Cotter Plate Identification and Remediation (Stage 1)

Completed

Fossil Fuels: Oil Gas and Coal(Oil and Gas, Refining, transport and storage of oil and gas)

Applied Research and Development

ENVIRONMENTAL SCIENCES (Geography and Environmental Studies)
ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering)

Not Cross-cutting

Project Contact
SGN

Network Innovation Allowance

Ofgem

01 March 2014

01 June 2014

3 months

£13,332

Technical Consultancy

South East

Network Innovation Allowance

Project Contact, SGN

The objectives of this project are to: ; Develop and refine a method to identify likely Cotter Plate locations; Create a shape file (GIS) output of trial areas in support of Stage 2 The key success criteria will be: ; Part 1: Polygon map created covering blocks of buildings that have the same classification - existence of bomb damage collected as an attribute code to the polygons. ; Part 2: Five trial areas of 2km x 2km agreed by both parties selected for Stage 2.

Over the years Scotia Gas Networks (SGN) has seen many changes in the types of materials used in the construction of its distribution networks and the way in which it is maintained. This project addresses problems associated with a specific piece of equipment previously used in operations to isolate part of the live gas network, a necessary step when repairs or modifications are required. The piece of equipment is a ‘Cotter Plate’ (sometimes referred to as a ‘Cottel’ Plate), and was used up to the early 1950s, particularly during WWII. When isolating a gas main, a hole is made in the main. A Cotter plate would be locked to the chiselled hole, as a method of re-sealing the gas main. Although fit for purpose at the time of use, the engineering has not aged well and fatigue of the clamp and corrosion has resulted in leakage at the Cotter plate contacts. This problem has been identified as a result of finding corroded Cotter plates when responding to public reported escapes. However, it is not possible to proactively identify Cotter plates, assess risk of failure and remediate where appropriate because there are no records of these assets’ locations. As a result, the objective of this project is to firstly undertake a study to determine the potential location of these plates throughout our network. Future work may then be carried out to investigate the reliability of the method of locating Cotter plates, their condition and develop a cost effective methodology for remediation of the seal failure over external encapsulation. This project represents Stage 1 of a three stage programme to develop a Method of locating and remediating Cotter plates: Stage 1: Develop a method to identify likely Cotter Plate locations and create an output of trial areas to support Stage 2. Stage 2: Internally inspect the identified locations for evidence of Cotter Plates. Stage 3: Develop and test a more cost effective methodology for remediation over encapsulation. Stage 1 Method OverviewSince Cotter plates were mainly used during WWII, to rapidly repair bomb damage to gas mains, it is believed that bomb damage to buildings can indicate areas where large diameter gas mains may have been damaged and subsequently repaired with a Cotter Plate. Very little bomb damage to buildings was repaired during the war. Buildings which were bomb damaged during the war can be identified and where the detail exists, a distinction between highly damaged and less damaged can be drawn. Secondly, new structures which replaced badly bomb damaged buildings can be identified, with the inference that the gas mains were also damaged and possibly repaired. The Method trialed in this project will be use of bomb maps and historic aerial imagery (compiled by the project supplier) combined with SGN’s maps of network infrastructure in existence during WWII to create a GIS map of likely Cotter plate locations, based on proximity of gas mains to bomb damaged buildings.Note : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above

09/08/18