For the past six months engineers at the UK’s WRc product testing facility in Swindon, Wiltshire have been completing a Long Term Hydrostatic Test of the PatchBox Pipe Repair Kit for localised renovation of pipeline defects in clay pipes. PatchBox is a product of the Sewer Centre, a trading division of Ant Hire Ltd, which is currently utilised by contractors across the UK for the renovation of pipeline defects, open joints and pipe connections on pitch fibre, plastic and clay pipes. In Ireland the product is available through Trench Control Ltd. Following a successful Short Term External Hydrostatic Water Pressure Test in 1999, WRc recently developed a technique for ‘Long Term testing of sewer repair and sealing techniques’ of such systems.



The WRc test was sponsored by MC-Building Chemicals of Germany to highlight the outstanding performance of not only its own product but also the complete PatchBox system under a variety of simulated operating conditions over a long period of time.
MC-Building Chemicals is one of the largest European manufacturers specialising in the production of environmentally friendly epoxy resins for the sewer rehabilitation industry, such as the Konudur 250 OM-PL two-part resin that forms a major constituent of the PatchBox lining process.

To complete the test MC-Building Chemicals took three 1 m long sample installations of the PatchBox liner and installed them into lengths of DN 300 clay pipe, each of which had a standard 100 mm by 100 mm hole defect in the centre of the test pipe length. The defect was positioned so that pooling of the repair resin would not occur during the PatchBox installation procedure.

The hydrostatic test rig comprised a steel tube with adapters bolted to each end as well as inlet and outlet valves to allow water to be pumped into and out of the annulus between the test sample and the test casing to create the external pressure loadings.

Two of the test sample repairs were made with no hydrostatic head on the test pipe during the repair procedure and the third was undertaken with a hydrostatic pressure head of 1 m applied to the outside of the test pipe.

The tests themselves were carried out with a maximum hydrostatic head of 5 m of water, with 1 m and 2.5 m test pressures being applied using a timer device during a cyclic test rotation of pressure and conditions over a six-month period as follows: 1 month under cyclic pressure (i.e. ‘wet’), 1 month with no hydrostatic pressure and all valves left open (i.e. ‘damp’),
1 month ‘wet’, 2 months ‘damp’ and 1 month ‘wet’. The wet/damp cycle was intended to simulate the seasonal changes in ground water level.


The results of the tests were excellent with the official WRc report stating that: “All three PatchBoxrepairs passed the long term external hydrostatic water pressure (leak tightness) test carried out in accordance with the revised Appendix C of the Specification for Local Sewer Repairs, Issue 2, 2005.” When asked to comment on the test results, Dr Andy Russell, who supervised the test procedure for WRc said: “The system was tested using various simulated ground water conditions with the samples being exposed to external hydrostatic pressures with everything from simulated high ground water pressure conditions to just standing, damp conditions. On monitoring the amount of infiltration around the test ‘Patches’ no inflow at all was measured from any of the repairs.” On that basis it could be said that the PatchBox system passed the test with flying colours.




Available online or direct from Sewer Centre, the PatchBox kit comprises an application system for 100 mm and 150 mm diameter pipes including (to order): a Glass Fibre mat cut to the customers specification and size; the appropriate resin requirements in two separate storage bottles; a 100/150mm by 1.5 m Sava lateral inflatable Packer; a Locking inflation coupling; a Heavy duty eye bolt and stainless steel extension with brass adapter to connect to drain rods; a Heavy duty hand pump; an Inflation Controller complete with safety valve and fail safe regulator; a 30 m inflation hose with locking self sealing couplings; and a Check Gauge to monitor pressure in the Packer whilst the repair is curing.

In site applications, several regular contracting customers have noted that using the PatchBox Kit is very easy and, in comparison to other kits available on the market, the use of the MC-Building Chemicals resin is preferred as this resin gives operators a longer working time to prepare the patch for a very high standard installation before curing occurs. 


Details of the products, kits or test procedures mentioned are available from:


For the Test Work

WRc plc, Frankland Road, Blagrove, Swindon, Wiltshire SN5 8YF, UK

Tel: +44 (0)1793 865000. Fax: +44 (0)1793 865001. Email:  HYPERLINK ""


For the PatchBox Kit

Sewer Centre, Queen Street, Stourton, Leeds LS10 1SL, UK

Tel: 0845 125 9595. Fax: 0845 125 9598. Email:  HYPERLINK "" Website:  HYPERLINK ""


Consultants for MC-Building Chemicals

CJ Kelly Associates Ltd, Coppice House, Main Street, Hemington,
Peterborough PE8 5QJ, UK

Tel: +44 (0)1832 293030. Fax: +44 (0) 1832 293311. Email:  HYPERLINK ""



Picture caption: PatchBox kit.jpg

The PatchBox Kit – available across the UK from Sewer Centre, a trading division of Ant Hire Ltd.