BACKGROUND
SGN Gas to Grid Project Co1 is a specialist subsidiary of SGN delivering renewable gas infrastructure projects supporting the recovery, upgrading and injection of biomethane into the UK gas distribution network.
As part of its decarbonisation strategy, SGN Gas to Grid initiated the Blackburn Meadows Biomethane-to-Grid Project in partnership with Yorkshire Water to increase the injection of renewable biomethane into the gas network.
The Blackburn Meadows site, located in Sheffield, operates as a live Yorkshire Water Wastewater Treatment Plant (WWTP) incorporating anaerobic digesters (AD) for the treatment of sewage sludge.
Biogas generated through the anaerobic digestion process has historically been used to fuel Combined Heat & Power (CHP) units and auxiliary boilers, with excess gas managed via an existing waste gas burner system.
To improve sustainability and maximise utilisation of renewable gas generated on site, SGN developed a new biogas upgrading facility to process raw biogas and convert it into grid-compliant biomethane suitable for injection into the Cadent gas network.
The scheme forms part of the SGN wider low-carbon energy strategy and, once operational, is expected to generate enough renewable biomethane to meet the annual heat demand of approximately 4,000 homes.
The mechanical piping design for the facility had already been completed as part of the wider development programme, while civils works and packaged plant installations were undertaken concurrently by others within the live operational site environment.
As part of the development, SGN required a specialist mechanical contractor to undertake the fabrication, installation, testing and commissioning support of above-ground interconnecting pipework for the Biogas Upgrading Plant (BUP) and Grid Entry Unit (GEU).
SCOPE
Rayden Engineering Ltd (REL) was appointed as Principal Contractor under CDM 2015 to deliver the specialist above-ground mechanical pipework installation works.
This comprised of fabrication, installation, testing and commissioning of stainless steel and carbon steel interconnecting pipework systems between the site battery limits and packaged plant equipment associated with the BUP and GEU.
Scope included:
- Offsite fabrication of stainless steel & carbon steel pipework spools & support steelwork.
- Installation of raw biogas inlet pipework between Yorkshire Water condensate pot outlet & BUP.
- Installation of interconnecting pipework between BUP & GEU.
- Installation of associated above-ground pipe supports & mechanical components.
- NDT inspections, hydrostatic testing, pressure testing, QA assurance & completion of commissioning support activities in accordance with IGEM GL/5 requirements.
SERVICES DELIVERED
Project Management & Pre-Construction
REL managed and coordinated the mechanical pipework package from pre-construction through to final handover, including fabrication planning, procurement, technical reviews and interface coordination within the live Blackburn Meadows WWTP environment.
Pre-construction activities included:
- Site surveys & dimensional verification.
- Preparation & approval of fabrication drawings.
- Procurement of stainless steel & carbon steel materials.
- Preparation & approval of welding procedures.
- Development of RAMS & SHEQ documentation.
- Coordination of installation sequencing in line with wider project activities.
All works were delivered in accordance with SGN milestone requirements, NEC4 programme obligations, applicable IGEM standards, GIS specifications and project-specific quality assurance requirements.
As Principal Contractor, REL maintained responsibility for health, safety and environmental management throughout the works in accordance with CDM 2015, the Pipeline Safety Regulations and the Management of Health and Safety at Work Regulations. Project-specific RAMS, SHEQ documentation and environmental controls were implemented to ensure safe delivery within a live operational environment.
Offsite Fabrication
To minimise on-site installation durations and maximise quality assurance, all pipework spools and support steelwork were prefabricated within the REL controlled workshop environment prior to delivery to site.
The fabrication scope comprised the following above-ground pipework systems:
Biogas Inlet Pipework:
- Fabrication & galvanising of dedicated pipe support assemblies to SGN/SP/CE/1 & SGN/SP/CE/4.
- Fabrication of ≈27.5m of DN300 PN10 Stainless Steel 316L raw biogas inlet pipework manufactured in accordance with ANSI B36.19.
GEU Interconnecting Pipework:
- Fabrication & galvanising of dedicated pipe support assemblies to SGN/SP/CE/1 & SGN/SP/CE/4.
- Fabrication of ≈22m of DN80/DN100 carbon steel interconnecting pipework manufactured in accordance with SGN/SP/DAT/6.
Workshop fabrication activities included:
- Dimensional verification & fit-up inspections.
- Coded welding to approved WPS documentation & applicable T/SP/P/1 & T/SP/P/2 requirements.
- NDT inspections & testing to T/SP/NDT/2.
- Preparation, preservation & packaging of completed pipework assemblies for transport to site.
Mechanical Installation Works
Construction activities were undertaken within the live operational environment of Blackburn Meadows WWTP. This required close coordination with SGN, Yorkshire Water and other specialist contractors operating across the wider biomethane facility development.
To minimise disruption and reduce on-site construction durations, works were delivered over a focused 8-day installation programme following completion of offsite fabrication activities.
Site installation activities included:
- Mobilisation & establishment of work areas & welfare facilities.
- Delivery & controlled offloading of prefabricated pipework assemblies.
- Installation of 5 no. new pipe supports for raw biogas inlet pipework.
- Installation of 4 no. new pipe supports for GEU interconnecting pipework.
- Fixing support steelwork to existing concrete foundations using anchor bolt systems.
- Installation, alignment & fit-up of prefabricated pipework spools for raw biogas & GEU inlet systems.
- Elevated pipework routing & support integration.
- Completion of tie-ins to packaged plant equipment & connection interfaces.
- Grouting & finishing works to support locations.
- Dimensional verification & mechanical inspections.
- Final mechanical completion & demobilisation activities.
Pipework Routing & Installation
The ≈27.5m stainless steel raw biogas inlet pipeline was installed above ground on dedicated support steelwork running from the Yorkshire Water biogas source connection point to the inlet of the pre-treatment plant.
The installation incorporated multiple bends, vertical risers, a DN300 to DN250 reduction arrangement and a 1:50 graded fall back to the condensate pot in accordance with the approved design requirements.
The GEU inlet pipeline comprised ≈22m of DN80/DN100 carbon steel interconnecting pipework, including ≈17m of elevated above-ground routing alongside the BUP before tying into the GEU DN100 inlet flange connection.
The GEU interconnecting pipework transitioned from a DN80 PN25 flange arrangement at the BUP outlet to a DN100 PN16 flange connection at the GEU interface.
All above-ground pipework systems were labelled to identify process contents and flow direction in accordance with project specifications and IGEM requirements.
Testing, QA & Commissioning
REL completed all testing, assurance and commissioning support activities in accordance with SGN specifications, Yorkshire Water requirements and applicable IGEM standards.
QA and testing activities included:
- Weld traceability & coded welding certification.
- NDT inspections & radiography reporting.
- Pressure testing & system verification activities.
- Inspection of above-ground carbon steel coating systems to T/SP/PA/10 & GIS/PA10, including remedial repairs where required.
- Compilation of materials certification records.
- Preparation of pressure test certification.
- Completion of IGEM GL/5 installation & testing assurance documentation.
No additional coating systems were required for the stainless steel raw biogas inlet pipework.
Testing of the raw biogas pipework was completed in accordance with Yorkshire Water Engineering Specification Y2304 together with IGE/UP/1 requirements.
The BUP-to-GEU carbon steel interconnecting pipework underwent hydrostatic testing, drying and pressure testing in accordance with IGEM/TD/3 requirements prior to commissioning activities.
REL supported SGN throughout the final verification and commissioning phases to facilitate successful integration of the new biomethane upgrading systems into the Blackburn Meadows renewable gas facility.
Completion
Upon completion of the works, REL carried out final site demobilisation and submitted all QA, testing and handover documentation in accordance with SGN project requirements including:
- Weld records, NDT reports, pressure test certification & as-built quality records.
Standards & Compliance
Works were completed in accordance with industry legislation, SGN specifications and recognised gas industry standards including:
- Construction (Design and Management) Regulations 2015.
- Pipeline Safety Regulations 1996.
- Pressure Systems Safety Regulations 2000.
- IGEM/TD/3 – Steel & PE Pipelines for Gas Distribution.
- IGEM/TD/16 – Biomethane Injection.
- IGEM/TD/17 – Steel & PE Pipelines for Biogas Distribution.
- IGEM/GL/5 – Managing New Works, Modifications & Repairs.
- SGN/PM/MSL/1 – Distribution Main Laying & Service Laying Activities.
- T/SP/P/1 & T/SP/P/2 – Welding of Steel Pipelines & Installations.
- T/SP/NDT/2 – Non-Destructive Testing of Welded Joints.
- T/SP/PA/10 & GIS/PA10 – Specification for Protective Coating Systems.
- SGN & Yorkshire Water site safety procedures.
OUTCOME
REL successfully completed the Blackburn Meadows above-ground mechanical pipework installation package safely, on programme, within budget and in full compliance with SGN project requirements.
The completed works provided the critical above-ground mechanical interconnections between the BUP and GEU infrastructure at Blackburn Meadows WWTP. This supported successful commissioning of the biomethane-to-grid facility and enabled the injection of renewable biomethane into the gas distribution network as part of SGN’s wider decarbonisation strategy.
