Hi,
Concerning the first question.
Good news, ASME I safety valves have always been a clear problem to test on site, especially the blowdown. This was due to the allowance 7%full open / -4% reseat to compare withe ASME VIII or french code (NF32100) requirements which are +10% / -7%. From a...
You are correct. The boiler should be drained and filled with treated boiler water as defined in the O&M.
The temperature criteria is typically something like a maximum difference of 60°C-80°C/140°F-175°F (mainly depending on the drum thickness) between water and metal temperature (assumed to be...
We used an API standard for the design of our reform gas boilers a few years ago.
"API 941, Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants, Fifth Edition (1997, January). Supplement 1 (1998, April 1) also available."
Also...
OK.
I think I have a clear picture, even if not so nice. Thanks everybody for your advises. Concerning the installation of the flow nozzles after steam blows, there are few explanations. first, we do not want to have any restriction in the circuit during steam purging. Second, these items are...
Thanks for your answers,
The flow nozzles I am talking about are located on the Boiler external piping between superheaters outlet headers and the code stop valve. Two of them (Low pressure and medium pressure steam) are plain carbon steel pipe (A106 B or something) and we do not expect to have...
We have performed a complete hydrotest of the boiler before the steam blows. After this phase, we have to cut the steam pipes (3 pressure level boiler) to install and weld the flow nozzles. Unlike most of our previous projects, the nozzles are installed upstream the code stop valve (boiler...
Hi,
To avoid excessive vaccuum in the boiler ducts, NFPA 85 requires an interlock between the pressure measurement in the combustion chamber and the ID/Fan, if I remember well.
Otherwise you just have to check that the casing design pressure is correct, as well on overpressure as under vaccuum.
Thanks again to everybody for your advises,
In fact the Header is 24" and 30mm/1,25" thick. The problem was not availability but delays to get A335 P91.
The main concern is that the boiler is supposed to be supplied according to ASME I for evrything (design, material, tests, etc..) but NOT...
Hi,
Thanks a lot for your answer. I forgot to write one thing in my thread. The supplier does not refer to ASME II specification for its material but to ASTM 691 98. It seems that ASME II (at least the revision I have, 1998 if I am right) is referring to ASTM 691 93. I agree with you the...
Hello,
One of our boiler supplier have used welded pipe for the manufacturing of the reheater outlet Headers. Instead of A335 P91, he has used A691 Gr91 (according ASTM 98 seems). As per the ASTM/ASMEII spec., A 387 91 plates were used to manufacture the welded pipes.
Up to now everything is...
Hello,
I think everybody is right, depends on your plant. To avoid Hydrazine you can also use sodium bisulfite Na2SO3 as well, up to 20-30 bars, at higher temperature, you could see formation of H2S which could be quite detrimental to your steam condensate system. Anyway, it is a basic solution...
We have some problem. ASME code seems to allow the use of welded headers (A387 91) as well as seamless pipe (A335 P91) for the manufacturing of headers for boilers. Even if it seems, from some studies, that we can expect a more significant creep-fatigue interaction for 91 in HAZ than from 22...
Hello,
There is a reference for us which has to be amended according to your plant conditions and the discussions you should have with your boiler and turbine manufacturers. It comes from EPRI and is the counterpart of CS 4629 which is talking about fossil fired plants.
Interim Cycle Chemistry...
