Critical Friends Seminar Q&A
The excellent flexibility of MASiP pipe structure enables the pipe to be guided into a trench or on to supports using a guidance system as a single continuous process very similar to pipe installation offshore from a barge. This has a huge advantage over the conventional process as there is no requirement for pipe dumps along the right of way and no requirement to undertake stringing, pipeline girth welding, field joint coating, subsequent installation and further tie-in welding within the trench.
The mobile factory is containerised for transport to site and fits into standard containers and therefore modularised for easy transport.
The key elements are then plugged together and can then either be set up and mounted on a mobile platform. Pipe can be made either with the mobile factory in a stationary position – which may have an advantage for crossings or mounted on a moving vehicle for longer lengths.
How do you undertake pipeline the engineering as MASiP pipe properties are not easily transferable in standard industry software, like Autopipe etc?
We are developing a design guide that will develop equivalent pipe properties based on the FEA modelling and correlation with physical testing that has been undertaken. From this work equivalent pipe properties will be derived to enable input into standard pipeline industry software such as Abaqus, Autopipe etc.
There are no conventional field joints required as the pipe manufacturing is a continuous process. This includes the application of corrosion and abrasion coating protection for the pipeline. By using the automated process, this saves time and reduces manpower requirements.
Conventional pipeline girth welding for the MASIP pipe is not required.
Due to the nature of MASIP pipe of interlocking steel strip reinforcement overlaying the polymer liner, the following welding is required; butt fusion welding of the polymer liner pipe sections and steel strip butt welding to enable continuous automated pipe manufacturing.
Joining polymer pipe sections by fusion butt welding is very well established and semi-automated processes have been used for joining polymer gas pipe sections in the UK for more than a decade.
Steel strip feed is joined by an autogenous butt welding process which has been successfully trialled in pressure cycling tests – so far simulating 20 years life and still ongoing.
A connection is made by cutting the pipe to prepare for the application of a specially designed sleeve which then supports the swaging of a stem which in turn supports a flange. Then any type of pipe T-Joint or connection can be made to the flange in the normal way.
SPS will be developing a hot tap connection for the future.
Our fibre optic monitoring system is designed to detect very early stages of corrosion or potential damage from third party activity. Repairs can be carried out using standard systems such as Clockspring where additional outer layers are applied to the damaged pipe section. There are well established rehabilitation products such as Clockspring and similar products from Belzona. For potential pinhole leaks for example, we can apply a steel sleeve together with a belzona metallic resin injection that could also be used as a high strength external repair.
If there was damage to the fibre – this would be detected by the system itself and the fibre can be re-spliced quite simply once there is access.
In the event of a pipeline rupture, a new section can be installed and the damaged section cut out as would be the case for a conventional pipe repair. The largest threats to onshore pipelines are from third party interference activities, however with the fibre optic system in place, unauthorised activity would be detected well ahead of time.
There is no problem with liquids per se and we have tested with water. There is no problem as per any other type of pipe.
The high strength steel we are using suffers no derating loss of yield strength up to 200C, unlike convention carbon steels which should be derated for yield strength above 50C. DNVGL-ST-F101 recommends 100MPa drop at 125C for duplex steels.
HDPE is rated for service up to 80C for short periods and up to 60C for long service periods. PVDF is rated for service up to 140C and we are working with Solvay to demonstrate its use in our product for temperatures above 80C.
No not yet.
The polymer materials we are using (HDPE and PVDF) for fluid containment are inherently more resistant to any acidic conditions than steels. As such we do not need to separately qualify the polymer materials. PVDF in particular has had more than 30 years successful service in sour conditions in North Sea and elsewhere.
The high strength steel does not come in direct contact with the fluids and hence less risk than conventional materials. However, this can be qualified if required against ISO 15156.
No. The management of gas permeation through polymers is well established for high pressure flexible pipe used offshore – see API 17J, for example. There is more than 30years successful experience offshore around the world using PVDF at high temperatures and pressures.
Gas venting is engineered into our system. Each end fitting has a relief or collection valve to control gas build up as required. In addition, our reinforcement strip provides a natural relief system should the pressure exceed more than a few bar.
In the U.K. gas permeation has been extensively measured for HDPE pipe, which has been in extensive service for more than a decade. A published figure is 68 cu m per km per year. We have also modelled gas permeation using FEA and conducted physical permeation tests as a part of our development programme. We have a documented Gas Permeation Control Methodology.
No. The pipe needs to be thought of as part of an overall process because MASIP is manufactured in the field with mobile automated equipment which reduces construction time and labour cost.
In this context specific studies have shown up to 60% lower costs and 40% schedule savings. Actual figures depend on specific studies.
High strength steel is only marginally more expensive than regular steel and is already a commonly used material in automotive applications. Using high strength steel reduces the amount of steel needed. HDPE is widely used in gas pipe in the UK and is low cost. High temperature applications do require more expensive materials but that is true regardless of pipe structure. We are working with Solvay on a high temperature modest cost solution.
We are currently completing documentation of design guidance for pipeline engineers and procedures for mobile manufacture under the FMECA plan endorsed by DNVGL – the global accreditation agency- at TRL5 under their technology readiness scheme. Our test programme is qualifying 12inch diameter pipe for sweet gas service at working pressures up to 100bar and ambient UK temperature conditions. Tests will then be extended to higher temperatures.
MASiP is ready for service in a field trial environment.
MASIP is already in trials with National Grid who operate all gas transmission pipelines in the UK. We envisage that pipe for ambient temperature applications to be ready for commercial service in 2021. Readiness depends on trial conditions and a high temperature version for service with fluids above 80C is under development. We envisage the need for 12-18months of field trials under the specific service conditions required – also to satisfy regulators.