Quality Assurance elements related to the main activities in engineering and design

Fig. 6.2 gives a general view of the main activities and documents in the engineering and design phase.

The first activity is Review and detailing of Design Basis (Fig. 6.2). This is done on the basis of the Concept Report from the previous phase (Concept Defining). The Concept Report contains the superior Design Basis with separate chapters regarding loads, environmental data, functional requirements, conditions for use, geotechnical conditions and reference documents.

During this stage, a further analysis of the conditions for the structure, and an in-depth review of the consequences for the different disciplines, are carried out.

A general requirement to the results of all the activities during design, is that the documents must be correct and attend to all necessary regards to clarity, unambiguity and suitability for further use, including traceability and verifiability. This means that the configuration control and the document control must be satisfactory, as well. In relation to this, one should also realise that the iterative character of the engineering and design process makes it very important to be in total control of all changes that are made on the way. “Total control” here means that all consequences of the proposed changes should be considered thoroughly and

Fig. 6.2 Main activities and documents in engineering and design of marine concrete structures (DR=Design Review).

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evaluated at the right organizational level before they are implemented. This implies among other things that the person(s), who worked out the original requirement or the previous solution, should have an opportunity to assess the consequences of the proposed changes, before they are accepted and implemented.

When a change has been accepted, everyone who is in position of the original documents must be informed of the change at once.

During the review and detailing of the Design Basis for the different disciplines, Self-Checks, Discipline Self-Checks, and Inter Discipline Checks should be carried out. This is indicated with small parallelograms in Fig. 6.2.

A (Project) Quality Plan should be prepared at the same time as the review and detailing of the Design Basis (see Fig. 6.2). The Quality Plan describes the particular quality assurance activities that are to be carried out in the project to satisfy the requirements, and what resources should be used for this. Table 6.3 gives an example of the layout of a Quality Plan for the engineering and design phase.

The Quality Plan should be rooted in the operator’s Quality System and be co-ordinated with or constitute part of the Project Plan. The Quality Plan for the complete project should include the following elements as well (ref.: ISO 9004–1:1994, item 5.3.3 and ISO 9004–5 Guidelines for quality plans):

• Description of aims for quality

• Distribution of responsibility and authority in different project phases

• Procedures, methods and work instructions that are to be employed

Table 6.3. General layout of a Quality Plan during engineering and design (example)

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• Programs for testing, reviews, inspections and audits in the different phases

• System for change and modification of the Quality Plan as the project proceeds

• Other initiatives that are to be carried out in order to reach the goals.

The Design Brief (see Fig. 6.2) is prepared on the basis of the revised Design Basis. The Design Brief lays down the Design Criteria further, together with the design procedures, important interfaces and preferred methods for analysis and calculations. Other important parts are the results of criticality evaluations for the individual parts of the structure, and a specification of the software programs accepted for use.

During development of the Design Brief, the same quality elements as in the treatment of the Design Basis should be employed, that means Self-Check, Discipline Check, Inter Discipline Check and Design Review. Since the extent of the documents is steadily increasing as the project progresses, it is evident that the checks require more and more resources. To some extent, different kinds of competence are needed, too.

The analyses are carried out on the basis of the Design Brief. They consist of Dynamic Wave Analysis, Stability Analysis and Global Analysis.

Dynamic Wave Analysis results in dimensioning waves for different parts of the structure, hydrodynamic loads, masses and damping. The results are used as basis for the Global Analysis.

Stability Analysis gives an answer to whether the structure has the necessary stability against capsizing during the construction process, submerging, tow-out, installation, operation and service. Both floating stability and geotechnical stability has to be assessed.

Global Analysis gives an answer to what kind of strain the different parts of the structure is exposed to during submerging, tow-out, installation and operation.

The three above-mentioned analyses together make up the basis for the later dimensioning, and are therefore critical for the structure’s safety and fitness for use. Related to Figs. 6.1 and 6.2, there is a need for a more comprehensive quality assurance than previously, in this phase of the project. In addition to Self-Check, Discipline Check and possibly Inter Discipline Check, Third Party Verifications would therefore be needed and hence required by the authorities.

The dimensioning is carried out on the basis of a general view of the load effects. During dimensioning, the length and location of the reinforcement, the final wall thickness and the quality of the concrete and the reinforcement are determined.

The result of the dimensioning is entered in the Dimensioning Document. This should be subject to Self-Check, Discipline Check and possibly Design Review before the drawing work starts.

The drawing work will result in drawings, material lists and descriptions that are necessary for the construction to start (see Fig. 6.2). All sketches and specifications should be subject to Self-Check and suitable independent verification. A Design Review (“Engineering Readiness Review”) should be completed before release for construction and fabrication.