Over the past 13 years, spoolable glass-reinforced epoxy (SGRE) pipe has achieved widespread preference by the international pipeline community for in-field gathering and injection applications over welded steel and stick fibreglass (rigid GRE) pipelines. It is currently used in oil and gas fields throughout North America, with over 15,000 km installed for more than 450 operators to date.
Fast and safer installation, lower capital and operating costs, immunity from corrosion and low maintenance in service are the drivers for this rapid success – and it has now been installed for a major operator in Australia.
SGRE pipe is a patented product offered by a single manufacturer – Fiberspar. Trademarked as LinePipe™, it was initially developed by Fiberspar and ConocoPhillips in the early 1990s.Article continues below…
Fiberspar’s design uses a filament-wound glass-reinforced structural layer with the addition of a thermoplastic liner, which acts as both the manufacturing mandrel and fluid barrier. The entire structure is bonded together. The internal liner is normally made of high-density polyethylene (HDPE), but other thermoplastics have also been used. An external thermoplastic jacket is extruded on the finished, tested pipe to provide additional impact protection.
After the trench has been dug, the spoolable pipe is deployed from a hydraulically-powered spooling frame and is pulled into the trench by heavy equipment such as a backhoe. The process of installing the pipe in the ditch is very swift. A full reel can usually be deployed within one hour.
Some example reel lengths are as follows:
- 12.5 inch diameter pipe = 2,743 m per reel
- 4.5 inch diameter pipe = 1,372 m per reel
- 6 inch diameter pipe = 650 m per reel.
Due to the fact that SGRE pipe is flexible, a less precise, faster to make and lower-cost trench can be used without padding or expensive preparation.
Metallic end fittings – or pipe-to-pipe joints for longer lines – are affixed to the pipe with simple hand tools by the manufacturer’s technician or an installer certified by the manufacturer. The pipe fittings are made from alloy steel and are nickel-coated for corrosion protection. Specialised fittings such as stainless are available on request. No resins or bonding are required to make up the mechanical fittings used on SGRE pipe, and make-up time per fitting is typically less than 30 minutes. The pipe fittings do not leak or fail when used in burst certification tests.
In addition to its simple installation, SGRE pipe does not require a large crew. Normally, the only crew required is one supervisor from the pipe manufacturer and the onsite ditching crew.
Scarcity of skilled welding personnel, especially in remote regions, is a significant drawback to steel pipeline installation in Australia. SGRE pipe requires no welding, and its fittings, which are typically few in number, are completed with simple hand tools.
SGRE is also ideal for environmentally sensitive areas as the pipe can be installed using horizontal directional drilling with minimal connectors required due to the long spool lengths. SGRE is the only pipe system where the pipe-to-pipe connectors are stronger than the pipe itself.
SGRE pipe is cost-competitive for all 105 mm diameter or smaller pipe, and dual lines are often laid for 203 mm diameter pipe equivalent. It requires minimal use of heavy equipment, and installation can be completed in a matter of days or weeks instead of months – nearly 75 per cent faster than stick fibreglass or steel pipe.
SGRE in corrosive service
Another driver behind companies installing SGRE is its immunity to corrosion. This includes resistance to substances such as:
- Aromatic hydrocarbons – In Australia a large number of oil and gas pipelines contain aromatic hydrocarbons. Fiberspar’s design means that SGRE is well suited to these applications. The HDPE acts as a barrier layer to contain the fluid inside the pipe, and does not contribute structurally. The GRE layer is where this pipe derives its pressure-retaining ability and it is this layer that provides the product’s strength. This is in contrast to other composites or reinforced thermoplastics, where the internal and external layers are loaded as part of the pipe body construction and connector interface.
- CO2 – SGRE has a long history of use in the transportation of CO2. The majority of these lines transport CO2 as a gas, but there are also numerous lines in operation that transport high-pressure dense phase CO2. This dense phase fluid can be problematic for rigid GRE pipe as it attacks the resin and causes bruising, which in turn can cause failure. The HDPE layer on SGRE prevents this problem from occurring.
- Hydrogen sulfide (H2S) – Sour oilfield streams are incredibly common in some parts of the world and SGRE has a long service history operating with high concentrations of H2S.
Speedy installation in the Cooper Basin
In November 2011, the first SGRE line was installed in the Cooper Basin, South Australia. This was an onshore first for Australia, and involved successfully installing 50 km of SGRE pipe to tie-in the Moonanga Gas Field facilities. The line is currently operating as a gas pipeline with a 25 per cent aromatic stream at 75°Celsius.
Fiberspar’s 4.5 inch mm diameter 1500 (X) product was used for the installation, and it was found that running multiple lines in the same ditch was an economical way of increasing flow capacity. The SGRE pipe arrived at site on 4.8 m diameter spools, with each spool containing 1,372 m of pipe.
During installation, an average of 3,991 m of pipe – approximately three spools – was laid per day. Initially two spools per day were installed, with rates becoming faster once field contractors became familiar with the product. The maximum amount of pipe laid in one day was 8,232 m (six spools).
Using SGRE pipe, the total 50 km pipeline project was installed in 17 days.