Subsea Control System 

Before installation the SPS control system needs to be tested as an integrated system, which should include all of the deliverable components of the control system. If possible at least one item of the “real equipment” should be used, if they are not available, then simulators should be used.

This test is called the EFAT (Extended Factory Acceptance Test). Some contractors call this the FIT (Factory Integrated Test) and some carry out this test as part of the overall subsea system integration test (SIT). However due to project execution deadlines, completion of the Subsea Control System testing is often required very early in the project schedule, to allow components to be released for integration into e.g. topsides construction.

Careful planning needs to be undertaken to ensure the main items of the control system are available for the EFAT. These would include MCS/SCU, EPU/SPCU, HPU, Hydraulic fluid, Motor starters, SCM, SCMMB, ESD Panel, Operator stations, Subsea sensors (or Sensor simulators) including, PT/TT, LVDT, DHPT, ASD, APD, IRCD, MPFM, V-Cone Flow meter, interconnecting test cables, hydraulic hoses etc.

At the start of EFAT, it is assumed that all equipment has already been subjected to Factory Acceptance Testing (FAT) (the availability of the Test Records should be verified).

The EFAT should not commence unless all of the system components have each completed their respective FAT’s and are functioning correctly as standalone units.

Therefore, each item can be assumed to operate correctly and interface with its immediate external interfaces. The emphasis of the EFAT is therefore to verify that the overall control system operates as expected, in particular with equipment that has never been connected together as a system before.

Where Simulators are used; care should be taken that these have themselves previously been tested as both functional and fully representative of the unit they are simulating.

The proposed test procedure should be written and submitted to the Client for review and approval. No test should be performed until the document has reached an acceptable status; therefore, the first issue should be submitted to the Client at least 6 weeks before the test. A signed, approved copy of the test procedure should be used to perform the test and the test procedure should not then be modified without written permission from the Client; in any event, a corrected document should be issued.

Previous FAT Results should be available.

The results of the EFAT procedure should be recorded in a EFAT Acceptance Test Report document, usually included as an Appendix to the EFAT procedure itself. The Report document should then be supplied with the final project documentation.

It should be signed and dated by all witnessing parties.

The report should be written as concisely as possible. However, care should be taken that actual test values are recorded, as well as a statement of PASS/FAIL for each test, so that the document can be used to check differences between identical units, as evidence of drift in parameters, or be used as reference values for other future tests.

All tests should be witnessed by the Supplier's QA department and test results 'stamped' as official records of events.

Ideally, and time permitting, the Supplier should have performed each test procedure at least once, before notifying the Client to attend, so that errors in the procedure are detected at an early stage.

The following is a summary of parameters that should be tested as a minimum for a subsea control system during EFAT. It cannot be exhaustive, as each system will be different, but the Client will find that the more testing that can be performed onshore before installation, the better the chances of a trouble-free installation and commissioning.