Modular Pipe Rack

Hi all Pipers
I am Designing a Modular Pipe Rack . The Pipe rack is around 54 meter in length and I am dividing it into 4 parts (i.e. sub modules).
The pipe rack has 2 tiers with around 15 lines having the high pressure high temperature steam in it with around 2 % slope.
My concern only is how the site people will do welding at interface points between the sub-modules .
If any body has experience on site that how we usually weld the pipes on rack . Please share.
Regards
SG

Are you trying to get these "modules" to butt up end to end? "IF" so I'd flange the ends so all the field people need do is bolt it up. Failing that I'd still flange the module ends and have the field just fab spool peices to link the units. Trying to butt up plain end pipe in a "bundle" and weld it would a MAJOR pain!

No physical site experience with this but most projects I have worked on with modular pipe racks were welded connections for metallic pipe. As far as I am aware the installations went well.

A field weld at module interfaces, in my opinion, is the most economical and reliable method. The cost of fittings/ materials, shop welds, field install (bolt torquing/ tensioning), and inspection for a flanged joint would far exceed a welded connection for high press./ temp piping. Also, you increase the number of potential leak points at each interface.

Just my $0.02.

@echo ...these are very high pressure and high temperature lines so no point even in thinking of flanges code doesn't allow it.
@willis ....my only concern is interface between two sub modules .n would it be possible to maintain slope in 4 parts
Regards
SG

SK,
I had not come across this concept before this post. So thanks for the information posted. I just checked for this particular tag and following information looks good. However, there is very little from piping design point of view. Since you are in a stage ahead than preliminary so it may not be that useful but I am just posting the links in case if you have not considered any of the points discussed:
civildesignhelp.info/pr3.html
www.modularaccess.com/Pipe-Rack.aspx

The only concern that comes to my mind is:
You will need to finalize all the Routings and Loadings on these racks in advance and revisions at later date may prove difficult as well as costly.
Rgds,

@willis ....my only concern is interface between two sub modules .n would it be possible to maintain slope in 4 parts
Regards
SG

I don't see how a sub-module interface would be different than a module to module interface. Please explain further.

To maintain the designed slope on the modules, you could provide TOS or shim heights at each support location to module steel fabricator to install prior to the piping spools. In my experience, this has been the most cost effective and easiest method of achieving this. Further shimming can be done if required in the field for final fit-up between modules and sub-modules.