Steam coil classification in atmospeheric storage tank

[Jonesey1]

We have a approx. 65M diameter atmospheric storage built after API 650 (design pressure max. 0.5BarG) , which has a LP steam coil mounted in the botttom to provide heat to the crude oil when the ambient temperatures falls under approx. 10DegC. The LP steam has a design pressure of 5Barg and an operating pressure of 2.5BarG. According to Pressure Equipment Directive 97/23/EC article 1 point 2.1.2 heat exchangers consisting of pipes for the purpose of cooling or heating air shall be considered as piping. As we are not heating air, does that mean that our coil shall be considered as a pressure vessel ? Guideline 2/4 offers a little more help, but is not conclusive. I do not think that it was meant that the Pressure Equipment directive should be applied to API storage tanks, but there are people in our organisation that think it does. Any help would be appreciated.

 

[Duwe6]

Same thing, only different. API considers a heating coil [made of pipe] to be pipe.
"Pressure Equipment Directive 97/23/EC article 1 point 2.1.2 heat exchangers consisting of pipes for the purpose of cooling or heating air" is pipe.

I would write a memo and put it into the tank's Inspx file that you are treating the coil as pipe, per API. Include the welder(s) qualifications, NDE of the pipe welds [including Visual Inspx], and the hydro test of the pipe coil. This way, even it a government audit decides that you have classified the coil incorrectly, you have an engineering and inspection basis for your actions. And the records to prove it.

 

[SNORGY]

I think if you design, build and test your coil to ASME B31.3 you are fine.

Regards,

SNORGY.