Swiss TS is a small jewel of a company, with its headquarters located in the pretty Swiss village of Wallisellen, close to Zurich and about 10km from Zurich Airport.

The roots of Swiss TS were established in 1869 and today, after several metamorphoses and integrations, it is now a subsidiary company of both SVTI and TÜV Süd. Swiss TS is a notified body for pressure vessel testing in Europe; it employs 70 staff and has a turnover of €8m.

Swiss TS is more than a notified body, as it:

Provides independent testing facilities for pressure vessels, especially tanks and transportable gas cylinders
Undertakes conformity assessment
Provides critical training courses
Tests current technology for the automobile industry (CNG applications)
Innovates and develops novel non-destructive testing (NDT) equipment

Safety role played by Swiss TS for
Transportable Gas Cylinders (TGCs)

This little known company has taken tremendous strides in enhancing the safety of TGCs throughout the world.

During the 1970s, it became clear that the conventional way of re-testing gas cylinders using a hydraulic pressure test was not always sufficient. Many critical flaws formed by the previous gas service were going undetected and resulted in fragmentation of cylinders; with occasional fatalities e.g. stress-corrosion cracking of cylinders in coal-gas, carbon monoxide went unobserved with the hydraulic test.

Hence in 1974, the first automated ultrasonic machine was introduced for detecting cracks in gas cylinders by Swiss TS, which the hydro-test was incapable of finding. Such a non-destructive test gives the users of gas cylinders an advance warning of a potential rupture, before the defect connects the internal and external walls of a pressure vessel.The convincing results that followed meant that ultrasonic examination (UE) was officially recognised in regulations by National and International Authorities (ADR/RID/UN) as an acceptable alternative to hydrotesting. Fig. 1 shows a modern day machine.

Managed by a small team the UE project is led by Léon Kaelin, who is the Head of Testing Systems and has devoted almost his entire career developing ever-improving versions of the Swiss TS UE rigs.
Kaelin says, “Naturally we will be pleased to assist anyone, including cylinder manufacturers, to use ultrasonic testing to supplement their statutory requirements, but it is my sincere hope that gas companies will enhance their safety performance by installing UE for retesting TGCs, which is already mandatory for all new TGCs at time of manufacture in the EN and ISO standards.

Currently we have projects to install our equipment at both cylinder manufacturers and gas companies, while in the autumn of this year we will be taking our mobile rig to test a batch of about 500 cylinders at a customer’s site some 2000 km away from Switzerland.”

Apart from developing the UE machines, Swiss TS also trains staff to exacting procedures, will assist with the installation and commissioning of all their UE machines and also offer an excellent after sales service. All machines carry a one year or 2000 working hours guarantee, whichever is reached first. But since the machines are made using stainless steel coupled with the detailed and precise ways of the Swiss worker, the machines’ robustness is high, with few operational problems once they are correctly installed.

The reliability of their UE equipment is further evidenced by the fact that some industrial gas companies are still using the original mechanical rigs almost ten years after they were installed by Swiss TS’s competent engineers.

The ultrasonic examination machines
From the early beginnings, Swiss TS has been making continuous improvements with its UE machines over the past 30 years. It has now developed and innovated numerous features in its UE systems, which mean that a typical 50 litre, 1.5 metre-long cylinder can be tested in about 45 seconds.

Since the method does not involve introducing any water into the cylinder, this eliminates the steps of emptying or drying, as would be the case for the hydrotest. This not only ensures that the cylinder’s internal is kept totally dry, but also helps to preserve the very high product purity (parts per billion) specified by users of gases worldwide.

Swiss TS will either come to your site with its mobile UT system, “AutosonicTM Light” (and test the cylinders on a customer’s premises) or an entire system such as the “AutosonicTM” or even the “AutosonicTM Light” can be purchased, whenever the throughput of cylinders is low or if a testing on different plants is required.

Many leading industrial gas companies in Germany, UK, Australia, Spain have already bought an AutosonicTM machine, which is often tailor-made by Swiss TS to suit individual company requirements. There are numerous advantages of using UE to examine the integrity of gas cylinders and Swiss TS, with its varied competencies, will be very happy to answer your questions.

Further details can be obtained from
Léon Kaelin
Head of Testing Systems
Swiss TS Technical Services AG
Testing systems
Richtistrasse 15,
CH-8304 Wallisellen, Switzerland
Tel: +41 44 877 61 80 Fax: +41 44 877 62 15,