Technical Articles
Engineer for quality
Published 03 January 2019

It is generally agreed that causes of most manhole failures are due to incorrect installation, poor product choice or subsurface defects. Good installation can be achieved by understanding a variety of factors relating to performance characteristics and product interaction with bedding material and chamber structure.  Product longevity is undoubtedly determined by several factors, including design considerations for:

  • Seating areas
  • Flange thickness
  • Load tolerances and dispersion
  • Bedding mortar
  • Build type
  • Installation

Considering load stresses and the way they are distributed across the cover and frame, and subsequently into the bedding material, is important. Good product design has to ensure that the loadings are distributed as evenly as possible, minimising the impact on chamber top installations and reducing the risk of early failure. The aim is to increase the life of the product and avoid the need for frequent and costly reinstatement!

Clark-Drain - Technical excellence based on modern foundations

Design to material sourcing, through production line methods with varying degrees of manufacturing value can all affect our product choices - No two suppliers are necessarily the same! So what ensures the right products are being chosen? First: it’s about manufacturers understanding their use and performance. How they are going to be trafficked and how they help create a better everyday life for people, vehicle use and function of the built environment.

During design, for example, good practice with product engineers should optimise and validate each design step using CAD simulations to ensure quality, performance and safety.  Load dispersion models, often created in 3D, can help to provide Finite Element Analysis (FEA) to calculate component displacements, strains and stresses under internal and external static and dynamic loads.  

Third-party accreditations verify that products are fit for purpose and at Clark-Drain manufactured processes operate under BSI-Certified IS0 9001:2015 Quality Management Systems. Furthermore, all cast iron products are third-party accredited by BSI under their Kitemark scheme for further assurance of performance and quality. All manufacturing processes are routinely audited and products re-tested throughout their lifetime to ensure on-going quality and conformance to performance requirements. All Highways products are designed in accordance with the relevant UK Highways Agency design requirements (HA104/09). Furthermore, our steel products benefit from an in-house fabrication facility deploying the very latest in CNC and robotic manufacturing methods. This enables further control within the manufacturing route as well as control over manufacturing costs. As well as fabrication Clark-Drain’s modern and efficient galvanising and powder coating facilities are used to process its own in-house products as well as a range of external products.


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