INSPECTION AND TESTING OF EQUIPMENTS

Inspection and testing of the purchased equipment is one of the most important tasks in the engineering of a project. Its importance is sometimes underestimated. The first serious tests that the purchaser will witness are those in the factory where the equipment is assembled. These tests will also include a physical inspection of the equipment.

It is therefore important to state clearly in the specification what inspection and testing will be required and, where appropriate, what are the acceptable limits of the results. Most tests required in the oil industry are covered in international specifications and these can be used as references.

However, not all those in the reference documents need to be carried out in all cases. It is therefore prudent to state the requirements in the project specification in one or more of the following methods:

• Write a detailed description of exactly what is required, including the limits that are acceptable and the form in which the results should be reported. This method ensures a ‘self-contained’ approach that is very beneficial during the actual testing operation. Often time is limited to perform tests and to have all the requirements to hand without having to search through related documents enables the work to be completed very efficiently.

• Quote the exact clause numbers and sub-section headings in the reference documents for the particular tests to be performed. This may be less efficient when the time of the tests becomes due, especially if the reference documents are not easily to hand. If a statement is made such as ‘the switch gear shall be tested in accordance with the XYZ-123 international standard’ and no other clarification is included, then many debates can arise at the time of testing.

Whichever method is used it should be carefully checked by a quality assurance department before the specification is approved for purchasing the equipment.

Some types of equipment require ‘production tests’, ‘type tests’, ‘performance tests’, ‘routine tests’, ‘abbreviated tests’ or ‘special tests’, or a combination of these tests. The subtitles are sometimes used with different meanings. Production tests are required for complex equipment such as high voltage generators and motors, and these tests are performed in the factory before the complete unit is assembled. For example the rotors are balanced without the stator, air-to-water heat exchanges can be tested to withstand hydraulic pressure, winding insulation and individual coil insulation can be tested.

Type tests are performed on one from a group of identical units. These tests are comprehensive and some of which are usually only performed once in the life span of the equipment.

If the equipment is a standard product of the manufacturer for which existing certificates can show that a type test has previously been carried out, then the purchaser may wish to accept the certificate without repeating the test. This is largely a matter of choice than necessity.

Routine and abbreviated tests are generally the same form of tests. These are applied to those units in a group that have not been type tested. If only one unit is to be purchased and a type test has been waived then a routine test is usually performed and the results compared to those of a previous type test. The number of different tests included in the routine tests is less than that of the type tests.

Some of the tests may be identical in each category. Routine tests are usually witnessed by the owner or purchaser.

Performance tests are those tests that need to be carried out on combined equipment such as a gas-turbine driven generator or a pump driven by a high-voltage motor. In such cases the dynamic relationship between the various equipment's is of interest. For example, rotor vibration, critical speeds, run-up time to full speed, starting up and shutting down sequences, full-load and over-load performances, heat dissipation and cooling medium performance. Occasionally ‘special tests’ may be required. These may be due to the need to operate the unit in an unusual mode or to test special control systems that may involve associated equipment such as a power management system or a control panel. Special tests may be needed to verify the operation of protective devices in the equipment rather than the equipment itself, but which require the device to be in its fully functional position on its host equipment. The owner or the purchaser usually witnesses performance and special tests.

Routine tests usually include a thorough inspection of the equipment both before and after the testing is complete. Routine testing should not be confused with sample testing. For example a switchboard may consist of many panels of essentially the same type, e.g. motor starters, transformer feeders. The testing schedule should state whether samples of similar types could be tested in lieu of testing all the units. In either case a full routine test is generally required. Functional testing of mechanical operation should be applied to all the units, e.g. open and close contactors, rack in and out circuit breakers, operate switches and controls.