Welded connection and flanged connection

[tranvietnga1905]

Hi guys,

I am coping with many connections that connect to wash column tower. But I don't definately clear when to use flanged connections and when to use welded connections. Is there anyone able to help me. would you please explain as well as point me to a document to study in details.

Thank you very much,

tranvietnga

 

[BigInch]

Welded connections should be used to help minimize the number of potential leak points, unless a break point at the location is or will be needed for reasons such as,

ease of transportation,
ease of assembly or installation,
entry point for cleaning pipe and internals,
entry point for inspection,
valve or equipment replacement,
access or equipment passage (to reach other side of line),
quicker reconfiguration for temporary piping (spec blinds),
to make reconfigurations not requiring hot work permits,
replacement or removal of internal items,
to attach devices or instrumentation needing frequent work,
upgrading or increasing capacity at a later date,
disassembly during maintenance, or
to make a convenient tie-in point for a future connection that would not require testing the existing piping.

Any others? Must be a few.

Flanged connections may not be absolutely necessary for some of the reasons given above, but all could possibly influence your decision.

http://virtualpipeline.spaces.msn.com

 

[JLSeagull]

Some limit normal connections to welded fittings due to the potential exposure to extremely toxic or otherwise really nasty fluids. For example, if a wash column tower is associated with the rich amine in a hydrogen sulfide sweetening unit with the potential for 50% H2S then consider all welded connections.

 

[rconner]

I agree with other comments that while some flanged joints are quite formidable connections, they in general may not be as structurally stiff nor as robust in other respects as good quality welded connections. For such reasons I believe the use of flanged joints is minimized in some applications, and particularly also for some buried services where there may be subsequent uncertain loading, settlements, or other movements etc.without any other specific provision for flexibility. However, along with the specific applications of flanged joints mentioned by others, it could also be mentioned that flanged joints unlike welded joints can also in some cases uniquely allow for electrical isolation with some degree of effectiveness with the use of special insulating flanged kits (where this is judged desirable). Of course also with the use shop-fabricated flanged piping that is subsequently specially coated and/or lined, it is of course also not generally necessary in the field assembly of shop fabricated flanged pipes to field-apply any extreme at least localized heat as is required to melt metals in weld/fusing (nor is there necessarily a subsequent need for field patching/repair of welded/heated areas on the inside or outside of the pipe).

 

[Adasi]

tranvietnga1905,

The first consideration is safety, then maintenance. If the fluid in the pipeline can cause instant health hazard when its exposed into the environment (i.e H2S or High pressure/temperature steam) go with welded connections.

The next step would be to contact maintenance group to discuss shut down requirements or frequencies for the unit so you can place flanges across items that are frequently replaced.

 

[tranvietnga1905]

Thank you very much for your prompt reply,
Kindest,
tranvietnga