Pub29_OffshoreInstallations

8/8/2019 Pub29_OffshoreInstallations

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Rules for Building and ClassingOffshore Installations

1997

American Bureau of ShippingIncorporated by Act of the Legislature ofthe State of New York 1862

Copyright 1997American Bureau of ShippingTwo World Trade Center, 106th FloorNew York, NY 10048 USA

Special Committee on Offshore Installations


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Contents

Introduction

Table 1 Division and Numbering of RulesPart 1 Classification, Testing and Surveys

SECTION1 Scope and Conditions of Classification......................................................................................... 52 Surveys During Construction and Installations...........................................................................113 Surveys After Construction..........................................................................................................174 Definitions and Design Documentation.......................................................................................21

Part 2 Materials and Welding

SECTION1 Materials ........................................................................................................................................27

2 Welding and Fabrication...............................................................................................................33

Part 3 Design

SECTION1 Environmental Conditions............................................................................................................412 Loads..............................................................................................................................................453 General Design Requirements......................................................................................................514 Steel Structures..............................................................................................................................555 Concrete Structures.......................................................................................................................596 Foundations ...................................................................................................................................697 Marine Operations.........................................................................................................................75

Part 4 Extension of Use and Reuse

SECTION1 Extension of Use ...........................................................................................................................792 Reuse..............................................................................................................................................81

APPENDIX A Material Selection ................................................................................................85APPENDIX B References by Organization.................................................................................87


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Introduction

These Rules apply to the design, construction and installation of Offshore Installations defined in 1/4.1.7, aswell as the periodic surveys which are to be carried out after installation for maintenance of classification. Theserviceability of an installation is also addressed in these Rules, but only to the extent that the proper functioningof the structure or its components will affect safety. These Rules are also applicable to the Certification or Veri-fication of either the design, construction or installation of an offshore installation or any combination of them.ABS will Certify or Verify the design, construction or installation of an offshore installation when requested bythe owner of an installation or mandated by government regulations to verify compliance either to these Rules,set of specific requirements, national standards or other applicable industry standards. If ABSs Certification orVerification of the offshore installation is in accordance with these Rules and covers the design, constructionand installation, then the offshore installation is also eligible for ABS Classification.

The Rules have been written for worldwide application and as such, the satisfaction of individual requirementsmay require comprehensive data, analyses and plans to demonstrate the adequacy of the structure. This instancemay arise for unique structural types or structures located in frontier areas, which are those characterized byrelatively great water depth or areas where little or no operating experience has been obtained. Conversely,many provisions of these Rules often can be satisfied merely on a comparative basis of local conditions or pastsuccessful practices. The Bureau acknowledges that a wide latitude exists as to the extent and type of documen-tation which is required for submission to satisfy these Rules. It is not the intention of these Rules to imposerequirements or practices in addition to those which have previously proven satisfactory in similar situations.

Where available, design requirements in these Rules have been posed in terms of existing methodologies andtheir attendant safety factors, load factors or permissible stresses which are deemed to provide an adequate levelof safety. Primarily, the Bureaus use of such methods and limits in these Rules reflects what is considered to bethe current state of practice in offshore installation design. At the same time, it is acknowledged that new meth-ods of design and construction are constantly evolving along with new structural types, or new uses for estab-lished structural types and components. In recognition of these facts, the Rules specifically allow for such inno-vations. The application of these Rules by the Bureau will not seek to inhibit the use of any technological ap-proach which can be shown to produce an acceptable level of safety.

This Rule book supersedes and replaces the section 1 of ABS Guide for Building and Classing Undersea Pipe-line Systems and Risers 1991 and all relevant cross references to ABS Rules for Building and Classing Off-shore Installations 1983 in ABS Guide for Building and Classing Facilities on Offshore Installations 1991.

The new requirements become effective 19 May 1997.


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Scope and Conditions of Classification Section 1

1997 Offshore Installations ABS1

Part 1 Classification, Testing and Survey


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Table 1 Division and Numbering of Rules

Division Number

Part 1/Section 1/1Subsection 1/1.1

Paragraph 1/1.1.1Subparagraph 1/1.1.1aItem 1/1.1.1a1Subitem 1/1.1.1a1a


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PART 1

SECTION 1 Scope and Conditions

of Classification

1/1.1 Classification

1/1.1.1 Process

The Classification process consists of a) the devel-opment of Rules, Guides, Standards and other crite-ria for the design and construction of offshore in-stallations, materials, equipment and machinery,b) the review of design, and survey during and after

construction to verify compliance with such Rules,Guides, Standards or other criteria, c) the assignmentand registration of class when such compliance hasbeen verified and d) the issuance of a renewableclass certificate, with annual endorsements, valid forfive years.

The Rules and Standards are developed by Bu-reau staff and passed upon by committees made upof naval architects, marine engineers, shipbuilders,engine builders, steel makers and by other technical,operating and scientific personnel associated withthe worldwide maritime industry. Theoretical re-

search and development, established engineeringdisciplines, as well as satisfactory service experienceare utilized in their development and promulgation.The Bureau and its committees can act only uponsuch theoretical and practical considerations in de-veloping Rules and Standards.

1/1.1.2 Certificates and Reports

a Plan review and surveys during and after con-struction are conducted by the Bureau to verify toitself and its committees that an offshore installa-tion structure, item of material, equipment or ma-

chinery is in compliance with the Rules, Guides,Standards or other criteria of the Bureau and tothe satisfaction of the attending Surveyor. All re-ports and certificates are issued solely for the useof the Bureau, its committees, its clients and otherauthorized entities.

b The Bureau will release information from reportsand certificates to the Port State to assist in recti-fication of deficiencies during port state controlintervention. Such information includes text ofconditions of classification, survey due dates, andcertificate expiration dates. The owner will be ad-

vised of any request and/or release of information.c The Bureau will release certain information to theoffshore installation underwriters and P&I clubs

for underwriting purposes. Such information in-cludes text of overdue conditions of classification,survey due dates, and certificate expiration dates.The owners will be advised of any request and/orrelease of information. In the case of overdueconditions of classification, the owners will begiven the opportunity to verify the accuracy of theinformation prior to release.

1/1.1.3 Representations as to Classification

Classification is a representation by the Bureau as tothe structural and mechanical fitness for a particularuse or service in accordance with its Rules and Stan-dards. The Rules of the American Bureau of Shippingare not meant as a substitute for the independent

judgment of professional designers, naval architects,marine engineers, owners, operators, masters andcrew nor as a substitute for the quality control proce-dures of constructors, steel makers, suppliers, manu-facturers and vendors of marine structures, materials,machinery or equipment. The Bureau, being a techni-cal society, can only act through Surveyors or otherswho are believed by it to be skilled and competent.

The Bureau represents solely to the offshore in-stallations Owner or other client of the Bureau thatwhen assigning class it will use due diligence in thedevelopment of Rules, Guides and Standards, and inusing normally applied testing standards, proceduresand techniques as called for by the Rules, Guides,Standards or other criteria of the Bureau for the pur-pose of assigning and maintaining class. The Bureaufurther represents to the offshore installations Owner

or other client of the Bureau that its certificates andreports evidence compliance only with one or moreof the Rules, Guides, Standards or other criteria ofthe Bureau in accordance with the terms of such cer-tificate or report. Under no circumstances whatso-ever are these representations to be deemed to relateto any third party.

1/1.1.4 Scope of Classification

Nothing contained in any certificate or report is to bedeemed to relieve any designer, builder, Owner,

manufacturer, seller, supplier, repairer, operator,other entity or person of any warranty expressed orimplied. Any certificate or report evidences compli-


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ance only with one or more of the Rules, Guides,Standards or other criteria of the American Bureauof Shipping and is issued solely for the use of theBureau, its committees, its clients or other authorizedentities. Nothing contained in any certificate, report,plan or document review or approval is to be deemed

to be in any way a representation or statement be-yond those contained in 1/1.1.3. The validity, appli-cability and interpretation of any certificate, report,plan or document review or approval are governedby the Rules and Standards of the American Bureauof Shipping who shall remain the sole judge thereof.The Bureau is not responsible for the consequencesarising from the use by other parties of the Rules,Guides, Standards or other criteria of the AmericanBureau of Shipping, without review, plan approvaland survey by the Bureau.

The term approved shall be interpreted to mean

that the plans, reports or documents have been re-viewed for compliance with one or more of the Rules,Guides, Standards, or other criteria of the Bureau.

The Rules are published on the understandingthat responsibility for operation, reasonable handlingand loading, as well as for avoidance of distributionsof loads, which are likely to set up abnormally se-vere stresses in offshore installations, does not restupon the Committee.

1/1.2 Suspension and Cancellation

of Class

1/1.2.1 Termination of Classification

The continuance of the Classification of any offshoreinstallation is conditional upon the Rule require-ments for periodical, damage and other surveys be-ing duly carried out. The Committee reserves theright to reconsider, withhold, suspend, or cancel theclass of any offshore installation or any part of themachinery for noncompliance with the Rules, for de-fects reported by the Surveyors which have not beenrectified in accordance with their recommendations,or for nonpayment of fees which are due on account

of classification and other surveys. Suspension orcancellation of class may take effect immediately orafter a specified period of time.

1/1.2.2 Notice of Surveys

It is the responsibility of the owner to ensure that allsurveys necessary for the maintenance of class arecarried out at the proper time. The Bureau will giveproper notice to an owner of upcoming surveys. Thismay be done by means of a letter, a quarterly vesselstatus or other communication. The non-receipt ofsuch notice, however, does not absolve the owner

from his responsibility to comply with survey re-quirements for maintenance of class.

1/1.2.3 Special Notations

If the survey requirements related to maintenance ofspecial notations are not carried out as required, thesuspension or cancellation may be limited to thosespecial notations only.

1/1.2.4 Suspension of Class Includes:

a Class is suspended for any use, operation, loadingcondition or other application of any offshore in-stallation for which it has not been approved andwhich affects or may affect classification or thestructural integrity, quality or fitness for a par-ticular use or service.

b If the periodical surveys required for maintenanceof class are not carried out by the due date and noRule allowed extension has been granted, classwill be suspended.

c If recommendations issued by the Surveyor arenot carried out within their due dates, class will besuspended.

d Class is suspended for any damage, failure, dete-rioration or repair that has not been completed asrecommended.

e If proposed repairs as referred to in 1/1.15.1have not been submitted to the Bureau andagreed upon prior to commencement, class maybe suspended.

1/1.2.5 Cancellation of Class

a If the circumstances leading to suspension ofclass are not corrected within the time specified,the offshore installations class will be canceled.

b An offshore installations class is canceled imme-diately when an offshore installation resumes op-eration without having completed recommenda-tions which were required to be dealt with beforeresuming operations.

1/1.3 Class Designation

1/1.3.1 Offshore Installations Built Under

Survey

Offshore installations which have been built underthe supervision of the Surveyors of the Bureau to therequirements of these Rules or to their equivalent,where approved by the Classification Committee,will be classed and distinguished in the Record bythe symbols @ A1 Offshore Installation.

Offshore Installations which have been built tothe satisfaction of the Surveyors of the Bureau, to therequirements as contained in the Guide for Buildingand Classing Facilities on Offshore Installationsand/or Guide for Building and Classing Undersea

Pipeline Systems and Risers, and which are ap-proved by the Committee will be classed and distin-


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guished in the Record by the symbols @ A1 OffshoreInstallation followed by the appropriate notation:

@ A1 Offshore InstallationHydrocarbonProcessing

@ A1 Offshore InstallationHydrocarbon

Production@ A1 Offshore InstallationElectric Gener-

ating Plant (electric generating plantex-port load)

@ A1 Offshore InstallationUndersea Pipe-line

@ A1 Offshore InstallationChemical Proc-essing

@ A1 Offshore InstallationMetals/Ore Proc-essing

1/1.3.2 Offshore Installations Not Built Under

SurveyOffshore Installations which have not been built un-der the supervision of the Surveyors of the Bureau,but which are submitted for classification, will besubject to a special classification survey. Wherefound satisfactory, and thereafter approved by theClassification Committee, they will be classed anddistinguished in the Record in the manner as de-scribed as in 1/1.3.1 but the mark @ signifying thesurvey during construction will be omitted.

1/1.3.4 Classification Data

Data on offshore installations will be published inthe Record as to the latitude and longitude of the lo-cation of the structure, structure type, structural di-mensions and the depth of water at the site.

1/1.5 Rules For Classification

1/1.5.1 Application of Rules

These Rules are applicable to offshore installationsas defined in 1/4.1.7 and are generally intended toremain at a particular site for support of offshore fa-cilities.

These Rules are applicable to those features ofthe system that are permanent in nature and can beverified by plan review, calculation, physical surveyor other appropriate means. Any statement in theRules regarding other features is to be considered asa guidance to the designer, builder, owner, et al.

1/1.5.2 Alternatives

The Committee is at all times ready to consider al-ternative arrangements and scantlings which can beshown, through either satisfactory service experience

or a systematic analysis based on sound engineeringprinciples, to meet the overall safety, serviceabilityand strength standards of these Rules. The Commit-

tee will consider special arrangements, or equipment,or machinery which can be shown to comply withstandards recognized in the country in which the off-shore installation is registered or built, provided theyare not less effective.

1/1.5.3 Novel Features

Offshore installations with novel features of designin regard to structural arrangements, machinery,equipment, etc., to which these Rules are not directlyapplicable, may be classed when approved by theCommittee on the basis that these Rules, insofar asapplicable, have been complied with and that specialconsideration has been given to the novel features,based on the best information available at the time.

1/1.5.4 Effective Date of Rule Change

a) Six Month Rule

Changes to these Rules are to become effectivesix (6) months from the date on which the Tech-nical Committee approves them. However, theBureau may bring into force individual changesbefore that date if necessary or appropriate.

b) Implementation of Rule Changes

In general, the Rules in effect will apply unlessapplication of new Rules before their effectivedate is specifically requested by the party sig-natory to the application for classification.

Where designs for one or more offshore instal-lation comply with the Rules applicable at thetime of approval, no retroactive application oflater Rule changes to such offshore installationswill be required unless necessary or appropriate.

1/1.5.5 Other Conditions

The committee reserves the right to refuse classifi-cation of any offshore installation where items forwhich there are Rule requirements are found not inaccordance with the Rules.

1/1.7 Other Regulations

1/1.7.1 Governmental and Other Regulation

While these Rules cover the requirements for theclassification of new offshore installations, the at-tention of Owners, builders, and designers is directedto various governmental regulations which controlstructural, machinery, and electrical features par-ticularly in hazardous areas where gas may be pres-ent or accumulate. Other considerations may includethe arrangement and extent of watertight bulkheads

and decks, fire-retarding bulkheads, the acceptabilityof watertight and weathertight closures, ventilation,and means of escape.


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1/1.7.2 Governmental Regulations

Where authorized by a government agency and uponrequest of the Owners of a classed offshore installa-tion or one intended to be classed, the Bureau willsurvey and certify a new or existing offshore instal-

lation for compliance with particular regulations ofthat government on its behalf.

1/1.9 IACS Audit

The International Association of Classification So-cieties (IACS) conducts audits of process followedby all its member societies to assess the degree ofcompliance with the IACS Quality System Certifi-cation Scheme requirements. For this purpose, audi-tors from IACS may accompany ABS personnel atany stage of the classification or statutory workwhich may necessitate the auditors having access to

the offshore installation or access to the premises ofthe manufacturer or the fabricator.

In such instances, prior authorization for the audi-tors access will be sought by the local ABS office.

1/1.11 Plans and Design Data

to be Submitted

1/1.11.1 Submission of Site Condition Reports

As required in subsequent sections of these Rules,site condition reports are to be submitted. The prin-cipal purpose of these reports is to demonstrate that

site conditions have been evaluated in establishingdesign criteria. Among the items to be discussed are:

Environmental conditions of waves, winds, currents,tides, water depth, air and sea temperature and ice;

Seabed topography, stability, and pertinent geotech-nical data; Seismic conditions;

Where appropriate, data established for a previousinstallation in the vicinity of the installationproposed for classification may be utilized if ac-ceptable in the opinion of the Bureau.

1/1.11.2 Submission of Design Data and

Calculations

Information is to be submitted for the offshore in-stallation which describes the methods of design andanalysis which were employed to establish its de-sign. The estimated design service life of an offshoreinstallation is also to be stated. Where model testingis used as a basis for a design, the applicability of thetest results will depend on the demonstration of theadequacy of the methods employed, including enu-meration of possible sources of error, limits of appli-cability, and methods of extrapolation to full scale

data. Preferably, procedures should be reviewed andagreed upon before model testing is done.

As required in subsequent sections, calculationsare to be submitted to demonstrate the sufficiency ofthe proposed design. Such calculations are to be pre-sented in a logical and well-referenced fashion em-ploying a consistent system of units. Where the cal-culations are in the form of computer analysis the

submitted is to provide input and output data withcomputer generated plots for the structural model. Aprogram description (not listings), user manuals, andthe results of program verification sample problemsmay be required to be submitted.

1/1.11.3 Submission of Plans and Specifications

Plans or specifications depicting or describing the ar-rangements and details of the major items of the off-shore installation are to be submitted for review orapproval in a timely manner.

Where deemed appropriate, and when requestedby the Owner, a schedule for information submittaland plan approval can be jointly established by theOwner and the Bureau. This schedule, which the Bu-reau will adhere to as far as reasonably possible, is toreflect the construction schedule and the complexityof the platform as it affects the time required for re-view of the submitted data.

1/1.11.4 Information Memorandum

An information memorandum on the offshore in-stallation is to be prepared and submitted to the Bu-

reau. The Bureau will review the contents of thememorandum to establish consistency with otherdata submitted for the purpose of obtaining classifi-cation. The Bureau will not review the contents ofthe memorandum for their accuracy or the featuresdescribed in the memorandum for their adequacy.

An information memorandum is to contain, asappropriate to the installation, the following:

Site plan indicating the general features at the siteand the exact location of the installation;

Environmental design criteria, including the recur-rence interval used to assess environmental phe-nomena (see 3/1.5.1);

Plans showing the general arrangement of the off-shore installation;

Description of the safety and protective systems pro-vided;

The number of personnel to be normally stationed atthe installation;

Listing of governmental authorities having cogni-zance over the installation;

Listing of any novel features;Brief description of any monitoring proposed for use

on the installation;

Description of transportation and installation proce-dures.


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1/1.15 Conditions for Surveys after

Constructions

1/1.15.1 Damage, Failure and Repair

a) Examination and Repair Damage to off-

shore installation structure, machinery, equipment,or which affects or may affect classification, is to besubmitted by the Owners or their representatives forexamination by the Surveyor, at the first opportunity.All repairs found necessary by the Surveyor are to becarried out to his satisfaction.

b)Representation Nothing contained in thissection or in a rule or regulation of any governmentor other administration, or the issuance of any reportor certificate pursuant to this section or such a rule orregulation, is to be deemed to enlarge upon the rep-resentations expressed in 1/1.1.1 through 1/1.1.4thereof and the issuance and use of any such reports

or certificates are to be governed in all respects by1/1.1.1 through 1/1.1.4 thereof.

1/1.15.2 Notification and Availability for Survey

The Surveyors are to have access to classed offshoreinstallations at all reasonable times. For the purpose ofSurveyor monitoring, monitoring surveyors shall alsohave access to classed offshore installations at all rea-sonable times. Such access may include attendance atthe same time as the assigned Surveyor or during asubsequent visit without the assigned Surveyor.

The offshore installations Surveyors are to un-dertake all surveys on classed offshore installationsupon request, with adequate notification, of theOwners or their representatives and are to reportthereon to the Committee. Should the Surveyors findoccasion during any survey to recommend repairs orfurther examination, notification is to be given im-mediately to the Owners or their representatives inorder that appropriate action may be taken.

The Surveyors are to avail themselves of everyconvenient opportunity for carrying out periodicalsurveys in conjunction with surveys of damages andrepairs in order to avoid duplication of work.

1/1.15.3 Attendance at Port State Request

It is recognized that port State authorities legallymay have access to an installation. In cooperationwith port States, ABS Surveyors will attend on boarda classed installation when so requested by a portState, and upon concurrence of the offshore installa-tions owner, will carry out a survey in order to fa-cilitate the rectification of reported deficiencies orother discrepancies that affect or may affect classifi-cation. ABS Surveyors will also cooperate with PortStates by providing inspectors with background in-

formation, if requested. Such information includestext of conditions of class, survey due dates, andcertificate expiration dates.

Where appropriate, the offshore installationsflag state will be notified of such attendance and sur-vey.

1/1.17 Fees

Fees in accordance with normal ABS schedules willbe charged for all services rendered by the Bureau.Expenses incurred by the Bureau in connection withthese services will be charged in addition to the fees.Fees and expenses will be billed to the party re-questing that particular service.

1/1.19 Disagreement

1/1.19.1 Rules

Any disagreement regarding either the proper inter-pretation of the Rules, or translation of the Rulesfrom the English language edition, is to be referredto the Bureau for resolution.

1/1.19.2 Surveyors

In case of disagreement between the Owners orbuilders and the Surveyors regarding the material,workmanship, extent of repairs, or application of theRules relating to any offshore installations classed orproposed to be classed by this Bureau, an appeal

may be made in writing to the Committee who willorder a special survey to be held. Should the opinionof the Surveyor be confirmed, the expense of thisspecial survey is to be paid by the party appealing.

1/1.21 Limitation of Liability

The combined liability of the American Bureau ofShipping, its committees, officers, employees, agentsor subcontractors for any loss, claim, or damagearising from its negligent performance or nonper-formance of any of its services or from breach of any

implied or expressed warranty of workmanlike per-formance in connection with those services, or fromany other reason, to any person, corporation, partner-ship, business entity, sovereign, country or nation,will be limited to the greater of a) $100,000 or b) anamount equal to ten (10) times the sum actually paidfor the services alleged to be deficient.

The limitation of liability may be increased upto an amount twenty-five times that sum paid forservices upon receipt of Clients written request at orbefore the time of performance of services and uponpayment by Client of an additional fee of $10.00 forevery $1,000.00 increase in the limitation.


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Surveys During Construction and Installation Section 2


Part 1

Section 2 Surveys During Construction

and Installation

1/2.1 General

1/2.1.1 Scope

This section pertains to surveys during the construc-tion and installation of an offshore structure. The re-quirements of 1/2.1 are to apply to all structures cov-ered by these Rules regardless of structural type.Additional requirements specifically for steel struc-tures are contained in 1/2.3 and additional require-

ments for concrete structures are contained in 1/2.5.The phases of construction covered by this sec-

tion include: material manufacture, fabrication, load-out, transportation, positioning, installation and finalfield erection.

1/2.1.2 Quality Control Program

A quality control program compatible with the type,size and intended function of the planned structure isto be developed and submitted to the Bureau for re-view. The Bureau will review, approve and, as neces-sary, request modification of this program. The Fabri-

cator is to work with the attending Surveyor toestablish the required hold points on the quality con-trol program to form the basis for all future surveys atthe fabrication yard. As a minimum, the items enu-merated in the various applicable subsections beloware to be covered by the quality control program. Sur-veyors will be assigned to monitor the fabrication ofclassed structures and assure that all tests and inspec-tions specified in the quality control program are be-ing carried out by competent personnel. It is to benoted that the monitoring provided by the Bureau is asupplement to and not a replacement for inspections tobe carried out by the Fabricator or Operator.

1/2.1.3 Access and Notification

During construction, Surveyors are to have access tostructures at all reasonable times. The attending Sur-veyor is to be notified as to when and where parts ofthe structure may be examined. If, at any visit, Sur-veyors find occasion to recommend repairs or furtherinspection, notice is to be made to the Fabricator orhis representatives.

1/2.1.4 Identification of Materials

The fabricator is to maintain a system of materialtraceability to the satisfaction of the attending Sur-

veyor, for all special and primary applicationstructures. Data as to place of origin and results ofrelevant material tests for structural materials shallbe retained and made readily available during allstages of construction (see 1/2.3.12 and 1/2.5.9).Such data are to be available to the Surveyors uponrequest.

1/2.3 Steel Structures1/2.3.1 Quality Control Program

The quality control program (see 1/2.1.2) for theconstruction of a steel structure is to include the fol-lowing items, as appropriate.

Material quality and traceabilitySteel FormingWelder qualification and recordsWelding procedure specifications and qualificationsWeld inspectionTolerances alignments and compartment testing

Corrosion control systemsTightness and hydrostatic testing proceduresNondestructive testingInstallation of main structure

The items which are to be considered for each of thetopics, mentioned above are indicated in 1/2.3.2through 1/2.3.11.

1/2.3.2 Material Quality and Traceability

The properties of the material are to be in accor-dance with Section 1 of Part 2. Manufacturers cer-tificates are to be supplied with the material. Veri-fication of the materials quality is to be done bythe Surveyor at the plant of manufacture, in accor-dance with Section 2/1 of ABS Requirements for Materials and Welding. Alternatively materialmanufactured to recognized standards may be ac-cepted in lieu of the above Steel Requirements pro-vided the substitution of such materials is approvedby the Bureau. Materials used are to be in accor-dance with those specified in the approved designand all materials required for classification pur-poses are to be tested in the presence of an ABSSurveyor. The Constructor is to maintain a material

traceability system for all the Primary and Specialapplication structures.


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1/2.3.3 Steel Forming

When forming changes base plate properties beyondacceptable limits, appropriate heat treatments are tobe carried out to reestablish required properties. Un-less approved otherwise, the acceptable limits of the

reestablished properties should meet the minimumsspecified for the original material before forming.The Bureau will survey formed members for theircompliance with the forming dimensional tolerancesrequired by the design.

1/2.3.4 Welder Qualification and Records

Welders who are to work on the structure are to bequalified in accordance with the welder qualificationtests specified in a recognized code or, as applicable,ABSRule Requirements for Materials and Weldingto the satisfaction of the attending Surveyor. Certifi-

cates of qualification are to be prepared to recordevidence of the qualification of each welder qualifiedby an approved standard/code, and such certificatesare to be available for the use of the Surveyors. Inthe event that welders have been previously tested inaccordance with the requirements of a recognizedcode and provided that the period of effectiveness ofthe previous testing has not lapsed, these welderqualification tests may be accepted.

1/2.3.5 Welding Procedure Specifications

and Qualifications

Welding procedures are to be approved in accor-dance with ABS Rule Requirements for Materialsand Welding. Welding procedures conforming to theprovisions of a recognized code may, at the Sur-veyor's discretion, be accepted. A written descriptionof all procedures previously qualified may be em-ployed in the structures construction provided it isincluded in the quality control program and madeavailable to the Surveyors. When it is necessary toqualify a welding procedure, this is to be accom-plished by employing the methods specified in therecognized code, and in the presence of the Sur-

veyor.

1/2.3.6 Weld Inspection

As part of the overall quality control program, a de-tailed plan for the inspection and testing of welds isto be prepared and this plan is to include the applica-ble provisions of this Section of these Rules.

1/2.3.7 Tolerances and Alignments

The overall structural tolerances, forming tolerances,and local alignment tolerances are to commensurate

with those considered in developing the structuraldesign. Inspections are to be carried out to ensurethat the dimensional tolerance criteria are being met.

Particular attention is to be paid to the out-of-roundness of members for which buckling is an an-ticipated mode of failure. Structural alignment andfit-up prior to welding shall be monitored to ensureconsistent production of quality welds.

1/2.3.8 Corrosion Control Systems

The details of any corrosion control systems em-ployed for the structure are to be submitted for re-view. Installation and testing of the corrosion controlsystems are to be carried out to the satisfaction of theattending Surveyor in accordance with the approvedplans.

1/2.3.9 Tightness and Hydrostatic Testing

Procedures

Compartments which are designed to be permanently

watertight or to be maintained watertight during in-stallation are to be tested by a procedure approved bythe attending Surveyor. The testing is also to be wit-nessed by the attending Surveyor.

1/2.3.10 Nondestructive Testing

A system of nondestructive testing is to be includedin the fabrication specification of the structures. Theminimum extent of nondestructive testing shall be inaccordance with these Rules or recognized designCode. All nondestructive testing records are to be re-viewed and approved by the attending Surveyor. Ad-

ditional nondestructive testing may be requested bythe attending Surveyor if the quality of fabrication isnot in accordance with industry standards.

1/2.3.11 Installation of Main Structure

Upon completion of fabrication and when the struc-ture is to be loaded and transported to site for instal-lation, the load-out, tie-down and installation are tobe surveyed by an attending Surveyor from the Bu-reau. All load-out, transportation and installationprocedures are to be submitted to the Bureau for re-view and approval as described in Section 3/7.

The Surveyor is to verify the following activi-ties, as applicable to the planned structure, to ascer-tain whether they have been accomplished in a man-ner conforming to the approved procedures.

Load-out and Tie-downLaunching, flotation, lifting and up-endingPositioning at the site and levelingInstallation of Decks and ModulesPiling and GroutingWelding and Nondestructive TestingFinal field erection and levelingPre-Tensioning

Significant deviations from approved plans and pro-cedures or any incidents such as excessive titling of


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the jacket or abnormal vibrations during pile drivingmay require resubmittal of supporting documentationto provide an assessment of the significance of devia-tion and any necessary remedial actions to be taken.

To ensure that overstressing of the structureduring transportation has not occurred, the Bureau is

to have access to towing records to ascertain if con-ditions during the towing operations exceeded thoseemployed in the analyses required in Section 3/7.

1/2.3.12 Records

A data book of the records of construction activitiesis to be developed and maintained so as to compile arecord as complete as practicable. The pertinent rec-ords are to be adequately prepared and indexed to as-sure their usefulness, and they are to be stored so thatthey may be easily recovered.

For a steel structure, the construction record is to

include, as applicable, the following: material trace-ability records including mill certificates, weldingprocedure specification and qualification records,shop welding practices, welding inspection records,construction specifications, structural dimensioncheck records, nondestructive testing records, rec-ords of completion of items identified in the qualitycontrol program and towing and pile driving records,position and orientation records, leveling and eleva-tion records, etc. The compilation of these records isa condition of classing the structure.

After fabrication and installation, these records

are to be retained by the Operator or Fabricator forfuture references. The minimum time for record re-tention is not to be less than the greatest of the fol-lowing: the warranty period, the time specified inconstruction agreements, or the time required bystatute or governmental regulations.

1/2.5 Concrete Structures

1/2.5.1 Quality Control Program

The quality control program (see 1/2.1.2) for a con-crete structure is to cover the following items, as ap-propriate.

Inspections prior to concretingInspection of batching, mixing and placing concreteInspections of form removal and concrete curingInspection of prestressing and groutingInspection of jointsInspection of finished concreteInstallation of Main StructureTightness and Hydrostatic testing as applicable(See 1/2.3.9)

The items which are to be considered for each of thetopics mentioned above are indicated in 1/2.5.2

through 1/2.5.8.

1/2.5.2 Inspections Prior to Concreting

Prior to their use in construction, the manufacturersof cement, reinforcing rods, prestressing tendons andappliances are to provide documentation of the perti-nent physical properties. These data are to be made

available to the attending Surveyor who will checkconformity with the properties specified in the ap-proved design.

As applicable, at the construction site, the Sur-veyor is to be satisfied that proper consideration isbeing given to the support of the structure duringconstruction, the storage of cement and prestressingtendons in weathertight areas, the storage of admix-tures and epoxies to manufacturers specifications,and the storage of aggregates to limit segregation,contamination by deleterious substances and mois-ture variations within the stock pile.

Forms and shores supporting the forms are to be

inspected to insure that they are adequate in numberand type, and that they are located in accordancewith the approved plans. The dimensions and align-ment of the forms are to be verified by the attendingSurveyor, and the measurements are to be within theallowable finished dimensional tolerances specifiedin the approved design.

Reinforcing steel, prestressing tendons, post-tensioning ducts, anchorages and any included steelare to be checked, as appropriate to the plannedstructure, for size, bending, spacing, location, firm-ness of installation, surface condition, vent locations,

proper duct coupling, and duct capping.

1/2.5.3 Inspection of Batching, Mixing and

Placing Concrete

The production and placing of the concrete are toemploy procedures which will provide a well mixedand well compacted concrete. Such procedures arealso to limit segregation, loss of material, contami-nation, and premature initial set during all opera-tions.

Mix components of each batch of concrete are tobe measured by a method specified in the quality

control program. The designer is to specify the al-lowable variation of mix component proportions, andthe constructor is to record the actual proportions ofeach batch.

Testing during the production of concrete is tobe carried out following the procedures specified inthe quality control program. As a minimum, the fol-lowing concrete qualities are to be measured by theConstructor.

ConsistencyAir contentDensity or Specific Gravity

Strength


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Field testing of aggregate gradation, cleanliness,moisture content, and unit weight is to be performedby the constructor following standards and schedulesspecified in the quality control program. The fre-quency of testing is to be determined taking into ac-count the uniformity of the supply source, volume of

concreting, and variations of atmospheric conditions.Mix water is to be tested for purity following meth-ods and schedules specified in the quality controlprogram.

1/2.5.4 Inspections of Form Removal and

Concrete Curing

The structure is to have sufficient strength to bear itsown weight, construction loads and the anticipatedenvironmental loads without undue deformations be-fore forms and form supports are removed. Theschedule of form removal is to be specified in the

quality control program, giving due account to theloads and the anticipated strength.

Curing procedures for use on the structure are tobe specified in the quality control program. Whenconditions at the construction site cause a deviationfrom these procedures, justification for these devia-tions is to be fully documented and included in theconstruction records.

Where the construction procedures require thesubmergence of recently placed concrete, specialmethods for protecting the concrete from the effectsof salt water are to be specified in the quality control

program. Generally, concrete should not be sub-merged until 28 days after placing. (See also3/5.11.2e.)

1/2.5.5 Inspection of Prestressing and Grouting

A schedule indicating the sequence and anticipatedelongation and stress accompanying the tensioningof tendons are to be prepared. Any failures toachieve proper tensioning are to be immediately re-ported to the designer to obtain guidance as toneeded remedial actions.

Pre- or post-tensioning loads are to be deter-

mined by measuring both tendon elongation and ten-don stress. These measurements are to be compared,and should the variation of measurements exceed thespecified amount, the cause of the variation is to bedetermined and any necessary corrective actions areto be accomplished.

The grout mix is to conform to that specified inthe design. The constructor is to keep records of themix proportions and ambient conditions during groutmixing. Tests for grout viscosity, expansion andbleeding, compressive strength, and setting time areto be made by the constructor using methods and

schedules specified in the quality control program.Employed procedures are to ensure that ducts arecompletely filled.

Anchorages are to be inspected to ensure thatthey are located and sized as specified in the design.Anchorages are also to be inspected to assure thatthey will be provided with adequate cover to mitigatethe effects of corrosion.

1/2.5.6 Inspection of Joints

Where required, leak testing of construction joints isto be carried out using procedures specified in thequality control program. When deciding which jointsare to be inspected, consideration is to be given tothe hydrostatic head on the subject joint during nor-mal operation, the consequence of a leak at the sub-

ject joint, and the ease of repair once the platform isin service.

1/2.5.7 Inspection of Finished Concrete

The surface of the hardened concrete is to be com-pletely inspected for cracks, honeycombing, pop-outs, spalling and other surface imperfections. Whensuch defects are found, their extent is to be reportedto the Surveyor and to the designer for guidance onany necessary repairs.

The structure is to be examined using a calibratedrebound hammer or a similar nondestructive testingdevice. Where the results of surface inspection, cylin-der strength tests or nondestructive testing do not meetthe design criteria, the designer is to be consulted re-garding remedial actions which are to be taken.

The completed sections of the structure are to bechecked for compliance to specified design toler-ances for thickness, alignment, etc., and to the extentpracticable, the location of reinforcing andprestressing steel and post-tensioning ducts. Varia-tions from the tolerance limits are to be reported tothe designer for evaluation and guidance as to anynecessary remedial actions.

1/2.5.8 Installation of Main Structure

Upon completion of fabrication and when the struc-ture is to be loaded and transported to site for instal-lation, the load-out, tie-down and installation proce-dures are to be surveyed by an attending Surveyorfrom the Bureau. All load-out, transportation and in-stallation procedures are to be submitted to the Bu-reau for review and approval.

The Surveyor is to witness the following opera-tions, as applicable to the planned structure, to verifythat they have been accomplished in a manner con-forming to plans or drawings covering these operations.

Load-out and tie-downTowing arrangementsPositioning at the site

InstallationFinal field erectionPre-Tensioning


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Significant deviations from approved plans and pro-cedures may require resubmittal of supportingdocumentation to provide an assessment of the sig-nificance of the deviation and the remedial actions tobe taken.

To ensure that overstressing of the structure

during transportation has not occurred, the Bureau isto have access to towing records to ascertain if con-ditions during the towing operations exceeded thoseemployed in the analyses required in Section 3/7.Results are to be submitted to demonstrate compli-ance with the reviewed design analysis.

1/2.5.9 Records

Reference is to be made to 1/2.3.12 regarding theneed to compile construction records. For a concretestructure, the construction records are to include, asapplicable, all material certificates and test reports,

tensioning and grouting records, concrete records in-cluding weight, moisture content and mix propor-tions, a listing of test methods and results, ambientconditions during the pours, calibration data for testequipment, towing records, data on initial structuralsettlements, and the inspectors logs. These recordsare to be retained by the Operator.


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.


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Surveys After Construction Section 3


Part 1

Section 3 Surveys After Construction

(Platforms and Self-Elevating Units in Site Dependent Services)

1/3.1 Condition for Surveys after

Construction

1/3.1.1 Damages, Failure and Repair

a Examination and Repair

Damage, failure, deterioration or repair to the classedstructure, which affects or may affect classification,is to be submitted by the Owner or their representa-

tives for examination by the Surveyor at first oppor-tunity. All repairs found necessary by the Surveyorare to be carried out to his satisfaction.

b Repairs on Site

Where repairs to the structure, which affect or mayaffect classification, are intended to be carried out atsite, complete repair procedure including the extentof proposed repair and the need for Surveyors atten-dance on site is to be submitted to and agreed uponby the Surveyor reasonably in advance. The above isnot intended for routine maintenance.

c Representation

Nothing contained in this section or in a regulationof any government or other administration, or the is-suance of any report or certificate pursuant to thissection or such a rule or regulation, is to be deemedto enlarge upon the representations expressed inSection 1/1 of these rules.

1/3.1.2 Notification and Availability for Survey

The Surveyors are to have access to a classed struc-ture at all reasonable times. The Surveyors are to un-

dertake all surveys on classed installation upon re-quest, with adequate notification, from the Ownersor their representatives and are to report thereon tothe committee. Should the Surveyors find occasionduring any survey to recommend repairs or furtherexamination, notification is to be given immediatelyto the Owners or their representatives so that appro-priate action may be taken. The Surveyors are toavail themselves of every convenient opportunity forcarrying out periodical surveys in conjunction withsurveys of damages and repairs in order to avoid du-plication of work. For the purpose of Surveyormonitoring, monitoring surveyors shall also have ac-

cess to classed offshore installations at all reasonabletimes. Such access may include attendance at the

same time as the assigned Surveyor or during a sub-sequent visit without the assigned Surveyor.

1/3.1.3 Annual Surveys

Annual Class Surveys of the structures are to bemade within three months either way of each annualanniversary date of crediting of the previous specialsurvey or original construction date. Where Survey-

ors are engaged in the survey of a grouping of struc-tures of similar design and location, and where re-quested by the operator, special consideration will begiven to the timing of annual surveys and specialsurveys such that all periodical survey due dates canbe harmonized.

1/3.1.4 Special Periodic Surveys

Special surveys are to carried out at least once everyfive years. If a special survey is not completed at onetime, it will be credited as of the completion date ofthe survey provided the due date of the special peri-odical survey is not overdue by more than six (6)months. Where Surveyors are engaged in the surveyof a grouping of structures of similar design and lo-cation, and where requested by the Operator, specialconsideration will be given to the timing of SpecialSurveys so that the due dates for all periodical sur-veys can be harmonized.

1/3.1.5 Continuous Surveys

At the request of the Operator, and upon approval ofthe proposed arrangement, a system of Continuous

Surveys may be undertaken whereby all the SpecialSurvey requirements are carried out in regular rota-tion and completed within the normal Special Surveyinterval. For Continuous Surveys, a suitable notationwill be entered in the Record and the date of com-pletion of the cycle published. If any defects arefound during this Survey, they are to be examinedand dealt with to the satisfaction of the Surveyor.

1/3.1.6 Reactivation Surveys

In the case of structures which have been out ofservice for an extended period, the requirements for

surveys on reactivation are to be specially consideredin each case, due regard being given to the status of


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surveys at the time of the commencement of the de-activation period, the length of the period, and con-ditions under which the structure had been main-tained during that period.

1/3.1.7 Incomplete Surveys

When a survey is not completed, the Surveyors are toreport immediately upon the work done in order thatthe Operator and the Committee may be advised ofthe parts still to be surveyed.

1/3.1.8 Alterations

No major alterations which affect classification ofthe installation are to be made to a classed structureunless plans of the proposed alterations are submit-ted and approved by the Bureau before the altera-tions are undertaken. Such alterations are to be car-

ried out to the satisfaction of the Surveyors. Nothingcontained in this section or in a rule or regulation ofany government or other administration, or the issu-ance of any report or certificate pursuant to this sec-tion or such a rule or regulation, is to be deemed toenlarge upon the representations expressed in 1/1.1.1through 1/1.1.4 and the issuance and use of any suchreports or certificates are to be, in all respects, gov-erned by 1/1.1.1 through 1/1.1.4

1/3.1.9 Self Elevating Units Deployed as

Offshore Installation

Self-elevating Mobile Offshore Units which havebeen converted to site dependent platform structureswill be subjected to surveys as applicable in thesesections in addition to the applicable structural ex-aminations required by the ABS Rules for Buildingand Classing Mobile Offshore Drilling Units. Sur-veys are to include Annual and Special Surveys withan underwater exam in lieu of drydocking of theabove mudline sections of the legs, mats, spud cansand platform twice in each five year Special Surveyperiod in accordance with applicable sections of theABS Mobile Offshore Drilling Units Rules. Spud

cans and mats which will be located below the mudline will be considered inaccessible and fatigue,structural and corrosion analyses shall be provided to

justify the integrity of these inaccessible areas for thedesign life of the installation.

1/3.1.10 Survey for Extension of Use

Existing installations to be used at the same locationfor an extended period of time beyond their originaldesign life are subject to additional surveys to deter-mine the actual condition of the platform. The extentof the survey will depend on the completeness of theexisting survey documents. ABS will review andverify maintenance manual, logs and records. Any

alterations, repairs or installation of equipment sinceinstallation should be included in the records.

Those survey requirements in 1/3.5 for the spe-cial survey have to be included in the survey for ex-tension of use. The surveys generally cover exami-nation of splash zone, inspection of above water and

underwater structural members and welds for dam-ages and deteriorations, examination and measure-ments of corrosion protection systems and marinegrowth, sea floor condition survey, examination ofsecondary structural attachments, risers and riserclamps. Special attention should be given to the fol-lowing critical areas.

Areas of high stressAreas of low fatigue lifeDamage incurred during installation or while

in serviceRepairs or modifications made while in service

Abnormalities found during previous surveys.An inspection report of the findings is to be

submitted to ABS for review and evaluation ofthe condition of the platform.

The need for more frequent future periodical surveyswill be determined based on the calculated remainingfatigue life described in Section 4/1 and past inspec-tion results.

1/3.1.11 Relocation of Existing Installations

Existing installations that are classed at a specified

location require special consideration when reloca-tion to a new site is proposed. The Owner is to ad-vise ABS of the proposal to change locations ad-dressing removal, transportation and re-installationaspects of the change. Survey requirements de-scribed in Section 1/2 and 1/3.1.10, wherever appli-cable, are to be complied with in addition to an engi-neering analyses required to justify the integrity ofthe installation for the design life at the new location.

1/3.3 Annual Surveys

Each annual survey is to include a thorough visualexamination of all above water structure. Special at-tention will be given to the splash zone for possibledamage or deterioration from corrosion. Addition-ally, where it appears that significant deterioration ordamage has occurred to an installation since the lastsurvey, a general examination, by diver, underwatercamera, submersible, or other suitable means, of theunderwater structure, the sea floor, and the corrosioncontrol system shall be carried out. Underwater ex-aminations are to be contracted by the Operator andmonitored by a Surveyor.

Any novel features incorporated in the designare to be given special attention according to proce-dures agreed to during review of the design.


25/94



Particular attention is to be given to significantmodifications or repairs made as a result of findingsat the previous survey.

The Annual Survey is also to include verifica-tion that the approved design life has not been ex-ceeded. The surveyor is to confirm the design life

limits and the technical office should be consultedfor verification. If the end of the design life has beenreached then the provisions of Section 4/1 are to beapplied and specific requirements for maintaining theclass of the structure are to be obtained from thetechnical office.

1/3.5 Special Periodic Surveys

The requirements of the Annual Survey are to be metduring the Special Periodic Survey. Additionally,underwater inspection of selected areas of the in-stallation is to be carried out. Also, nondestructivetesting is to be carried out on representative joints ofthe structures and if found necessary, structural sup-ports of conductors and risers. The extent and meth-ods to be employed in such testing, cleaning, and in-spection of the structure are to be in accordance withan approved inspection plan. The inspection plan,which is to be submitted for approval, is to cover allspecial surveys for the design life of the structure. Itis to enumerate in detail the items to be surveyed, thetesting and inspection procedures to be employed,and where necessary, cleaning and nondestructivetesting procedures. The plan is to include sufficiently

detailed drawings which can be used by the Surveyorto reference and locate the items to be surveyed. Thetesting, cleaning, and inspection services are to beprovided by the Operator and monitored by a Sur-veyor. Divers carrying out structural inspections andnondestructive testing on the structures are to besuitably qualified.

The special survey is also to include monitoringof the effectiveness of the corrosion protection sys-tem. The effectiveness of the corrosion protectionsystem is to be monitored by taking measurements ofthe potential voltages generated by such systems.

Scour in way of platform legs, tilt and subsidence arealso to be checked and witnessed by the attendingsurveyor.

The Special Periodic Survey is also to includeverification that the approved design life has notbeen exceeded. The surveyor is to confirm the designlife limits and the technical office should be con-sulted for verification. If the end of the design lifehas been reached then the provisions of Section 4/1are to be applied and specific requirements formaintaining the class of the structure are to be ob-tained from the technical office.

1/3.7 Gaugings

Thickness gaugings are required to be taken at eachSpecial Survey. Suspect areas including structures inway of the splash zone are to be tested for thickness andresults submitted to the attending Surveyor for review.

Offshore installations consisting of converted self-elevating units will require thickness gauging where ac-cessible in accordance with the applicable gauging re-quirements contained in the ABS Rules for Buildingand Classing Mobile Offshore Drilling Units.

1/3.9 Structural Deterioration

Where thickness measurement and visual examinationshow evidence of significant structural deteriorationthe structural integrity of the structure for continuoususe shall be justified by engineering analyses. Deterio-rated structural members should be modeled such that

they will add hydrodynamic or wind loads to the plat-form, but will not continue the strength of platform.Results of these analyses are to be submitted to ABSfor review and approval. If the results show that overall structural integrity of platform is adequate, the de-teriorated structural members may be left as it is. Ot h-erwise the deteriorated structural members are to besuitably reinforced or removed and replaced with newmaterials having required dimensions and propertiesin accordance with approved procedure.

1/3.11 Maintenance of Marine Growth

During any Annual or Special Survey, assessment ofthe degree of marine growth shall be carried out.Should marine growth be found to be thicker thanthe original approved design, it is to be removed. Ifthe Operator decides to leave the marine growthgreater than what is allowed in the approved design,the Operator is to show justification that the higherhydrodynamic loading due to the additional marinegrowth will not affect the structural integrity of thestructure. The Operator is to at least submit an in-place analysis to justify that the installation is capa-ble of withstanding environmental wave loads re-

sulting from the maximum marine growth that theOperator is prepared to maintain.

1/3.13 Statutory Certification

When the Bureau is authorized to perform certifica-tion on behalf of a governmental authority, or whenrequested by the Operator, requirements as specifiedby the governmental authority or Operator shall becertified accordingly and the reports and certificatesin accordance with those requirements shall be is-sued as appropriate.


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.


27/94

Definitions and Design Documentation Section 4


Part 1

Section 4 Definitions and Design

Documentation

1/4.1 Definitions

1/4.1.1 Recurrence Period

The recurrence period is a specified period of timewhich is used to establish design values of randomparameters such as wave height.

1/4.1.2 Owner

An owner is any person or organization who ownsthe platform.

1/4.1.3 Operator

An operator is any person or organization empow-ered to conduct operations on behalf of the Ownersof an installation.

1/4.1.4 Constructor

A constructor is any person or organization havingthe responsibility to perform any or all of the fol-

lowing: fabrication, erection, inspection, testing,load-out, transportation, and installation.

1/4.1.5 Consultant

A consultant is any person who, through educationand experience, has established credentials of profes-sionalism and expertise in the stated field.

1/4.1.6 Surveyor

A Surveyor is a person employed by the Bureauwhose principal functions are the surveillance during

construction and the survey of marine structures andtheir components for compliance with Bureau-issuedRules or other standards deemed suitable by the Bu-reau.

1/4.1.7 Offshore Installations

A buoyant or nonbuoyant structure, supported by orattached to the sea floor, whose design is based onfoundation and long term environmental conditionsat a particular installation site where it is intended toremain. The sea floor attachment afforded to theplatform may be obtained by pilings, direct bearing,

mooring lines, anchors, etc. The site-specific data foran offshore installation employed by the designer

and submitted for review by the Bureau will form apart of its classification.

Examples of structures covered by these Rulesare the types of fixed structures characterized as pilesupported or gravity platforms, various forms ofcompliant structures, and other moored buoyantstructures. Specifically excluded from the coverageof these Rules are mobile units and manned sub-mersibles, which are treated in Rules separately is-

sued by the Bureau. Where doubt exists concerningthe applicability of these Rules clarification may beobtained from the Bureau.

An offshore installation consists of one or moreof the following.

I. Platform StructureII. Undersea Pipeline Systems and RisersIII. Offshore Facilities

a. Machinery, Electrical and Piping Systemsb. Production Equipment

1/4.1.8 Platform Structures

Various types of offshore structures to which theseRules may be applied are defined below.

Pile Supported Platform This type of structureis characterized by slender foundation elements, orpiles, driven into the sea floor.

Gravity Structure This type of structure restsdirectly on the sea floor. The geometry and weight ofthe structure are selected to mobilize the availablecohesive and frictional strength components of thesea floor soil to resist loadings.

Compliant Tower This type of structure con-sists of a slender tower supported at the sea floor byan installed foundation (or by a large spud can) andmay also be partially supported by buoyancy aids.Guy lines may or may not be used for lateral re-straint.

Various provisions of these Rules are to be ap-plied to partially or fully buoyant structures whichare permanently (see 1/1.5.1) connected to the seafloor by mooring lines or other non-rigid means.Structural types including the articulated buoyanttower and the tension leg platform, which are de-fined below, are included in this category. For thesebuoyant structures, classification will be based on

compliance with the applicable portions of theseRules, those of the Bureaus Rules for Building and


28/94



Classing Mobile Offshore Drilling Units, and otherrequirements which the Bureau, in consultation withthe Owner, deems appropriate.

Articulated Buoyant Tower This type of struc-ture depends on buoyancy acting near the water sur-face to provide necessary righting stability. Because

of its tendency towards relatively large horizontaldisplacements, the articulated buoyant structure canbe provided with a pivot near the sea floor.

Tension Leg Platform This type of structure isfully buoyant and is restrained below its natural flo-tation line by mooring elements which are attachedin tension to gravity anchors or piles at the sea floor.

Additionally, these Rules may be employed, asapplicable, in the classification of structural types notmentioned above, when they are to be used as per-manent offshore installations (see 1/1.5.3).

1/4.1.9 Extension of Use

An existing platform to be used at the same locationfor a specified period of time beyond its original de-sign life. See Section 4/1.

1/4.1.10 Reuse

An existing platform to be moved to a new locationto continue its operation for a specified period oftime. See Section 4/2.

1/4.3 Design Documentation

The design documentation to be submitted is to in-clude the reports, calculations, plans, and otherdocumentation necessary to verify the structural de-sign. The extensiveness of the submitted documen-tation should reflect the uniqueness of the structureor the lack of experience with conditions in the areawhere the structure is to be located. In general, sig-nificantly less detailed documentation is required fora pile supported platform in calm, shallow watersthan for an unusual structural configuration sited indeep waters. Existing documentation may be usedwhere applicable.

1/4.3.1 Reports

Reports by consultants and other specialists used as abasis for design are to be submitted for review. Thecontents of reports on environmental considerations,foundation data, and materials are, in general, tocomply with the recommended list of items givenbelow.

a Environmental Considerations Reports onenvironmental considerations are to describe all en-vironmental phenomena appropriate to the areas of

construction, transportation, and installation. Thetypes of environmental phenomena to be accountedfor, as appropriate to the type and location of the

structure, are: wind, waves, current, temperature,tide, marine growth, chemical components of air andwater, snow and ice, earthquake, and other pertinentphenomena.

The establishment of the environmental pa-rameters is to be based on appropriate original data

or, when permitted, data from analogous areas. De-monstrably valid statistical models to extrapolate tolong-term values are to be employed, and any calcu-lations required to establish the pertinent environ-mental parameters should be submitted.

Preferably, a report on the various environ-mental considerations is to present data and conclu-sions on the relevant environmental phenomena. Thereport is, however, required to separately present asummary showing the parameters necessary to definethe Design Environmental Condition and OperatingEnvironmental Conditions, as defined in Section 3/1;

where applicable, the likely environmental condi-tions to be experienced during the transportation ofthe structure to its final site; and where necessary,the Strength and Ductility Level Earthquakes, as de-fined in 3/1.5.1.

The report on environmental considerations mayalso contain the calculations which quantify the ef-fects or loadings on the structure where these are notprovided in other documentation.

b Foundation Data A report on foundationdata is to present the results of investigations or,when applicable, data from analogous areas on geo-physical, geological and geotechnical considerationsexisting at and near the platform site. The manner inwhich such data is established and the specific itemsto be assessed are to be in compliance with 3/6.3.The report is to contain a listing of references tocover the investigation, sampling, testing, and inter-pretive techniques employed during and after the siteinvestigation.

The report is to include a listing of the predictedsoil-structure interaction, such as p-y data, to be usedin design. As appropriate to the planned structure,the items which may be covered are: axial and lateralpile capacities and response characteristics, the ef-

fects of cyclic loading on soil strength, scour, settle-ments and lateral displacements, dynamic interactionbetween soil and structure, the capacity of pilegroups, slope stability, bearing and lateral stability,soil reactions on the structure, and penetration resis-tance.

Recommendations relative to any special antici-pated problem regarding installation are to be in-cluded in the report. Items such as the following areto be included, as appropriate: hammer sizes, soilerosion during installation, bottom preparation, andprocedures to be followed should pile installation

procedures significantly deviate from those antici-pated.


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c Materials and Welding Reports on structuralmaterials and welding may be required for metallicstructures, concrete structures or welding procedureswhere materials and procedures are used which donot conform to those provided for in Sections 2/1and 2/2.

For metallic structures, when it is intended toemploy new alloys not defined by a recognizedspecification, reports are to be submitted indicatingthe adequacy of the materials metallurgical proper-ties, fracture toughness, yield and tensile strengths,and corrosion resistance, with respect to their in-tended application and service temperatures.

For concrete structures, when it is not intended totest or define material properties in accordance withapplicable standards of the American Society forTesting and Materials (ASTM) as listed in Section2/1, a report is to be provided indicating the standards

actually to be employed and their relative adequacywith respect to the corresponding ASTM standards.

1/4.3.2 Calculations

Design and analysis calculations are to be submittedfor items relating to loadings, structural stresses anddeflections for in-place and marine operations. Inthis regard, calculations are to be in general compli-ance with the items listed below. Calculations whichmay be required in association with environmentalconsiderations, and foundation data have been dis-

cussed in 1/4.3.1.a Loadings Calculations for loadings are to besubmitted in accordance with Section 3/2.

b Structural Stresses and Deflections Thestress and deflection calculations to be submitted areto include, those required for nominal element ormember stresses and deflections. As applicable, andwhere required in subsequent sections of these Rules,calculations may also be required for the stresses inlocalized areas and structural joints, the dynamic re-sponse of the structure, and fatigue life of criticalmembers and joints. For pile supported structures,calculations for the stresses in piles and the load ca-

pacity of the connection between the structure andthe pile are to be submitted. Similarly, for gravitystructures, calculations are to be submitted for the ef-fects of the soils reaction on the structure.

When accounting for the stress resultants de-scribed above, and those resulting from considerationof marine operations (see Section 3/7), calculations

are to demonstrate the adequacy of the structural ele-ments, members or local structure. Also, the calcula-tions are to demonstrate, as applicable, that the de-flections resulting from the applied loadings andoverall structural displacement and settlement do notimpair the structural performance of the platform.

c Marine Operations As applicable, calculationsare to be submitted in compliance with Section 3/7.

d Other Calculations As required, additionalcalculations which demonstrate the adequacy of theoverall design are to be submitted. Such calculationsshould include those performed in the design of thecorrosion protection system.

1/4.3.3 Plans and Other Data

Generally, structural plans and other data are to besubmitted in quadruplicate. These plans are to in-clude the following, where applicable.

Arrangement plans, elevations, and plan viewsclearly showing in sufficient detail the overallconfiguration, dimensions and layout of thestructure, its facilities and foundation

Layout plans indicating the locations of equipmentand locations of the equipment loads and otherdesign deck loads, fender loads, etc., which areimposed on the structure

Structural plans indicating the complete structural ar-rangement, dimensions, member sizes, platingand framing, material properties, and details of

connections and attachments; for concretestructures, arrangements and descriptions of re-inforcement procedures for construction are tobe indicated

Pile plans indicating arrangements, nominal sizes,thicknesses and penetration

Welding details and procedures, and schedule ofnondestructive testing

Corrosion control systemsStructural plans indicating the complete arrange-

ments of structures, such as helidecks, cranepedestals, equipment foundations and manner ofreinforcement, fendering, various houses and

other structures which are not normally consid-ered vital to the overall structural integrity of theoffshore structure

Various information in support of novel featuresutilized in the offshore structure design, such ashydrostatic and stability curves, elements of anymooring system, etc.


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Materials Section 1


Part 2 Materials and Welding


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Materials Section 1


Part 2

Section 1 Materials

2/1.1 Structural Steels

2/1.1.1 General

a Scope This subsection covers specifications formaterials used for the construction of offshore steelstructures. It is not intended for metals used in rein-forced or prestressed concrete. (See 2/1.3.) All materi-als are to be suitable for intended service conditions,they are to be of good quality, defined by a recognizedspecification and free of injurious imperfections.

b Material Selection Materials used are required

to exhibit satisfactory formability and weldability char-acteristics. As required, documentation is to be submit-ted to substantiate the applicability of a proposed steel.Reference can be made to Tables 2/1.2A and 2/1.2B forASTM and API steel grades and to Appendix A forguidance on the selection of ABS grades of steel.

When material other than steel is to be used as astructural material, documentation is to indicate thetensile, toughness, fatigue and corrosion characteris-tics of the proposed material.

c Corrosion Control Details of corrosion con-trol systems (such as coatings, sacrificial anodes orimpressed current systems) are to be submitted withadequate supporting data to show their suitability.Such information is to indicate the extent to whichthe possible existence of stress corrosion, corrosionfatigue, and galvanic corrosion due to dissimilarmetals to be considered. Where the intended sea en-vironment contains unusual contaminants, any spe-cial corrosive effects of such contaminants shouldalso be considered. Appropriate coatings may beused to achieve satisfactory corrosion protection formiscellaneous parts such as bolts and nuts.

d Toughness Materials are to exhibit fracturetoughness which is satisfactory for the intended ap-

plication as supported by previous satisfactory serv-ice experience or appropriate toughness tests. Wherethe presence of ice is judged as a significant envi-ronmental factor, material selection may require spe-cial consideration.

e Through Thickness Stress In cases whereprincipal loads, from either service or weld residualstresses, are imposed perpendicular to the surface ofa structural member, the use of special steel with im-proved through thickness (Z-direction) propertiesmay be required.

2/1.1.2 Steel Properties

a General Material specifications are to besubmitted for review or approval. Due regard is to begiven to established practices in the country in whichmaterial is produced and the purpose for which thematerial is intended.

b Tensile Properties In Table 2/1.1, the desig-nation Group I, II or III is used to categorize tensileproperties.

c Toughness Appropriate supporting informa-tion or test data are to indicate that the toughness of

the steels will be adequate for their intended applica-tion and minimum service temperature. Criteria in-dicative of adequate toughness are contained in2/1.1.3.

d Bolts and Nuts Bolts and nuts are to havemechanical and corrosion characteristics comparableto the structural elements being joined and are to bemanufactured and tested in accordance with recog-nized material standards.

2/1.1.3 Toughness Criteria for Steel Selection

a General When members are subjected tosignificant tensile stress, fracture toughness is to beconsidered in the selection of materials.

b Steel Classification Steels are to be classi-fied as Groups I, II or III according to their tensileproperties as listed in Table 2/1.1. It should be notedthat the yield strengths given in Table 2/1.1 are pro-vided only as a means of categorizing steels.

TABLE 2/1.1 Steel Tensile Properties

Yield Strength fy

Group ksi MPa

III fy < 40 f y < 275

III 40 fy 60 275 fy 415

III 60 fy 100 415 fy 690

Some of the typical ASTM and API steels belongingto the groups of Table 2/1.1 are shown in Tables2/1.2A and 2/1.2B. Steels other than those men-tioned therein may be used, provided that theirchemical composition, mechanical properties andweldability are similar to those listed.


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TABLE 2/1.2A Structural Steel Plates and Shapes

Yield Strength Tensile Strength

Group Specification & Grade ksi MPa ksi MPa

I ASTM A36-94 (to 2 in. thick)

ASTM A131-94 Grade A (to in. thick) (ABS Grade A)

36

34

250

235

58-80

58-75

400-550

400-515

ASTM A285-90 Grade C (to C\ v in. thick) 30 205 55-75 380-515

ASTM A131-94 Grades B, D (ABS Grades B, D) 34 235 58-75 400-515ASTM A516-90 Grade 65 35 240 65-85 450-585

ASTM A573-93a Grade 65 35 240 65-77 450-530ASTM A709-93a Grade 36T2 36 250 58-80 400-550

ASTM A131-94 Grade E (ABS Grade E) (ABS Grades CS, E) 34 235 58-75 400-515

II ASTM A572-94b Grade 42 (to 2 in. thick) 42 290 60 min. 415 min.

ASTM A572-94b Grade 50 (to in. thick*) 50 345 65 min. 450 min.

ASTM A588-94 (to 2 in. thick) 50 345 70 min. 485 min.

ASTM A709-93a Grades 50T2, 50T3 50 345 65 min. 450 min.

ASTM A131-94 Grade AH32 (ABS Grade AH32) 46 315 68-85 470-585

ASTM A131-94 Grade AH36 (ABS Grade AH36) 51 350 71-90 490-620

API Spec 2H-Grade 42 42 290 62-80 425-550

API Spec 2H-Grade 50 (to 2 in. thick) 50 345 70-90 485-620

(over 2 in. thick) 47 325 70-90 485-620

API Spec 2W-Grade 42 (to 1 in. thick) 42-67 290-460 62 min. 425 min.(over 1 in. thick) 42-62 290-430 62 min. 425 min.

Grade 50 (to 1 in. thick) 50-75 345-515 65 min. 450 min.

(over 1 in. thick) 50-70 345-485 65 min. 450 min.

Grade 50T (to 1 in. thick) 50-80 345-550 70 min. 485 min.(over 1 in. thick) 50-75 345-515 70 min. 485 min.

API Spec 2Y-Grade 42 (to 1 in. thick) 42-67 290-460 62 min. 425 min.


Grade 50 (to 1 in. thick) 50-75 345-515 65 min. 450 min.


Grade 50T (to 1 in. thick) 50-80 345-550 70 min. 485 min.


ASTM A131-94 Grades DH32, EH32 (ABS Grades DH32, EH32 46 315 68-85 470-585Grades DH36, EH36 (ABS Grades DH36, EH36) 51 350 71-90 490-620

ASTM A537-91 Class 1 (to 2 in. thick) 50 345 70-90 485-620

ASTM A633-94a Grade A 42 290 63-83 435-570

Grades C, D 50 345 70-90 480-620ASTM A678-94a (80) Grade A 50 345 70-90 485-620

III ASTM A537-91 Class 2 60 415 80-100 550-690

ASTM A633-94a Grade E 60 415 80-100 550-690

ASTM A678-94a (80) Grade B 60 415 80-100 550-690

API Spec 2W-Grade 60 (to 1 in. thick) 60-90 415-620 75 min. 515 min.


API Spec 2Y-Grade 60 (to 1 in. thick) 60-90 415-620 75 min. 515 min.


ASTM A710-Grade A Class 3 (to 2 in. thick) 75 515 85 min. 585 min.

65 450 75 min. 515 min.

60 415 70 min 485 min.

*To 2 in. Thick for Type 1

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