Argon causing a stall in heat ramp rate in HIP vessel

[tryangle]

I've got an issue with a HIP vessel here. Its max operation limits are 5KSI and 600C. It's comprised of the vessel with an internal furnace. Gas enters the bottom of the vessel, seeps into the furnace, then exits the bottom of the furnace. We can pressurize just fine and heat without pressure. But when we heat with pressure, the ramp rate slows down by a considerable amount. And if we heat first, then add gas, we lose temperature. We haven't run this HIP in a while and our other HIPs behave as expected. Normally, pressure causes our heat ramps to increase. And we normally don't have problems heating a pressurized vessel.

Any ideas why this is happening? Internal volume of the vessel is 47 Cu. Ft.

 

[metengr]

tryangle;
If what you reported is correct, it might be moisture carryover. Are you using a dryer for the gas on this HIP? It might be that you are carrying over condensation in the Argon gas that takes additional heat to boil off. This boil off could be slowing down your heating of the vessel under pressure.

 

[tryangle]

metengr, there is about 150 ft of tubing from the compressor to the vessel but it is unlikely that it is picking up moisture. An adjacent 15 KSI vessel uses the same compressor and doesn't display the same behavior. I think the next step is to look into electrical interference between the transducer and the SCR's.