Re: safety rules : I would be very grateful if you advise me about carrieng NDT personnels by crane and bascket to do ultrasonic thickness measurements on elevated structures such as boiler stacks. Is there any safety rules for this duty? best regards
My experience is in the United Kingdom at a government operated site working on an experimental wind turbine. We used a basket to access the outside of the turbine, and climbed the tower to access the inside (gearboxes etc). This mix of access had developed because it was identified that transferring from the basket to the tower (a practice we had done before) was a very dangerous and should only ever be carried out by a fully trained (4 day course) climber.
All of us that accessed the turbine (higher than 2 metres) had a short course with a trainer who came to train us on the specific turbine tower. I think that was the right level of training.
Equipments (ropes, harnesses, hardhats, hooking on points, etc.) were all regularly inspected and renewed when worn.
All activities were "Risk Assessed" which is the core of UK safety practice. You must spend time considering each risk, take measures to prevent and reduce any effects. If you don't take reasonable measures or fail to identify significant risks then you will be liable to be sued for negligence. The idea of this is that you consider your own case properly - don't just try and apply a safety formula; I think it is entirely reasonable.
If the NDT inspection staff arrive and find that safety has not been properly assessed and provided for they should quite reasonably refuse and expect payment for their wasted time.
If they are staying in the basket (which I hope they are) then there is probably some standard guidance available, try the UK HSE (Health & Safety Executive). If they are being asked to transfer then I would expect that they should have (a fairly high level of) climbing training; and there needs to be provison like proper attachement points - ie only for the purpose of safety attachment. You should also make sure there are rescue arrangements in place if there is an incident, eg is the local fire brigade equipped with a high enough ladder because the access crane may be part of the problem and an independent alternative will be needed.
If it all works out too onerous then it may actually be cost effective to build a stairway or appropriate ladder up to the testing point.
Don't take any of that as formal advice - I'm not a safety professional; it's more a memoir of some of the issues my group went through as we developed policies on access to our fairly short (15m) turbine.