Rank: New forum user 
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Hi Folks,
Does anyone know where I can find design spec and safety guidance on the correct access/ egress requirements for a process pressure vessel that will require routine valve operation?
I am prety sure there must be two openings dependant on the requirement for regular access.
I suspect its in tbe CDM regs sonewhere, but would appreciate a pointer.
Cheers,
Colin
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Rank: Super forum user
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The answer you seek will NOT be in the CDM regs - CDM is just a generic design and construction set of regulations. The pressure vessel's access ladders/platform will have been designed to a particular engineering/technical standard. If you are in the UK, possibly The Engineering Equipment and Materials Users Association (EEMUA) publication 105 'Factory stairways, ladders and handrails' Or British Standard 4211 Specification for permanently fixed ladders
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 1 user thanked Ian Bell2 for this useful post.
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Rank: Super forum user
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What liquid is in the vessel? Hydrocarbon? considerations/travel distances will also dictate the number of access ladders to the platform if the contents are flammable.
Also human factors consideration in terms of the expected frequency of valve operation should be given
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Rank: New forum user
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Originally Posted by: Ian Bell2  What liquid is in the vessel? Hydrocarbon?considerations/travel distances will also dictate the number of access ladders to the platformif the contents are flammable.
Also human factors consideration in terms of the expected frequency of valve operation should be given
You guessed right Ian, HC's
One visit per day routine visit and isolation activities 3 or 4 times per anum.
I would expect it to be infrequent operation.
Cheers
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Rank: Super forum user
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OGP 454 gives you some very high level guidance on the subject of valve access based on frequency and emergency use (Section 7.2). This references ASTM F1166-07, which provides some detailed specifications that are strictly applicable to marine applications but generally entirely appropriate to all applications.
In practice, companies tend to set their own standards for valve access and means of escape. The requirement for two means of escape usually depend on the size of the access platform (i.e. if only small only one stair/ladder is required).
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Rank: Super forum user
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OGP publication 434-5 Human factors in QRA also gives data and examples of estimating human error, also assessment techniques for assessing human factors.
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Rank: Super forum user
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Manual valve operation on a routine basis for an elevated valve on a pressure vessel!!! Have the designers never heard of pneumatic/hydraulic/electronic valve operation? Back in my chemical engineering time I would have been shot for even contemplating such a design.
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Rank: Super forum user
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Obviously we don't know enough about the design/situation - but you are possibly introducing a source of ignition in to a hazardous area - electronic/electrical sparks or hot surfaces from hydraulic systems. Will require ATEX rating. Manual valves on a low frequency operation/access requirement, might be a better option.So maybe not such a great idea. Inherent safety principles and all that...
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Rank: Super forum user
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Originally Posted by: Ian Bell2 Obviously we don't know enough about the design/situation - but you are possibly introducing a source of ignition in to a hazardous area - electronic/electrical sparks or hot surfaces from hydraulic systems. Will require ATEX rating. Manual valves on a low frequency operation/access requirement, might be a better option.So maybe not such a great idea. Inherent safety principles and all that...
The use of pneumatic controls was and is pretty standard throughout the petrochem industry. I can only think of one where it was manual - the boiler blowdown valves
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