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A36 Steel Plate Superheater Pipe Support

03/29/2011 2:06 AM

I have seen in a 14" superheater line (70barg and 560C), a sliding plate support (fully insulated and fixed to concrete floor) using A36 material. But when i refered ASME part II D, it is A36 steel is allowable only up to 385 C.

I would like to hear your valuable advices on the above matter as we are renewing some supports on this line.

Thanks in Advance

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#1

Re: A36 Steel plate_Superheater Pipe support

03/29/2011 2:51 AM

When you say "fully insulated" do you mean that the A36 plate is insulated from the superheater line, or only from the concrete?

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#4
In reply to #1

Re: A36 Steel plate_Superheater Pipe support

03/29/2011 7:10 AM

The superheater line insulation is 300mm. And also most of the support is also insulated together with the line.

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Guru
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#2

Re: A36 Steel plate_Superheater Pipe support

03/29/2011 2:59 AM

If 5600C is the temp of superheated steam and line is insulated, in that case support plate will be experiencing much lower temp than of 5600C, On that ground A36 steel might had been accepted by original designer, actual plate temp can be measured before renewal process,

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Guru

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#3

Re: A36 Steel plate_Superheater Pipe support

03/29/2011 6:47 AM

Ehhh, the 14 inch line (Normally A335 P91)is supported directly to the A36 sliding plate fixed to the concrete? or there is a shoe welded, and PWHT to/with the 14" line, and this shoe is supported on the A36 Slidind plate?. If this is the case you have No problem. Also, the sliding plate of the shoe could be P22.

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#5
In reply to #3

Re: A36 Steel plate_Superheater Pipe support

03/29/2011 7:17 AM

Hi Whitephone, Line is P22 material S-160. The A36 plate is welded to a C-clamp (A387 Gr.22) which is then bolted to the pipe. The A36 plate is 15mm thick plate and has axial movements only.

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Guru

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#7
In reply to #5

Re: A36 Steel plate_Superheater Pipe support

03/29/2011 9:31 AM

Then is Ok. (if there are not specific requires by your client).Your A36 sliding plate is not a pressure part.

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#10
In reply to #7

Re: A36 Steel plate_Superheater Pipe support

03/30/2011 1:21 AM

Thanks Whitephone.

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Guru

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#6

Re: A36 Steel Plate Superheater Pipe Support

03/29/2011 8:42 AM

Does the plate show any signs of distress? If not, and if it has been working for a significant time, I wouldn't change it.

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Guru
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#8

Re: A36 Steel Plate Superheater Pipe Support

03/30/2011 12:10 AM

No problem when you use A36 as a support with a superheated steam line. In any steam generation plant, all pipe racks/ways are fabricated from structural steel A36.

But, if there is a part of that support needed to be welded into the pipe itself, we have to select its material to match with the pipe material to withstand higher temp. The same phenomenon (of matching the material of a welded support) is applied in case of cryogenic piping systems to withstand very low temp. and match the MDMT of the whole system, also to avoid rapid rust accumulation due to moisture condensation on CS.

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#9
In reply to #8

Re: A36 Steel Plate Superheater Pipe Support

03/30/2011 1:18 AM

Hello Sir, My doubt is since the pipe wall temperatures will be close to 500 C, the pipe clamp which is A387 Gr. 22 will also be 1 or 2 C less than the pipe wall. So if this is transferred to the A36 plate its mechanical properties will decline suddenly, right? But i understand that what ever the excess heat generated in the pipe wall is transferred to the concrete floor though the A36 steel support (which also takes the whole weight of the pipe line) many thanks for replying to my post.

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#11
In reply to #9

Re: A36 Steel Plate Superheater Pipe Support

03/30/2011 9:24 AM

Wild idea.....

What about a drawing of the pipe support with insulation/materials etc noted ?

Why don't you use an infrared "heat gun" to find the actual temperatures of the existing A36 components while the plant is running ?

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#12

Re: A36 Steel Plate Superheater Pipe Support

03/30/2011 9:45 AM

Steels do lose strength above 650°F or so, depending on alloy, but the drop-off is not sudden or severe, especially if some insulation intervenes. I agree that a drawing would be helpful.

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#13
In reply to #12

Re: A36 Steel Plate Superheater Pipe Support

03/31/2011 12:29 AM

Sorry for not posting the image. I tried to copy paste the image in to this reply, but it is not working. Is there any guide lines for inserting pics and formatted texts ? Thanks

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#14
In reply to #13

Re: A36 Steel Plate Superheater Pipe Support

03/31/2011 12:47 AM

Finally i installed firefox.

This is how my support looks like. Item number "10" is the A36 plate

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#15

Re: A36 Steel Plate Superheater Pipe Support

03/31/2011 1:16 AM

Many thanks for all those who replied.

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