Class Rules & Guides


The pre-commissioning of the submarine pipelines is one of the most important and essential parts of the project. It is commonly made of several operations including flooding, cleaning, gauging, pressure test of the system, de-watering, drying and inerting. It should be noted, however, that some of the submarine pipelines do not require drying and inerting.

Most of the regulatory codes applicable to the submarine pipelines provide technical requirements to pressure testing and gauging of the pipelines. But this recommended practice specifically covers pre-commissioning operations taking into account the overall design and arrangements of the systems, planning and management activities, major functional requirements and also execution principles.

The objective of this volume is to give a good guidance on safe, effective and reliable design, planning and then execution of the above mentioned activities. The philosophy in this documents shall apply to both new and existing submarine pipeline systems. The content of the book does not address flexible pipeline systems, but flexible pipeline sections may actually be pre-commissioned with the rest of the system.

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Another recommended practice prepared and released by DNV GL classification society. The opening section of the document provides general introductory information about pipeline IMS, i.e. integrity management system, application of the document, and pipeline failure causes, statistics and repair systems. The second section is dealing with the basic safety philosophy - the content of this section also covers systematic review, qualification and limit state design.

The next three sections cover the pipeline repair activities, design basis and exposures. The fourth section is devoted to the fitting design including failure causes and modes, fitting strength and grip capacity, seal capacity and other aspects. The remaining sections of the publication are dealing with the installation of the pipelines and attachment to them, seal protection design, limitations imposed at the misalignment, control and monitoring, activation etc., isolation plugs including testing of the associated isolation tools, hot tapping covering structural integrity and failure modes, welding and testing considerations, quality assurance, documentation etc.

The appendices provide additional information about the design factors and code breaks, typical tests and fitting capacity, failure statistics and risk assessment, checklist for qualification, design resistance etc.

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The official DNV GL - released recommended practice devoted to the on-bottom stability design of the submarine pipelines. This is the latest edition of the document. The authors of the recommended practice consider the stability design for the pipelines that are normally subjected to the current and wave loads. The content of the document is based on the technical experience and development.

The basic principles are compliant with the recognized rules; they reflect the industry practice and results of the latest researches in the field. The main intent of the document is to provide industry with the rational and reasonable design criteria together with the guidance for assessing the stability. The first general section of the volume covers the relationship of this practice with the other codes and touches the safety philosophy.

The next section is dealing with the design including load combinations and weight and resistance calculations plus the design criterion. The other two sections address the established design methods including vertical stability in water, on and in soil, dynamical, generalized, and absolute lateral static stability methods, free spans, seabed stability and other important aspects.

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The officially released DNV GL recommended practice for the offshore leak detection. The experience gained from the offshore industry incidents have resulted in the increased concerns and closer attention to the operations of the offshore oil and gas fields with the particular focus on the detection of leaking hydrocarbons. It should be clearly understood that the earlier the leak is detected, the easier it will be to prevent an occurrence from its escalating into a serious accident.

Therefore the operators shall implement a good and effective leak detection system; such system shall be reliable and shall allow detection of the leaks with due level of certainty. In addition, the system shall of course meet the requirements of all regulatory documents. The content of the present recommended practice has been specifically developed to be used for the planning and design of such systems, their integration and operation offshore.

However, it shall be noted and remembered at all times that application of the leak detection system shall never be considered a reason for reduction in safety level on any other system installed on the installation in terms of their design and manufacture etc.

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This official recommended practice released by DNV GL class society is devoted to the management of the environmental aspects as well as the impacts of seabed mining. The volume starts with the chapter introducing the subject and telling readers about seabed mining and what impact human activities commonly result in.

This introductory section addresses the scope and application of the document, risk based approach, its relationship with other regulatory documents, standards and codes, and general structure. The next two sections are dealing with definitions used in this recommended practice, and applicable regulatory requirements.

They are followed by the sections addressing environmental risk management including the baseline study and assessment of the environmental impact, associated management plan, site decommissioning, post-operations survey and other relevant issues.

There is also one good example case included in the content of the recommended practice for better illustration of the material contained and for making the understanding easier. In short, this is quite needful and practical reference source for the people involved in seabed mining.

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The content of this recommended practice released by DNV GL classification society is mainly based on the observations and accumulated practical experience of the specialists of this entity in advising the owners of the ships on the procedures to be followed when laying up ships and is representing a completer revision of the recommended practices issued by DNV GL earlier.

It includes the experience and recent technical knowledge of lay-up as well as preservation and subsequent re-commissioning of the MODUs. The main objective of this volume is to provide ship owners with the clear recommendations on effective and systematic approach to be applied when the vessel is being prepared for lay-up; it will also advise them how to maintain their vessels is safe and also cost effective condition during the lay-up period.

The document applies equally to the ships and MODUs. Note, however, that the recommendations provided in the pages of this publication is not intended to substitute classification requirements and are for guidance only. The book covers the lay-up conditions, guidance for preservation, lay-up and re-commissioning, statement of compliance for the providers, applicable rules and regulations, insurance aspects and many other important areas.

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The Recommended Practice developed and distributed by DNV GL classification society to provide all required guidance for the personnel involved in the routing inspection and periodical maintenance of the jacking systems. Following correct procedures for their maintenance and inspection is quite challenging tasks because of the high turnover of personnel possessing specific technical knowledge on board and evolving nature and intermittent use of the jacking systems, and this challenge will be addressed in the pages of the present document.

The objective of this recommended practice is to ensure the safe and correct functioning of the jacking systems of an electric rack-and-pinion style during jacking and holding operations throughout the working lifetime of the system. This would include establishing required levels of competence of different specialists engaged in maintenance and inspection, providing guidance to the designers of the systems, construction yards and manufacturers on what information shall be given, highlighting the points considered critically important and also the areas with little attention paid, as indicated by the experience collected during numerous observations, and many other aspects.

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The present service specification released by DNV GL classification society is aiming to provide a proper methodology used for assurance of the safety and reliability of various oil and gas assets through the management of the integrity of the major safety and environmental accident barriers during the in-service phase. In-service verification of these assets would normally include their verification in the course of the operation and also the verification relating to the changes in the materials or during the repairs/modifications during the lifetime of the particular asset.

The opening part of the document provide short introduction to the subject, followed by the references including DNV GL and external resources, definitions and abbreviations, and concepts of the verification process including barrier management mentioned above, verification scheme and associated activities, performance requirements etc.

The next chapter is devoted to the methodology of the verification process, planning, execution and reporting of verification and management of change etc. The rest of the document is dealing with the operator responsibilities, effective verification schemes, review and audit, and many other important aspects. There are several appendices with supplementary information.

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