Re: Heaters for Pressure Vessel

Curious, not quite sure what you mean 36 U shaped heating element. Is that 36 tubes (Or 18 there and back)

here's a few other questions;

• 45 bar using a 300# flange,... even with the exception of 100º to 150º C not recommended. especially loading the flange with a U-Tube HX
• is this a electrical element or steam?
• Is this vessel ASME certified with a 'U' stamp? If it is, do you want it to remain ASME certified?, if you do, you need to contact a ASME certified shop, that carries a 'R' stamp. And the worries and liability is no longer yours.

Otherwise, getting a opinion, working with the criteria stated will be difficult just due to the liability. but good luck.

There are 36 heating elements i.e 72 limbs..the shell is ASME certified and I want to remain it that way.. I am told to manufacture a heater bundle for the shell and the only thing that I am thinking is how to braze heating elements to the flange. Usually we braze with silver alloys but that will it be hold 45 bar pressure??

No-one can answer the question other than the individual indicated in #2⇓. The reason is that no-one else has access to the vessel periodical inspection records that is also responsible for the insurance liability on the vessel.

There are other questions: will this proposal affect the designated maximum operating temperature on the vessel, for example, and the pressure relief arrangements on the contents at that temperature (rhetorical questions - NNTR)?

Usually we braze with silver alloys but that will it be hold 45 bar pressure??

I'm familiar with silver solder

When you say 'shell', do you mean the shell of the U-Tube HX?, or the tank you're putting it in?

Are you a ASME certified shop to carry the 'R' Stamp, you have to determined the loading on the nozzle. I can't recall the ASME text and verse.

If you are not ASME certified, you need to have one involved to keep the ceritication of the tank.

There are more qualified people here on CR4 then me. All I need to say, is ASME basically is there for traceability to identify the responsibility party if things go wrong.

Sir,it is electrically operated. U tube hair pin type electrical heating elements.

So?

Yes. The Engineer/Surveyor from the company responsible for supplying burst/collapse indemnity insurance cover for this vessel can advise this. Pick up the phone, and ask that individual directly. The individual's name will be on the last inspection report document that was generated by that organisation in pursuit of that insurance cover.

You also need to be careful about how much you heat the contents as this reduces the Max Allowable Pressure

At 38C 51.0barg

At 93C 46.5 barg

I believe you can interpolate linearly between these.

With a max Operating Pressure at 45barg I would expect a Design Pressure at 49.5barg which would put the Max temp at 56C. I think. I am a process engineer so familiar with flange ratings but not the detail of ASME

My other gut feeling is that drilling 72 holes in this flange is going to weaken it beyond possible use but again thats gut feel guess

As mentioned above there is an inspection plan and the work must be done by certified fabricators.

The link I posted had it in, but nice direct post for concern