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Nozzle loads Economizer

Nozzle loads Economizer

Nozzle loads Economizer

(OP)
Hello piping engineers,

I need to design feedwater piping that is connected to an economizer. ( DN 250, 10";Pdes=25 Barg;Tdes = 226°C). The manufacturer of the economizer states that all nozzle loads must be avoided in Z-direction (gravity).

Can anyone tell me if the vendor is right about this, I think that he should issue some max load values to us?

How can I make this clear, is there a code for economizers like there is for rotating equipment and pressure vessels?

Kind regards,

StressedPiper

 

RE: Nozzle loads Economizer

The manufacturer should be giving you hard limits for example Fx=600 lbs, Fy=1000 lbs, Fz=20 lbs. Mx=500 ft-lbs, ect. Any reputable vendor should be able to provide you with hard limits on maximum allowable nozzle loads for their equipment.

I would not deal with a vendor who could not do so. All the ASME B31 series codes state not to violate equipment nozzle load limits. Only the vendor knows what reactions their equipment is capable of safely handling without failure, therefore they must provide me with that information.

Often times I find vendors don't like to go to their engineers to get the numbers for me. Usually takes a week or two time wise and sometimes requires few threats regarding never specifying their equipment again to get the info I need to do my job.

Just my two cents worth.

 

Always remember, free advice is worth exactly what you pay for it!   

RE: Nozzle loads Economizer

Tell your Procurement and Q/A departments that the mfgr has sent an incomplete or erroneous data sheet.

In the meantime, locate a constant load spring can nearby and try to minimize the load there.

**********************
"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/

RE: Nozzle loads Economizer

If you are going to bolt up piping to that economizer, there are going to be imparted loads.  You can take steps to minimize them, but zero load is simply not possible.  The vendor needs to give you a real number to work with.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

RE: Nozzle loads Economizer

What is it about this particular economizer design that makes it not want loads in the Z (gravity) direction?  It may be that they don't want you hanging all the piping from the hotwell up to the economizer on their nozzles hence their use of the word "avoided".  Avoided to me doesn't say Zero load as much as it says 'don't count on hanging all your pipe on our economizer-use properly designed supports'.  Some people treat all pieces of equipment, pumps, vessels, exchangers, etc as pipe supports and anchors.  Support it as BigInch suggests.  Avoiding loads in the Z direction would also prohibit setting the spring cans so tight that you are trying to lift the economizer nozzle(s) as well.

rmw

RE: Nozzle loads Economizer

All...

Generally speaking, I agree will all of the comments above.

I would like to add that, for many equipment vendors, allowable nozzle loads are a "game" that may enable the vendors to bill "extra charges" at the end of the contract when he reviews and approves "excessive" piping loads from the AE firm.

All loads, of course, become "excessive" when the allowable is zero....

ColonelSanders: You have said:

"All the ASME B31 series codes state not to violate equipment nozzle load limits."

Really...???  Where..???

My opinion only

-MJC

   

RE: Nozzle loads Economizer

MJCronin: Yes really, here's where (although I do not have B31.4, B31.8 and B31.11 I suspect they will have similar verbage).

ASME B31.1 "119.10.2 Reaction Limits. The reactions computed shall not exceed limits which the attached equipment can sustain. Equipment allowable reaction limits forces and moments) on piping connections are normally established by the equipment manufacturer."

ASME B31.3 "319.1.1 Basic Requirements. Piping systems shall have sufficient flexibility to prevent thermal expansion or contraction or movements of piping supports and terminals from causing: (c) detrimental stresses or distortion in piping and valves or in connected equipment pumps and turbines, for example), resulting from excessive thrusts and moments in the piping"

ASME B31.5 "519.1.1 Objectives : Piping systems shall be designed to have sufficient flexibility to prevent thermal expansion from causing: (c) detrimental distortion of connected equipment (pumps, turbines, valves) resulting from excessive thrusts and moments"

ASME B31.9 "919.7 Reactions: Terminal reactions and resulting moments shall be taken into consideration where supporting structure or connected equipment is likely to be affected by such loadings.Determination of these loads may require analysis as specified in para. 919.4.1(b)."

These force an evaluation of the reaction at conected equipment, since the equipment is normally supplied by a vendor, the vendor must provide real limits to compare to. Otherwise there is no way to judge the acceptibilty of the reactions, and it becomes nigh on impossible to meet code.

Just my two cents worth, (except the code quotes, those are fact)

Always remember, free advice is worth exactly what you pay for it!   

RE: Nozzle loads Economizer

B31.4 "Introduction"

Quote:

The Code sets forth engineering requirements deemed necessary for safe design and construction of pressure piping. While safety is the basic consideration, this factor alone will not necessarily govern the final specifications for any piping system. The designer is cautioned that the Code is not a design handbook.

Codes only give the minimum requirements.
Just because something is not specifically stated in the code does not mean you don't have to do it.

**********************
"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/

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