NEXT GENERATION

Cindy Trahan, FlexSteel, USA, discusses significant steps in the evolution of steel pipelines and presents the latest developments.

Pipelines have been in existence globally for thousands of years. Even before the Roman aqueducts, hollow bamboo pipes were used in ancient China to convey water. As early as 400 BC, the Chinese used bamboo pipe to transmit natural gas to light the capital city of Peking.1

Centuries later, in 1815, the first welded steel pipeline was built from old musket barrels; this pipe system was used to provide coal lamp oil throughout the city of London. The success of this pipeline created a demand for long metal tubes, the precursors to our modern day stick pipe.2

Some 50 years later, Samuel Van Syckel revolutionised the way that oil was moved from wellheads to refineries when he created the first oil pipeline in Pennsylvania, USA.3 Pipeline construction was spurred on by the extremely high wages that the teamsters charged to haul wagonloads of oil barrels to the point of sale. The need to transport natural gas and oil over greater distances prompted the development of high strength steel

Figure 1. Flexsteel’s pipe was

hand placed in an environmentally

protected wildlife refuge in the northeastern US;

the company had to wrap tree trunks with padding

and pull the pipe manually to keep from scarring

a single tree.

THE

pipes. The introduction of welded pipe joints in the 1920s led to more leak-proof pipelines that could contain greater pressure.

The first reeled pipelineThe first reeled pipeline was pioneered during World War II to supply large quantities of fuel to allied armed forces in Europe. Known as Operation PLUTO (pipe line under the ocean), the top-secret subsea pipeline was constructed from flexible steel pipe and run under the English Channel from England to France. PLUTO was an unprecedented leap in pipe technology that established reeled pipe as an efficient means of installation.4

Offshore steel reinforced spoolable pipe The French Petroleum Institute (IFP) championed flexible steel pipeline technology in the early 1970s with its patent for a high pressure, flexible pipe.5 The IFP prototypes laid the groundwork for the development of flexible subsea flowlines. Flexible pipelines quickly revolutionised the offshore oil industry, enabling the exploration and production of a new frontier, the petroleum reservoirs buried deep beneath oceans.

Onshore steel reinforced spoolable pipe Pipeline technology rapidly advanced over the following decades, with Wellstream International Limited emerging as significant innovator of deepwater flowlines and risers for the oil and gas industry. Now a GE company, Wellstream drew on more than two decades of experience manufacturing steel reinforced pipe for demanding offshore environments to pioneer the best possible solution for onshore and shallow water pipeline applications.

The new product line was called FlexSteel, and it combined chemically resistant high density polyethylene (HDPE) plastic with steel reinforcements. Full production of FlexSteel began in 2004, bringing to market a product that couples the best features of flexible pipe with the durability of steel. The FlexSteel business unit was later acquired by a privately owned firm in Houston, Texas, and now operates under the name FlexSteel Pipeline Technologies, Inc.

Design standardsThe FlexSteel™ pipe design features an extruded polymer liner, a layer of helically wrapped steel strips and an outer shield. The smooth HDPE liner and shield provide resistance to corrosion. The combination of the helically wound steel strips and HDPE layers result in a strong, flexible pipe product that has a minimum bend radius of 3 - 5 ft, among the lowest of any spoolable reinforced pipe. The pipe is connected using a swaged system of end fittings that are designed, manufactured and tested to API 15S. The pipe can be spooled for continuous pipe lengths ranging from 591 ft (for the 8 in. dia. pipe) up to 6578 ft (for the 2 in. dia. pipe). Longer lengths mean fewer connections and consequently, faster installation. Since connections can be points of increased vulnerability along a pipeline, reducing the number of connections also reduces the number of potential leak paths.

Material selectionThe strength of the FlexSteel pipe structure is provided by the steel reinforcement, which consists of contra-wound sets of steel strips applied over the liner. The steel used in the

Figure 3. Up to 6578 ft of continuous steel reinforced pipe can be spooled onto a single reel.

Figure 2. The extruded polymer liner and shield provide corrosion resistance.

REPRINTED FROM World Pipelines / JANUARY 2015

Figure 4. Pipe deployment from a barge in Lake Maracaibo, Venezuela.

Figure 5. Corrosion resistance and zero-emissions ensure minimal pipeline disturbance to the environment. (Photograph courtesy of Carnegie Wave Energy)

reinforcement layer is a widely available commercial grade with excellent strength in both pressure containment and axial load bearing capability. An alloy steel grade is available that provides excellent resistance to sulphide stress cracking and hydrogen induced cracking.

The corrosion resistant liner and the corrosion resistant shield are produced from a high density polyethylene compound with carbon black additions for resistance to ultraviolet radiation. A white masterbatch has been developed for more extreme temperature and UV exposure in unburied desert applications. The white pipe has withstood over 10 years of outdoor exposure in a North American desert and accelerated weathering tests replicating 20 years in an Oman desert.

Qualification testingQualification testing is conducted on all flexible steel pipe designs to ensure pipe integrity:

) Burst tests verify that the flexible steel pipe meets design criteria.

) Axial tension testing provides practical limits during installation.

) Collapse pressure tests determine the maximum water depth for marine applications.

) The end connection accelerated life test uses elevated temperature to accelerate creep and stress relaxation of the thermoplastic layers within the end connection to ensure a leak-tight connection.

Product successWithin two years of being introduced to the market, FlexSteel’s steel reinforced spoolable pipe won the prestigious “Enbridge International New Pipeline Technology Award” at the inaugural International Pipeline Awards held at the 2006 International Pipeline Exposition, Calgary. This award was presented to the company who, in the opinion of the judges, had contributed significantly to the development of the pipeline industry. The product gained momentum quickly, requiring FlexSteel to add a second manufacturing plant to keep up with the market demands for production.

The company was also honoured with the “2013 Plastics Pipe Institute Energy Piping Systems Division Project of the Year Award” at the PPI’s Annual Meeting.

The highly competitive award pays tribute to innovative installations and uses of polyethylene (PE) pipe throughout the USA. PPI selected FlexSteel for the award because a project in which 16 900 ft of its newly developed 8 in. dia. 1500 psi pipeline was installed to transport water to a drilling site in the mountainous terrain of the Marcellus Shale Basin. The 8 in. steel reinforced polyethylene flexible pipeline was

JANUARY 2015 / REPRINTED FROM World Pipelines

Figure 6. Steel reinforcement can also provide the required weight for negative buoyancy. (Photograph courtesy of Carnegie Wave Energy).

installed in one-third of the time of traditional steel pipe alternatives and delivered a variety of critical cost-saving and performance benefits.

More recently, FlexSteel pipe has been selected for use in Australia’s high profile Carnegie Wave Energy Project. Supported by the Australian Renewable Energy Agency’s Emerging Renewables Program, the project converts wave energy into zero emission electricity and desalinated water. Steel reinforced spoolable pipe was chosen due to its durability and corrosion resistance, and because the steel reinforcement provides the weight for increased on-bottom stability.

FlexSteel was also the subject of a paper presented at the 2014 International NACE conference in San Antonio, Texas.6 The paper documents test research conducted by a Venezuelan oil company to evaluate FlexSteel materials and

operational performance during service of multiphase oil, water and gas flowlines in the Lake Maracaibo oilfields. Due to the novelty of offshore flexible steel pipe systems in South America, the customer mandated that the pipe be evaluated both in the lab and during real offshore operation conditions. The test programme was developed per API 17J and API 17B requirements to assure the mechanical integrity of the flexible pipes. Every three months, testing was conducted on both new and aged samples extracted from the field. These tests included mechanical properties tests, hydrostatic pressure tests,

gas-venting tests, ageing tests and gauge tests. The pipeline was also subjected to continuous inspection and monitoring of the gas venting system during service. After three years of service, no failure or damage was detected in any of the nine experimental flowlines.

The report findings are consistent with the feedback that the company has received from its other customers. The product has proven to maintain integrity and is not de-rated as often occurs with corroded welded pipelines, thus reducing operational cost expenditures. Highly corrosion resistant and more durable than other pipeline products, FlexSteel combines the best features of all currently available pipe options to deliver superior lifecycle performance and value. As a result, FlexSteel’s sales more than tripled between 2010 and 2012, and the company continues to expand globally, installing over 8000 km of pipe in 30 different countries.

References1. LIU, H.,“Pipeline (Technology)”, http://www.britannica.com/EBchecked/

topic/461356/pipeline/64238/History, published by Encyclopaedia Britannica.

2. HOWELL, D., “A Brief History of Steel Pipe”, http://www.pipelineequities.com/A-Brief-History-of-Steel-Pipe.php], August 2010.

3. PEES, S., “Oil History: 1865, The Van Syckel Pipeline”. Petroleum History Institute, http://www.petroleumhistory.org/OilHistory/pages/Pipelines/van_syckel.html]

4. “PLUTO, Secret Pipelines of WWII”, American Oil and Gas Historical Society, Washington, DC, http://aoghs.org/petroleum-in-war/secret-pipelines/#more-780

5. DAWANS, F., JARRIN, J., LEFEVRE T. and PELISSON, M., “Improved Thermoplastic Materials for Offshore Flexible Pipes”, Paper presented at the 1986 Offshore Technology Conference, Houston, Texas, OTC-5231-MS.

6. FERNANDEZ, C., and LOPEZ, C., (March 2014). “Use of Flexible Flowlines for Offshore Conditions in the Lake Maracaibo Oil/Gas Fields”, Paper presented at NACE Corrosion 2014 Conference, San Antonio, Texas.

Figure 7. Spoolable pipe deploys quickly along a narrow right of way.

Figure 8. Flexible steel reinforced pipe structure.

REPRINTED FROM World Pipelines / JANUARY 2015