LIVE MAINS INSERTION

The cast iron mains replacement technique offering maximumoperational flexibility

Live Gas Mains Insertion is similar to normal insertion of polyethylene pipe (PE) into an old cast iron main with one very beneficial difference. By using a special gland box, the old main is kept live throughout the insertion process and the new PE is gassed up to maintain gas supplies to customers.

Once insertion is complete, the main is still kept live to supply customers via the annular space until it is operationally convenient to transfer the services to the new main.

Live Mains Insertion is used for the insertion of low pressure (up to 75mbar) cast iron mains from 3” upwards and a wide range of PE/cast iron diameter combinations are possible.

Companies using the technique have recorded cost savings of up to 14% compared with dead mains insertion and up to 38% compared with open trench replacement *.

From a health and safety aspect, a minimum number of excavations need to be open at any one time. Being a low-dig technique, the environmental impact of Live Mains Insertion is reduced.

As consumers are off gas for a minimum time, the technique is also good for customer relations.

*Research in the UK has found that in the replacement of the most common pipe diameters (up to 6”/150mm), where the insertion is at least 150 metres in length, live mains insertion is more cost effective between 5% and 14%.

Statistics from the US show that when compared with open trench mains replacement, live mains insertion can save between 30% and 38% of costs.

• Cost savings of up to 14% compared with dead insertion

• Minimum traffic disruption–fewer excavations open at any one time

• Lower environmental impact

• Customers off gas for minimum time

• One-hit service renewal–only one purge and re-light per customer; no wasted fittings

• Services can be transferred in line with labour and customer availability

• CPs and AEs are required onsite for only short periods during insertion process

GAS WATER NUCLEAR CONTRACTSERVICES

BENEFITS

355 Pipe Handler Inserting 250mm PE into an existing 12” main

LYONTEC™ gland boxes

The Hexi Pipe Coil Trailer handles 500m coils of up to 90mm PE

Steve Vick Pipe Handler inserting 250mm PE into a 12” main

EQUIPMENT & CONSUMABLES

BACKGROUND

PIPE SIZE COMBINATIONS

APPLICATIONS

Steve Vick International supplies all the hardware, application equipment and consumables required to carry out Live Mains Insertion.

The company has developed specialist foam sealants for use in Insertion Seals and End Seals. These fully meet the gas industry standard specification GIS/LC14.

The use of pipe pushing machines and/or pipe handlers and pipe coil trailers is necessary for the safe, efficient implementation of live mains insertion. These can be hired or purchased from Steve Vick International.

Steve Vick International has been closely involved with the Gas Industry for over 30 years in the on-going development of the Live Gas Mains Insertion technique. The company is also the licensee of Gaz de France for the LYONTEC™ disposable gland box developed jointly by the two organisations.

One question frequently asked about Live Mains Insertion is whether the annular space between the inserted PE and the cast iron is sufficient to feed the given number of customers. In fact, the capacity is more than adequate in most cases. For example, inserting 75mm PE into a 4” main leaves an annulus equivalent to a 75mm diameter pipe.

Please contact us for a copy of the Steve Vick International Matrix which gives the capacity of the annulus expressed as the nearest equivalent PE diameter, or download it now from stevevick.com

Although used principally in the replacement of low pressure cast iron mains between 3” and 18”, live mains insertion can also be carried out on ductile and steel mains when window cutting is required. It is also possible to carry out the procedure on medium pressure mains although this operation would be executed by a Steve Vick International Contracts team.

When inserting PE up to 180mm diameter it is usual to ‘gas up’ the PE prior to insertion and use a live head to allow gas to pass between the PE and the annulus. Above this diameter, where straight sticks of PE are used instead of a coil, it is possible to carry out the procedure without first gassing up the PE.

4” Main

Annulus75mm

PE75mm

PEAnnulus equal to

2

OUTLINE PROCEDURE FOR PE SIZES UP TO 180mm

• Install and commission by-pass

• Insert flowstopping bags

• Cut out section of main between bags

• Fit live head and test end on either end of PE

• Install and commission PE purge by-pass

• Push live head into gland box until it pierces membrane

• Remove flowstopping bags

• Push PE to required length

• Squeeze off PE and cut out at suitable point•

• Cap off end of main not being inserted

• Fit LYONTEC™ gland box assembly

• Fit Pipe Handler to excavator

• Open test end valve

• Let gas purge PE until 100% gas is registered

• Close test end valve

• Connect PE into new or existing main

• LYONTEC™ gland box is left in position as an end seal

• Close by-pass, plug holes, backfill

For more information on Live Mains Insertion call our Technical Support Team on 01225 864 864

3

Scan here to watch the Live Mains Insertion Animation

Steve Vick International Ltd. Treenwood Industrial Estate, Bradford on Avon, Wiltshire, BA15 2AU

+44 (0) 1225 864 864 stevevick.cominfo@stevevick.com

TRANSFERRING THE SERVICES

RECOVERY OF LIVE HEAD ORDERING

It is recommended that 2, 3 or more services are undertaken using one Insertion Seal (foam-off kit). Transfer of services must begin at the service furthest from the live head and proceed towards it.

For two-way fed mains, a bypass must be set up between old and new mains and a bagstop operation is required.

Lengths of inserted main should be carefully measured so that the position of the live head is known.

To recover the live head on completion of the procedure, foam is injected into the annulus near to the ivehead. A section of main is broken out and the PE is squeezed off. The end of the PE with the live head attached can then be pulled out. The PE is capped and the squeezed-off removed.

Please note that Insertion Seals and End Seals are available from stock to fit a wide range of PE/main diameters. For diameters from 400mm in 3” up to 400mm in 18”, are available to special order. LYONTEC™ Gland Boxes, Reversible Standpipes and Application Guns are also available from stock.

Please call Technical Sales Support on 01225 864 864 for advice on ordering.

• Excavate first group of services

• Remove existing fitting and install foam injection equipment

• Inject Insertion Seal foam following instructions

• Test foam has made a good seal at second service position New service transferred to the inserted main showing ENDSEAL™

Live Head, Modified Wask Night Cap & Reversible Standpipe

Scan here to watch an ENDSEAL demonstration video

Scan here to watch an Insertion Seal demonstration video

• Remove old section of main at that position and transfer service

• On completion of service transfer, fit End Seal

• Backfill