During the construction of a 56km long 16 in. carbon steel sour gas pipeline, repetitive surface
preparation failures were detected during visual inspection of pipeline girth weld internal surface prior to
coating application. Such failures represented 67% of the total pipeline girth welds and were manifested
by excessive sharp-edges at the root pass. To identify the failure causes, an investigation was
performed through reviewing the pipeline, fabrication and coating application specifications and
procedures, quality control records and performing an extensive visual inspection through an advanced
video robotic crawler on all pipeline girth welds made. Upon investigation analysis, the failures were
caused by sharp-edges in the root pass which were attributed to improper practices during
manufacturing, field fabrication and pre-coating quality control. The failure analysis indicated that the
mechanized Gas Metal Arc Welding process, with the parameters used, was not suitable for internal
girth weld coating application. In addition, a more stringent requirement should be applied to the
acceptable pipe-end diameter tolerance and pre-coating quality control to ensure absence of similar
premature surface preparation failures. The pre-coating quality control can be improved through
utilization of robotic laser contour mapping crawler for precise detection and sizing of unsatisfactory
surface weldment defects, including sharp edges.

Recently the oil, gas and petrochemical sectors have been facing together safety, environmental and mechanical integrity regulations as well as challenges associated with the need for cost reduction to improve competitiveness. Therefore, continual inspection and corrosion control health assessments and investigations are key towards sustaining reliability and availability together with value creation through avoiding unplanned production loss and asset failures. The present paper discusses an inspection and corrosion control technical assessment performed on thirteen (13) subsea flowlines. These flowlines supply wet sour gas feed from two offshore fields, gather through two 36 in” trunk lines. In order to meet the health and integrity objective, the assessment covers a review on the susceptibility and control of three (3) damage mechanisms using available literature covering field and empirical data. In addition, a review and discussion on the available and required inspection methods to combat the susceptible damage mechanisms are performed. This review is extended to an exploration and evaluation of (6) inline inspection techniques and two (2) remotely operated vehicles (ROV) to complement damage mechanism inspection methods.

Hydrocracking and other refinery hydroprocessing units have a common goal to convert organic sulfur compounds to hydrogen sulfide (H2S) that can be removed, thereby producing low-sulfur refinery products. Corrosion and equipment degradation risks range from high-temperature hydrogen attacks (HTHA) to ammonium bisulfide and ammonium chloride corrosion in the downstream heat recovery and fluid separation equipment.
This paper provides an overview of corrosion management principles that can be applied to reduce operating risks in new and existing units, focusing equipment susceptible to ammonium bisulfide (NH4HS) and ammonium chloride (NH4Cl) corrosion. Best practices for materials selection, as well as designing for corrosion management through adequate provision of corrosion management related instrumentation and sampling points are covered.