DNV-ST-0194 Lifting Devices: Crane Certification

DNV-ST-0194 is the primary DNV standard for certification of lifting devices installed on ships, offshore units, and floating structures under DNV classification. It covers marine cranes, crane pedestals, offshore knuckle-boom cranes, and all permanently installed lifting appliances — establishing requirements for design, manufacture, proof testing, and the periodic inspection regime that keeps certification current throughout service life.

1. Scope and Applicability

DNV-ST-0194 applies to permanently installed lifting devices on ships and offshore units classed by DNV, including:

• Ship cranes (deck cranes, hatch cover cranes, provision cranes)
• Offshore knuckle-boom cranes (subsea lift, diving support, well intervention)
• Marine pedestal cranes on semi-submersibles, jack-ups, FPSOs, and drill ships
• Monorail systems and overhead gantry cranes installed on vessels
• A-frames and stern roller systems used for submerged equipment deployment
• Crane pedestals and slewing rings as distinct structural components

The standard does not apply to portable lifting equipment (slings, shackles, wire rope assemblies) — these fall under NORSOK R-002. It also does not govern land-based cranes (EN 13001 series) or offshore container lifts (ISO 10855 / EN 12079).

2. Crane Classes and Duty Classifications

DNV-ST-0194 assigns duty classifications to cranes based on expected total number of load cycles over the design life, consistent with the ISO 4301 classification system. The duty class drives the structural fatigue assessment and the frequency of inspection intervals:

The duty class is declared by the crane designer based on the anticipated operational profile. The owner/operator is responsible for ensuring actual usage does not exceed the declared cycle count — exceeding design cycles is a material change requiring reassessment.

3. Safe Working Load (SWL) Determination

The Safe Working Load is the maximum load that the lifting device is certified to lift under specified operating conditions. Under DNV-ST-0194, SWL is not a single value but a function of several operating parameters:

The SWL is stamped on the crane structure and crane certificate. Any modification that affects any of the above parameters — including boom extension, wire rope replacement with a different SWL rope, or changes to the hook block — requires reassessment of the SWL and recertification.

4. Design Factors and Load Combinations

DNV-ST-0194 §4 specifies design loads and partial safety factors for structural verification of crane components. The fundamental design check for any crane structural member is:

Where σ_Ed is the design stress from combined loads and γ_M is the material factor (typically 1.1 for structural steel). Load combinations include:

• Regular operation (LC1): Rated load (SWL) + dynamic amplification + crane self-weight + 15° list + wind
• Overload test (LC2): Proof load (1.25 × SWL) in worst-case position — static check only, reduced partial factors
• Survival (LC3): Stowed position + extreme wind (100-year return period for the installation site) + vessel motion
• Emergency (LC4): Dropped load arrested by brake — shock load impulse on hook block and boom tip

The structural design of the crane pedestal and the vessel deck interface must also be verified for all four load combinations. The pedestal is a shared boundary between the crane manufacturer's scope and the vessel naval architect's scope — clear interface documentation is required.

5. Proof Load Testing

Proof load testing is the mandatory acceptance test that demonstrates the crane can safely carry its rated load before it is placed in service. DNV-ST-0194 §8 specifies:

The proof load test procedure:

1. Test load is applied at the most unfavourable outreach position (maximum radius for maximum boom moment)
2. Crane is tested in all slewing positions around the full 360° arc (or the operational arc if restricted)
3. Load is held for minimum 15 minutes without lowering — structural deflections are monitored
4. All brakes are tested under load: hoist brake, slewing brake, luffing brake
5. Load indicators and overload cutouts are verified at 100% and 110% SWL
6. After test: full visual inspection of all structural members, welds, wire ropes, blocks, and hooks for permanent deformation or damage

Offshore lift reduced proof load

For offshore pedestal cranes where full proof load testing at quayside is impractical (e.g., FPSO installed cranes or jack-up cranes already on location), DNV-ST-0194 permits a reduced proof test of 1.10 × SWL combined with enhanced design documentation review and non-destructive testing of all critical welds. This requires specific agreement with DNV surveyor.

6. Boom and Wire Rope Requirements

Boom design

The boom (jib) is the primary load-bearing structural element. DNV-ST-0194 §5 requires:

• Boom structure designed to DNV-OS-C101 (structural steel) or equivalent, using LRFD partial factors
• Buckling check for boom compression members using column stability curves — slenderness ratio λ ≤ 2.5 for welded tubular booms
• Boom tip deflection under SWL documented and verified not to cause interference with vessel structures or adjacent equipment
• All boom-to-pedestal pins and kingpost connections: non-destructive testing (MT or PT) at fabrication and at each 5-year periodic inspection

Wire rope requirements

Wire rope is a consumable with a defined discard criterion. DNV-ST-0194 §6 specifies minimum design factors and mandatory discard criteria:

Wire rope discard criteria (DNV-ST-0194 Table 2 / ISO 4309):

• Broken wires: ≥ 10% of total wires in any rope lay length (6 × rope diameter)
• Visible corrosion on outer wires, or internal corrosion detected by magnetic flux leakage (MFL) test
• Diameter reduction exceeding 10% of nominal diameter (indicates internal wire fractures or core collapse)
• Kinking, birdcaging, or crushing deformation anywhere along the rope
• Heat damage: any evidence of discolouration or hard-spot from heat contact
• End fitting damage, or rope pulled through swaged fitting
• Time-based discard: maximum 4 years service regardless of condition for hoist wires on offshore cranes in continuous operation

7. Periodic Thorough Examination

DNV-ST-0194 §9 establishes the periodic inspection regime to maintain class and certification currency. Thorough examinations are performed by a competent person (DNV surveyor or accredited inspector) and cover the entire crane system:

The crane logbook (maintenance log, inspection record, and operational record) must be maintained onboard and presented at each survey. A gap in the logbook record is treated as a suspension of class for the crane.

8. Certification Process and Documentation

The DNV-ST-0194 certification cycle produces three primary documents:

Type Approval Certificate

Issued by DNV for a specific crane model following review of design documentation (drawings, calculations, materials certificates, and weld procedures). The type approval is valid for a model series — each individual unit still requires a unit certificate. Type approval review covers: structural analysis, fatigue assessment (for L2/L3/L4 duty classes), control system safety functions, overload protection, and wire rope design.

Unit (Lifting Appliance) Certificate

Issued for each individual crane after proof load testing and initial survey. Contains: crane serial number, SWL at all radii, maximum operating Hs, maximum wind speed, wire rope specifications, and expiry date (5 years). The certificate must be kept onboard.

Register of Lifting Appliances

Each vessel must maintain a Register of Lifting Appliances listing all cranes and permanently installed lifting devices, their SWL, certificate number, and next survey due date. The register is reviewed at each annual survey and at port state control inspections.

9. Class Notation: CRANE

Vessels and offshore units with lifting devices certified under DNV-ST-0194 receive the class notation CRANE, optionally with qualifiers indicating capability:

The CRANE notation appears in the Vessel Register maintained by DNV and is visible to charterers, insurers, and marine warranty surveyors when reviewing vessel capabilities for a planned offshore lifting operation.

10. Common Pitfalls

• Using SWL without DAF for offshore lift planning. SWL is a static capacity rating. For offshore lifts, the rigged weight must be multiplied by the applicable Dynamic Amplification Factor (≥ 1.15 for onboard lifts per DNV-ST-0378, higher for wet lifts) before comparing to crane SWL. Ignoring DAF is the most common cause of overloading events.
• Confusion between crane certificate SWL and rigging SWL. The crane SWL refers to the hook load. The rigging (slings, shackles, spreader bars) has its own SWL rating that must also be checked. The total rigged system must be rated to 100% of the hook load at the operating DAF — crane certificate alone does not certify the entire lift system.
• Missing wire rope replacement at 5-year survey. Unless condition is verified by magnetic flux leakage (MFL) testing performed by a certified rope inspection service, hoist wires on continuously operated offshore cranes must be replaced at the 5-year survey regardless of visual condition. MFL testing is often omitted to save cost but is required to justify an extension.
• Operating beyond declared Hs limit. The crane certificate specifies a maximum operating Hs — this is an absolute weather limit, not a guidance value. Operations in sea states exceeding the certificate limit are uncertified and will void insurance for the lift. Operational Hs limits should be verified against the marine warranty surveyor's approval for each specific offshore lifting operation.
• Pedestal foundation not in crane scope. DNV-ST-0194 governs the crane from the pedestal top flange upward. The pedestal base connection to the vessel deck, and deck local stiffening, is the vessel designer's responsibility and is checked during class renewal for the vessel — not the crane. Verify the interface scope clearly in the project FEED phase.
• Engage DNV surveyor early for offshore FPSO or jack-up crane installations. Marine warrant surveyor (MWS) requirements and flag state requirements for offshore cranes on production units can add requirements beyond ST-0194 minimum. Confirming the certification pathway with the DNV project office before detailed design begins avoids costly late changes.