Conventional Stainless Steel Loop

The most conventional way to distribute compendial water around a facility is via a stainless steel ring mains, daisy-chain or serial loop. Whilst this is currently the most conventional, it is not without its challenges.

Correct design of a stainless steel ring mains is critical as it will determine the current and future capacity, guaranteed flows rates and diversity at each user-point as well the impact on any future iterations.

Because each user-point can directly affect the surrounding user-points in a serial loop, it is important to consider the routing (shortest, most economical route taking into account user-point prioritisation), pipe size and pump capacity to ensure diversity and guaranteed flow rates.


The basic system requirements for a conventional stainless steel distribution loop according to CFR 212 are:

  • Flow velocity to be a in the range of 1-3m/sec at all times
  • Control temperature to be <20° and > 65°C
  • Ensure smooth surfaces through the whole loop including all welds
  • Minimise or eliminate crevices – use (sanitary) joints only where necessary
  • Avoid “dead-legs” and areas of stagnation
  • Design the loop to allow drainage through gravity (ie loop must have a slope)
  • Ensure correct “hydraulic balancing” of the system
  • Make provision of sanitisation procedures (heat, Ozone, chemical)
  • Consider volumetric throughput and system capacity (pipe size, storage and pump)

The use of Stainless Steel 316L is preferred in most conventional loops. Different grades of Stainless Steel 316L are available, as shown in table 1 below. Systems designed and installed by Honeyman come with a traceable material certificate including all fittings to prove all 316L is of the same quality grade.

Table 1 316L Stainless Steel Composition

All pipework will come internally polished, with a RA (Roughness Average) typically around 0.4 – 0.6μm and all dimensional tolerances meet ASTM 269 / 270. All welds are square face butts, TIG welded using automated radial welding machines with minimal crevasses. All stainless steel systems are flushed, degreased and fully passivated prior to commissioning.

Our engineering and design team has been involved in countless water systems, from feasibility, through to URS, design, installation, commissioning, validation, maintenance and upgrading.

Honeyman’s design and engineering team have decades of experience, dating back to the 1970’s where water distribution systems evolved from a “Christmas tree” design (with many dead legs and no circulation) to the conventional serial loop to the now more commonly used parallel loop or HydroGienic®.

Whether you need advise at the start of your project for the feasibility, URS or design stages, or you need help in maintaining your current conventional loop, our team at Honeyman is keen to find a workable and economical solution for you.

For a free initial consultation, please contact us.

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