Installing linepipe by reeling can have advantages when compared to installation by S or J-lay methods, depending on the specific project requirements. In this work, a qualification method was developed to determine the effects of reeling on the sour service performance of line pipe and associated girth welds by using full-pipe-body reeling simulations, followed by either full-pipe four point bend, or small scale four point bend sulfide stress cracking tests. It was found that large scale SSC tests and the 250 HV hardness criteria were better discriminators of sour service performance of reeled line pipe than small scale four point bend tests per NACE MR0175/ISO 15156-2.

INTRODUCTION

Installing linepipe by reeling can have financial advantages when compared to installation by S or J-lay methods, depending on the specific project requirements. The cost benefits of reeling are a result of the following:

  1. almost all of the welding, inspection and field joint coating are conducted on-shore, and off critical path,

  2. there is minimal in-field vessel time, which

  3. reduces the risk of stopping installation operations due to weather.

The primary disadvantage of reeling is that the pipe experiences significantly more mechanical deformation than installation by S or J-lay. This deformation occurs when the linepipe is spooled on, and off the reel. The effects of this mechanical deformation prior to the exposure to sour environments needs to be adequately considered during qualification testing. Hardness is a mechanical measurement that has been correlated to sulfide stress cracking (SSC) resistance (NACE MR0I75/ISO 15156- 2:2003(E)a, and EFC 16, 2002a). C-Mn steel line pipe with a Rockwell Hardness HRC less than 22 and Vickers Hardness (HV) less than 250 in the weld area is generally considered suitable for sour service. (DNV OS-F101, 2007a, API 5L, 2007a). It is unknown whether this hardness criterion also applies to plastically deformed materials. A review of the literature has shown that excessively cold worked materials can have higher susceptibility to SSC (Sourmail, 2006).

Keywords:
strain history, corrosion management, upstream oil & gas, susceptibility, small scale specimen, specimen, ssc crack, oilfield chemistry, production chemistry, sour service performance
Subjects:
Production Chemistry, Metallurgy and Biology, Pipelines, Flowlines and Risers, Corrosion inhibition and management (including H2S and CO2)
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2009. The International Society of Offshore and Polar Engineers
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