Tie-in Spool Connection between Riser and Pipeline

[RAJATH]

Hi,

I am facing a problem in Tie-in spool design which connects Pre-installed Riser and Pipeline. The Expansion in the pipeline is 755mm and Virtual Anchor length is 1788m. The concerete thickness of pipeline is 50mm. the maximum displacement allowed near riser bend is 200mm, even after providing 2 90 degree bend(Expansion Spool) i am not able to limit the displacement to 200mm as the displacement is coming as 500mm. I am following the design of DNV 1981. Can anybody tell me how to minimize the displacement?

Regards,

Rajath

[rainie1284]

Whats your design temperature? Pipeline size? The simplest i can think of a quickie is to increase the CWC thickness

[RAJATH]

Thank you for the reply.

Temperature-91 Deg and size is 12". Whether I should increase the CWC in only spool or in the whole pipeline so that whole expansion and Vitrual Anchor Length is decreased?.

[tokiero]

Dear RAJATH
To better answer your question we need to know pipeline scheme. Could you provide us with it?
Is 755 mm too much? Maybe it is a mistake?

Considering your question about incresing thickness of concrete shell - I may assume that it could not give you expected result.

Regards,
J.V.