Pressure testing of fittings

Exciting and significant results achieved with stainless steel CrimpLink piping and fittings.

The manufacturers of our fittings have upgraded their pressure rating of 16 bar to 40 bar.

We decided to prove this statement and supplied samples of piping with fittings in 28 dia and 54 mm diameter to a recognised testing laboratory.

The test procedure called for the samples to be brought up to a pressure of 40 bar and held there for 8 hours at ambient temperature. The samples passed this test comfortably.

We then had the same samples pressurised to bursting pressure.

The maximum pressure their pump could handle was 98 bar. The 28 mm samples were taken up to this pressure and maintained there for an hour without failure.

 54 mm sample was brought to a pressure of 97 bar at which stage the stop end was pushed off the tube and pressure dropped to Zero.

These results are significant and of great importance to all Mechanical Wet Services Engineers.

 Multi story high rise buildings do not need multi stages to lift water to upper levels as our CrimpLink piping and fittings can handle a single stage push without failure. This should have significant benefits in application and design and ultimately, costs.

Stainless steel piping and crimp fittings

Stainless steel is typically considered an expensive solution, however the benefits of stainless steel in terms of longevity, quality and maintenance needs show that it is a comparative solution.

Design criteria

When designing a plumbing system historically, architects and engineers generally worked on the old standards developed when galvanized and black mild steel piping were in fashion.

Subsequently copper tubing became very popular, with good flow characteristics. This improved design criteria, as dimensions were slightly smaller, but flow and pressure losses were not negatively affected. The major problem has become theft from site of copper with the attendant losses of wasted labour and water losses and downtime in bringing in more stock.

With the introduction of plastic piping, wall thicknesses were increased to handle the same pressure. External diameters were increased to accommodate this, or internal diameters were reduced. What really impacts system design was that the fittings in many cases, had significantly reduced internal bores. Therefore, in an installation with a relatively high incidence where tees and other fittings are required, this has an impact on pressure and flow losses.

All these systems are limited in total pressure that they can sustain, which affects design and installation criteria

Stainless steel however, uses thin wall tubing, and the crimp-on fittings can comfortably handle higher pressures without affecting wall thicknesses. Also, the same internal bore of the tubing is maintained with the fittings, due to the flared-end design of the fittings, which fit over the tube, and are then hydraulically deformed onto the tube to give a consistently reliable joint. This also maintains excellent flow characteristics.

This is an incredibly rapid process providing a permanent, guaranteed leak-free joint rated  now at a pressure of 40 bar, with all the benefits that stainless steel provides. Pipe sizes are available from a 15mm diameter to 108mm diameter. As a pipe reticulation system, it is highly user and installer friendly, hugely time saving, and resultantly cost-effective which tick all of the boxes when efficiency is required.

Written by: Arius Wantenaar