FEATURE HAZARDOUS AREAS & SAFETY
35th Anniversary
he Kittiwake offshore platform, in the North Sea, was installed in 1990. It has several decks - including cellar, production, mezzanine, drilling and helipad – and living quarters for the 70 personnel which are typically on board at any one time. As with any oil and gas platform, safety
is underpinned by the functionality and reliability of its Fire & Gas Detection (FGD) system; which includes sensors, alarms and some form of logic processing. On Kittiwake, there are 63 circuits for
flame detection (with each circuit having one or two detectors assigned), 93 circuits for smoke detection (with up six detectors per circuit), 162 gas detectors and numerous emergency push buttons around the platform. Cables for the above all terminate at six
marshalling cabinets in the platform’s control room and until recently the FGD system’s functionality had been delivered through a mix of hard-wired relay and solid-state logic; built to cause and effect engineering diagrams. Behaviour, defined through logic, includes ‘voting’ to avoid spurious alarms. For instance, a single detector triggering would be logged but it would take the triggering of a second detector (in the same zone) to raise an alarm and possibly initiate an automated response, such as water deluge. The control room also includes large
mimic panels for monitoring and controlling the FGD system, along with the platform’s processing functions. In the event of an incident, the operator manages an appropriate response on a zone by zone basis. However, whilst the zone and condition (e.g. smoke, fire or manual trigger) were known, identifying
HIMA-SELLA ALSO CELEBRATES A MILESTONE ANNIVERSARY
As this issue marks the 35th anniversary of Process & Control, it is worth noting that Hima-Sella celebrated its 40th anniversary just last year. Headquartered in Stockport, Hima-Sella has regional offices in Leicestershire and Aberdeen, employs
more than 100 full-time personnel and has a turnover in excess of £10million. It operates in sectors including Oil & Gas, Nuclear, Petrochemical, Rail, Steel and Power Generation. During its 40 year history the company has not only responded quickly to customer requirements and changes in legislation but, in many cases, has been well ahead of the game. For example, in the 1990s (and long before the ‘Buncefield Incident’ of 2005), Hima-Sella was implementing tank overfill protection, as part of broader and automated Emergency Shutdown systems. John Blackwell, managing director, said: “Our unwavering approach to safety, and the fact that we never forget that our customers seek operational efficiency through the high-availability of plant, equipment and infrastructure, have earned Hima-Sella a fantastic reputation. That reputation has been nurtured through the dedication and loyalty of some of the best engineers and a host of support personnel in the business.”
Logical logging of fire and gas alarms T
According to Andy Tonge, sales manager, Hima- Sella, an upgrade of the Fire & Gas Detection system on the Kittiwake platform means it is now one of the most advanced systems in the world
the exact sensor required wading through printouts. Also, it was a cumbersome process to inhibit parts of the FGD or modify it, if a change was required. An independent obsolescence review recently concluded that the FGD system was reaching the end of its maintainable life. A tendering process followed, and in 2013 safety instrumentation systems provider Hima-Sella was awarded the contract to develop an upgraded FGD system. It was a requirement that the existing
marshalling cabinets be used, along with existing field cabling and many of the sensors and detectors already in place: all gas detection was changed out for new technology (IR). Another requirement was that the installation of the new FGD must have minimal impact on operations (i.e. minimal shutdown) and that future modifications be easily accommodated. The system would also need to present operators with clear views, on four monitor screens, of incidents (triggers) so they could make informed decisions. The new FGD system was built around a
HIMA HIMax Programmable Electronic System (PES), rated to Safety Integrity
On the Kittiwake offshore platform, safety is underpinned by the functionality and reliability of its Fire & Gas (FGD) system
Level (SIL) 2 in accordance with IEC 61508. The functionality was extracted from the
An operator’s view of the new FGD system. On the right hand side is a layered view of Kittiwake. The triggered alarm is highlighted in red and detailed (logged) below in the black area of the screen
original relay and solid state logic drawings, cause and effect diagrams, safety case, operational procedures plus input from operators and other personnel. It was coded in SILworX, a constrained integrated development environment for building systems using safety-certified functional logic blocks. Compiled and tested code resides with the HIMax to replicate the functionality of the legacy FGD system, along with parts of Kittiwake’s Heating Ventilation and Air Conditioning (HVAC) system, the behaviour of which must be closely tied to FGD. All hardware and software meets the requirements of the IEC 61508 standard. The HIMax occupies three new cabinets,
installed in the control room alongside the existing marshalling cabinets. HIMax’s ability to support hardware and software changes on the fly is currently enabling a zone-by-zone migration of the legacy FGD system, without interrupting operational processes or compromising safety. Future updates will be accommodated with similar ease. As for monitoring and controlling the new FGD, this is via a menu-driven user interface developed using Panorama E2, a SCADA package, presented on four screens. In the event of a detector triggering, or a manual alarm being raised, the precise location of the event is automatically logged and presented on the control station screen. Operators must acknowledge any and all triggers. They are able to inhibit some signals and prevent alarms from being raised - if welding, for example, is being done - but not a manual action, such as an emergency button being pressed. Nor can they inhibit an automated response, such as a deluge. Operators therefore have better control over the new FGD system, without compromising any of its core fail- safe behaviour.
Hima-Sella T: 0161 429 4500
www.hima-sella.co.uk
14 JUNE 2015 | PROCESS & CONTROL
Enter 211 / PROCESS&CONTROL
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