A 335 grade P5 +Any chance of having it at 745 C temperature?

[Hansito]

Dear Coleagues,

We have a consult from a Refinery previewing a De-cocking procedure. Their systems are design for about 480 C. The basic material is A 335 grade P5. The De-cocking operation is arround 710C operation - 745 C design.

This is far beyond the temperature tabulated in ASME B31.3 allowable stress. According to that the maximum temperature for that material is 650 C.

The operation will last 10 hours.

Does anybody knows some paragraph or statament on B31.3 which could allow this use?

Regards,
Hansito

 

[BigInch]

Its 700 ºF

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Hansito]

No BigInch

First I thought the same, but it is really Degree C.


Regards,
Hansito

 

[insult2injury]

There are allowances in the Codes for abnormal temperature/pressure excursions providing the yield stress is not passed; however, a 10 hour process would not fit into this category.

I2I

 

[BigInch]

Right. I was on the wrong page.
I see it is 1100F (so 593 C) is the limit and its a very very low stress allowable too.

No, it is as I2I says.

Can you reduce operating pressure during that time?

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[stanweld]

These actions are common Coker practices. Repairs are also common. Replacement starts the cycle anew.

 

[Hansito]

It is an existing furnace, I believe it is operating for more than 20 years, at arround 480 degree C.

What I undertood (We are still in the process of receiving information) is that now they need a De cocking operation, which is (as far as I understand) a kind for dust cleaning.

They just asked us about a possible new Piping Stress Study for the new temperature, but when I saw the data and the basic Material I think to myself that if your out the temperature code limits there is no much we can do about stress. I agree that 10 hour is too much time to consider the extras previewed on the code.

Thank you very much for all responses, I really appreciated them and I will keep struggling with this. If this come to a techinical reasonable end I will included in here, and please if someone more has more information, opion or similar experience let me know.

Regards,
Hansito

 

[0707]

For that material P5 the decoking procedure with steam air the skin temperature of pipes shall not be more than 650ºc.

In API STD 530 the limiting design temperature for A335 P5 is also 650ºC.

If they are afraid of tube stress induced by the temperature process of decoking with steam air, instead they can do a mechanical decoking with pigs

Please go to

http://www.cokebusters.com/

Luis marques