Hopefully one of the Coker Licensors like Foster and /or EPC contractors like Fluor/ABB/Bechtel Wheeler/ConocoPhillips will jump in and give their view – but here is perspective of long time observer /sometime meddler of process:
When the project is in Planning stage & size addition or expansion is developed for the budgeted level of cost it moves into the FEED stage (Front End Engineering & Design) where throughputs are maximized for investment cost range while optimizing the production of higher end products and minimizing lower valued products & byproducts. The coker design is developed & as the project moves into the EPC (Engineering, Procurement & Construction) stage the coke licensor is selected (sometimes it is done in FEED stage).
The coke licensing often has great deal impact on the coker design & later fabrication since the guarantee’s are only good if the company insures they are followed in the engineering/design/fabrication stages as specified in the “technology offering”. Since the coker requires at least 2year lead time for construction stage – it is usually one of the first item que up on Procurement stage to get scheduled with fabricator & insure delivery time consistent with the completion goal in construction stage. So unless project revision midprocess = size coker changes or crude supply change impacts type coke formed ie shot vs sponge ; the parameters are well set before fabricator gets ahold procurement & design package.
Some impactors “in mine & others opinion” is that some of Coker Licensors who often also do EPC really “think” more like EPC companies and are willing to cut some corners / allow more flexibility to get the job and hence the licensed/design specifications are not followed as strictly and can result in “less than stellar” fabrication procedures that can lead to drum issues &/or thru-wall cracks and such. Most of strict licensors like COP and others have a list of “recommended / suggested” suppliers for critical equipment that can cause delays on timing or higher cost but seldom result in “less than stellar” fabrication procedures others run into.
Bottom line is that although the client / company may pay for a license or design service … it is often their choice whether or not to follow the advice of the experts (although majority of the time they do – expecially marjor/mutiple coking unit refiners).