Heater coil design code 3

[Mussha]

we have heater coil, material of coil is SS310 , OD 89mm & 4.5mm thick. but one thing i noticed in the drawing is that the design code is ASME Sec-VIII div.I. is this suitable or they should go with API530 or else?
Recently we observed bulging in the tube after 1.5yrs of service due to coking inside the tube. (for info.)

 

[XL83NL]

There's too little info provided to help you. I've seen tubes (although 88.9x4.5 more sounds like pipe) be part of a vessel or HEX type vessel design in exhaust channels, but also tubes included in vessel for heat exchange to generate steam (not a HEX).
have you check the limits of ASME VIII-1? Where is this item placed? US states may have additional authorities/requirements.

Huub
- You never get what you expect, you only get what you inspect.

 

[Mussha]

Thanks XL83NL,
its just a coil in furnace box working as cracker. upstream another equipment is HEX that is design as per TEMA & ASME which looks fine. But for heater coil i am little confused. Might be designer consider closed furnace box as vessel.

 

[XL83NL]

Again, too little info. Whats the pressure and temperature, whats the medium. Where is this thing located?

Huub
- You never get what you expect, you only get what you inspect.

 

[Mussha]

Design Temp. : 850degC Design Pr. : 6Bar & Medium is Benzen. Location mean country or something else.

 

[XL83NL]

Country may matter.

Have you checked U-1?

Im assuming you use SA312 TP310S, TP310H or something similar? Have you checked the allowable temperature limits from ASME IID?
It seems 850°C wont work with VIII-1, theyre all limited to 816°C.

Huub
- You never get what you expect, you only get what you inspect.

 

[Christine74]

See Section VIII Div. 1 U-1(c)(2)(-b) which states that fired process tubular heaters are not included in the scope of that code.

Typically heater coils are designed in accordance with ASME B31.3 and API 530.


-Christine

 

[XL83NL]

Correct, but they still may be designed under the rules of VIII-1.

In this case however, when there’s a heat source such as a flame, a different design code may be better as it has a broader perspective on other relevant factors.

Huub
- You never get what you expect, you only get what you inspect.

 

[Mussha]

Gentlemen,,
Might designer consider fired box as vessel because fired box is not heated by burners, its electrically heated in closed box. And coil is inside the box at atm. pressure. refer attached schematic drg. And also this heater is U-stamped.