On Line Test Systems for Safety Valves

On Line Test System for Safety Valves

Swiss Approval Advanced NDT Laboratory has put in place, and use specific technology for Testing of Safety Valves.

Such technology encompasses a comprehensive safety concept to safeguard the User, the Test Object (safety valve) and the Test System itself against damage. The inspection system is supported by specific Software, which generates reporting and maintains traceability of inspection activities.

The On Line Inspection System of Valves, enables Plant Managers to test the spring operated safety valves on site without interrupting the process operation. With this so called “hot testing” the safety valve stays on-line, and no dismantling of the valve or plant shut-down is required. The main advantages are:


The system is a dedicated test system for on line / on site Safety Valve Testing. To test a safety valve on line or on site, the following tasks have to be dealt with:

  1. Lift the valves disk from the outside using a force generating unit
  2. Measure lifting force, disk lift and system pressure (line pressure) while lifting the disk.
  3. Control the lifting process
  4. Visualise, analyse, print and store measured values

Task 1 – Lifting the valve disk
The inspection System is using hydraulic mechanism to generate the lifting force. A hydraulic pump with an attached valve block is used to operate a hydraulic cylinder up and down. The pump and valves are built into the Power Box. The hydraulic cylinder is part of the Test Rig that has to be mounted onto the safety valve and connected with the safety valves spindle via an adapter system. To operate the hydraulic cylinder up and down two hoses lead from the Power Box towards the hydraulic cylinder.

Task 2 – Measure
Force, lift and line pressure as well as other parameters are measured directly with dedicated sensors. Force and lift sensor are attached to the Test Rig whereas others are free to be mounted wherever suitable. All sensors are connected to the Electronic Subsystem, located inside the Power Box. The Electronic subsystem converts physical sensor signals into digital data and sends those via a data communication cable to the specific Software, running on a connected Computer.

Task 3 – Control
Pump and valves are controlled directly from the Software running on the connected specific computer. Every command as well as every hydraulic pressure adjustment, is generated from the Software itself, and send via a data communication cable to the Electronic inside the Power Box. The Electronic subsystem converts those data into physical signals, send to the pump and valves.

Task 4 – Analyse, visualise.
Visualisation, analysis as well as printing are handled by the Software running on the connected computer. Storage of recorded data is done in a specific database.

Typical System Graphs and Reporting

The graphs produced are genuine examples from conducted tests. They show typical results of test to be found in every day work. Based on the knowledge gained from the experience, the analysis is absolutely clear and free of doubt.

An Inspection report, containing all data used for each specific test, is saved in the system, and available upon request for review and verification.

Calibration Blocks

Swiss Approval Laboratory Staff is working consistently to guaranty the maximum efficiency and reliability of our Testing Results.

Specific Calibration Valves for each kind of safety Valves and working pressure values, are designed and developed within our Laboratory, in order to build in house our Know-How, necessary for service delivery of excellence.

Such development of inspection resources and capacity represents for Swiss Approval Top Management, substantial commitments of time, high qualified personnel and significant capital investment.

Accreditation ISO 17025

Swiss Approval Advanced Laboratory based in Europe, is currently under ISO 17025 accreditation process.