INTRODUCTION
From 1975 to 2003, guidelines and latest industry practices to avoid sulfide stress cracking (SSC) in upstream H2S-containing services have been published in NACE Standard MR0175. Over those years, many changes have been made to the standard, culminating in its evolution to NACE MR0175/ISO 15156 seven years ago. However, there have been difficulties for Owner/Operators in the application of this latest standard, and for vendors in meeting its requirements. As a result, there are those who are choosing to invoke NACE MR0175-20021, instead. This paper will discuss some of the reasons why this is so, including the effects of changes in the sour service definitions. Examples of exceptions taken will be examined. And cost issues involved in meeting MR0175/ISO 15156 will be presented
With the cooperation of NACE and the European Federation of Corrosion (EFC), Working Group 7 of Technical Committee ISO/TC 67 prepared ISO 15156, basing that standard on NACE MR0175 and EFC Reports 162 and 173. NACE International adopted ISO 15156 and in 2003, published the last two parts of a threepart document “… to provide requirements and recommendations for materials qualification and selection for safe application in environments containing wet H2S in oil and gas production systems.” In 2008, the last of eight technical corrigenda and circulars was published. These eleven documents are collectively known as NACE MR0175/ISO 151564, hereby referred to as “NACE/ISO”. The result of these efforts was an expansion in scope and detail for the requirements for materials in wet H2S service. Now, it is not uncommon for project specifications and corporate policies to invoke the latest revision of a published industry standard in order: to apply the latest available information, technology and lessons learned; to mitigate liability in the case of an accident; and, for some state and provincial jurisdictions, to comply with mandated legislation. However, here in western Canada, the land where the seeds for NACE MR0175 were first sown over 40 years ago, some owner/operators of sour service facilities have been taking exception to NACE/ISO. Between the authors, we know of at least three projects that have chosen to invoke NACE MR0175-2002, instead of NACE/ISO, and as recently as in 2010 - seven years after the initial NACE/ISO publication. Material suppliers and fabricators have also take exception to the requirements for compliance with NACE MR0175/ISO 15156. The question naturally arises, “why deviate from the latest available industry standard?” The fact is that there are difficulties in the application of the standard. The intention of this paper is to bring attention to some of those difficulties encountered in the application of NACE/ISO, its technical circulars and corrigenda. We will compare and contrast differences between NACE MR0175 -2002 and NACE/ISO. We will present data collected during surveys with vendors. Finally, we will offer some recommendations for improvement in the use of the standard.
