Hot spot evaluation procedure 2

[DesertEagle01]

Hi,

I am currently struggling to work out a "hot spot evaluation procedure". We frequently face the problem of hot spots on pressure vessels with refractory lining. Without an obvious reason a hot spot may arise during operation which in the worst case forces a plant shutdown.

I was informed that in API 579 (Fitness for service) there is a section on how to evaluate hot spots and on how to decided whether the plant can still be operated or needs to shut down. Unfortunately I can't find that section in the respective API code.

Does somebody know where I may find guidelines on this topic?

 

[Dhurjati Sen]

Dear DesertEagle01,

The following best practice might be of some help.

1. Find the temperature of the hot spot using pyrometer / temperature gun.

2. Compare the oxidation temperature of the material of the pressure vessel with the above.

3. Take thickness at the hot spot location after removing insulation using hot probe.

The above could give you a small window to run the plant.

In any case, you need to shut down the plant and carry out refractory repair at the earliest.

Regards.

DHURJATI SEN

 

[chicopee]

Flame impingement could be one source of hot spot on the refractory. Furthermore, consult with the manufacturer of the unit.

 

[cap1a79]

You can proceed with risk evaluation as per API 581. If you see section 5 of the reference, there is a "lining damage factor" and table 5.1 mentions refractory lining.
Once you have got final result as risk ranking from the analysis, you could see how risk your equipment is.

The monitoring of refractory degradation can be carried out by heat indicating paint & IR scan.
The typical reasons of refractory degradation would be summarized as below.

1) Erosion
2) Vibration
3) Thermal shock, Thermal expansion (including anchor bolt & needles)
4) Compatibility of refractory with fluid (To be confirmed by vendor)
- Sulfidation, oxidation, dew point corrosion (including anchor bolt & needles)




Lee SiHyoung,
WorleyParsons Oman Engineering,