Piping Hydrotest After Alignment with Rotating Equipment

[Tilas]

Hi,

I have an API 610 pump being installed at site. Before we could go with the final alignment, we would need to align the piping with the pump flange.

There is a chance that the piping might need heating or cut and weld to have the flange gap and angularity to within API 686 criteria (in case moving of the supports is not enough to have the pipe alignment within tolerance).

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API 686 4.6.3 : For piping flange outer diameters smaller than 25 cm (10 in.), the flanges shall be parallel to 250 micrometers (0.010 in.) or less. For raised face flanges, feeler gauge readings shall be taken at the raised face.
API 686 4.6.4: Flange face separation shall be within the gasket spacing ±1.5 mm (1/16 in.). Only one gasket per flanged connection shall be used.
========

My question would be (considering that all the pipe spools were hydro tested already prior to pipe alignment):

1. In case they heated the pipe flange or do some small cut and re-weld to the pipe flange to get the gap to within the API 686 tolerance , would they need to dismantle the last spool again for hydro testing (spool connected to be connected to the pump nozzles).

3. Can we just opt for a 100 RT in order not to remove the aligned pipe in its position instead of doing a hydrotest if we are to cut and re-weld or heat?

2. If they remove the last spool for hydro test I am afraid that they would have difficulty on getting the required flange gaps and angularity again.

Please let me know if how did you did it for your API 610 pumps during installation.

Thanks in advance.
Tilas

 

[LittleInch]

Well try and get it right first time.

I've seen fit up before where the piping fitter sets it out and gets either marks on the pipe or tack welds the whole thing then removes it for welding and testing then brings it back for repeat alignment checks before or after hydro.

sure getting alignment again can be difficult but that's in the art of pipe fitting

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Tilas]

Thanks LittleInch,

In this case , I would have them fit it up then remove the pipe for welding then let them hydro test first before installing again for parallelism/torqueing and let them figure out how to align it (I hope our fitters are good enough to have the pipe alignment within limits again after reinstallation).

Thanks again
Tilas

 

[Artisi]

What do you mean by hydrotest before reinstalling the pipe, surely hydro test should include the pump and pipework?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Tilas]

Hi Artisi,

I mean make the last spool connected to the pump nozzles parallelism and gap within tolerance by heating or cutting of the pipe flanges as well as adjusting the supports. Then when alignment, gap and parallelism is achieved , I would have to remove the last spool again then hydro test it before putting it back for final box up with the pump flanges(since they did cutting and rewilding in the pipe flanges to get the parallelism.

I cannot hydro test the pipes together with the pump as the design pressure of the pump seal might not be enough to handle the hydro test pressure of the line , so i would have to do it separately for that last spools connected to the suction and discharge of the pump alone (provided the rest of the suction and discharge piping are all hydro tested already).

Thanks,
Tilas

 

[Artisi]

OK, understand.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[DanTh3Man]

If this is an ASME B31.3 system the spool would need to be re-hydro'd unless:
[ul]
[li]You use a closure weld (and the jurisdiction allows it)[/li]
[li]It is new construction and you follow the requirements of B31.3 para 345.2.6 (i.e. owner waives the requirement and appropriate precautions are taken[/li]
[/ul]