Hi all,
upon entering a an atmospheric crude distillation fired heater in a turnaround we are faced with severely deformed heater tubes. Most likely due to coke buildup
and associated high tube metal temperatures during a 1 year time span in the previous run (we did a pig clean during the run...
Thanks for the replies so far.
@Geoff13:
Even without an earthquake the described wave is a credible scenario (e.g. due to gutter type corrosion). Only tank in tank systems wouldn't face something like that.
Regarding advanced analysis. I was thinking about performing a pushover analysis. But I...
Hi All,
We have to revisit the seismic design of some older flat bottom tanks.
Initial assessment is that the tanks themselves won’t be able to resist the seismic loads. They are built on crushed stone/sand pads, are not anchored, and have a diameter-to-height-ratio of less then 2.
Our...
Jay_pv: Nitriding sounds certainly doable. But I would be worried about introducing new damage mechanisms when doing this. E.g. a decreased resistance to SCC.
It also depends on the amount of flanges you are worried about. Only some vessel flanges or all the piping flanges in a new unit?
What...
I have seen the 30 HB being specificed on a couple of units.
The reason is you want to avoid deformation of the RTJ groove in the flange, which could lead to problems with resealing after breaking the flange for maintenance.
So far we had no luck in reliably sourcing low hardness rings.
We...
In Germany you first apply full test pressure and hold it (1 hour) afterwards you lower it to maximum 60% of rated pressure and hold. Only when the pressure is thus reduced are you allowed to access the boiler and check for leaks and deformations.
If the weight is supported entirely by the nozzles you should use AD2000 S3/& which handles nozzles with additional loads.
This standard references WRC 107 and 297 for estimating stresses. Allowables can be determined with aD2000 S3/0.
As for the stresses in the vessel itself. Those are mainly...
Depending on the dimensions of the reactor I would be worried about hydrogen embrittlement resulting in cracks in the base metal during shut-down/start-up.
API TR 934F (and API RP934F, whenever it will be finally published) have al lot of guidance on calculating safe minimum pressurisation...
I would suggest talking to your customer before you do the stepwise PWHT.
Maybe suggest a weld overlay, so your only have to do PWHT of the base metal acc. to ASME code
I'll try to answer your questions:
@littleinch: local cathodic protection is a bit different from classical CP. A good explanation is found here https://www.sciencedirect.com/science/article/pii/B9780884150565500198
So while it is true that a huge portion of the current will go to other...
Hi all,
I'm not sure if this is the best Forum for the question, so please tell me if you know of a better one.
We have a burried pipe in a tank farm, that is protected with local cathodic protection. As such there are no Isolation Flanges to the attached storage tanks.
We want to assess the...
Thanks for pointing out additional tobics to be aware of.
Here is a link with some videos and information on the technology:
https://www.rprtech.com/coating-removal-on-storage-tanks/
Hi,
we have a large storage tank (70m) where we will have to renew the internal protective coating of the bottom and 1st shell course.
So far coating removal on our site was done by grit blasting which is quite costly and takes a long time.
There are some companies advertising coating removal...
MJCronin,
to answer your questions:
Some Questions:
------ Is this a constant or variable spring hanger ? - Have you checked for any failed/corroded spring coils ? - Can you see the coils ? -> variable spring, yes- yes
------ Has this hanger been "topping" or "bottoming" out at piping...
Hi all,
I have an existing line with an old Grinnell spring hanger. Due to corrosion on the can we would like to replace the spring hanger. Unfortunately the type label on the hanger is unreadable (I can only see B-268).
I tried to identify the figure number of the hanger by measuring the...
Hello all,
we have an atmospheric storage tank (fixed roof, gasoline) that has somwhat settled over the years. Now the chime area has a lower elevation than the apron of the foundation (compacted gravel foundation with bitumen/sand cover; apron covered with asphalt).
This prevents free draining...
To answer your query Arulkumar P:
In higher alloyed steels the inclusions are not a problem.
MnS inclusions usually start globular in the steel. During rolling of the steel to form plate the inclusions get flattened out and can cover large areas in the steel.
Carbons steel get corroded in the...
Defining a higher percentage is sometimes specified as a way to ensure steel cleanliness.
Laminations and inclusions (manganese sulfide,...) tend to lead to a more brittle failure mode through the thickness combined with only minimal area reduction.
We sometimes specify the additional...
