals, spreader frames, lay spreads, reels, carousels, chutes, SIT frames, installations aids, Free issue item, wet welding, friction stud welding. Crane masters. ROVs TMS.

3.4Project and CommercialDelivery dates, design completion dates, formal issues to subcontractors to begin fabrication.

4.0Project Specific Design Criteria

4.1Design Objective and RequirementsDiscuss the requirements of the design. What does it need to do, why do we need it

4.2Client Provided DataInformation from the Client Basis of Design which is pertinent to the design should be listed. Design Life, marine growth, water depth. Water depth varies with storm (LAT, MSL, Max 1 yr storm LAT+ xm, Max 50yr storm LAT + Xm), current profile. Storm surge current (HSE Fig 9)

4.3Design AssumptionsIf there is no information available and you have made assumptions in order to progress the design then these should be listed and the basis for choice described. Geotechnical requirements or limits. Marine Growth levels. Significant waves, associated period, underlying current, item weights, structures, equipment. Which vessel will be used or has been assumed. Hook height. Crane operating with heave comp.

4.4AbbreviationsA basic list of abbreviations contained within the report.

4.5Structural Materialse.g steel to BS EN 10225, or 10025, 10027,10210 etc. Bolts grade 8.8 to BS 3692 ISO metric precision bolts, nuts Grade 8 nuts, washers, grating grade, steel GRP, ballast, lead, concrete grade, timber for packing, Anodes, grout bags, frond mats. Modulus of elasticity, yield stress, ultimate stress, density, poisson ratio, welding and electrode strength. Mechanical properties

4.6Reference Drawings and DocumentationList all of the project documents and drawings you have referenced during the design. This could also include installation procedures and any pertinent aspects.

4.7Design Codes and Standards AdoptedSpecify which code the design is carried out to primarily.

Listing all the standards consulted during the design process and for what purpose

e.g. [1] NORSOK. Subsea Production Systems. Norsok U-001. Norwegian Technology Centre, Rev 3, October 2002.

5.0Design Philosophy and Approach

5.1Structural Concept, Load Transfer and StabilityIdentify the concept of how the structure will work. Is it going to be stable? Is it braced or moment resisting? How do you want your structure to work bearing in mind you want to transfer your forces to a foundation of some description? Do you have degrees of redundancy? Progressive collapse. If sitting on vessel deck give location in relation to frame numbers, identify which frames are taking the load.

5.2Analysis MethodologyHand calculations or computer based. Elastic, plastic, elasto-plastic for impact, local damage tolerated not to detriment of overall structure. Working stress or ultimate limit state, LRFD.

Parallel hand calculations to support computer based analysis. Sensitivity analysis performed by varying components such as wave height, heading etc

6.0Design Load Cases Identify all the possible loads which may be applied to your structure. These may be from dead weight, imposed loads from plant or operational? Live floor loads? Are there dynamic effects? Seismic effects? Wind loading? Hydrodynamic effects? Accidental loads such as impact? Does it need to be lifted?

6.1Design Factors Identify any load factors used such as dynamic amplification, boom tip acceleration, ultimate limit factors is used, consequence factors, specific design code requirements, weight growth factors, rigging design factors, load factors, material factors, gravity factors

6.2Self WeightRefer Weight Control, manual or inventor. Primary steelwork, secondary steelwork, roof panels, floor panels, grating, side panels, pipe supports control supports, valve supports, valves, anodes, controls, control tubing/wiring/cable trays, mudmats, installation equipment (gyros, transponders, bullseye levels etc), ballast insitu and post installed, future expansion loads, additional piping

6.3Fabrication LoadsTemporary propping causes different structural behaviour, warping stresses due to hot dip galvanising, residual stress from welding, post weld heat treatment (stress relief) in thick materials.

6.4EnvironmentalMaximum wave heights and associated periods. General circulation currents, tidal currents. Limit of wave theory. Which one most applicable, airy, stokes, cnoidal. Basis for assessment of added mass and drag (circular members API/DNV non circular DNV). Wave Loader software. Wind loads? Ice?. VIV on circular members, resonance and natural frequency analysis. Seismic

6.5Lifting and InstallationSkew loads, DNV rules, including loadout and offshore deployment. Design of slings and FOS. DAF 1.3 onshore DAF 2.0 Offshore. Natural frequency of structure check (compare against roll period of vessel). Resonance and vibration. Installation loads, lift and shift loads, pull in loads, wind load induced sway, loadout and mobilisation. Lift and deployment for a range of Tz to suit one Hs. Vessel heading for lift and deployment (vary if required). DAF 3.0 used for ROV installations. Orcaflex, MACSI or Simo for lift analysis. Heave compensated systems (active or passive), slamming, slack rigging. Loadout

6.6TransportationOn what basis have the seafastenings been calculated. What heading for the vessel, where on the deck is the structure, what stiffeners have been used, is the deck adequate (specific checks on deck tees, torsion), Roll heave pitch acceleration, greenwater loading, on what basis, RAOs Noble Denton DNV Lloyds etc

Road transportability requirements. CMotion software. Sideways slam on overhanging structures (related to vessel speed) DNV ship rules deck equipment pt3 ch 1 sec4 C500. initial laydown on deck ~(bearing contact pressure). Total weight not exceeding deck allowable 10t/m2

6.7In Situ/Operational/FunctionalPipeline thrusts, displacement loads 25mm, ROV loads due to thrusts on panels, expansion loads, contraction loads. Pressure, temperature. Uneven footing, only 3 of four supports used, imposed floor loading 5kN/m2

6.8Accidental/AbnormalOvertrawlability, anchor impact, fishing snag loads, trawl board impact, , Dropped Object on roof panel and steelwork. different impact areas and energies Norsok, DNV RP C204 (accidental loads), Vertical impact 10% weight, lateral impact 5% weight

6.9Fatigue AnalysisFatigue Sensitive structures (less than 25N/mm^2 max ignore). Joint fatigue. Low cycles not an issue

6.10Recovery/DecommissioningOn bottom suction, dismantling loads, lack of stability, loads induced by removal of members causing deflection. Structural integrity during lifting. Demolition sequence. Member capacity reduction due to corrosion and damage.

7.0Design Load CombinationsIdentify all the different design load case combinations considered along with the relevant factors. For lifting, transportation and in situ, heave and roll, heave and pitch etc, positive and negative

8.0Detailed Design and ResultsDiscussion on the design undertaken. Critical members. Code checks. URs, maximum stresses global and local. Can break down in either load combination or member type with critical load case.

8.1Primary SteelworkMember design, joint checks. Through thickness loading of joints (padeyes and joints). Piling. If local reinforcement is required describe on what basis. Welds and bolts.

8.2Secondary SteelworkDiver access platforms, ballast arrangements, grating supports, ROV grab bars

8.3Equipment SupportsPiping, anodes, controls all spares included, also futures.

8.4Hydrostatic CollapseFor tubular members., drain holes with cross cut rubber grommets

8.5Impact Analysise.g Tubular member, overall structure, individual member, plates , grating

8.6Lifting PointsThrough thickness properties of attached member? Different spec EN 10225?

8.7Lift Rigging

8.8Results Summary and DiscussionMaximum forces and stresses I which members. Identify the critical members and under which load case this occurs. Give maximum ur values.

8.9Serviceability IssuesCould include discussion on Material deterioration, corrosion, abrasion erosion, fatigue, weathering, deflection, cracking, integrity, condensation, transmission (noise, thermal) vibration, creep deformation, fatigue, wear (surface, adhesive, abrasive, corrosive), Thermal Shock. Lamellar tearing

8.10Operational AspectsStructure markings, SWL on lift points and padeyes

8.11Installation Aids

9.0Weight Control and Material Take Off

10.0Design restrictions on Installation Proceduree.g specific installation method, method of work, design issues member 1 bracing member 2, demolition procedure

11.0Interface with other DisciplinesFabrication specifications, piping, vessels for deck layout and transport location. Welding procedures and qualifications. Different types of metal to metal welding. CP and anodes. Galvanising painting specs

12.0Computer Model HistoryUseful for large designs. Keeps a list of the filename for each model and details of the model. Also can be used to list the history of changes between various revisions of the model.

13.0Design Risk AssessmentIdentify any major risks that have been removed, reduced by design changes. Pass on information relating to residual risks which have not been eliminated. Eliminate, Reduce, Inform, Control. MHASAWR

APPENDICESClient Drawings, vendor drawings, subsea 7 drawings, all calculations, computer inputs, analysis and outputs, hand calcs, mathcad sheets, graphical software outputs with URs deflections , vibration, natural frequency plots etc.