Application of Veritas Rules For Submarine PipeIines recent Experiences From North Sea Projects
Authors: Babala Dale J. 
Published: March 2010

Introduction

The paper addresses four topical areas related to off shore pipelines.The philosophy behind VERITAS Rules for Submarine Pipelines.Statistical information on the operational reliability of land and offshore pipeline systems including North Sea pipeline performance to date.Property planned and executed in-service inspection programs constitute an effective technique for reducing the operational failure rates of offshore lines.Research and development work related to determination of safe (reduced) operating pressures for flawed and dented pipelines and risers.

VERITAS Rules for Submarine Pipelines

VERITAS Rules for Submarine Pipelines (introduced in (976) are generally accepted throughout the free world as the industry standard. These rules set out minimum requirements related to safety and reliability, but design optimization as such. Appendices contain methods for calculating environmental loads and other specifics. VERITAS Rules do not exclude other methods of assessment, but layout methods used by VERIT AS personnel for certification and inspection of design and fabrication.

The nine major functional sections in VERITAS Rules deal with environment loads, strength and in-place stability, materials requirements for pipes and piping components, corrosion protection and weight coating, installation, operations and maintenance, and nondestructive testing. Five appendices pertain to methods for calculating various environmental loads, Buckling calculations, materials quality control and field welding specifications procedures, guidelines for corrosion control, and pressure testing criteria.

VERITAS" certification services include: design reviews, risk analysis, fabrication and installation inspection and quality assurance, in-service inspection programs and major commitments to related R&D. This provides the ongoing knowledge used La maintain our Rules for Submarine Pipelines as a state-of- the-art engineering standard.

Reliability of Pipeline Systems

In 1979 VERITAS conducted a joint industry study to assess the reliability of North Sea pipelines(2). For comparative purposes the study included both major land and marine pipeline systems on a worldwide basis (see Table 1). Although significant differences amongst the data sets for the pipeline systems studied were difficult to compare, several interesting inferences can be drawn. Although failure rates for both land and submarine pipeline systems average well under 1 failure per 1000 km of pipeline per operational year, two causes, corrosion and damage by outside forces account for about 75% of all failures. One may also assume that a significant percentage of external corrosion is initiated by third-party damage and not reported as such.

The data also suggests a negative exponential relationship exists between failure rate and pipeline diameter, i.e. as diameter increases, failure rate decreases exponentially. Age-related failures such as corrosion and third-party damage are more manifest in the older small diameter pipelines.

Final Acceptance Surveys and In-Service Inspections

Advancements in design methodologies, materials and their applications, fabrication and construction procedures, and quality assurance methods will continue to improve submarine pipeline reliability. However, periodic inspections are required for assessment of a pipeline's ongoing suitability for service. Unfortunately inspection programs often suffer from inadequate planning, misappropriation of efforts and inconsistent record keeping.