Standards Development

Scope

This standard covers the assessment of the integrity of new or existing structures using fracture mechanics, properties of materials and non-destructive testing (NDT) methods, providing acceptance levels for any flaws that might be revealed.

The assessment methods given in this standard provide a quantitative measure of the acceptability of a flaw in a structure where failure of the structure under assessment could pose an unjustifiable or intolerable risk to the surrounding environment or population. The derivation of acceptance levels for flaws is based upon the principle of fitness-for-service whereby a structure is considered adequate for its purpose provided the conditions to cause failure are not reached. The guidance is used as part of a wider integrity management plan for the structure or system. Use of the standard is entrusted to appropriately qualified and experienced Engineers, for whose use it has been produced. Users interact with the standard by extracting information which guides them through defined assessment frameworks, providing recommendations and guidance for both analysis methods and input data. Furthermore, the standard is referenced by several regulatory bodies and application standards globally.

The framework of the standard’s scope is unchanged but the standard needs to be updated and potentially extended to include new scientific knowledge within its assessment methods and to address requirements arising from climate change and the energy transition affecting many of the standard’s user groups.

The standard is one of only two providing frameworks for fitness-for-service assessments, the other is API 579-1/ASME FFS-1. There are no standards providing similar guidance in EN or ISO organisations. The standard maintains its relevance and prominent status by regularly incorporating advances in the underlying science of analysis methods, recommended input data, advances in metallic materials and inspection technology, and changing demands of industry. Should the proposed revision not go ahead, the standard gradually will become outdated, failing to offer the level of guidance required by users and regulators.

Purpose

The precursor to this standard was first introduced as a fracture and fatigue assessment procedure in 1980 as PD 6493 and revised once in 1991.  It was elevated from published document status to a standard, BS 7910, with its revision in 1999. The standard has subsequently undergone several revisions and amendments, in 2005 (amended later the same year), 2013 (amended in 2015), and the most recent being in December 2019.

Since its inception, the standard has been highly regarded nationally and internationally, remains in widespread use, is referenced in many application standards, and remains industrially relevant primarily to the energy, transport and civil engineering sectors, but also amongst many others. There are important aspects of the standard which naturally require updating, both periodically and in response to emerging challenges. Therefore, a full revision is now proposed. New or amended guidance will be evidence- and physics-led as already the case for the standard in its present form.

The standard requires a full revision to:

• Align the standard with developments in regulations, current practice and other relevant standards, including R6 and API 579-1/ASME FFS-1.

 • Align the standard to reflect national developments from relevant bodies such as FESI, where a recently published position paper on development of the UK’s structural integrity capability could inform future practice and offer direction for improvement of the standard.

• Update the guidance provided by the standard as deemed necessary by each of the committee’s 11 technical panels.

• Provide clarifications.

• Incorporate the committee’s comprehensive log of comments and feedback received from committee members, panels and users of the 2019 revision.

• Review the status and integrity of additively manufactured components for potential inclusion in the standard’s scope.

Of the 22 informative Annexes contained in the standard, several are mature for review and potentially for revision:

• Annex B Assessment procedures for tubular joints in offshore structures: this Annex has remained unaltered for a prolonged period and across several revisions of the standard. It needs a status review but is also a candidate for incorporating new guidance addressing the structural integrity needs of offshore wind structures.

• Annex K Probabilistic assessment: the provisions in this Annex were amended in a previous revision to remove the partial safety factor approach due to widespread misuse by users. The current guidance is now rudimentary and could be revised considering advances elsewhere.

• Annex T Guidance on the use of NDT with ECA: the guidance will be updated to incorporate new NDT techniques and to enhance guidance for existing techniques with new and improved performance information. An industrial study is presently underway that is specifically intended to support the annex.

Section 8 provisions for fatigue crack growth rates (from HSE report OTH 98 511) have been recently reconfirmed by work at TWI. There remains a need to review more recent test data from modern material production to confirm the existing recommendations remain appropriate for this group of metals, or to propose new guidance.

Additionally, the revision is proposed to cover the following challenges emerging from climate change initiatives, which may also influence the scope of the standard should the necessary changes prove to be significant:

• Generation and transport of hydrogen and blended fuel gases.

• Capture, transport and storage of carbon dioxide.

• Advancements in nuclear power.

• Offshore wind infrastructure.

NOTE Academic and industrial research and study work on materials and integrity aspects of H₂ and CO₂ is presently underway in national and international settings and the influence of this on the standard ultimately depends on the availability, nature and timescale of any appropriate new knowledge created.