thickness of spade less than pipe class requirements

[mike mufdi]

As we are approaching commissioning of the oil plant, use of blinds, and spades will be needed to provide double isolation (spade after valve) . in some locations the lines are tight with very heavy wall thikness making it almost impossible to insert a temp spade with thickness to match the line class. since in theory these spades will not see the actual working pressure, is there anything in the Shell DEP or ASME B31.3 that allows using thinner spades in this situation ?

thanks

 

[LittleInch]

Not that I'm aware of.

The piping should allow for these as spectacle blinds.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

since in theory these spades will not see the actual working pressure,

It may not be 100% correct should the process leak through the closed valve.

 

[KevinNZ]

I would say the spades need to be designed to the pipeline design pressure not the working pressure. Things could go wrong and the pressure can get up to design pressure. (e.g safety valve set pressure)

Also consider a bleed valve on the edge of the spade so you can relive the pressure between the valve and spade when it comes time take the spade out.

 

[mike mufdi]

Generally I would not allow this to happen, What we are worried about are few locations that are challenging in terms of providing the space for these spades due to the very heavy wall thickness and the configuration of the spools, these spades will be used mainly during commissioning stage and are not permanent material, I was asking if I can depend on any code or standard to help me take the decision of allowing the contractor to use thinner spades .

 

[LittleInch]

There should be no difference in any respect just because this is commissioning.

Don't start to use the "it's not permanent" argument. It just won't wash if anything goes wrong.

It's either compliant with the requirements or it isn't.

There is always another way, just people try to find short cuts.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mike mufdi]

There should be no difference in any respect just because this is commissioning.

Don't start to use the "it's not permanent" argument. It just won't wash if anything goes wrong.

It's either compliant with the requirements or it isn't.

There is always another way, just people try to find short cuts.

yes you are right in this, I gave my response as not allowing, contractor to follow code requirements ..

 

[danschwind]

BWO'S FPSO Cidade de São Mateus exploded and killed 9 people because of something very similar to this.

Daniel
Rio de Janeiro - Brazil

 

[TGS4]

There was an article/Journal Paper written about this exact topic. There may be some flexibility in the piping codes to allow for thinner spectacle/slip blinds.

 

[DanTh3Man]

Could you replace the valves with DIB valves? Or is there confined space work downstream?