Automated system speeds up
time-consuming hose testing and
adds data recording capability
Frank Smith
Vice President of DHAS Automation Services
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DHAS Automation Services, Inc., an OEM and a systems integrator in Alpharetta, GA, was recently faced with the challenge of developing an automated system for pneumatic and hydrostatic pressure testing of metal hoses at American BOA in Cumming, GA. American BOA specializes in the design, development, and manufacturing of high quality flexible metal hose products, as well as products such as expansion joints, automotive exhaust bellows, and cryogenic transfer hoses.
The type of hose manufacturing performed at American BOA requires 100% pressure testing. The company had always tested hoses manually for pressure integrity, but the testing was a time-consuming task. Hoses had to be tested one at a time and data was entered manually when the test was completed. The manual system also had the potential to be very dangerous when air pressure became high. If a hose ruptures, it causes a sudden and violent expansion that can be very dangerous. "When we started to think about developing a new automated system, safety concerns were a big issue. The driving factors in a new test system were not just increased production, but also improving the safety of the tests," says Steve Goley, manufacturing engineer with the hose division at American BOA.
DHAS Automation was asked to develop an automatic system that would allow hydrostatic and pneumatic tests to be conducted on hoses of varying sizes diameters and lengths for pressures up to 2,000 psi. The goal was to speed up the process, develop an accurate means of testing, make the process safe, and enable the system to record historical data so that if a hose failed in the future, the company would be able to go back and examine test data.
American BOA and DHAS worked together to design the automated test system. Goley was responsible for designing and purchasing "quick connect" couplings for the various sizes and types of hose being tested. DHAS was responsible for the design of the electronic controls and necessary hardware to automate the test procedure itself. DHAS developed a PLC-controlled testing system using a D2-250 CPU, Ethernet communication module and 10" operator interface screen, all from AutomationDirect. This system was combined with Dataworx PLC, a software package that collects and stores testing data, developed by INTEWORX.NET, a software and application service provider that specializes in remote-monitoring systems that can be linked to the Internet.
The system is operator-controlled from a simple interface on the operator panel. From the panel, an operator sets up the system for testing to test based on the size of the hose. Setup parameters include the test type (air pressure or water pressure), the product's part number, the length and diameter of the hose, the length of time the test will be conducted, and the test pressure. Depending on the size of the hose, up to four hoses can be connected and tested at one time. The system automatically fills each hose with the required amount of air or water to conduct the test. To address safety concerns, a guard was placed over the test tank to contain any sudden loss of pressure.
Upon completion of a test, the PLC sends the test results to a Microsoft® Access database through Dataworx PLC. This method is a report-by-exception function that gives the PLC complete control to write to a text file or database through a server-based application. The PLC utilizes an Ethernet link and will receive a message confirming that data was stored in the database. In the event the confirmation message is not received, the PLC can store the test results locally until the network link can be re-established. Once the data is stored in a database, it is then available to plant personnel over the company intranet. The system also contains a n ASCII printer connected directly to the serial port of the the D2-250 PLC CPU so that data can be printed immediately after each test. The data collection allows no operator modifications, so the integrity of the data is secure. With Dataworx PLC, the system offers higher data integr it e tit y than the continuous polling methods employed by traditional SCADA software . continuous polling of the PLC allows the data collection to continue where it left off.
The system has been coined the "Minute Man IV Pressure Test System" as it is able to tackle once-cumbersome manual testing in a matter of minutes. The Minute Man IV is a scalable, skid-mounted test system that can be used for any type of pressure testing of hoses, pressure vessels, tanks, etc. It can be offered with as many test ports as a customer needs and can be created as a pneumatic-only system or in both pneumatic and hydrostatic configurations.
With the implementation of the system at American BOA, the company now has a quick, reliable means of testing their hoses and a way to easily record data for analysis. Both American BOA and DHAS Automation view the new system as a success. Says Goley, "Introducing a new pressure test system has been a challenging and rewarding upgrade to our hose division operations. We now have the ability to optimize our test methods and procedures and customize them for future systems."
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