Helideck reverse engineering
 

Hello guys,

Perhaps someone can help me out:
I am working in a shipyard team on the renovation of a Jack-up drilling platform.
For the accommodation renovation we need to place some containers on the helideck.
The only load information on the helideck is that it is S61N 9,3 ton rated steel deck on a steel truss frame.

I know from my history as shipbuilding engineer that a helideck would be designed with certain safety factors to allow for a crash landing on the far end of the deck. I also know that there are some formulas to relate tire foot print to steel plate hickness.

Can someone direct me to these safety factors and formulas, or give me some general directions how much such a deck can take?
Now the barge engineer allows us max 9,3 ton but we do not crash land the container.

Thanks SLB

CAP 437: Standards for Offshore Helicopter Landing Areas would be a good place to start. It will also guide you towards other documents with more technical information.

Having lived next to a port for a short period I can affirm that containers are perhaps not crash landed, but are subjected to routine heavy landings.

No energy absorbing gear either.

9,3 t x 2,5 is standard crash safety factor...

To be on safe side, make Solidworks model and simulate static load,
take in consideration real measures of steel construction elements.
Real thickness, after years within salt environment (corrosion), can be measured by ultrasound...

Putting down a steel object on a steel deck produces short term loads that are like crash loads, it is not hard to get 2X from a simple fork lift operation. The loud noise hear when a load is set down is precisely the noise of a 2G impact on the deck (but 2G for only a few milliseconds).
Use some thick rubber pads to absorb the shock and soften the blow, and I would bet the set-down loads reduce to less than 1.5X

I agree with Budgie, CAP 437 should be your first port of call. This is a 'Rumour' site and should not be used for any safety related engineering questions. If I knew which rig you are working on I would give it a very wide berth!

I believe that the definitive requirements are in ISO 19901-3:2014 "Petroleum and natural gas industries — Specific requirements for offshore structures — Part 3: Topsides structure" which has recently been updated.

Thanks guys,

CAP 437 is usefull.
It specifies 200 kg per square meter loading.
That will be a good starting point for our more detailed structural calculations.
load spreading and impact padding were already considered.
The 2G impact sound theory is very interesting but hardly relevant

If we are not allowed to discuss safety (engineering or otherwise, all seem equally relevant to me) , this will be a very quiet forum.
If you are in the neighbourhood you are welcome to visit the rig to see how we address safety. Please pm me upfront.

SLB

CAP 437 is a start but limited in what you need.

Class Notation Rules of the vessel would determine?

ABS? DNV? BV? GL? LRS?