During the last few years, the oil and gas industry has experienced several failures in 13Cr WMSS pipeline materials associated with either girth welds or anode pads. The main cause of failure has been attributed to the following three different mechanisms:

• External failures due to Hydrogen Induced Stress Cracking (HISC) with hydrogen supplied by the Cathodic Protection (CP) system,
• Internal failures due to Sulphide Stress Corrosion Cracking (SSCC) with hydrogen supplied by a corrosion process adjacent to the crack area, and
• Internal failures as a result of high temperature (e.g. 110 C) embrittlement due to intergranular cracking associated with stress corrosion cracking (sensitization).

As a result of the recent failures, the industry has become somewhat hesitant to utilize 13Cr WMSS linepipe material in new projects. Worldwide, several different organizations are carrying out research in order to understand the respective governing fracture mechanisms.

INTEC is currently evaluating the use of high alloyed 13Cr WMSS pipeline material for a project in Australia (temperature - 110 ¡C, H2S - 6 mbar, CO2 - 1.8 mol%). As part of this evaluation process, several of the current failure cases have been studied, in addition to having had discussions with some of the key personnel from the various research groups that are investigating these failure mechanisms.

The key driving forces for the three above mentioned failure mechanisms are:

HISC:
The elements that will have to be present to allow this type of fracture mechanism to take place are: i) presence of nascent (atomic) hydrogen, ii) local plastic strain (particularly tri-axial stresses) and iii) a material that is susceptible to hydrogen embrittlement.

SSCC:
SSCC is induced by corrosion at a relatively high static load. For this mechanism, the hydrogen source is the cathodic reaction associated with a corrosion process in the vicinity of the crack tip and not the cathodic protection system (CP can be excluded as the hydrogen source for SSCC). The hydrogen will migrate towards areas with high tri-axial stresses and further embrittle the material in the same manner as described for HISC.

Sensitization:
The sensitization phenomenon is caused by precipitation of Cr-carbides along the prior austenite grain boundaries during. As a result of the carbides, there will be narrow Cr depleted zones running along the grain boundaries with inferior corrosion resistance (less Cr available to form protective oxide films), causing grain boundary corrosion.

Both of the internal failure mechanisms have only been observed in the "lean" 13Cr WMSS grades (low Ni and Mo). Laboratory testing has clearly demonstrated that a remedial action to reduce the probability of failure occurrence is to post weld heat treat (PWHT) the welds at 620 to 650¡C for 3 minutes. This testing shows an apparent reduction in the material's propensity to fail due to any of the above failure mechanisms when PWHT is applied. There is still some research required to fully explain the restitution mechanisms taking place during the heat treatment process.

To mitigate the risk for any of these failure mechanisms to occur, the following recommendations should be considered:

• Use high alloyed 13Cr WMSS (2% Mo and 5-6% Ni).
• Minimize local plastic straining (e.g. thin anode pads, not too long free spans reduce the operation pressure).
• Use 25Cr SDSS filler material followed by PWHT for the girth welds (there are also some encouraging results on matching filler material).
• Use Inconel 625 filler material followed by PWHT for welding of anode pads.
• Ensure that both the field joint coating and the coating applied at the coating yard have good bonding.
• Ensure minimum hydrogen charging at the cathode (e.g. by applying a diode CP system that adjusts the negative potential from the normal value of -1050 to -800 mVAg/AgCl/Seawater).
• Weld the anodes pads to either 25Cr super duplex stainless steel or Inconel 625 clad carbon steel pup pieces.
• There is also investigation taking place to develop alternative ways of attaching the anodes.

The project comprises the enlargement and refurbishment of the existing plant, with all the associated operational and security restrictions. The plant collects crude oil from different wells for a first separation stage (water and sludge) prior to pumping the crude to either a pipeline or to storage tanks.

The INTEC-ARCAN scope of work includes supply of all materials and equipment, performance of detail engineering based on engineering supplied by PAE, and execution of civil, mechanical and electrical works, as well as instrumentation installation. The contract period is 195 days, with an extra 45 days for commissioning and start-up of the facilities. All work should be wrapped up by July 7th. The project is 70% complete as of the end of April.

The following equipment and devices, among other items, are to be installed as part of our job:

• two screw pumps for crude oil (supplied by PAE)
• two FWKO separators, weighing 60 tons each (supplied by PAE)
• one horizontal convective oven, weighing 45 tons (supplied by PAE)
• two API gravity separators, (supplied by PAE)
• three centrifugal pumps for water recirculation
• one Plan Scape DCS by Honeywell
• one electric power transformer
• the complete fire detection and fire fighting system

All tasks are being performed in full compliance of the quality, safety and environmental standards as defined by the Integrated Management System which is in place at INTEC-ARCAN.

For INTEC's Julio Daneri, help was a few keystrokes away with AskINTEC. Using just the internet and a web browser, Julio tapped into part of INTEC's "brains." AskINTEC provides references to documents in INTEC's extensive electronic technical resources (knowledge base), as well as to INTEC subject matter experts and previous AskINTEC Q&A's. While Julio slept in China, experts in INTEC's Buenos Aires and Houston offices provided just the information he needed.

Likewise, David Raby in Australia received 10 responses to a query about proposed and actual diameters and wall thicknesses for pipelines laid deeper than a specified depth. "The quality of information provided via AskINTEC enabled INTEC's Houston deepwater experience to be put forward to a client located in East Timor," Raby says. Although 14 hours and more than 10,000 miles away from most of his INTEC colleagues, David received overnight the information he required from INTEC experts including Senior V.P. Technology David McKeehan, Gene Mullee, Alvin Alleyne, and Andre Nogueira. This input formed the basis of one of the five sections of David's report. One example: "I was able to cut and paste a table David McKeehan provided straight into the report. If I had to do the work myself, it would have taken weeks of research and several review cycles, and the results may not have been as good," Raby says.

A query from a Houston project engineer was referred to a relatively new INTEC employee in the UK with more than 20 years' industry experience who had been working on an almost identical problem for about six months. The answer, received overnight, "provided a major contribution to the project," potentially shaving several months and saving considerable cost, according to the project lead engineer.

INTEC engineer Stephen Lyon has shared his expertise by answering several questions during downtime while on a lay barge in the Mediterranean. Lyon accesses the AskINTEC questions by logging into webmail on INTEC's intranet. Lyon adds that INTEC's intranet itself provides valuable knowledge to remote employees. Lyon also has used AskINTEC to get input from colleagues around the world.

How does AskINTEC work? AskINTEC users enter questions or searches via the intranet from anywhere in the world via standard web browser. Instantly the user gets both a list of all INTEC electronic resources (technical library, archives, codes, standards, specifications, recent Q&A and FAQ's, etc.) on the subject and a list of related experts. (See Diagram) If the documentation does not answer the question, the user can ask one or more experts to review and answer questions regardless of their physical location. Q&A's are indexed and saved for future reference. Questioners can also post questions on topical bulletin boards and browse "home pages" for various engineering disciplines.

Paul Laws, global leader of INTEC's materials technology group and one of INTEC's most popular and responsive subject matter experts, says he prefers whenever possible to answer questions in AskINTEC instead of by e-mail, telephone, or personal visit, because he knows his answer will be saved and available for use by future questioners.

While the Q&A format between questioner and expert is valuable, most information in AskINTEC queries actually is found via a search of existing INTEC documentation such as the technical library, project archives, and previous AskINTEC dialogs. AskINTEC helps INTEC greatly improve its knowledge base by identifying which documents are most useful and highlighting where current documentation needs improvement. In addition, every time an employee answers a question or adds a FAQ, resource, or Best Practice, Ask INTEC is learning what they know and automatically updating their skill profile. This provides INTEC increased and updated knowledge about who knows what in the organization.

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AskINTEC is a proprietary customization of AskMe knowledge management software. AskMe is being used by leading companies such as Ford, Honeywell, and Boeing. To our knowledge, INTEC is the only company in its market sector broadly employing this kind of technology to its clients' benefit.

t an airport I passed through recently I saw a poster with the word "Thalassotherapy", and thought: that's us! Old Xenophon described the trek of a Greek army returning from battle in Persia around 400 BC and recorded their daily travails with a repetitiveness guaranteed to put to sleep student readers 2400 years later. As one of these students, I did remember that when the Greeks finally reached the Black Sea which indicated they were getting close to home, they exclaimed "Thalassa". The other Greek word "therapy" is still in use, so I thought "eureka" and realized that a healing marine practice fits as a description of what we do.

We provide these healing marine services to Clients who we make feel better by creating healthy projects. If we were getting paid more, one could actually think of our engineering discipline as thalassotherapeutic medicine. I believe that actually was the meaning of the poster I saw, as it depicted some seaside spa and a woman whose looks had obviously benefited from saline treatment. Whether this was by ingesting it or bathing in it was not clear, but it demonstrated how the sea can make you look good, something we try to do every day.

We also find it therapeutic to ourselves to be busy with things under water and on the bottom of oceans. We have become familiar with that wet world as we design things that have to be installed there and operate for a long time. We study the behavior of the ocean currents and waves, and of the seabed so that what we design can withstand this environment. One of the more extreme hazards we sometimes need to take into account is the tsunami, enormous waves caused by submarine earthquakes. A recently published book about the 1883 eruption of the Krakatau volcano in Strait Sunda, between Java and Sumatra, describes how this cataclysmic event generated a wave of as much as 40 m high that slammed ashore on the nearby coasts of above mentioned islands and wiped out many towns

The explosion generated a pressure wave that was recorded bouncing around the globe seven times, starting with a pressure surge of 80 mbar. The whole 800 m high Krakatau volcano disappeared and turned into a 300 m deep hole in the sea. In the 120 years since, it has been growing back and an island has reappeared that has all the traits of its parent, and one day will blow again. This event also made the world realize that what happens at one far end of the globe can have an effect on another, a notion that now seems obvious.

Fortunately there is little oil or gas to be found in basalt as it comes up from deep in the earth at the place where the north-moving Australia plate dips under the Asia plate, but the effects of resulting earthquakes and volcanic eruptions can be felt at distant project locations. Such an event could cause severe "thalassotrauma" to our oil and gas facilities, but fortunately continental drift and plate tectonics are very slow processes, so that only one in many generations of thalassotherapists needs to worry about it. In the meantime let's keep looking good under water.

W. J. Timmermans
President

The group is working on a wide variety of projects, ranging from Chevron Angola Project overall field layout to detailed route selection pipeline soil interaction studies for the BP Mardi Gras, Shell Bonga and Pioneer Harrier projects, and the Chevron Congo River crossing high-level concept studies. These projects integrate results from a wide range of data acquisition systems including ultra-high resolution bathymetry, sidescan sonar and state of the art CHIRP subbottom profiler data in water depths up to 7,500 feet. We are providing positioning oversight on pipeline installation, LBL array design, deployment and calibration, and ROV clearance and verification surveys.

The expertise in the survey group is not limited to surveying in the classical sense. Being able to help someone decipher the more unusual mapping datums such as "Old Egyptian 1907 MRE" or even "Louisiana State Plane" is still gratifying. INTEC's Simon Bonnell is one of the most experienced all-round surveyors in the offshore industry. Marc Bik and Andrew Grubb bring their strong backgrounds in geotechnical field and theoretical work. Nigel Tootill is an expert in geophysical surveying and positioning, while Angus Reid is a geotechnical engineer who is well versed in pipeline design with a flair for software and rugby. James Nicholls has worked with just about every type of survey system and knows what to focus on, and Justin Brown is indispensable for his TerraModel andANSYS bottom roughness skills. Todd Phillips brings his experience in ocean engineering and pipeline design to the group, and Raymond Rojas, the most recent addition to the team, brings experience in civil engineering construction and oceanography. Martin Morrison has been kicking around the onshore/offshore investigation and construction survey world for nearly 20 years.

While our team resides under the Pipeline Group umbrella, the other INTEC groups frequently turn to us for technical assistance in servicing their clients. Our experience in geotechnical data collection and design calculations has proven invaluable for a variety of fixed seabed structures, design and execution of ultra-high 3D seismic surveys for seabed installations and conductors. We have planned and completed bathymetry studies in water depths from 0 to 10,000 ft with resolution and accuracy in the subdecimetric range. Our expertise in this surface and subsurface positioning extends from preliminary field layout studies to installation and construction activities. We make maps that you can read and understand!

We are working to expand in areas beyond INTEC's traditional oil and gas capabilities. We are in the process of consolidating our individual stand-alone expertise in nearshore skills in harbor, breakwater, shore protection and coastal development into a unified approach. The nearshore and coastal market is one of the most rapidly growing fields in development engineering as urban and environmental pressure on this narrow strip of land continues to grow. Expansion into these areas will make good alternative use of the high level of engineering expertise within INTEC.

The ability of the offshore personnel to handle the various multi-tasks is what makes for such a unique working environment. The conditions onboard the many vessels currently employed in the pursuit of hydrocarbons is one of relative luxury compared to those same conditions years ago. The workers are able to relax after their 12-hour shift by lifting weights, watching movies, reading, playing cards, and occasionally by sprawling in the spa onboard. There are 4 daily meals served in the galley onboard these vessels, and one finds himself typically eating all four meals whether one needs to or not.

The working hours in the oilfield are usually described as tours (pronounced "towers") and start and end at noon or midnight. The logic is fairly simple, work 12 hours and sleep 12 hours because then you are only awake for half the time you are onboard, thereby reducing the number of days you are gone. This mental trickery works for some but not others. Being in a relatively isolated environment can be a positive or detrimental situation. It is usually positive because it allows everyone to focus on the job at hand and not have to worry about who is picking up the dry-cleaning or cooking dinner that night because those things are all done by others onboard.

However, when your 12 hours of time off have expired, there is no doubt in these people's mind of what is expected of them. The work is extremely physical and demanding. Even though the majority of vessels used have some form of automation involved in the process, mechanical and human failures often lead to major ordeals and repairs. Everyone works for a common goal at the end of the day, accomplish the job, be safe, protect your work colleagues from unseen hazards, and be ready to get on the helicopter when your time is up.