New Pressure Test Installation Enables York Refrigeration to Safely Verify Vessel Integrity

February 15, 2001

Faster final certification of refrigeration components at the York Refrigeration, formerly Sabroe, plant in Aarhus, Denmark, has eliminated a severe production bottleneck and resulted in a production increase of 150 percent. The plant manufactures compressors, vessels, and finished condensing units to meet the requirements of a growing customer base throughout the world.

According to Jan Marcussen, Quality Director with York Refrigeration, the increase was made possible by replacing a slow, expensive hydrotest procedure with air pressure testing to speed up the final certification of pressure vessels and reduce energy costs. However, the existing test chambers could no longer be used because any flaws in a vessel could result in an explosion under high air pressures. To provide a safe environment for personnel conducting tests, the company built a new, stateof-the-art facility that safely accommodates compressed air testing.

New Test Facility

Engineers from Fisher-Rosemount, who are in charge of the pressure tests, Dansk Trykluft Industri, the compressed air supplier, and York Refrigeration agreed that, in addition to fulfilling safety considerations, the test facility must:

Accommodate several independent pressure tests simultaneously in various chambers to eliminate the bottleneck problem.

Withstand an explosion of a 15 cubic meter vessel.

Allow pressure to be relieved following a test without exceeding local noise limits.

Fulfill the requirements of the various authorities and accredited agencies concerned with the execution of pressure testing, certification of results, and safety.

Support procedures that are traceable and consistent with the end-user's status as an ISO 9000 company.

The new test facility is constructed of reinforced concrete (similar to World War II bunkers) with four separate test chambers. The two larger chambers can each accommodate six separate pressure tests, and the smaller chambers are for testing two vessels each. Every test stand is equipped with a pair of Baumann 54-24577SB control valves with Fisher-Rosemount DVC5010-SD positioners (one valve works Fail Open and the other works Fail Close) plus a Rosemount 3051 HART pressure transmitter. The installation has a total of 38 valves and 17 pressure transmitters. One pressure transmitter is a master, calibrated regularly against a National standard at an accredited laboratory. Test pressure loads as high as 90 bar (1300 psig) are possible.

As a part of the approval process for the large pressure chambers, an explosion of a weakened vessel was performed. The result is shown below. The test chamber "survived", even though the air lock built in the roof was damaged. The test did not go by unnoticed, as underground vibrations set off several automobile alarms in the neighborhood. However, the noise limit was not exceeded, and the chamber received regulatory approval.

Pressure Testing

Actual pressure tests are started by connecting the test items to the respective test outputs in one chamber. The specifications for each test sequence are then loaded into a DeltaV automation system, which controls each individual test. Safety loops verify that the large 4,000 kg (8,800 lbs) doors are fully closed and sealed with a separate air pressure system to avoid leakage before a test sequence can be initiated. Should a fault occur during a test, pressure in vessels under test is immediately relieved to the outside through an internal piping and silencer system, and the compressed air supply for the chamber is also cut off.

If the safety loops are okay, test sequences begin simultaneously. When all sequences are finished, the chamber can be opened and the items removed.

During the test period, all results are logged and related curves are printed out, verifying that the test period and specified pressure levels were in accordance with specified requirements.

Fisher-Rosemount Asset Management Solutions (AMS) software is used to document test results for each vessel or compressor in order to maintain York Refrigeration's ISO 9000 certification. Every test is verified by the data recorded on each vessel tested.

The AMS software is also a valuable part of the maintenance program for the pressure test facilities to document the performance of the test equipment and identify devices that may need repair or replacement.

Jan Marcussen said that the company expects to recover its investment in the test facility within the anticipated time frame, based solely on reduced energy consumption using the new procedure. However, eliminating the production bottleneck by instituting new test procedures was the major benefit. All things considered, the project has been an unqualified success, Marcussen said.

Publication date: 02/19/2001