Gå til hovedinnhold

Audit of offshore cranes – Rowan Gorilla VI

The Petroleum Safety Authority Norway (PSA) has conducted an audit of offshore cranes on the jack-up drilling facility Rowan Gorilla VI (RG6). Three non-conformities and two areas of improvement were identified.


Rowan Gorilla VI (Source: Rowandrill Inc)
Rowan Gorilla VI

The verification activity on board the RG6 was performed by the PSA during the period  5-6 October 2009, while the facility was in yard stay in Dundee UK, for 5 years class survey and upgrades on the rig.

Background
Rowan Gorilla VI (RG6) is a jack-up drilling facility. An application for acknowledgement of Compliance (AOC) has been submitted to the Petroleum Safety Authority (PSA) for this facility prior to its intended work on the Norwegian continental shelf (NCS) in 2009.

Purpose of the audit
The purpose of the audit was to verify compliance with relevant regulatory requirements for the offshore cranes.

Result
As a general observation, Rowan has made considerable improvements regarding the offshore cranes compared to the status at the previous verification in December 2007.

During the verification on board the RG6, three non-conformities and two area of improvement were identified.

Non-conformities

  • Automatic overload protection system (AOPS) – verification: AOPS verification is outstanding.
    • Basis: Verification of the AOPS response time and consequent additional loading is outstanding.
      The performed testing of the AOPS does not verify anything about the system’s response time and additional dynamic loading.
      Some calculations on the system’s dynamic response were carried out during the 5th of October 2009. These calculations did include additional loading due to mass inertia of rotating parts.
      However, the calculations did not include for the event that AOPS is activated during hoisting at full speed.
      No verification of the system’s response time for releasing the brakes, and the consequent additional dynamic loading, has been carried out.
    • Requirements: The framework regulations section 3 on use of maritime legislation in the petroleum activities; cf. FOR 2007-07-04 nr 854: Forskrift om dekkskraner mv. på flyttbare innretninger (kranforskriften)7, and EN 13852-1, sections 5.7 and 6.
       
  • Personnel rescue: A fully independent control system is not provided.
    • Basis: The crane itself has only one PLC. If this goes down, the crane will be dead and cannot be operated by the secondary control system.
    • Requirements: The framework regulations section 3 on use of maritime legislation in the petroleum activities; cf. FOR 2007-07-04 nr 854: Forskrift om dekkskraner mv. på flyttbare innretninger (kranforskriften)7, and EN 13852-1, section 5.8.6.
       
  • Limit switches: Electromechanical limit switches does not meet the requirement of category 2 with regard to the mechanical part of the switch.
    • Basis: The mechanical part of the switches is not being checked by the cranes control system, and this safety related part can therefore not be considered as category 2 as required. Hence the operator will not receive an alarm in case of a malfunction of the mechanical part.
    • Requirements: The framework regulations section 3 on use of maritime legislation in the petroleum activities; cf. FOR 2007-07-04 nr 854: Forskrift om dekkskraner mv. på flyttbare innretninger (kranforskriften)7, and EN 13852-1, section 5.3.1, and EN 954-1, section 6.2.3.

Areas of improvement:

  • Crane capacity: The crane capacity for load handling to and from supply vessels is on the lower side of the normal for operation in the North Sea.
    • Basis: The crane capacity for the port crane, the number one crane for load handling to and from supply vessels, is on the lower side of the normal for operation in the North Sea.
      The crane has a whip line capacity of 6 to 7 tonnes at a sea state of 3 to 4m significant wave height at approx. 32m outreach. Normal cargo loads are in the range of 5 to 10 tonnes.
      For handling of MOB boat, the capacity at 2m significant wave height is approx. 2.5 tonnes at max. outreach. At 5m significant wave height the capacity is hardly anything at max. outreach.
      At the time of review, the weight of the MOB boat planned for use was unknown.
    • Requirements: The activity regulations section 25, critical activities, requires it to be ensured that critical activities are conducted within the operational limits assumed in the design and in the risk analyses as mentioned in the Management Regulations Section 13 on general requirements to analyses, cf. also these regulations Section 28 on actions during conduct of activities.
       
  • Radio activation: Radio activation is provided by a foot pedal.
    • Basis: The operator cannot see the pedals from his seated position. Since there are several pedals, the risk for unintended activation is present. It should be evaluated if radio activation from a spare button on the joystick would be a safer arrangement.
    • Requirements: The framework regulations section 3 on use of maritime legislation in the petroleum activities; cf. FOR 2007-07-04 nr 854: Forskrift om dekkskraner mv. på flyttbare innretninger (kranforskriften)7, and EN 13852-1, sections 5.5.