Modernization of OCTG Performance and Design Standards
Authors: Payne M. 
Published: October 2008

Substantial activities have been ongoing within API and ISO standardization organizations on the modernization of key oilcountry tubular goods (OCTG) standards. This includes advancement of testing guidelines for OCTG connections, modernization of OCTG performance properties, and generation and harmonization of corresponding API and ISO standards. These achievements are important advances for the industry and also noteworthy in terms of their improved technical basis. Further modernization of OCTG standards and inspection and design practices is also needed. More efficient practices for design, procurement and use of tubulars have been enabled by advances in inspection technology and sophistication in well engineering methods. To take advantage of these advances and deliver economic benefits, OCTG specification, performance and design standards must also advance. In this usage, standards refers both the formal API and ISO documents and de-facto standards such as well design practices in use within the operator community. This paper will review some of the ongoing advances within API and ISO, discuss opportunities for improvements in OCTG utilization, highlight the benefits of such practices, and outline areas where further advancementis needed.

Introduction

OCTG standards are effectively governed world-wide by API Sub-Committee 5 (SC5) documents with varying levels of supplementary specifications from individual companies. Collaboration between API and ISO is now also producing a number of ISO standards, with the intent to obtain equivalency between API and ISO standards to the fullest extent possible. Several standards are being pursued as joint API / ISO documents. The focus of API/ISO standards has changed historically. Originally, tubular standards were pursued because of the number of dissimilar tubular products prevented interchangeability between operating areas and operators. The lack of standards and common pipe and thread dimensions prevented exchange of inventories and resulted in gross inefficiencies. This was not acceptable for an industry critical for wartime support of the nation, so standards were pursued in order to agree common specifications. The standardization of products in use remained a focus for many years. During this time, proprietary products such as BTC and X-line were donated to the API OCTG standards. Over time, focus shifted towards improvement in quality systems and the advancement of more sophisticated grades and metallurgies. Currently, API / ISO standards provide a wide range of tubular products and offer a solid foundation for quality such that API / ISO tubulars should fully comply with the specifications and be fit-for-purpose provided the design has been properly executed.

The following sections review key recent advancements in API and ISO standardization concerning connection testing andOCTG performance properties. Additionally, discussion is provided concerning additional advancements that are warranted and needed in the standards and their application.

WG2A: Connection Testing Procedures - ISO 13679

Connections remain a critical aspect of tubular and well integrity. The overwhelming majority of OCTG failures involve connection leaks or structural failures [1]. This situation can be understood when the nature of connections is reviewed. Tubular connections represent a mechanical discontinuity in the pipe which must overcome both structural and sealing requirements within a tight dimensional constraint.